WO2018061563A1 - Affine motion vector derivation device, prediction image generation device, moving image decoding device, and moving image coding device - Google Patents

Abstract

An affine motion vector derivation device that makes it possible to appropriately switch between applying 4-parameter affine processing and 6-parameter affine processing. According to the present invention, an AMVP prediction parameter derivation unit (3032) and an affine prediction unit (30372): calculate a movement vector for each of a plurality of sub-blocks that constitute a target block by referencing a movement vector at a control point that has been established in a reference block that shares a vertex with the target block; and, in accordance with the shape and/or size of the target block, switch between performing 4-parameter affine processing and 6-parameter affine processing.

Description

Affine motion vector deriving device, predicted image generating device, moving image decoding device, and moving image encoding device

Embodiments described herein relate generally to an affine motion vector deriving device, a predicted image generating device, a moving image decoding device, and a moving image encoding device.

In order to efficiently transmit or record a moving image, a moving image encoding device that generates encoded data by encoding the moving image, and a moving image that generates a decoded image by decoding the encoded data An image decoding device is used.

Specific examples of the moving image encoding method include a method proposed in H.264 / AVC and HEVC (High-Efficiency Video Coding).

In such a moving image coding system, an image (picture) constituting a moving image is a slice obtained by dividing the image, a coding unit obtained by dividing the slice (coding unit (Coding Unit : CU)), and a hierarchical structure consisting of a prediction unit (PU) and a transform unit (TU) that are obtained by dividing a coding unit. Decrypted.

In such a moving image coding method, a predicted image is usually generated based on a local decoded image obtained by encoding / decoding an input image, and the predicted image is generated from the input image (original image). A prediction residual obtained by subtraction (sometimes referred to as “difference image” or “residual image”) is encoded. Examples of the method for generating a predicted image include inter-screen prediction (inter prediction) and intra-screen prediction (intra prediction).

In addition, the affine prediction of Non-Patent Document 1 can be cited as a moving picture encoding and decoding technique in recent years.

"Algorithm" Description "of" Joint "Exploration" Test "Model" 3 "," JVET-C1002, "Joint" Video "Exploration" Team "(JVET)" of "ITU-T" SG "16" WP "3" and "ISO / IEC" JTC "1 / SC" 29 / WG "11," 2016-05-31 " Improved affine motion prediction, JVET-C0062, Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11, 2016-05-17

In the affine prediction of Non-Patent Document 1, based on affine prediction with four degrees of freedom (four parameter affine), each motion vector of a plurality of sub-blocks included in the target block is referred to the motion vector of two control points. To calculate. In the affine prediction of Non-Patent Document 2, based on affine prediction with 6 degrees of freedom (6-parameter affine), the motion vectors of the sub-blocks are calculated with reference to the motion vectors of the three control points.

The 6-parameter affine processing contributes to the improvement of the coding efficiency as a whole compared with the 4-parameter affine processing. However, when the individual blocks are viewed, the movement of the control points necessary for the affine processing is considered. There has been a problem that the amount of codes in vector encoding increases. In addition, since it is easily affected by the accuracy of the motion vector of the control point, when the accuracy of the motion vector of the control point is low and the deviation from the true motion vector is large, the motion vector calculated by applying the 6-parameter affine processing There was a first problem that the accuracy of the above would further decrease.

In the 4-parameter affine processing, two control points set in the reference block are used. When the appropriate two points are not used as control points, there is a second problem that the accuracy of the four-parameter affine processing is lowered.

In order to solve the first problem, in the affine motion vector deriving device for deriving the motion vector of each of the sub blocks constituting the target PU, the affine motion vector deriving device includes a plurality of sub blocks included in the target block. Each motion vector of a block is calculated with reference to a motion vector at a control point set in a reference block sharing a vertex with the target block, and at least one of the shape and size of the target block Accordingly, the motion vector of two control points is calculated to perform 4-parameter affine processing, or the motion vector of three control points is calculated to perform 6-parameter affine processing.

In order to solve the first problem described above, a predicted image generation apparatus according to an aspect of the present invention provides a predicted image generation apparatus for generating a predicted image used for encoding or decoding a moving image. A motion vector deriving unit and a predicted image generating unit, wherein the affine motion vector deriving unit stores each motion vector of a plurality of sub-blocks included in the target block in a reference block sharing a vertex with the target block. It is calculated with reference to the motion vector at the set control point, and the four-parameter affine processing is performed by calculating the motion vector of the two control points according to at least one of the shape and size of the target block. Or the motion vector of the three control points is calculated and the six parameter affine processing is switched. Generating a predicted image by referring to the motion vector of the control points.

In order to solve the first problem described above, a predicted image generation apparatus according to an aspect of the present invention provides a predicted image generation apparatus for generating a predicted image used for encoding or decoding a moving image. A motion vector deriving unit and a predicted image generating unit, wherein the affine motion vector deriving unit stores each motion vector of a plurality of sub-blocks included in the target block in a reference block sharing a vertex with the target block. This is calculated with reference to the motion vector at the set control point. According to at least one of the shape and size of the reference block, the motion vector of the two control points is calculated and the four-parameter affine processing is performed. Or the motion vector of the three control points is calculated and the six parameter affine processing is switched. Generating a predicted image by referring to the motion vector of the control points.

In order to solve the second problem described above, a predicted image generation device according to an aspect of the present invention provides a predicted image generation device for generating a predicted image used for encoding or decoding a moving image. A motion vector deriving unit and a predicted image generating unit, wherein the affine motion vector deriving unit stores each motion vector of a plurality of sub-blocks included in the target block in a reference block sharing a vertex with the target block. The motion vector is calculated by referring to a motion vector at a set control point, and the control point used for the 4-parameter affine process is changed according to the shape of the target block or the shape of the reference block, and the prediction The image generation unit generates a predicted image by referring to the motion vector of the control point.

According to the embodiment of the present invention, whether to apply 4-parameter affine processing or 6-parameter affine processing in order to calculate each motion vector of a plurality of sub-blocks included in the target block with high accuracy. Can be switched appropriately. Also, it is possible to reduce the amount of code required for encoding the motion vector of the control point, which is necessary when affine processing is performed.

Further, according to the embodiment of the present invention, an appropriate control point can be used in the processing of the four parameter affine.

It is a figure which shows the hierarchical structure of the data of the encoding stream which concerns on this embodiment. It is a figure which shows the pattern of PU division | segmentation mode. (A) to (h) respectively show the partition shapes when the PU partitioning modes are 2Nx2N, 2NxN, 2NxnU, 2NxnD, Nx2N, nLx2N, nRx2N, and NxN. It is a conceptual diagram which shows an example of a reference picture and a reference picture list. It is a block diagram which shows the structure of the image coding apparatus which concerns on this embodiment. It is the schematic which shows the structure of the image decoding apparatus which concerns on this embodiment. It is the schematic which shows the structure of the inter estimated image generation part of the image coding apparatus which concerns on this embodiment. It is the schematic which shows the structure of the merge prediction parameter derivation | leading-out part which concerns on this embodiment. It is the schematic which shows the structure of the AMVP prediction parameter derivation | leading-out part which concerns on this embodiment. It is a flowchart which shows the operation | movement of the motion vector decoding process of the image decoding apparatus which concerns on this embodiment. It is the schematic which shows the structure of the inter prediction parameter encoding part of the image coding apparatus which concerns on this embodiment. It is the schematic which shows the structure of the inter estimated image generation part which concerns on this embodiment. It is the schematic which shows the structure of the inter prediction parameter decoding part which concerns on this embodiment. It is a figure which shows the example which derives | leads-out the motion vector spMvLX [xi] [yj] of each subblock which comprises PU (horizontal width nPbW) which is the object which estimates a motion vector. (A) is a figure for demonstrating bilateral matching (Bilateral (matching) matching). (B) is a figure for demonstrating template matching (Template | matching). It is a figure which shows the example of the position of the prediction unit utilized for derivation | leading-out of the motion vector of the control point in AMVP mode and merge mode. It is a figure which shows the example of the subblock of a square with one side BW in which the control point V0 of the object block (horizontal width W, height H) which is an object which predicts a motion vector is located in an upper left vertex. It is a flowchart which shows an example of the process in which the inter prediction parameter decoding part determines the number of the control points which derive | lead-out a motion vector based on the shape of object PU. It is a flowchart which shows another example of the process in which the inter prediction parameter decoding part determines the number of the control points which derive a motion vector based on the shape of object PU. It is a flowchart which shows another example of the process in which the inter prediction parameter decoding part determines the number of the control points which derive | lead-out a motion vector based on the shape of object PU. It is a flowchart which shows an example of the process in which the inter prediction parameter decoding part determines the number of the control points which derive a motion vector based on the size of object PU. It is a flowchart which shows another example of the process in which the inter prediction parameter decoding part determines the number of the control points which derive a motion vector based on the size of object PU. 10 is a table showing processing for each size when log2 (puWidth) + log2 (puHeight) is used as a value indicating the size of the target PU. 10 is a table showing processing for each size when min (puWidth, puHeight) is used as a value indicating the size of the target PU. It is a flowchart which shows an example of the process in which the inter prediction parameter decoding part determines the number of the control points which derive | lead-out a motion vector based on both the shape and size of object PU. It is a flowchart which shows another example of the process in which the inter prediction parameter decoding part determines the number of the control points which derive | lead-out a motion vector based on both the shape and size of object PU. It is a table | surface which shows an example of a process of the affine estimation part for every size and shape of object PU. It is a table | surface which shows another example of the process of an affine prediction part for every size and shape of object PU. It is a flowchart which shows an example of the process in which an inter prediction parameter decoding part determines which process of 4 parameter affine and 6 parameter affine is performed based on the shape of an adjacent block. It is a figure for demonstrating the example of selection of the number of control points by the process shown in FIG. It is a flowchart which shows an example of the process in which an inter prediction parameter decoding part determines which process of 4 parameter affine and 6 parameter affine is performed based on the size of an adjacent block. It is a figure for demonstrating the example of selection of the number of control points by the process shown in FIG. It is a flowchart of the process which determines the position of the control point from which the inter prediction parameter decoding part derives a motion vector based on the shape of object PU. It is a figure which shows the example of the position of the control point which the inter prediction parameter decoding part of 3rd Embodiment determines. It is a flowchart of the process in which the inter prediction parameter decoding part determines the position of the point of the adjacent block used for derivation | leading-out of the motion vector of a control point based on the shape of an adjacent block. It is a figure which shows the example of the position of the control point which the inter prediction parameter decoding part of 4th Embodiment determines. It is a flowchart of the process which determines the position of the control point from which the inter prediction parameter decoding part derives a motion vector based on the shape of an adjacent block. It is a figure which shows the example of the position of the control point which the inter prediction parameter decoding part 303 of 5th Embodiment determines. It is the figure shown about the structure of the transmitter which mounts the image coding apparatus which concerns on this embodiment, and the receiver which mounts an image decoding apparatus. (A) shows a transmission device equipped with an image encoding device, and (b) shows a reception device equipped with an image decoding device. It is the figure shown about the structure of the recording device carrying the image coding apparatus which concerns on this embodiment, and the reproducing | regenerating apparatus carrying an image decoding apparatus. (A) shows a recording device equipped with an image encoding device, and (b) shows a playback device equipped with an image decoding device. It is the schematic which shows the structure of the image transmission system which concerns on this embodiment.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 40 is a schematic diagram illustrating a configuration of the image transmission system 1 according to the present embodiment.

The image transmission system 1 is a system that transmits a code obtained by encoding an encoding target image, decodes the transmitted code, and displays an image. The image transmission system 1 includes an image encoding device (moving image encoding device) 11, a network 21, an image decoding device (moving image decoding device) 31, and an image display device 41.

The image encoding device 11 receives an image T indicating a single layer image or a plurality of layers. A layer is a concept used to distinguish a plurality of pictures when there are one or more pictures constituting a certain time. For example, when the same picture is encoded with a plurality of layers having different image quality and resolution, scalable encoding is performed, and when a picture of a different viewpoint is encoded with a plurality of layers, view scalable encoding is performed. When prediction is performed between pictures of a plurality of layers (inter-layer prediction, inter-view prediction), encoding efficiency is greatly improved. Further, even when prediction is not performed (simultaneous casting), encoded data can be collected.

The network 21 transmits the encoded stream Te generated by the image encoding device 11 to the image decoding device 31. The network 21 is the Internet, a wide area network (WAN: Wide Area Network), a small network (LAN: Local Area Network), or a combination thereof. The network 21 is not necessarily limited to a bidirectional communication network, and may be a unidirectional communication network that transmits broadcast waves such as terrestrial digital broadcasting and satellite broadcasting. The network 21 may be replaced with a storage medium that records an encoded stream Te such as a DVD (Digital Versatile Disc) or a BD (Blue-ray Disc).

The image decoding device 31 decodes each of the encoded streams Te transmitted by the network 21, and generates one or a plurality of decoded images Td decoded.

The image display device 41 displays all or part of one or more decoded images Td generated by the image decoding device 31. The image display device 41 includes, for example, a display device such as a liquid crystal display or an organic EL (Electro-luminescence) display. In addition, in the spatial scalable coding and SNR scalable coding, when the image decoding device 31 and the image display device 41 have a high processing capability, a high-quality enhancement layer image is displayed and only a lower processing capability is provided. Displays a base layer image that does not require higher processing capability and display capability as an extension layer.

<Operator>
The operators used in this specification are described below.

>> is right bit shift, << is left bit shift, & is bitwise AND, | is bitwise OR, | = is sum operation (OR) with another condition.

X? Y: z is a ternary operator that takes y when x is true (non-zero) and takes z when x is false (0).

Clip3 (a, b, c) is a function that clips c to a value between a and b, but returns a if c <a, returns b if c> b, otherwise Is a function that returns c (where a <= b).

<Structure of encoded stream Te>
Prior to detailed description of the image encoding device 11 and the image decoding device 31 according to the present embodiment, a data structure of an encoded stream Te generated by the image encoding device 11 and decoded by the image decoding device 31 will be described. .

FIG. 1 is a diagram showing a hierarchical structure of data in the encoded stream Te. The encoded stream Te illustratively includes a sequence and a plurality of pictures constituting the sequence. (A) to (f) of FIG. 1 respectively show an encoded video sequence defining a sequence SEQ, an encoded picture defining a picture PICT, an encoded slice defining a slice S, and an encoded slice defining a slice data It is a figure which shows the coding unit (Coding | unit: CU) contained in the coding tree unit contained in data and coding slice data, and a coding tree unit.

(Encoded video sequence)
In the encoded video sequence, a set of data referred to by the image decoding device 31 for decoding the sequence SEQ to be processed is defined. As shown in FIG. 1A, the sequence SEQ includes a video parameter set (Video Parameter Set), a sequence parameter set SPS (Sequence Parameter Set), a picture parameter set PPS (Picture Parameter Set), a picture PICT, and an addition. Includes SEI (Supplemental Enhancement Information). Here, the value indicated after # indicates the layer ID. Although FIG. 1 shows an example in which encoded data of # 0 and # 1, that is, layer 0 and layer 1, exists, the type of layer and the number of layers are not dependent on this.

The video parameter set VPS is a set of encoding parameters common to a plurality of moving images, a plurality of layers included in the moving image, and encoding parameters related to individual layers in a moving image composed of a plurality of layers. A set is defined.

The sequence parameter set SPS defines a set of encoding parameters that the image decoding device 31 refers to in order to decode the target sequence. For example, the width and height of the picture are defined. A plurality of SPSs may exist. In that case, one of a plurality of SPSs is selected from the PPS.

In the picture parameter set PPS, a set of encoding parameters referred to by the image decoding device 31 in order to decode each picture in the target sequence is defined. For example, a quantization width reference value (pic_init_qp_minus26) used for picture decoding and a flag (weighted_pred_flag) indicating application of weighted prediction are included. There may be a plurality of PPSs. In that case, one of a plurality of PPSs is selected from each picture in the target sequence.

(Encoded picture)
In the coded picture, a set of data referred to by the image decoding device 31 in order to decode the picture PICT to be processed is defined. As shown in FIG. 1B, the picture PICT includes slices S0 to S _NS-1 (NS is the total number of slices included in the picture PICT).

In the following description, if it is not necessary to distinguish each of the slices S0 to _SNS-1 , the subscripts may be omitted. The same applies to data included in an encoded stream Te described below and to which other subscripts are attached.

(Encoded slice)
In the coded slice, a set of data referred to by the image decoding device 31 for decoding the slice S to be processed is defined. As shown in FIG. 1C, the slice S includes a slice header SH and slice data SDATA.

The slice header SH includes an encoding parameter group that is referred to by the image decoding device 31 in order to determine a decoding method of the target slice. Slice type designation information (slice_type) for designating a slice type is an example of an encoding parameter included in the slice header SH.

As slice types that can be specified by the slice type specification information, (1) I slice using only intra prediction at the time of encoding, (2) P slice using unidirectional prediction or intra prediction at the time of encoding, (3) B-slice using unidirectional prediction, bidirectional prediction, or intra prediction at the time of encoding may be used.

Note that the slice header SH may include a reference (pic_parameter_set_id) to the picture parameter set PPS included in the encoded video sequence.

(Encoded slice data)
In the encoded slice data, a set of data referred to by the image decoding device 31 for decoding the slice data SDATA to be processed is defined. The slice data SDATA includes a coding tree unit (CTU) as shown in FIG. A CTU is a block of a fixed size (for example, 64x64) that constitutes a slice, and is sometimes called a maximum coding unit (LCU: Large Coding Unit).

(Encoding tree unit)
As shown in (e) of FIG. 1, a set of data referred to by the image decoding device 31 in order to decode the encoding tree unit to be processed is defined. The coding tree unit is divided by recursive quadtree division. A tree-structured node obtained by recursive quadtree partitioning is referred to as a coding node (CN). An intermediate node of the quadtree is an encoding node, and the encoding tree unit itself is defined as the highest encoding node. The CTU includes a split flag (cu_split_flag), and when cu_split_flag is 1, it is split into four coding nodes CN. When cu_split_flag is 0, the coding node CN is not divided and has one coding unit (CU: Coding Unit) as a node. The encoding unit CU is a terminal node of the encoding node and is not further divided. The encoding unit CU is a basic unit of the encoding process.

In addition, when the size of the coding tree unit CTU is 64 × 64 pixels, the size of the coding unit can be any of 64 × 64 pixels, 32 × 32 pixels, 16 × 16 pixels, and 8 × 8 pixels.

(Encoding unit)
As shown in (f) of FIG. 1, a set of data referred to by the image decoding device 31 in order to decode an encoding unit to be processed is defined. Specifically, the encoding unit includes a prediction tree, a conversion tree, and a CU header CUH. The CU header defines a prediction mode, a division method (PU division mode), and the like.

In the prediction tree, prediction information (a reference picture index, a motion vector, etc.) of each prediction unit (PU) obtained by dividing the coding unit into one or a plurality is defined. In other words, the prediction unit is one or a plurality of non-overlapping areas constituting the encoding unit. The prediction tree includes one or a plurality of prediction units obtained by the above-described division. Hereinafter, a prediction unit obtained by further dividing the prediction unit is referred to as a “sub-block”. The sub block is composed of a plurality of pixels. When the sizes of the prediction unit and the sub-block are equal, the number of sub-blocks in the prediction unit is one. If the prediction unit is larger than the size of the sub-block, the prediction unit is divided into sub-blocks. For example, when the prediction unit is 8 × 8 and the sub-block is 4 × 4, the prediction unit is divided into four sub-blocks that are divided into two horizontally and two vertically.

The prediction process may be performed for each prediction unit (sub block).

There are roughly two types of division in the prediction tree: intra prediction and inter prediction. Intra prediction is prediction within the same picture, and inter prediction refers to prediction processing performed between different pictures (for example, between display times and between layer images).

In the case of intra prediction, there are 2Nx2N (the same size as the encoding unit) and NxN division methods.

Also, in the case of inter prediction, the division method is encoded by the PU division mode (part_mode) of encoded data, 2Nx2N (same size as the encoding unit), 2NxN, 2NxnU, 2NxnD, Nx2N, nLx2N, nRx2N, and NxN etc. 2NxN and Nx2N indicate 1: 1 symmetrical division, and 2NxnU, 2NxnD and nLx2N and nRx2N indicate 1: 3 and 3: 1 asymmetric division. The PUs included in the CU are expressed as PU0, PU1, PU2, and PU3 in this order.

(A) to (h) of FIG. 2 specifically illustrate the shape of the partition (the position of the boundary of the PU partition) in each PU partition mode. 2A shows a 2Nx2N partition, and FIGS. 2B, 2C, and 2D show 2NxN, 2NxnU, and 2NxnD partitions (horizontal partitions), respectively. (E), (f), and (g) show partitions (vertical partitions) in the case of Nx2N, nLx2N, and nRx2N, respectively, and (h) shows an NxN partition. The horizontal partition and the vertical partition are collectively referred to as a rectangular partition, and 2Nx2N and NxN are collectively referred to as a square partition.

Also, in the conversion tree, the encoding unit is divided into one or a plurality of conversion units, and the position and size of each conversion unit are defined. In other words, a transform unit is one or more non-overlapping areas that make up a coding unit. The conversion tree includes one or a plurality of conversion units obtained by the above division.

The division in the conversion tree includes a case where an area having the same size as that of the encoding unit is assigned as a conversion unit, and a case where recursive quadtree division is used, as in the case of the CU division described above.

Conversion processing is performed for each conversion unit.

(Prediction parameter)
A prediction image of a prediction unit (PU: Prediction Unit) is derived from a prediction parameter associated with the PU. The prediction parameters include a prediction parameter for intra prediction or a prediction parameter for inter prediction. Hereinafter, prediction parameters for inter prediction (inter prediction parameters) will be described. The inter prediction parameter includes prediction list use flags predFlagL0 and predFlagL1, reference picture indexes refIdxL0 and refIdxL1, and motion vectors mvL0 and mvL1. The prediction list use flags predFlagL0 and predFlagL1 are flags indicating whether or not reference picture lists called L0 list and L1 list are used, respectively, and a reference picture list corresponding to a value of 1 is used. In this specification, when “flag indicating whether or not it is XX” is described, when the flag is not 0 (for example, 1) is XX, 0 is not XX, and logical negation, logical product, etc. 1 is treated as true and 0 is treated as false (the same applies hereinafter). However, other values can be used as true values and false values in an actual apparatus or method.

Syntax elements for deriving inter prediction parameters included in the encoded data include, for example, PU partition mode part_mode, merge flag merge_flag, merge index merge_idx, inter prediction identifier inter_pred_idc, reference picture index refIdxLX, prediction vector index mvp_LX_idx, There are a difference vector mvdLX, a PU affine application flag pu_affine_enable_flag, and a PU affine mode flag pu_affine_mode_flag.

(Reference picture list)
The reference picture list is a list including reference pictures stored in the reference picture memory 306. FIG. 3 is a conceptual diagram illustrating an example of a reference picture and a reference picture list. In FIG. 3A, a rectangle is a picture, an arrow is a picture reference relationship, a horizontal axis is time, I, P, and B in the rectangle are intra pictures, uni-predictive pictures, bi-predictive pictures, and numbers in the rectangles are decoded. Indicates the order. As shown in the figure, the decoding order of pictures is I0, P1, B2, B3, and B4, and the display order is I0, B3, B2, B4, and P1. FIG. 3B shows an example of the reference picture list. The reference picture list is a list representing candidate reference pictures, and one picture (slice) may have one or more reference picture lists. In the illustrated example, the target picture B3 has two reference picture lists, an L0 list RefPicList0 and an L1 list RefPicList1. When the target picture is B3, the reference pictures are I0, P1, and B2, and the reference picture has these pictures as elements. In each prediction unit, which picture in the reference picture list RefPicListX is actually referred to is specified by the reference picture index refIdxLX. The figure shows an example in which reference pictures P1 and B2 are referenced by refIdxL0 and refIdxL1.

(Merge prediction and AMVP prediction)
The prediction parameter decoding (encoding) method includes a merge prediction (merge) mode and an AMVP (Adaptive Motion Vector Prediction) mode. The merge flag merge_flag is a flag for identifying these. The merge prediction mode is a mode in which the prediction list use flag predFlagLX (or inter prediction identifier inter_pred_idc), the reference picture index refIdxLX, and the motion vector mvLX are not included in the encoded data and are derived from the prediction parameters of already processed neighboring PUs. The AMVP mode is a mode in which the inter prediction identifier inter_pred_idc, the reference picture index refIdxLX, and the motion vector mvLX are included in the encoded data. The motion vector mvLX is encoded as a prediction vector index mvp_LX_idx for identifying the prediction vector mvpLX and a difference vector mvdLX.

The inter prediction identifier inter_pred_idc is a value indicating the type and number of reference pictures, and takes one of PRED_L0, PRED_L1, and PRED_BI. PRED_L0 and PRED_L1 indicate that reference pictures managed by the reference picture lists of the L0 list and the L1 list are used, respectively, and that one reference picture is used (single prediction). PRED_BI indicates that two reference pictures are used (bi-prediction BiPred), and reference pictures managed by the L0 list and the L1 list are used. The prediction vector index mvp_LX_idx is an index indicating a prediction vector, and the reference picture index refIdxLX is an index indicating a reference picture managed in the reference picture list. Note that LX is a description method used when L0 prediction and L1 prediction are not distinguished from each other. By replacing LX with L0 and L1, parameters for the L0 list and parameters for the L1 list are distinguished.

The merge index merge_idx is an index indicating whether any prediction parameter is used as a prediction parameter of a target PU (target block) to be decoded from prediction parameter candidates (merge candidates) derived from a PU for which processing has been completed.

(Motion vector)
The motion vector mvLX indicates a shift amount between blocks on two different pictures. A prediction vector and a difference vector related to the motion vector mvLX are referred to as a prediction vector mvpLX and a difference vector mvdLX, respectively.

(Inter prediction identifier inter_pred_idc and prediction list use flag predFlagLX)
The relationship between the inter prediction identifier inter_pred_idc and the prediction list use flags predFlagL0 and predFlagL1 is as follows and can be converted into each other.

inter_pred_idc = (predFlagL1 << 1) + predFlagL0
predFlagL0 = inter_pred_idc & 1
predFlagL1 = inter_pred_idc >> 1
Note that a prediction list use flag or an inter prediction identifier may be used as the inter prediction parameter. Further, the determination using the prediction list use flag may be replaced with the determination using the inter prediction identifier. Conversely, the determination using the inter prediction identifier may be replaced with the determination using the prediction list use flag.

(Determination of bi-prediction biPred)
The flag biPred as to whether it is a bi-prediction BiPred can be derived depending on whether the two prediction list use flags are both 1. For example, it can be derived by the following formula.

biPred = (predFlagL0 == 1 && predFlagL1 == 1)
The flag biPred can also be derived depending on whether or not the inter prediction identifier is a value indicating that two prediction lists (reference pictures) are used. For example, it can be derived by the following formula.

biPred = (inter_pred_idc == PRED_BI)? 1: 0
The above formula can also be expressed by the following formula.

biPred = (inter_pred_idc == PRED_BI)
For example, a value of 3 can be used for PRED_BI.

(PU affine application flag, PU affine mode flag)
The PU affine application flag pu_affine_enable_flag is a flag indicating whether to apply affine prediction. The PU affine mode flag pu_affine_mode_flag (also simply referred to as affine mode) is a flag indicating whether to apply 4-parameter affine or 6-parameter affine.

(Configuration of image decoding device)
Next, the configuration of the image decoding device 31 (moving image decoding device) according to the present embodiment will be described. FIG. 5 is a schematic diagram illustrating a configuration of the image decoding device 31 according to the present embodiment. The image decoding device 31 includes an entropy decoding unit 301, a prediction parameter decoding unit (prediction image decoding device) 302, a loop filter 305, a reference picture memory 306, a prediction parameter memory 307, a prediction image generation unit (prediction image generation device) 308, and inversely. A quantization / inverse DCT unit 311 and an addition unit 312 are included.

The prediction parameter decoding unit 302 includes an inter prediction parameter decoding unit 303 and an intra prediction parameter decoding unit 304. The predicted image generation unit 308 includes an inter predicted image generation unit 309 (predicted image generation unit) and an intra predicted image generation unit 310.

The entropy decoding unit 301 performs entropy decoding on the coded stream Te input from the outside, and separates and decodes individual codes (syntax elements). The separated codes include prediction information for generating a prediction image and residual information for generating a difference image.

The entropy decoding unit 301 outputs a part of the separated code to the prediction parameter decoding unit 302. Some of the separated codes are, for example, a prediction mode predMode, a PU partition mode part_mode, a merge flag merge_flag, a merge index merge_idx, an inter prediction identifier inter_pred_idc, a reference picture index refIdxLX, a prediction vector index mvp_LX_idx, and a difference vector mvdLX. Control of which code is decoded is performed based on an instruction from the prediction parameter decoding unit 302. The entropy decoding unit 301 outputs the quantization coefficient to the inverse quantization / inverse DCT unit 311. The quantization coefficient is a coefficient obtained by performing quantization by performing DCT (Discrete Cosine Transform) on the residual signal in the encoding process.

The inter prediction parameter decoding unit 303 decodes the inter prediction parameter with reference to the prediction parameter stored in the prediction parameter memory 307 based on the code input from the entropy decoding unit 301.

The inter prediction parameter decoding unit 303 outputs the decoded inter prediction parameter to the prediction image generation unit 308 and stores it in the prediction parameter memory 307. Details of the inter prediction parameter decoding unit 303 will be described later.

The intra prediction parameter decoding unit 304 refers to the prediction parameter stored in the prediction parameter memory 307 on the basis of the code input from the entropy decoding unit 301 and decodes the intra prediction parameter. The intra prediction parameter is a parameter used in a process of predicting a CU within one picture, for example, an intra prediction mode IntraPredMode. The intra prediction parameter decoding unit 304 outputs the decoded intra prediction parameter to the prediction image generation unit 308 and stores it in the prediction parameter memory 307.

The intra prediction parameter decoding unit 304 may derive different intra prediction modes depending on luminance and color difference. In this case, the intra prediction parameter decoding unit 304 decodes the luminance prediction mode IntraPredModeY as the luminance prediction parameter and the color difference prediction mode IntraPredModeC as the color difference prediction parameter. The luminance prediction mode IntraPredModeY is a 35 mode, and corresponds to planar prediction (0), DC prediction (1), and direction prediction (2 to 34). The color difference prediction mode IntraPredModeC uses one of the planar prediction (0), the DC prediction (1), the direction prediction (2 to 34), and the LM mode (35). The intra prediction parameter decoding unit 304 decodes a flag indicating whether IntraPredModeC is the same mode as the luminance mode. If the flag indicates that the mode is the same as the luminance mode, IntraPredModeC is assigned to IntraPredModeC, and the flag is luminance. If the mode is different from the mode, planar prediction (0), DC prediction (1), direction prediction (2 to 34), and LM mode (35) may be decoded as IntraPredModeC.

The loop filter 305 applies filters such as a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) to the decoded image of the CU generated by the adding unit 312.

The reference picture memory 306 stores the decoded image of the CU generated by the adding unit 312 at a predetermined position for each decoding target picture and CU.

The prediction parameter memory 307 stores the prediction parameter in a predetermined position for each decoding target picture and prediction unit (or sub-block, fixed-size block, pixel). Specifically, the prediction parameter memory 307 stores the inter prediction parameter decoded by the inter prediction parameter decoding unit 303, the intra prediction parameter decoded by the intra prediction parameter decoding unit 304, and the prediction mode predMode separated by the entropy decoding unit 301. . The stored inter prediction parameters include, for example, a prediction list utilization flag predFlagLX (inter prediction identifier inter_pred_idc), a reference picture index refIdxLX, and a motion vector mvLX.

The prediction image generation unit 308 receives the prediction mode predMode input from the entropy decoding unit 301 and the prediction parameter from the prediction parameter decoding unit 302. Further, the predicted image generation unit 308 reads a reference picture from the reference picture memory 306. The prediction image generation unit 308 generates a prediction image of the PU using the input prediction parameter and the read reference picture in the prediction mode indicated by the prediction mode predMode.

Here, when the prediction mode predMode indicates the inter prediction mode, the inter prediction image generation unit 309 uses the inter prediction parameter input from the inter prediction parameter decoding unit 303 and the read reference picture to perform prediction of the PU by inter prediction. Is generated.

For the reference picture list (L0 list or L1 list) for which the prediction list use flag predFlagLX is 1, the inter predicted image generation unit 309 performs a motion vector mvLX with reference to the target PU from the reference picture indicated by the reference picture index refIdxLX. The reference picture block at the position indicated by is read from the reference picture memory 306. The inter prediction image generation unit 309 performs prediction based on the read reference picture block to generate a prediction image of the PU. The inter prediction image generation unit 309 outputs the generated prediction image of the PU to the addition unit 312.

When the prediction mode predMode indicates the intra prediction mode, the intra predicted image generation unit 310 performs intra prediction using the intra prediction parameter input from the intra prediction parameter decoding unit 304 and the read reference picture. Specifically, the intra predicted image generation unit 310 reads, from the reference picture memory 306, neighboring PUs that are pictures to be decoded and are in a predetermined range from the target PU among the PUs that have already been decoded. The predetermined range is, for example, one of the left, upper left, upper, and upper right adjacent PUs when the target PU sequentially moves in the so-called raster scan order, and varies depending on the intra prediction mode. The raster scan order is an order in which each row is sequentially moved from the left end to the right end in each picture from the upper end to the lower end.

The intra predicted image generation unit 310 performs prediction in the prediction mode indicated by the intra prediction mode IntraPredMode for the read adjacent PU, and generates a predicted image of the PU. The intra predicted image generation unit 310 outputs the generated predicted image of the PU to the adding unit 312.

When the intra prediction parameter decoding unit 304 derives an intra prediction mode different in luminance and color difference, the intra prediction image generation unit 310 performs planar prediction (0), DC prediction (1), direction according to the luminance prediction mode IntraPredModeY. Prediction image of luminance PU is generated by any of prediction (2 to 34), and planar prediction (0), DC prediction (1), direction prediction (2 to 34), LM mode according to color difference prediction mode IntraPredModeC A predicted image of the color difference PU is generated by any of (35).

The inverse quantization / inverse DCT unit 311 inversely quantizes the quantization coefficient input from the entropy decoding unit 301 to obtain a DCT coefficient. The inverse quantization / inverse DCT unit 311 performs inverse DCT (Inverse Discrete Cosine Transform) on the obtained DCT coefficient to calculate a residual signal. The inverse quantization / inverse DCT unit 311 outputs the calculated residual signal to the addition unit 312.

The addition unit 312 adds the prediction image of the PU input from the inter prediction image generation unit 309 or the intra prediction image generation unit 310 and the residual signal input from the inverse quantization / inverse DCT unit 311 for each pixel, Generate a decoded PU image. The adding unit 312 stores the generated decoded image of the PU in the reference picture memory 306, and outputs a decoded image Td in which the generated decoded image of the PU is integrated for each picture to the outside.

(Configuration of inter prediction parameter decoding unit)
Next, the configuration of the inter prediction parameter decoding unit 303 will be described.

FIG. 12 is a schematic diagram illustrating a configuration of the inter prediction parameter decoding unit 303 according to the present embodiment. The inter prediction parameter decoding unit 303 includes an inter prediction parameter decoding control unit 3031, an AMVP prediction parameter deriving unit 3032 (affine motion vector deriving unit, affine motion vector deriving device), an adding unit 3035, a merge prediction parameter deriving unit 3036, and sub-block prediction. A parameter deriving unit 3037 is included.

The inter prediction parameter decoding control unit 3031 instructs the entropy decoding unit 301 to decode a code (syntax element) related to inter prediction, and a code (syntax element) included in the encoded data, for example, PU partition mode part_mode , Merge flag merge_flag, merge index merge_idx, inter prediction identifier inter_pred_idc, reference picture index refIdxLX, prediction vector index mvp_LX_idx, and difference vector mvdLX are extracted.

The inter prediction parameter decoding control unit 3031 first extracts a merge flag merge_flag. When the inter prediction parameter decoding control unit 3031 expresses that a certain syntax element is to be extracted, it means that the entropy decoding unit 301 is instructed to decode a certain syntax element, and the corresponding syntax element is read from the encoded data. To do.

When the merge flag merge_flag is 0, that is, indicates the AMVP prediction mode, the inter prediction parameter decoding control unit 3031 uses the entropy decoding unit 301 to extract the AMVP prediction parameter from the encoded data. Examples of AMVP prediction parameters include an inter prediction identifier inter_pred_idc, a reference picture index refIdxLX, a prediction vector index mvp_LX_idx, and a difference vector mvdLX. The AMVP prediction parameter derivation unit 3032 derives a prediction vector mvpLX from the prediction vector index mvp_LX_idx. Details will be described later. The inter prediction parameter decoding control unit 3031 outputs the difference vector mvdLX to the addition unit 3035. The adding unit 3035 adds the prediction vector mvpLX and the difference vector mvdLX to derive a motion vector.

When the merge flag merge_flag is 1, that is, indicates the merge prediction mode, the inter prediction parameter decoding control unit 3031 extracts the merge index merge_idx as a prediction parameter related to merge prediction. The inter prediction parameter decoding control unit 3031 outputs the extracted merge index merge_idx to the merge prediction parameter derivation unit 3036 (details will be described later), and outputs the sub-block prediction mode flag subPbMotionFlag to the sub-block prediction parameter derivation unit 3037. The subblock prediction parameter deriving unit 3037 divides the PU into a plurality of subblocks according to the value of the subblock prediction mode flag subPbMotionFlag, and derives a motion vector in units of subblocks. That is, in the sub-block prediction mode, the prediction block is predicted in units of blocks as small as 4x4 or 8x8. In the image encoding device 11 to be described later, a sub-block prediction mode is used for a method in which a CU is divided into a plurality of partitions (PUs such as 2NxN, Nx2N, and NxN) and the syntax of prediction parameters is encoded in units of partitions. Since a plurality of sub-blocks are grouped into a set and the syntax of the prediction parameter is encoded for each set, motion information of a large number of sub-blocks can be encoded with a small amount of code.

More specifically, the sub-block prediction parameter derivation unit 3037 performs sub-block prediction in the sub-block prediction mode, and a spatio-temporal sub-block prediction unit 30371, an affine prediction unit 30372 (affine motion vector derivation unit, affine motion vector derivation device) ), And at least one of the matching prediction units 30373.

(Subblock prediction mode flag)
Here, a method for deriving a sub-block prediction mode flag subPbMotionFlag indicating whether a prediction mode of a certain PU is a sub-block prediction mode in the image decoding device 31 and the image encoding device 11 (details will be described later) will be described. . The image decoding device 31 and the image encoding device 11 derive a sub-block prediction mode flag subPbMotionFlag based on which of spatial sub-block prediction SSUB, temporal sub-block prediction TSUB, affine prediction AFFINE, and matching prediction MAT described later is used. To do. For example, when the prediction mode selected by a certain PU is N (for example, N is a label indicating the selected merge candidate), the sub-block prediction mode flag subPbMotionFlag may be derived by the following equation.

subPbMotionFlag = (N == TSUB) || (N == SSUB) || (N == AFFINE) || (N == MAT)
Here, || represents a logical sum (the same applies hereinafter).

Also, the image decoding device 31 and the image encoding device 11 may be configured to perform some predictions among the spatial sub-block prediction SSUB, temporal sub-block prediction TSUB, affine prediction AFFINE, and matching prediction MAT. That is, when the image encoding device 11 is configured to perform spatial subblock prediction SSUB and affine prediction AFFINE, the subblock prediction mode flag subPbMotionFlag may be derived as follows.

subPbMotionFlag = (N == SSUB) || (N == AFFINE)
Note that the image decoding device 31 and the image encoding device 11 may decode the affine application flag pu_affine_enable_flag from the encoded data and derive subPbMotionFlag as 1 when the affine application flag pu_affine_enable_flag is 1. In this case, when the affine application flag pu_affine_enable_flag is 1, the affine prediction unit 30372 may be applied.

(Sub-block prediction unit)
Next, the sub-block prediction unit will be described.

(Spatio-temporal sub-block prediction unit 30371)
The spatio-temporal sub-block prediction unit 30371 calculates the target PU from the motion vector of the PU on the reference image temporally adjacent to the target PU (for example, the immediately preceding picture) or the motion vector of the PU spatially adjacent to the target PU. The motion vector of the sub-block obtained by dividing is derived. Specifically, the motion vector spMvLX [xi] [yj] (xi = xPb) of each sub-block in the target PU is obtained by scaling the motion vector of the PU on the reference image according to the reference picture referenced by the target PU. + nSbW * i, yj = yPb + nSbH * j, i = 0, 1, 2, ..., nPbW / nSbW-1, j = 0, 1, 2, ..., nPbH / nSbH-1) Derived (temporal sub-block prediction). Here, (xPb, yPb) is the upper left coordinate of the target PU, nPbW, nPbH are the size of the target PU, and nSbW, nSbH are the sizes of the sub-blocks.

Also, by calculating a weighted average according to the distance between the motion vector of the PU adjacent to the target PU and the sub-block obtained by dividing the target PU, the motion vector spMvLX [ xi] [yj] (xi = xPb + nSbW * i, yj = yPb + nSbH * j, i = 0, 1, 2, ..., nPbW / nSbW-1, j = 0, 1, 2, ...・, NPbH / nSbH-1) may be derived (spatial sub-block prediction).

The above-described temporal sub-block prediction candidate TSUB and spatial sub-block prediction candidate SSUB are selected as one mode (merge candidate) of the merge mode.

(Affine prediction unit)
The affine prediction unit 30372 derives the affine prediction parameters of the target PU. In this embodiment, motion vectors of two or three control points of the target PU are derived as affine prediction parameters. For example, in the case of three control points (V0, V1, V2), motion vectors (MV0_x, MV0_y) (MV1_x, MV1_y) (MV2_x, MV2_y) are derived.

Specifically, the motion vector of each control point may be derived by prediction from the motion vector of the adjacent PU of the target PU, or the difference vector mvdLX derived from the control point prediction vector mvpLX and the encoded data The motion vector of each control point may be derived by the sum of.

FIG. 13 shows the motion vector spMvLX of each sub-block (xi, yj) constituting the target PU (nPbW × nPbH) from the motion vector (MV0_x, MV0_y) of the control point V0 and the motion vector (MV1_x, MV1_y) of V1. It is a figure which shows the example derived | led-out. The motion vector spMvLX of each subblock is derived as a motion vector for each point located at the center of each subblock, as shown in FIG.

The affine prediction unit 30372, based on the affine prediction parameters of the target PU, the motion vector spMvLX [xi] [yj] (xi = xPb + nSbW * i, yj = yPb + nSbH * j, i of the target PU = 0, 1, 2, ..., nPbW / nSbW-1, j = 0, 1, 2, ..., nPbH / nSbH-1) are derived using the following equations.

spMvLX [xi] [yj] [0] = MV0_x + (MV1_x-MV0_x) / nPbW * (xi + nSbW / 2)-(MV1_y-MV0_y) / nPbH * (yj + nSbH / 2)
spMvLX [xi] [yj] [1] = MV0_y + (MV1_y-MV0_y) / nPbW * (xi + nSbW / 2) + (MV1_x-MV0_x) / nPbH * (yj + nSbH / 2)
Here, xPb and yPb are the upper left coordinates of the target PU, nPbW and nPbH are the width and height of the target PU, and nSbW and nSbH are the width and height of the sub-block.

(Process flow)
Hereinafter, as an example of a more specific implementation configuration, the process flow in which the affine prediction unit 30372 or the AMVP prediction parameter derivation unit 3032 derives the motion vector mvLX of each sub-block using affine prediction will be described in steps. To do. The process in which the affine prediction unit 30372 or the AMVP prediction parameter derivation unit 3032 derives the motion vector mvLX of the subblock using the affine prediction includes the following four steps (STEP 1) to (STEP 4).

(STEP 1) Derivation of control point vector The affine prediction unit 30372 or the AMVP prediction parameter derivation unit 3032 uses representative points (in this case, V0 and V1) as two or more control points used for affine prediction for deriving candidates. ) To derive the respective motion vectors. Note that a point on the target block or a point near the target block is used as the representative point of the block. In this specification, a block representative point used as a control point for affine prediction is referred to as a “block control point”. Control points for affine prediction that are not representative points of blocks are expressed as “reference control points” and may be distinguished.

(STEP 2) Derivation of sub-block vector The affine prediction unit 30372 or the AMVP prediction parameter derivation unit 3032 converts the motion vector of the block control points (control points V0 and V1) that are representative points of the target block derived in STEP 1 to the target block. This is a step of deriving a motion vector of each included sub-block. From (STEP 1) and (STEP 2), the motion vector mvLX of each sub-block is derived.

(STEP 3) Sub-block motion compensation The motion compensation unit 3091 receives the reference picture from the reference picture memory 306 based on the prediction list use flag predFlagLX, the reference picture index refIdxLX, and the motion vector mvLX input from the inter prediction parameter decoding unit 303. Performs sub-block-based motion compensation by generating a motion-compensated image predSamplesLX by reading out and filtering the block at a position shifted by the motion vector mvLX from the position of the target block on the reference picture specified by the index refIdxLX. It is a process.

(STEP 4) Storage of motion vector of sub-block In the case of AMVP mode, the motion vector mvLX of each sub-block derived by the AMVP prediction parameter deriving unit 3032 in (STEP 2) is stored in the prediction parameter memory 307. Similarly, also in the merge mode, the motion vector mvLX of each sub-block derived by the affine prediction unit 30372 in (STEP 2) is stored in the prediction parameter memory 307.

Note that the derivation of the sub-block motion vector mvLX using affine prediction can be performed in both the AMVP mode and the merge mode. In the following, some processes of (STEP 1) to (STEP 4) will be described for the AMVP mode and the merge mode, respectively.

(STEP1 details)
First, regarding the processing of (STEP 1), the AMVP mode and the merge mode will be described below with reference to FIG. FIG. 15 is a diagram illustrating an example of the position of a prediction unit used for deriving a motion vector of a control point in the AMVP mode and the merge mode.

(Derivation of motion vector of control point in AMVP mode)
The AMVP prediction parameter derivation unit 3032 derives a vector candidate mvpLX from the motion vector stored in the prediction parameter memory 307 based on the reference picture index refIdx. Then, the AMVP prediction parameter deriving unit 3032 refers to the read motion vector and predicts (derived) the motion vectors of the representative points (here, the points V0, V1, and V2) of the target block.

In the AMVP mode, the inter prediction parameter decoding control unit 3031 uses the entropy decoding unit 301 to extract AMVP prediction parameters from the encoded data. This AMVP prediction parameter includes a separately encoded difference vector mvdLX for correcting the prediction vector mvpLX of the representative points (point V0, point V1 and point V2).

As shown in FIG. 15A, the AMVP prediction parameter derivation unit 3032 is adjacent to one of the representative points (here, the point V0), and blocks A and B that share the representative point (vertex) with the target block. , And C (reference block) motion vectors are referred to from the prediction parameter memory 307 to derive a representative point prediction vector mvpLX. Furthermore, the difference vector mvdLX of the representative point decoded from the encoded data is added to the derived prediction vector mvpLX to derive the motion vector mvLX of the control point V0. Note that the AMVP prediction parameter derivation unit 3032 may decode the index mvp_LX_idx from the encoded data and determine which of the motion vectors of the blocks A, B, and C is referred to as the prediction vector.

Similarly, as shown in FIG. 15A, the AMVP prediction parameter derivation unit 3032 is adjacent to a representative point (here, the point V1) different from the point V0, and sets the target block and the representative point (vertex). One of the motion vectors of the shared blocks D and E (reference block) is referred to from the prediction parameter memory 307 to derive the prediction vector mvpLX of the representative point V1. Further, the difference vector mvdLX of the representative point V1 decoded from the encoded data is added to the derived prediction vector mvpLX to derive the motion vector mvLX of the control point V1. Note that the AMVP prediction parameter derivation unit 3032 may decode the index mvp_LX_idx from the encoded data and determine which of the motion vectors of the blocks D and E is to be referred to as a prediction vector.

Similarly, as shown in FIG. 15B, the AMVP prediction parameter derivation unit 3032 is adjacent to a representative point (here, the point V2) different from the points V0 and V1, and the target block and the representative point (vertex) ) Is referenced from the prediction parameter memory 307 for any of the motion vectors of the blocks F and G (reference block) that share () to derive the prediction vector mvpLX of the representative point V2. Further, the AMVP prediction parameter deriving unit 3032 adds the difference vector mvdLX of the representative point V2 decoded from the encoded data to the derived prediction vector mvpLX, thereby deriving the motion vector mvLX of the control point V2. Note that the AMVP prediction parameter derivation unit 3032 may decode the index mvp_LX_idx from the encoded data and determine which of the motion vectors of the blocks F and G is referred to as the prediction vector.

More specifically, the AMVP prediction parameter derivation unit 3032 derives a prediction vector candidate of the control point VN (N = 0..2) and stores it in the prediction vector candidate list mvpListVNLX []. Furthermore, the AMVP prediction parameter derivation unit 3032 derives the motion vector (MVi_x, MVi_y) of the control point VN from the encoded data from the prediction vector index mvpVN_LX_idx of the point VN and the difference vector mvdVNLX by the following equation.

MVi_x = mvLX [0] = mvpListVNLX [mvpVN_LX_idx] [0] + mvdVNLX [0]
MVi_y = mvLX [1] = mvpListVNLX [mvpVN_LX_idx] [1] + mvdVNLX [1]
In addition, the position of the control point in STEP1 is not limited to the above. A vertex at the lower right of the target block or points around the target block may be used as will be described later.

As will be described later, in the configuration of switching between the 4-parameter affine and the 6-parameter affine, the AMVP prediction parameter derivation unit 3032 encodes the difference vector of two points, for example, the points V0 and V1, in the case of the 4-parameter affine. And motion vectors of two control points are derived. In the case of 6-parameter affine, the difference vectors of three points, for example, points V0, V1, and V2, are decoded from the encoded data, and the motion vectors of the three control points are derived. Note that control points derived in the case of a four-parameter affine are not limited to the points V0 and V1, but may be the points V0 and V2, the points V1 and V2, the points V0 and V2, or the other two points. In the case of 6-parameter affine, the derived control points are not limited to points V0, V1, and V2.

(General formula for affine prediction)
A general equation for the four-parameter affine will be described below. The motion vector (MVi_x, MVi_y) of the point Vi at the position (xi, yi) starting from the point V0 of the position (0, 0) and the motion vector mv_x, my_y has four parameters (mv_x, mv_y, ev, rv) That is, using the motion vector (translation vector mv_x, mv_y) of the enlargement and rotation center, the enlargement parameter ev, and the rotation parameter rv, the following general formula (eq1) can be obtained.

MVi_x = mv_x + ev * xi-rv * yi
MVi_y = mv_y + rv * xi + ev * yi (eq1)
Note that the motion vectors (MV0_x, MV0_y) at the point (xi, yi) = (0, 0) and the motion vectors (MVk_x, MVk_y) at the point (xi, yi) = (xk, yk) are substituted into the above. , (Ev, rv), the following equation is obtained.

ev = (xk * (MVk_x-MV0_x) + yk * (MVk_y-MV0_y)} / (pow (xk, 2) + pow (yk, 2))
rv = {-yk * (MVk_x-MV0_x) + xk * (MVk_y-MV0_y)} / (pow (xk, 2) + pow (yk, 2))
Note that pow (x, 2) indicates the square of x.

Next, the general formula of 6-parameter affine is explained below. The motion vector (MVi_x, MVi_y) at the position (xi, yi) starting from the point V0 of the position (0, 0) and the motion vector mv_x, my_y has four parameters (mv_x, mv_y, ev1, rv1, ev2, rv2) can be obtained by the following general formula (eq2).

MVi_x = mv_x + ev1 * xi + rv2 * yi
MVi_y = mv_y + rv1 * xi + ev2 * yi (eq2)
(Derivation of control point motion vectors in merge mode)
The affine prediction unit 30372 refers to the prediction parameter memory 307 for a prediction unit including blocks A to E as shown in (c) of FIG. 15, and confirms whether or not affine prediction is used. A prediction unit (here, reference block A in FIG. 15C) found first as a prediction unit in which affine prediction is used is selected as an adjacent block (merge reference block), and a motion vector is derived. Adjacent blocks do not necessarily have to be in direct contact with the target PU (there is no need to have a common edge). For example, a block having the same point as the target PU, such as an upper right point, an upper left point, and a lower right point of the target PU, can also be set as an adjacent block. Also, a neighboring block sufficiently close to the target PU can be used as an adjacent block. The same applies to the second to fifth embodiments described later.

The affine prediction unit 30372 uses the upper left corner point (point v0 in FIG. 15D) and the upper right corner point (of FIG. 15D) in which the affine prediction is used. The motion vector of the control point is derived from the point v1), the lower left corner point (point v2 in FIG. 15D), and two or three of the lower right points v3. In the case of a 4-parameter affine, in one example, motion vectors of V0 (first control point) and V1 (second control point) are derived. In the case of 6-parameter affine, motion vectors of V0, V1, and V2 (third control points) are derived. In the example shown in FIG. 15D, the block whose motion vector is to be predicted has a horizontal width of W and a height of H, and adjacent blocks (adjacent blocks including block A in the example shown in the figure). The width is w and the height is h.

In the 4-parameter affine, the motion vector (MVN_x, MVN_y) of the control point VN (N = 0..1) is derived by the following formula.

MVN_x = mv_x + ev * xN-rv * yN
MVN_y = mv_y + rv * xN + ev * yN
Here, (ev, rv) is an affine parameter, and (xN, yN) is a relative position viewed from a reference point (for example, v0) of the control point VN. mv_x and mv_y are translation vectors, for example, motion vectors (mv0_x, mv0_y) at the point v0. The translation vectors are not limited to (mv0_x, mv0_y), and motion vectors (mv1_x, mv1_y), (mv2_x, mv2_y), and (mv3_x, mv3_y) at the points v1, v2, and v3 may be used.

The relative position of the point Vi starting from the point v0 is derived as follows. First, when the position of the point v0 is (xRef, yRef) and the position Vi is (xPi, yPi), the relative position (xi, yi) of the point Vi starting from the point v0 is determined from the position of the point Vi. From the difference in position from the starting point v0,
xi = xPi-xRef
yi = yPi-yRef
It becomes. In the above example, the position of the point v0 is (xP−w, yP + H−h), and the positions of the points V0, V1, and V2 are (xP, yP), (xP + W, yP), (xP, yP + H), the relative position (xi, yi) (where i = 0..2) of the point Vi starting from the point v0 is derived as follows.

x0 = xP0-xRef = xP-(xP-w) = w
y0 = yP0-yRef = yP-(yP + H-h) = h-H
x1 = xP1-xRef = (xP + W)-(xP-w) = w + W
y1 = yP1-yRef = yP-(yP + H-h) = h-H
x2 = xP2-xRef = xP-(xP-w) = w
y2 = yP2-yRef = (yP + H)-(yP + H-h) = h
Further, the affine prediction unit 30372 may derive (MVN_x, MVN_y) by integer arithmetic using the following equation.

MVN_x = mv_x + ((evBW-rvBH) >> 1) + evBW * iN-rvBH * jN
MVN_y = mv_y + ((rvBW + evBH) >> 1) + rvBW * iN + evBH * jN
Here, (evBW, rvBW) and (evBH, rvBH) are affine parameters, and (iN, jN) are coordinates in units of sub-blocks of the control point VN. For example, (iN, jN) = (xN >> log2 (W), yN >> log2 (H)). Here, W and H are the width and height of the sub-block.

In 6-parameter affine, the motion vector of the control point is derived by the following formula.

MVN_x = mv_x + ev1 * xN + rv2 * yN
MVN_y = mv_y + rv1 * xN + ev2 * yN
Here, (ev1, rv1, ev2, rv2) are affine parameters.

The affine prediction unit 30372 may derive (MVN_x, MVN_y) by integer arithmetic using the following formula.

MVN_x = mv_x + ((ev1BW + rv2BH) >> 1) + ev1BW * iN + rv2BH * jN
MVN_y = mv_y + ((rv1BW + ev2BH) >> 1) + rv1BW * iN + ev2BH * jN
Here, (ev1BW, rv1BW, ev2BH, ev2BH) are affine parameters.

The method for deriving the affine parameters (ev, rv), (evBW, rvBW), (evBH, rvBH), (ev1, rv1, ev2, rv2), (ev1BW, rv1BW, ev2BH, ev2BH) is (STEP2 details) It will be described later. In derivation, control points V0, V1, V2, and V3 are replaced with reference points v0, v1, v2, and v3 on adjacent blocks, respectively, and motion vectors (MV1_x, MV1_y), (MV2_x, MV2_y) ), (MV3_x, MV3_y) are replaced with motion vectors (mv0_x, mv0_y), (mv1_x, mv1_y), (mv2_x, mv2_y), (mv3_x, mv3_y), respectively.

Also, the affine prediction unit 30372 represents the representative points on the target block from the motion vectors (mv0_x, mv0_y), (mv1_x, mv1_y), and (mv2_x, mv2_y) of the points v0, v1, and v2 in FIG. A motion vector of (control points V0, V1, and V2) may be derived. The derivation formula is as follows.

MVi_x = mv0_x + (mv1_x-mv0_x) / w * xi + (mv2_x-mv0_x) / h * yi
MVi_y = mv0_y + (mv1_y-mv0_y) / w * xi + (mv2_y-mv0_y) / h * yi
Here, (xi, yi) is the coordinates of the point to be derived (here, the control points V0, V1, and V2) starting from the point v0, and w and h are the reference point v1 and the base reference point v0, respectively. This corresponds to the distance (= X coordinate of point v1−X coordinate of point v0) and the distance between reference point v2 and base reference point v0 (= Y coordinate of point v2−Y coordinate of point v0).

The position (x0, y0) = (w, h−H) of the point V0 starting from the point v0 of the base reference point and the position (x1, y1) = (point of the point V1 are added to (xi, yi) of the above derivation formula. By substituting w + W, h-H), the motion vector (MV0_x, MV0_y) of the point V0 and the motion vector (MV1_x, MV1_y) of the point V1 are derived.
MV0_x = mv0_x + (mv1_x-mv0_x) / w * w + (mv2_x-mv0_x) / h * (h-H)
MV0_y = mv0_y + (mv1_y-mv0_y) / w * w + (mv2_y-mv0_y) / h * (h-H)
MV1_x = mv0_x + (mv1_x-mv0_x) / w * (w + W) + (mv2_x-mv0_x) / h * (h-H)
MV1_y = mv0_y + (mv1_y-mv0_y) / w * (w + W) + (mv2_y-mv0_y) / h * (h-H)
It becomes.

In STEP 1, the selection of control points is not limited to the above.

The affine prediction unit 30372 of this configuration derives the motion vector of the control point (V0, V1, V2, V3) from the motion vector of the reference point (v0, v1, v2, v3) of the adjacent block in (STEP 1). In (STEP2), the sub-block motion vectors are derived from the motion vectors of the control points (V0, V1, V2, V3), but (STEP1) and (STEP2) are integrated to form adjacent blocks. The motion vector of the sub-block may be derived from the motion vector of the reference points (v0, v1, v2, v3).

(STEP2 details)
Next, the processing of (STEP 2) will be described using FIG. FIG. 16 is a diagram illustrating an example in which the control point V0 of the target block (horizontal width W, height H) is located at the upper left vertex and is divided into sub-blocks having a width BW and a height BH. (W, H) and (BW, BH) correspond to the aforementioned (nPbW, nPbH) and (nSbW, nSbH).

The affine prediction unit 30372 (AMVP prediction parameter derivation unit 3032) refers to the motion vectors of two or three control points among the control points V0, V1, and V2, which are representative points on the block, derived in (STEP 1). In (STEP 2), an affine parameter is calculated. That is, the affine prediction unit 30372 (AMVP prediction parameter derivation unit 3032) performs one of the following processes.
The affine parameters (ev, rv) from two motion vectors of the motion vector (MV0_x, MV0_y) of the control point V0, the motion vector (MV1_x, MV1_y) of the control point V1, and the motion vector (MV2_x, MV2_y) of the control point V2 ) Is derived.
From the three motion vectors of the motion vector of the control point V0 (MV0_x, MV0_y), the motion vector of the control point V1 (MV1_x, MV1_y) and the motion vector of the control point V2 (MV2_x, MV2_y), affine parameters (ev1, rv1, ev2, ev2) is derived.

In the following description, the process of deriving affine parameters (ev, rv) from two motion vectors is referred to as “4-parameter affine”. The process of deriving affine parameters (ev1, rv1, ev2, ev2) from the three motion vectors is referred to as “6-parameter affine”.

Affine parameters can be handled as integers instead of decimal numbers. The decimal affine parameters are (ev, rv), (ev1, rv1, ev2, ev2), and the integer affine parameters are (evBW, rvBW), (evBH, rvBH), (ev1BW, rv1BW, ev2BH, ev2BH) It expresses.

The integer affine parameter is obtained by multiplying the decimal affine parameter by a constant (constant for integerization) according to the sub-block size (BW, BH). Specifically, the following relationship exists between the affine parameters for decimal numbers and the affine parameters for integers.

evBW = ev * BW = ev << log2 (BW)
rvBW = rv * BW = rv << log2 (BW)
evBH = ev * BH = ev << log2 (BH)
rvBH = rv * BH = rv << log2 (BH)
ev1BW = ev1 * BW = ev1 << log2 (BW)
rv1BW = rv1 * BH = rv1 << log2 (BW)
ev2BH = ev2 * BW = ev2 << log2 (BH)
rv2BH = rv2 * BH = rv2 << log2 (BH)
When the width BW and the height BH of the sub-block are equal, (evBW, rvBW) = (evBH, rvBH), so it is not necessary to distinguish (evBW, rvBW) from (evBH, rvBH). That is, in the derivation of the following affine parameters, it is sufficient to derive only (evBW, rvBW) or only (evBH, rvBH).

For example, when the motion vectors of the control points V0 and V1 are used, the affine prediction unit 30372 (AMVP prediction parameter derivation unit 3032) uses the following equation to determine the affine parameters:
evBW = (MV1_x-MV0_x) >> shiftWBW
rvBW = (MV1_y-MV0_y) >> shiftWBW
evBH = (MV1_x-MV0_x) >> shiftWBH
rvBH = (MV1_y-MV0_y) >> shiftWBH
shiftWBW = log2 (W)-log2 (BW)
shiftHBH = log2 (H)-log2 (BH)
And derived.

In addition, when using the affine parameter of the decimal number, use the following formula:
ev = (MV1_x-MV0_x) / W
rv = (MV1_y-MV0_y) / W
May be derived. This equation is a case where the position of the general formula control point V0 is (0, 0) and the position of the control point V1 is (W, 0).

In addition, when using the motion vectors of the control points V0 and V2, the affine prediction unit 30372 (AMVP prediction parameter derivation unit 3032) uses the following equation to determine the affine parameters:
evBW = (MV2_y-MV0_y) >> shiftHBW
rvBW =-(MV2_x-MV0_x) >> shiftHBW
evBH = (MV2_y-MV0_y) >> shiftHBH
rvBH =-(MV2_x-MV0_x) >> shiftHBH
shiftHBW = log2 (H)-log2 (BW)
shiftHBH = log2 (H)-log2 (BH)
And derived. Note that this equation is derived from the following affine parameter ev = (MV2_y-MV0_y) / H
rv =-(MV2_x-MV0_x) / H
Is equal to

Further, when using the motion vectors of the control points V1 and V2, the affine prediction unit 30372 (AMVP prediction parameter derivation unit 3032) uses the following formula to calculate the affine parameters:
evBW = {(MV1_x-MV2_x)-(MV1_y-MV2_y)} >> (shiftWBW + 1)
rvBW = {(MV1_x-MV2_x) + (MV1_y-MV2_y)} >> (shiftWBW + 1)
evBH = {(MV1_x-MV2_x)-(MV1_y-MV2_y)} >> (shiftWBH + 1)
rvBH = {(MV1_x-MV2_x) + (MV1_y-MV2_y)} >> (shiftWBH + 1)
And derived. This formula is derived from the following affine parameter derivation formula ev = {(MV1_x-MV2_x)-(MV1_y-MV2_y)} / 2W
rv = {(MV1_x-MV2_x) + (MV1_y-MV2_y)} / 2W
Is equal to

It is also possible to use a motion vector of a control point V3 (a control point located diagonally to V0 in the target block) that is different from any of the control points V0 to V2 described above. For example, when using the motion vectors of the control points V0 and V3, the affine prediction unit 30372 (AMVP prediction parameter derivation unit 3032) uses the following equation to determine the affine parameters:
evBW = (MV3_x-MV0_x + MV3_y-MV0_y) >> (shiftWBW + 1)
rvBW = (-MV3_x + MV0_x + MV3_y-MV0_y) >> (shiftWBW + 1)
evBH = (MV3_x-MV0_x + MV3_y-MV0_y) >> (shiftWBH + 1)
rvBH = (-MV3_x + MV0_x + MV3_y-MV0_y) >> (shiftWBH + 1)
And derived. This formula is derived from the following affine parameter ev = (MV3_x-MV0_x + MV3_y-MV0_y) / 2W
rv = (-MV3_x + MV0_x + MV3_y-MV0_y) / 2W
Is equal to

In addition, when using three motion vectors of control points V0, V1, and V2, the affine prediction unit 30372 (AMVP prediction parameter derivation unit 3032) uses the following formula to determine the affine parameters:
ev1BW = (MV1_x-MV0_x) >> shiftWBW
rv2BH = (MV2_x-MV0_x) >> shiftHBH
rv1BW = (MV1_y-MV0_y) >> shiftWBW
ev2BH = (MV2_y-MV0_y) >> shiftHBH
shiftWBW = log2 (W)-log2 (BW)
shiftHBH = log2 (H)-log2 (BH)
And derived. This equation is derived from the following affine parameter affine parameter ev1 = (MV1_x-MV0_x) / W
rv2 = (MV2_x-MV0_x) / H
rv1 = (MV1_y-MV0_y) / W
ev2 = (MV2_y-MV0_y) / H
Is equal to

(Derivation of sub-block motion vectors)
The affine prediction unit 30372 (AMVP prediction parameter derivation unit 3032) derives the motion vector of the sub-block using the affine parameters obtained by the above formula.

In the case of 4-parameter affine, the motion vector (MVi_x, MVi_y) of the subblock coordinates (xi, yi) is derived from the affine parameters (ev, rv) by the following formula AF4P_float.

MVi_x = mv_x + ev * xi-rv * yi
MVi_y = mv_y + rv * xi + ev * yi (Formula AF4P_float)
(MV0_x, MV0_y) may be used as the affine parameters mv_x, mv_y of the translation vector, but is not limited to this. For example, motion vectors (MV1_x, MV1_y), (MV2_x, MV2_y), and (MV3_x, MV3_y) other than (MV0_x, MV0_y) may be used as translation vectors. In particular, when V1 and V2 are used as control points, the motion vector (MV1_x, MV1_y) of V1 or the motion vector (MV2_x, MV2_y) of V1 may be used as a translation vector.

If the affine parameters are integer affine parameters (evBW, rvBW) and (evBH, rvBH), the motion vector (MVij_x, MVij_y) of the subblock at the subblock position (i, j) is derived by the following formula AF4P_integer To do.

MVij_x = mv_x + ((evBW-rvBH) >> 1) + evBW * i-rvBH * j
MVij_y = mv_y + ((rvBW + evBH) >> 1) + rvBW * i + evBH * j (expression AF4P_integer)
When (MV0_x, MV0_y) is used as the translation vector, the above equation becomes the following equation.

MVij_x = MV0_x + ((evBW-rvBH) >> 1) + evBW * i-rvBH * j
MVij_y = MV0_y + ((rvBW + evBH) >> 1) + rvBW * i + evBH * j
If the sub-block width BW and height BH are equal, (evBW, rvBW) = (evBH, rvBH)
Therefore, it is not necessary to distinguish (evBW, rvBW) from (evBH, rvBH) in the above derivation formula. That is, it may be derived only from (evBW, rvBW).

MVij_x = mv_x + ((evBW + rvBW) >> 1) + evBW * i-rvBW * j
MVij_y = mv_y + ((rvBW + evBW) >> 1) + rvBW * i + evBW * j
Alternatively, it may be derived only from (evBH, rvBH).

MVij_x = mv_x + ((evBH + rvBH) >> 1) + evBH * i-rvBH * j
MVij_y = mv_y + ((rvBH + evBH) >> 1) + rvBH * i + evBH * j
Here, the relationship between the sub-block position (i, j) and the sub-block coordinates (xi, yj) is as follows (formula XYIJ).

xi = BW / 2 + BW * i
yj = BH / 2 + BH * j (Formula XYIJ)
i = 0 .. (B / SW) -1, j = 0 .. (H / SH) -1
The point at sub-block position (i, j) is the intersection of the solid line parallel to the x-axis and the solid line parallel to the y-axis in FIG. Further, the point of sub-block coordinates (xi, yj) is an intersection of a broken line parallel to the x axis and a broken line parallel to the y axis in FIG. FIG. 16 shows, as an example, a point at subblock position (i, j) = (1, 1) and a point at subblock coordinates (x1, y1) with respect to the subblock position.

It should be noted that an integer derivation formula can be obtained from the decimal number derivation formula by the following modification. When the above formula XYIJ is substituted into (xi, yi) of the above-described decimal number formula AF4P_float and transformed,
MVij_x = mv_x + ev * (BW / 2 + BW * i)-rv * (BH / 2 + BH * j)
MVij_y = mv_y + rv * (BW / 2 + BW * i) + ev * (BH / 2 + BH * j)
It becomes. When further deformed,
MVij_x = mv_x + ev * BW * (1/2 + i)-rv * BH * (1/2 + j)
MVij_y = mv_y + rv * BW * (1/2 + i) + ev * BH * (1/2 + j)
It becomes. Furthermore, when deformed by ev * BW = evBW, rv * BH = rvBH, rv * BW = rvBW, ev * BH = evBH,
MVij_x = MV0_x + evBW * (1/2 + i)-rvBH * (1/2 + j)
MVij_y = MV0_y + rvBW * (1/2 + i) + evBH * (1/2 + j)
It becomes. When further deformed,
MVij_x = MV0_x + evBW / 2-rvBH / 2 + evBW * i-rvBH * j
MVij_y = MV0_y + rvBW / 2 + evBH / 2 + rvBW * i + evBH * j
And finally the above integer arithmetic expression AF4P_integer
MVij_x = mv_x + ((evBW-rvBH) >> 1) + evBW * i-rvBH * j
MVij_y = mv_y + ((rvBW + evBH) >> 1) + rvBW * i + evBH * j
It becomes. (MV0_x, MV0_y) may be used as the affine parameters mv_x, mv_y of the translation vector, but is not limited thereto. For example, motion vectors (MV1_x, MV1_y), (MV2_x, MV2_y), and (MV3_x, MV3_y) may be used as translation vectors.

In the case of 6-parameter affine, the motion vector (MVij_x, MVij_y) of the sub-block coordinates (xi, yi) from the affine parameters (ev1, rv1, ev2, ev2) is expressed by the following formula AF6P_float:
MVij_x = mv_x + ev1 * xi + rv2 * yi
MVij_y = mv_y + rv1 * xi + ev2 * yi (Formula AF6P_float)
And derived.

When the affine parameters (ev1, rv1, ev2, ev2) are integer affine parameters (ev1BW, rv1BH, ev2BW, ev2BH), the motion vector (MVij_x, MVij_y) of the subblock at the subblock position (i, j) ) Is derived by the following expression AF6P_integer.

MVij_x = mv_x + ((ev1BW + rv2BH) >> 1) + ev1BW * i + rv2BH * j
MVij_y = mv_y + ((rv1BW + ev2BH) >> 1) + rv1BW * i + ev2BH * j (expression AF6P_integer)
For example, when (MV0_x, MV0_y) is used as the translation vector, the above expression becomes the following expression.

MVij_x = MV0_x + ((ev1BW + rv2BH) >> 1) + ev1BW * i + rv2BH * j
MVij_y = MV0_y + ((rv1BW + ev2BH) >> 1) + rv1BW * i + ev2BH * j (expression AF6P_integer)
It should be noted that an integer derivation formula can be obtained from the decimal number derivation formula by the following modification. When the above formula XYIJ is substituted into (xi, yi) of the above-described decimal number formula AF6P_float,
MVij_x = mv_x + ev1 * (BW / 2 + BW * i) + rv2 * (BH / 2 + BH * j)
MVij_y = mv_y + rv1 * (BW / 2 + BW * i) + ev2 * (BH / 2 + BH * j)
It becomes. When further deformed,
MVij_x = mv_x + ev1 * BW * (1/2 + i) + rv2 * BH * (1/2 + j)
MVij_y = mv_y + rv1 * BW * (1/2 + i) + ev2 * BH * (1/2 + j)
It becomes. Furthermore, when deformed by ev1 * BW = ev1BW, rv2 * BH = rv2BH, rv1 * BW = rv1BW, ev2 * BH = ev2BH,
MVij_x = mv_x + ev1BW * (1/2 + i) + rv2BH * (1/2 + j)
MVij_y = mv_y + rv1BW * (1/2 + i) + ev2BH * (1/2 + j)
It becomes. When further deformed,
MVij_x = mv_x + ev1BW / 2 + rv2BH / 2 + ev1BW * i + rv2BH * j
MVij_y = mv_y + rv1BW / 2 + ev2BH / 2 + rv1BW * i + ev2BH * j
And finally, the above-described integer arithmetic derivation formula AF6P_integer
MVij_x = mv_x + ((ev1BW + rv2BH) >> 1) + ev1BW * i + rv2BH * j
MVij_y = mv_y + ((rv1BW + ev2BH) >> 1) + rv1BW * i + ev2BH * j
It becomes.

(Determining control points)
The inter prediction parameter decoding unit 303 determines which of four-parameter affine and six-parameter affine is to be executed by a predetermined process. An example of predetermined processing is shown below. In the flowchart used in the following description, puWidth indicates the width of the target PU, and puHeight indicates the height of the target PU. (PuWidth, puHeight) corresponds to (nPbW, nPbH) described above.

(Decision based on the shape of the target PU)
FIG. 17 is a flowchart illustrating an example of processing in which the inter prediction parameter decoding unit 303 determines the number of control points from which a motion vector is derived based on the shape of the target PU. In the example illustrated in FIG. 17, in the inter prediction parameter decoding unit 303, the inter prediction parameter decoding control unit 3031 first determines whether the width of the target PU is equal to the height of the target PU (SA1). When the width of the target PU is equal to the height of the target PU (Y in SA1), the affine prediction unit 30372 (or AMVP prediction parameter decoding unit 3032) performs 6-parameter affine processing (SA2). When the width of the target PU is not equal to the height of the target PU (N in SA1), the affine prediction unit 30372 (or AMVP prediction parameter decoding unit 3032) performs a 4-parameter affine process (SA3).

The determination in SA1 is equivalent to determining whether or not the target PU is a square. That is, in the example shown in FIG. 17, 6-parameter affine processing is performed when the target PU is square, and 4-parameter affine processing is performed when the target PU is not square.

Also, the process of deriving a motion vector based on the shape of the target PU may be applied only in the merge mode or only in the case of AMVP. FIG. 18 is a flowchart illustrating another example of the process in which the affine prediction unit 30372 determines the number of control points from which a motion vector is derived based on the shape of the target PU. In the example illustrated in FIG. 18, prior to the processing of SA1 illustrated in FIG. 17, the inter prediction parameter decoding control unit 3031 determines whether the merge flag is 1 (SB1). When the merge flag is 1, that is, in the merge mode (Y in SB1), the inter prediction parameter decoding unit 303 performs the processes of SB2 to SB4. The processing of SB2 to SB4 is the same as the processing of SA1 to SA3 shown in FIG. On the other hand, when the merge flag is 0, that is, when the merge mode is not set (N in SB1), the inter prediction parameter decoding unit 303 performs an AMVP motion vector derivation process.

In the example illustrated in FIG. 18, when the merge flag is 1, the affine prediction unit 30372 derives the affine parameters depending on whether the target PU is a square. However, on the contrary to the example shown in FIG. 18, the affine prediction unit 30372 of the present embodiment sets the affine parameter according to whether the target PU is square when the merge flag is 0, that is, when it is AMVP. Derivation may be performed. In this case, the affine parameter derivation is executed by the AMVP prediction parameter derivation unit 3032. The control point motion vector is derived in accordance with the above-described (derivation of the control point motion vector in the AMVP mode).

Although not described above, the inter prediction parameter decoding unit 303 may decode an affine application flag pu_affine_enable_flag that is a flag indicating whether to perform affine prediction. The inter prediction parameter decoding unit 303 performs affine prediction processing when the affine application flag pu_affine_enable_flag is 1, that is, indicates that affine prediction is applied, and does not apply affine prediction when the affine application flag pu_affine_enable_flag is 0. .

FIG. 19 is a flowchart illustrating yet another example of the process in which the inter prediction parameter decoding unit 303 determines the number of control points from which a motion vector is derived based on the shape of the target PU.

In the example shown in FIG. 19, in the case of AMVP, when the shape of the target PU is square, the PU affine mode flag that is a flag indicating 6-parameter affine and 4-parameter affine is decoded, and otherwise, Do not decode PU affine mode flags. More specifically, the inter prediction parameter decoding control unit 3031 first determines whether the merge flag is 1 (SC1). When the merge flag is 0 (indicating that the merge process is not performed) (N in SC1), the inter prediction parameter decoding control unit 3031 determines whether the width of the target PU is equal to the height of the target PU ( SC2). When the width of the target PU is equal to the height of the target PU (Y in SC2), the inter prediction parameter decoding control unit 3031 decodes the PU affine mode flag (SC3). Thereafter, the inter prediction parameter decoding control unit 3031 determines whether or not the PU affine mode flag is 1 (SC4).

When the PU affine mode flag is 1 (indicating that 6-parameter affine processing is to be performed) (Y in SC4), the AMVP prediction parameter derivation unit 3032 performs 6-parameter affine processing, and PU affine mode flag When is 0 (N in SC4), 4-parameter affine processing is performed. Further, the AMVP prediction parameter derivation unit 3032 performs the 4-parameter affine process even when the width of the target PU and the height of the target PU are not equal (N in SC2). On the other hand, when the merge flag is 1 (Y in SC1), motion vector derivation by merge prediction is performed.

In this configuration, the inter prediction parameter decoding unit 303 calculates the motion vectors of the two control points and performs 4-parameter affine processing according to the shape of the target block, or calculates the motion vectors of the three control points. Switches whether to perform 6-parameter affine processing. In the case of application to AMVP, at SC1, two motion vectors (difference vectors) are encoded / decoded according to the shape of the target block, or three motion vectors (difference vectors) are encoded / decoded. May be switched. When applying to merging, in SC1, the motion vector of the control point is derived by referring to the motion vector of two points according to the shape of the target block, or the motion of the control point by referring to the motion vector of three points. You may switch whether to derive a vector. Also, in SC2, whether to derive the motion vector of each subblock by referring to the two motion vectors according to the shape of the target block, or to derive the motion vector of each subblock by referring to the three motion vectors , May be switched.

(Determined by the size of the target PU)
FIG. 20 is a flowchart illustrating an example of processing in which the inter prediction parameter decoding unit 303 determines the number of control points from which a motion vector is derived based on the size of the target PU. In the example illustrated in FIG. 20, the inter prediction parameter decoding control unit 3031 first determines whether a value indicating the size of the target PU is equal to or greater than a predetermined threshold (SD1). When the size of the target PU is equal to or larger than the predetermined threshold (Y in SD1), the affine prediction unit 30372 performs a 6-parameter affine process (SD2). When the size of the target PU is not equal to or larger than the predetermined threshold (N in SD1), the affine prediction unit 30372 performs a 4-parameter affine process (SD3).

As a value indicating the size of the target PU, for example, the following can be used.
・ Max (puWidth, puHeight)
・ Min (puWidth, puHeight)
・ PuWidth + puHeight
・ PuWidth * puHeight
・ Log2 (puWidth) + log2 (puHeight)
However, the value indicating the size of the target PU is not limited to the above example.

The determination in SD1 may be as follows.
-Is the target PU size larger than a predetermined threshold?
-Is the size of the target PU less than or equal to a predetermined threshold?
-Is the size of the target PU smaller than a predetermined threshold?

FIG. 21 is a flowchart illustrating another example of processing in which the inter prediction parameter decoding unit 303 determines the number of control points from which a motion vector is derived based on the size of the target PU. In the example shown in FIG. 21, in the case of AMVP, the PU affine mode flag which is a flag indicating 6-parameter affine and 4-parameter affine is decoded in order to increase the size of the target PU, and in other cases, PU affine Do not decode mode flags. More specifically, as in the example shown in FIG. 19, the inter prediction parameter decoding control unit 3031 first determines whether the merge flag is 1 (SE1). When the merge flag is 0 (N in SE1), the inter prediction parameter decoding control unit 3031 determines whether the size of the target PU is equal to or larger than a predetermined threshold (SE2). Based on the determination result of SE2, the inter prediction parameter decoding unit 303 performs the processes of SE3 to SE6. The processing of SE3 to SE6 is the same as the processing of SC3 to SC6 shown in FIG.

FIG. 22 is a table showing processing for each size when log2 (puWidth) + log2 (puHeight) is used as a value indicating the size of the target PU. In the example illustrated in FIG. 22, the determination threshold is set to 8. In this case, in the example illustrated in FIG. 22, if log2 (puWidth) + 2log2 (puHeight) is 6 or 7, the affine prediction unit 30372 performs 4-parameter affine processing regardless of the shape of the target PU. If log2 (puWidth) + log2 (puHeight) is 8, the affine prediction unit 30372 performs 6-parameter affine processing regardless of the shape of the target PU.

FIG. 23 is a table showing processing for each size when min (puWidth, puHeight) is used as a value indicating the size of the target PU. In the example shown in FIG. 23, the determination threshold is set to 8. In this case, as shown in FIG. 23, if min (puWidth, puHeight) is 4, the affine prediction unit 30372 performs 4-parameter affine processing regardless of the shape of the target PU. If min (puWidth, puHeight) is 8 or 16, the affine prediction unit 30372 performs 6-parameter affine processing regardless of the shape of the target PU.

In this configuration, the inter prediction parameter decoding unit 303 calculates a motion vector of two control points and performs 4-parameter affine processing according to the size of the target block, or calculates a motion vector of three control points. Switches whether to perform 6-parameter affine processing. When applied to AMVP, in SE1, two motion vectors (difference vectors) are encoded / decoded according to the size of the target block, or three motion vectors (difference vectors) are encoded / decoded. May be switched. When applying to merging, in SE1, the motion vector of the control point is derived by referring to the motion vector of two points according to the size of the target block, or the motion of the control point by referring to the motion vector of three points. You may switch whether to derive a vector. In SE2, whether the motion vector of each subblock is derived by referring to the two motion vectors according to the size of the target block or whether the motion vector of each subblock is derived by referring to the three motion vectors , May be switched.

(Determined by the shape and size of the target PU)
FIG. 24 is a flowchart illustrating an example of processing in which the inter prediction parameter decoding unit 303 determines the number of control points from which a motion vector is derived based on both the shape and size of the target PU. In the example illustrated in FIG. 24, the inter prediction parameter decoding control unit 3031 first determines whether the size of the target PU is greater than or equal to a predetermined threshold (SF1). When the size of the target PU is equal to or larger than the predetermined threshold (Y in SF1), the affine prediction unit 30372 performs a 6-parameter affine process (SF3).

If the size of the target PU is not equal to or larger than the predetermined threshold (N in SF1), the inter prediction parameter decoding control unit 3031 continues to determine whether the width of the target PU is equal to the height of the target PU (SF2). When the width of the target PU is equal to the height of the target PU (Y in SF2), the affine prediction unit 30372 performs a 6-parameter affine process (SF3). When the width of the target PU is not equal to the height of the target PU (N in SF2), the affine prediction unit 30372 performs a 4-parameter affine process (SF4).

That is, in the example shown in FIG. 24, when the target PU is equal to or larger than a predetermined size or is a square, the affine prediction unit 30372 performs a 6-parameter affine process. On the other hand, when the target PU is smaller than the predetermined size and is not a square, the affine prediction unit 30372 performs a 4-parameter affine process.

FIG. 25 is a flowchart illustrating another example of the process in which the inter prediction parameter decoding unit 303 determines the number of control points from which a motion vector is derived based on both the shape and size of the target PU. In the example illustrated in FIG. 25, as in the examples illustrated in FIGS. 19 and 21, the inter prediction parameter decoding control unit 3031 first determines whether the merge flag is 1 (SG1). When the merge flag is 0 (N in SE1), the inter prediction parameter decoding control unit 3031 determines the size and shape of the target PU in the same manner as SF1 and SF2 illustrated in FIG. 24 (SG2, SG3). When the size of the target PU is equal to or larger than a predetermined threshold (Y in SG2), or when the size of the target PU is not equal to or larger than the predetermined threshold (N in SG2) and the target PU is square (Y in SG3), The affine prediction unit 30372 performs the processes SG4 to SG7 (similar to SC3 to SC6 shown in FIG. 19).

FIG. 26 is a table showing an example of processing of the affine prediction unit 30372 for each size and shape of the target PU. In the example shown in FIG. 26, log2 (puWidth) + log2 (puHeight) is used as a value indicating the size of the target PU, and the threshold is set to 8.

In the example shown in FIG. 26, when the value indicating the size of the target PU is 6 or 7, the affine prediction unit 30372 has 6 parameters only when the symmetric PU is a square (in the case of 8 * 8 in FIG. 26). Perform affine processing. In other cases, the affine prediction unit 30372 performs 4-parameter affine processing. On the other hand, when the size of the target PU is 8, the affine prediction unit 30372 performs 6-parameter affine processing regardless of the shape of the target PU.

FIG. 27 is a table showing another example of processing of the affine prediction unit 30372 for each size and shape of the target PU. In the example shown in FIG. 27, min (puWidth, puHeight) is used as a value indicating the size of the target PU, and the threshold is set to 16.

In the example shown in FIG. 27, when the value indicating the size of the target PU is 4 or 8, the affine prediction unit 30372 has six parameters only when the target PU is a square (in the case of 8 * 8 in FIG. 27). Perform affine processing. In other cases, the affine prediction unit 30372 performs 4-parameter affine processing. On the other hand, when the size of the target PU is 16, the affine prediction unit 30372 performs 6-parameter affine processing.

In this configuration, the inter prediction parameter decoding unit 303 calculates motion vectors of two control points and performs 4-parameter affine processing according to the shape and size of the target block, or calculates motion vectors of three control points. To switch whether to perform 6-parameter affine processing. When applying to AMVP, SG1 encodes and decodes two motion vectors (difference vectors) or encodes three motion vectors (difference vectors) according to the shape and size of the target block. You may switch whether to decode. When applying to merging, SG1 derives the motion vector of the control point by referring to the two motion vectors according to the shape and size of the target block, or refers to the control point by referring to the three motion vectors. It may be switched whether to derive the motion vector. In SG2, the motion vector of each sub-block is derived by referring to two motion vectors according to the shape and size of the target block, or the motion vector of each sub-block is derived by referring to three motion vectors. You may switch between.

(Matching prediction unit 30373)
The matching prediction unit 30373 derives the motion vector spMvLX of the sub-blocks constituting the PU by performing either bilateral matching or template matching. FIG. 14 is a diagram for explaining (a) bilateral matching and (b) template matching. The matching prediction mode is selected as one merge candidate (matching candidate) in the merge mode.

The matching prediction unit 30373 derives a motion vector by matching regions in a plurality of reference images, assuming that the object moves at a constant velocity. In bilateral matching, it is assumed that a certain object passes through a certain region of the reference image A, a target PU of the target picture Cur_Pic, and a certain region of the reference image B with constant velocity motion, and matching between the reference images A and B To derive the motion vector of the target PU. In the template matching, assuming that the adjacent vector of the target PU and the motion vector of the target PU are equal, a motion vector is derived by matching the adjacent region Temp_Cur of the target PU with the adjacent region Temp_L0 of the reference block on the reference picture. The matching prediction unit divides the target PU into a plurality of sub-blocks, and performs bilateral matching or template matching described later in units of the divided sub-blocks, so that the motion vector spMvLX [xi] [yj] (xi = xPb + nSbW * i, yj = yPb + nSbH * j, i = 0, 1, 2, ..., nPbW / nSbW-1, j = 0, 1, 2, ..., nPbH / nSbH-1) Is derived.

As shown in FIG. 14A, in bilateral matching, two reference images are referred to in order to derive a motion vector of the sub-block Cur_block in the current picture Cur_Pic. More specifically, first, when the coordinates of the sub-block Cur_block are expressed as (xCur, yCur), an area in the reference image (referred to as reference picture A) specified by the reference picture index Ref0,
(XPos0, yPos0) = (xCur + MV0_x, yCur + MV0_y)
Block_A having the upper left coordinates (xPos0, yPos0) specified by, and a region in the reference image (referred to as reference picture B) specified by the reference picture index Ref1,
(XPos1, yPos1) = (xCur + MV1_x, xCur + MV1_y) = (xCur-MV0_x * TD1 / TD0, yCur-MV0_y * TD1 / TD0)
Block_B having the upper left coordinates (xPos1, yPos1) specified by is set. Here, TD0 and TD1 represent the inter-picture distance between the target picture Cur_Pic and the reference picture A, and the inter-picture distance between the target picture Cur_Pic and the reference picture B, respectively, as shown in FIG. ing.

Next, (MV0_x, MV0_y) is determined so that the matching cost between Block_A and Block_B is minimized. The (MV0_x, MV0_y) derived in this way is a motion vector assigned to the sub-block.

On the other hand, (b) of FIG. 14 is a figure for demonstrating a template matching (Template | matching) among the said matching processes.

As shown in FIG. 14B, in template matching, one reference picture is referred to in order to derive a motion vector of the sub-block Cur_block in the target picture Cur_Pic.

More specifically, first, an area in a reference image (referred to as reference picture A) designated by a reference picture index Ref0,
(XPos0, yPos0) = (xCur + MV0_x, yCur + MV0_y)
The reference block Block_A having the upper left coordinates (xPos0, yPos0) specified by is specified. Here, (xCur, yCur) is the upper left coordinate of the sub-block Cur_block.

Next, a template region Temp_Cur adjacent to the sub-block Cur_block in the target picture Cur_Pic and a template region Temp_L0 adjacent to the Block_A in the reference picture A are set. In the example shown in FIG. 14B, the template region Temp_Cur is composed of a region adjacent to the upper side of the sub-block Cur_block and a region adjacent to the left side of the sub-block Cur_block. The template area Temp_L0 is composed of an area adjacent to the upper side of Block_A and an area adjacent to the left side of Block_A.

Next, it is determined that the matching cost between Temp_Cur and TempL0 is minimum (MV0_x, MV0_y), and the motion vector spMvLX is given to the sub-block.

FIG. 7 is a schematic diagram illustrating the configuration of the merge prediction parameter deriving unit 3036 according to the present embodiment. The merge prediction parameter derivation unit 3036 includes a merge candidate derivation unit 30361, a merge candidate selection unit 30362, and a merge candidate storage unit 30363. The merge candidate storage unit 30363 stores the merge candidates input from the merge candidate derivation unit 30361. The merge candidate includes a prediction list use flag predFlagLX, a motion vector mvLX, and a reference picture index refIdxLX. In the merge candidate storage unit 30363, an index is assigned to the stored merge candidate according to a predetermined rule.

The merge candidate derivation unit 30361 derives a merge candidate using the motion vector of the adjacent PU that has already been decoded and the reference picture index refIdxLX as they are. In addition, merge candidates may be derived using affine prediction. This method is described in detail below. The merge candidate derivation unit 30361 may use affine prediction for a spatial merge candidate derivation process, a temporal merge candidate derivation process, a combined merge candidate derivation process, and a zero merge candidate derivation process described later. Affine prediction is performed in units of sub-blocks, and prediction parameters are stored in the prediction parameter memory 307 for each sub-block. Alternatively, the affine prediction may be performed on a pixel basis.

(Spatial merge candidate derivation process)
As the spatial merge candidate derivation process, the merge candidate derivation unit 30361 reads and reads the prediction parameters (prediction list use flag predFlagLX, motion vector mvLX, reference picture index refIdxLX) stored in the prediction parameter memory 307 according to a predetermined rule. The predicted parameters are derived as merge candidates. The prediction parameter to be read is a prediction parameter related to each of the PUs within a predetermined range from the target PU (for example, all or part of the PUs in contact with the lower left end, the upper left end, and the upper right end of the target PU, respectively). The merge candidates derived by the merge candidate deriving unit 30361 are stored in the merge candidate storage unit 30363.

(Time merge candidate derivation process)
As the temporal merge derivation process, the merge candidate derivation unit 30361 reads the prediction parameter of the PU in the reference image including the lower right coordinate of the target PU from the prediction parameter memory 307 and sets it as a merge candidate. The reference picture designation method may be, for example, the reference picture index refIdxLX designated in the slice header, or may be designated by using the smallest reference picture index refIdxLX of the PU adjacent to the target PU. The merge candidates derived by the merge candidate deriving unit 30361 are stored in the merge candidate storage unit 30363.

(Join merge candidate derivation process)
As the merge merge derivation process, the merge candidate derivation unit 30361 uses two different derived merge candidate motion vectors and reference picture indexes already derived and stored in the merge candidate storage unit 30363 as the motion vectors of L0 and L1, respectively. Combined merge candidates are derived by combining them. The merge candidates derived by the merge candidate deriving unit 30361 are stored in the merge candidate storage unit 30363.

(Zero merge candidate derivation process)
As the zero merge candidate derivation process, the merge candidate derivation unit 30361 derives a merge candidate in which the reference picture index refIdxLX is 0 and both the X component and the Y component of the motion vector mvLX are 0. The merge candidates derived by the merge candidate deriving unit 30361 are stored in the merge candidate storage unit 30363.

The merge candidate selection unit 30362 selects, from the merge candidates stored in the merge candidate storage unit 30363, a merge candidate to which an index corresponding to the merge index merge_idx input from the inter prediction parameter decoding control unit 3031 is assigned. As an inter prediction parameter. The merge candidate selection unit 30362 stores the selected merge candidate in the prediction parameter memory 307 and outputs it to the prediction image generation unit 308.

FIG. 8 is a schematic diagram showing the configuration of the AMVP prediction parameter derivation unit 3032 according to this embodiment. The AMVP prediction parameter derivation unit 3032 includes a vector candidate derivation unit 3033, a vector candidate selection unit 3034, and a vector candidate storage unit 3035. The vector candidate derivation unit 3033 derives a prediction vector candidate from the already processed PU motion vector stored in the prediction parameter memory 307 based on the reference picture index refIdx, and the prediction vector candidate list mvpListLX [] in the vector candidate storage unit 3035 To store.

The vector candidate selection unit 3034 selects the motion vector mvpListLX [mvp_LX_idx] indicated by the prediction vector index mvp_LX_idx from the prediction vector candidates in the prediction vector candidate list mvpListLX [] as the prediction vector mvpLX. The vector candidate selection unit 3034 outputs the selected prediction vector mvpLX to the addition unit 3035.

Note that a prediction vector candidate is a PU for which decoding processing has been completed, and is derived by scaling a motion vector of a PU (for example, an adjacent PU) within a predetermined range from the target PU. The adjacent PU includes a PU that is spatially adjacent to the target PU, for example, the left PU and the upper PU, and an area that is temporally adjacent to the target PU, for example, the same position as the target PU, and has different display times. Includes regions derived from PU prediction parameters.

The addition unit 3035 adds the prediction vector mvpLX input from the AMVP prediction parameter derivation unit 3032 and the difference vector mvdLX input from the inter prediction parameter decoding control unit 3031 to calculate a motion vector mvLX. The adding unit 3035 outputs the calculated motion vector mvLX to the predicted image generation unit 308 and the prediction parameter memory 307.

(Inter prediction image generation unit 309)
FIG. 11 is a schematic diagram illustrating a configuration of an inter predicted image generation unit 309 included in the predicted image generation unit 308 according to the present embodiment. The inter prediction image generation unit 309 includes a motion compensation unit (prediction image generation device) 3091 and a weight prediction unit 3094.

(Motion compensation)
The motion compensation unit 3091 receives the reference picture index refIdxLX from the reference picture memory 306 based on the inter prediction parameters (prediction list use flag predFlagLX, reference picture index refIdxLX, motion vector mvLX) input from the inter prediction parameter decoding unit 303. In the reference picture specified in (2), an interpolation image (motion compensation image) is generated by reading out a block at a position shifted by the motion vector mvLX starting from the position of the target PU. Here, when the accuracy of the motion vector mvLX is not integer accuracy, a motion compensation image is generated by applying a filter for generating a pixel at a decimal position called a motion compensation filter.

(Weight prediction)
The weight prediction unit 3094 generates a prediction image of the PU by multiplying the input motion compensation image predSamplesLX by a weight coefficient. When one of the prediction list use flags (predFlagL0 or predFlagL1) is 1 (in the case of single prediction) and the weight prediction is not used, the input motion compensated image predSamplesLX (LX is L0 or L1) is represented by the number of pixel bits bitDepth The following equation is processed to match

predSamples [X] [Y] = Clip3 (0, (1 << bitDepth)-1, (predSamplesLX [X] [Y] + offset1) >> shift1)
Here, shift1 = 14−bitDepth, offset1 = 1 << (shift1-1).
When both of the reference list use flags (predFlagL0 and predFlagL1) are 1 (in the case of bi-prediction BiPred) and weight prediction is not used, the input motion compensation images predSamplesL0 and predSamplesL1 are averaged and the number of pixel bits The following equation is processed to match

predSamples [X] [Y] = Clip3 (0, (1 << bitDepth)-1, (predSamplesL0 [X] [Y] + predSamplesL1 [X] [Y] + offset2) >> shift2)
Here, shift2 = 15-bitDepth, offset2 = 1 << (shift2-1).

Furthermore, in the case of single prediction, when performing weight prediction, the weight prediction unit 3094 derives the weight prediction coefficient w0 and the offset o0 from the encoded data, and performs the processing of the following equation.

predSamples [X] [Y] = Clip3 (0, (1 << bitDepth)-1, ((predSamplesLX [X] [Y] * w0 + 2 ^ (log2WD-1)) >> log2WD) + o0)
Here, log2WD is a variable indicating a predetermined shift amount.

Furthermore, in the case of bi-prediction BiPred, when performing weight prediction, the weight prediction unit 3094 derives weight prediction coefficients w0, w1, o0, o1 from the encoded data, and performs the processing of the following equation.

predSamples [X] [Y] = Clip3 (0, (1 << bitDepth)-1, (predSamplesL0 [X] [Y] * w0 + predSamplesL1 [X] [Y] * w1 + ((o0 + o1 + 1) << log2WD)) >> (log2WD + 1))
<Motion vector decoding process>
Below, with reference to FIG. 9, the motion vector decoding process which concerns on this embodiment is demonstrated concretely.

As is clear from the above description, the motion vector decoding process according to the present embodiment includes a process of decoding syntax elements related to inter prediction (also referred to as motion syntax decoding process) and a process of deriving a motion vector ( Motion vector derivation process).

(Motion syntax decoding process)
FIG. 9 is a flowchart illustrating a flow of inter prediction syntax decoding processing performed by the inter prediction parameter decoding control unit 3031. In the following description of FIG. 9, each process is performed by the inter prediction parameter decoding control unit 3031 unless otherwise specified.

First, in step S101, the merge flag merge_flag is decoded, and in step S102,
merge_flag! = 0 (whether merge_flag is not 0)
Is judged.

When merge_flag! = 0 is true (Y in S102), the merge index merge_idx is decoded in S103, and the motion vector derivation process (S111) in the merge mode is executed.

When merge_flag! = 0 is false (N in S102), the inter prediction identifier inter_pred_idc is decoded in S104.

When inter_pred_idc is other than PRED_L1 (PRED_L0 or PRED_BI), the reference picture index refIdxL0, the difference vector parameter mvdL0, and the prediction vector index mvp_L0_idx are decoded in S105, S106, and S107, respectively.

When inter_pred_idc is other than PRED_L0 (PRED_L1 or PRED_BI), the reference picture index refIdxL1, the difference vector parameter mvdL1, and the prediction vector index mvp_L1_idx are decoded in S108, S109, and S110. Subsequently, a motion vector derivation process (S112) in the AMVP mode is executed.

(Effect of image decoding device)
In the image decoding device 31 of the present embodiment, the affine prediction unit 30372 performs either 4-parameter affine or 6-parameter affine processing based on the shape or / and size of the target PU. Therefore, highly reliable affine parameters can be derived. It is also possible to reduce the amount of code when the affine parameter is explicitly encoded.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described. In the first embodiment, the inter prediction parameter decoding unit 303 determines whether to perform 4-parameter affine or 6-parameter affine processing based on the shape or size of the target PU. In the present embodiment, the inter prediction parameter decoding unit 303 selects any one of 4-parameter affine and 6-parameter affine based on the shape or size of a block (adjacent block, merge reference block in the case of merging) adjacent to the target PU. Decide whether to perform processing. Note that the configuration of the inter prediction parameter decoding unit 303 is the same as that described in the first embodiment, and therefore will not be described again.

FIG. 28 is a flowchart illustrating an example of processing in which the inter prediction parameter decoding unit 303 determines which of 4-parameter affine and 6-parameter affine is to be performed based on the shape of an adjacent block. In the example illustrated in FIG. 28, in the inter prediction parameter decoding unit 303, first, the inter prediction parameter decoding control unit 3031 determines whether the width (neighWidth) and the height (neighHeight) of adjacent blocks are equal (SH1). In FIG. 28 and FIG. 29 described later, “neighWidth” and “neighHeight” are described as “width” and “height”, respectively.

When the width and height of adjacent blocks are equal (Y in SH1), the affine prediction unit 30372 (or AMVP prediction parameter decoding unit 3032) performs 6-parameter affine processing (SH2). When the width of the target PU is not equal to the height of the target PU (N in SH1), the affine prediction unit 30372 (or AMVP prediction parameter decoding unit 3032) performs a 4-parameter affine process (SH3).

(Determined by the shape of the merge reference block)
FIG. 29 is a diagram for explaining an example of selection of the number of control points by the processing shown in FIG. In FIG. 29, PU indicates a target PU and RB indicates an adjacent block.

In the example shown in FIG. 29A, the width and height of adjacent blocks are not equal. Accordingly, the affine prediction unit 30372 refers to two motion vectors (for example, v2 and v3) on adjacent blocks, derives a motion vector of two control points (for example, V1 and V2) on the target block, and processes four-parameter affine Execute.

In the example shown in FIG. 29B, the width and height of the adjacent block are not equal. Therefore, the affine prediction unit 30372 derives a motion vector of two control points (for example, V1 and V2) on the target block by referring to two motion vectors (for example, v1 and v3) on the adjacent block, and performs a four-parameter affine process Execute.

In the example shown in (c) of FIG. 29, the width and height of the adjacent block are equal. Therefore, the affine prediction unit 30372 derives motion vectors of three control points (for example, V0, V1, and V2) on the target block by referring to three motion vectors (for example, v1, v2, and v3) on adjacent blocks, and 6 Perform parameter affine processing.

In the example shown in FIG. 29 (d), the width and height of the adjacent blocks are equal. Therefore, the affine prediction unit 30372 refers to three motion vectors (for example, v0, v1, and v2) on adjacent blocks, derives motion vectors of three control points (for example, V0, V1, and V2) on the target block, and 6 Perform parameter affine processing.

In the description of FIGS. 29A to 29D, the affine prediction unit 30372 has been described to perform 4-parameter affine or 6-parameter affine processing. However, the AMVP prediction parameter decoding unit 3032 has 4-parameter affine or 6-parameter affine processing. Affine processing may be performed.

(Determined by the size of the merge reference block)
FIG. 30 is a flowchart illustrating an example of processing in which the inter prediction parameter decoding unit 303 determines whether to perform 4-parameter affine or 6-parameter affine processing based on the size of an adjacent block. In the example illustrated in FIG. 30, the inter prediction parameter decoding control unit 3031 first determines whether a value indicating the size of an adjacent block is equal to or greater than a predetermined threshold (SI1). When the value indicating the size of the adjacent block is equal to or greater than a predetermined threshold (Y in SI1), the affine prediction unit 30372 (or AMVP prediction parameter decoding unit 3032) performs a 6-parameter affine process (SI2). When the value indicating the size of the adjacent block is not equal to or greater than the predetermined threshold (N in SI1), the affine prediction unit 30372 (or AMVP prediction parameter decoding unit 3032) performs 4-parameter affine processing (SI3).

FIG. 31 is a diagram for explaining an example of selection of the number of control points by the process shown in FIG. In FIG. 31, PU indicates a target PU, and RB indicates an adjacent block. In the following description, log2 (neighWidth) + log2 (neighHeight) is used as a value indicating the size of the adjacent block.

FIGS. 31A and 31B show examples in which the size of the adjacent block is smaller than the predetermined threshold TH. FIGS. 31C and 31D show that the size of the adjacent block is equal to or larger than the predetermined threshold TH. Here is an example. In the example of FIG. 31, the size of the target block is 8 × 8 (log2 (puWidth) + log2 (puHeight) = 6), the sizes of adjacent blocks of (a), (b), (c), and (d) are each Although an example in which 4 × 4, 4 × 4, 8 × 8, 4 × 8, and TH = 5 is shown, the sizes and threshold values of the target block and the reference block are not limited thereto.

In the example shown in FIG. 31A, the size of the adjacent block is smaller than a predetermined threshold TH (log2 (neighWidth) + log2 (neighHeight) <TH). Accordingly, the affine prediction unit 30372 refers to two motion vectors (for example, v2 and v3) on adjacent blocks, derives a motion vector of two control points (for example, V1 and V2) on the target block, and processes four-parameter affine Execute.

In the example shown in FIG. 31 (b), the size of the adjacent block is smaller than the predetermined threshold TH (log2 (neighWidth) + log2 (neighHeight) <TH). Therefore, the affine prediction unit 30372 derives a motion vector of two control points (for example, V1 and V2) on the target block by referring to two motion vectors (for example, v1 and v3) on the adjacent block, and performs a four-parameter affine process Execute.

In the example shown in FIG. 31 (c), the size of the adjacent block is equal to or greater than a predetermined threshold TH (log2 (neighWidth) + log2 (neighHeight)> = TH). Therefore, the affine prediction unit 30372 derives motion vectors of three control points (for example, V0, V1, and V2) on the target block by referring to three motion vectors (for example, v1, v2, and v3) on adjacent blocks, and 6 Perform parameter affine processing.

In the example shown in (d) of FIG. 31, the size of the adjacent block is equal to or larger than a predetermined threshold TH (log2 (neighWidth) + log2 (neighHeight)> = TH). Therefore, the affine prediction unit 30372 refers to three motion vectors (for example, v0, v1, and v3) on adjacent blocks, derives motion vectors of three control points (for example, V0, V1, and V2) on the target block, and 6 Perform parameter affine processing.

As the value indicating the size of the target PU, for example, the following can be used.
Max (neighWidth, neighHeight)
・ Min (neighWidth, neighHeight)
・ NeighWidth + neighHeight
・ NeighWidth * neighHeight
・ Log2 (neighWidth) + log2 (neighHeight)
However, the value indicating the size of the target PU is not limited to the above example.

Further, the determination on the size of the adjacent block may be as follows.
-Is the target PU size larger than a predetermined threshold?
-Is the size of the target PU less than or equal to a predetermined threshold?
-Is the size of the target PU smaller than a predetermined threshold?

(Effect of image decoding device)
In the image decoding device 31 of the present embodiment, the affine prediction unit 30372 performs either 4-parameter affine or 6-parameter affine processing based on the shape or size of the adjacent block. Such an inter prediction parameter decoding unit 303 can also derive highly reliable affine parameters. It is also possible to reduce the amount of code when the affine parameter is explicitly encoded.

(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described. In the first embodiment, the inter prediction parameter decoding unit 303 determines whether to perform 4-parameter affine or 6-parameter affine processing based on the shape or size of the target PU. This embodiment relates to selection of control points in a four parameter affine. In the present embodiment, the inter prediction parameter decoding unit 303 may switch either 4-parameter affine or 6-parameter affine processing, or may always perform 4-parameter affine processing. The inter prediction parameter decoding unit 303 of the present embodiment determines the position of the control point from which the motion vector used for the 4-parameter affine is derived based on the shape of the target PU.

FIG. 32 is a flowchart of processing in which the inter prediction parameter decoding unit 303 determines the position of a control point from which a motion vector is derived based on the shape of the target PU. In the example illustrated in FIG. 32, in the inter prediction parameter decoding unit 303, the inter prediction parameter decoding control unit 3031 first determines whether the target PU is a square (SJ1). When the target PU is a square (Y in SJ1), the inter prediction parameter decoding control unit 3031 uses two vertices on the diagonal of the target PU as control points (SJ2). When the target PU is not a square (N in SJ1), the inter prediction parameter decoding control unit 3031 uses two vertices sandwiching the long side of the target PU as control points (SJ3). Thereafter, the affine prediction unit 30372 (or AMVP prediction parameter decoding unit 3032) performs four-parameter affine processing using the selected control point (SJ4).

FIG. 33 is a diagram illustrating an example of the position of the control point determined by the inter prediction parameter decoding unit 303 of the present embodiment. As shown in FIG. 33A, when the shape of the target PU is a square, the inter prediction parameter decoding unit 303 assigns two vertices (for example, control points V1 and V2) on the diagonal line of the target PU to 4 It is determined as a control point used for parameter affine processing.

When the shape of the target PU is not square as shown in (b) and (c) of FIG. 33, the inter prediction parameter decoding unit 303 uses the two vertices sandwiching the long side of the target PU for 4-parameter affine processing. It is determined as a control point to be used. Specifically, in the example illustrated in FIG. 33B, for example, the inter prediction parameter decoding unit 303 derives motion vectors of the control points V0 and V2, and uses the motion vectors for 4-parameter affine. Also, for example, in the example shown in (c) of FIG. 33, the inter prediction parameter decoding unit 303 derives the motion vectors of the control points V0 and V1, and uses the motion vectors for the 4-parameter affine.

The inter prediction parameter decoding unit 303 of the present embodiment determines the position of the control point according to the shape of the target PU. Therefore, the accuracy of the motion vector used for the 4-parameter affine by the inter prediction parameter decoding unit 303 is improved.

In the above example, the inter prediction parameter decoding unit 303 switches the control points to be referenced in three patterns when the shape of the target PU is a square, a horizontally long rectangle, and a vertically long rectangle. As a simple configuration, the control points may be switched in two patterns. For example, if the shape of the target PU is puWidth0> = puHeight, the inter prediction parameter decoding unit 303 determines the control points V0 and V1 as control points, and otherwise (puWidth <puHeight), the control points V0 and V2 Is determined as a control point. Moreover, the following structures may be sufficient. The inter prediction parameter decoding unit 303 determines the control points V0 and V1 as control points when the shape of the target PU is puWidth> puHeight, and controls the control points V0 and V2 otherwise (puWidth <= puHeight). Determine as a point.

(Fourth embodiment)
The fourth embodiment of the present invention will be described below. In the second embodiment, the inter prediction parameter decoding unit 303 determines whether to perform 4-parameter affine processing or 6-parameter affine processing based on the shape or size of adjacent blocks. This embodiment relates to selection of control points in a four parameter affine. In the present embodiment, the inter prediction parameter decoding unit 303 may switch either 4-parameter affine or 6-parameter affine processing, or may always perform 4-parameter affine processing. At this time, the inter prediction parameter decoding unit 303 changes the control points used for the 4-parameter affine processing according to the shape of the adjacent block. Specifically, the inter prediction parameter decoding unit 303 determines the position of the control point in the adjacent block from which the motion vector used for the 4-parameter affine is derived based on the shape of the adjacent block.

FIG. 34 is a flowchart of a process in which the inter prediction parameter decoding unit 303 determines the position of the adjacent block point used for deriving the motion vector of the control point based on the shape of the adjacent block. In the example illustrated in FIG. 34, in the inter prediction parameter decoding unit 303, the inter prediction parameter decoding control unit 3031 first determines whether the adjacent block is a square (SK1). When the adjacent block is a square (Y in SK1), the inter prediction parameter decoding control unit 3031 determines two points on the diagonal line of the adjacent block to be used for derivation of the motion vector of the control point (SK2). When the adjacent block is not square (N in SK1), the inter prediction parameter decoding control unit 3031 determines the points used for deriving the motion vector of the control point as two points sandwiching the long side of the adjacent block (SK3). Thereafter, the affine prediction unit 30372 (or AMVP prediction parameter decoding unit 3032) derives a motion vector of the control point using the points of the selected adjacent block, and performs 4-parameter affine processing (SK4).

FIG. 35 is a diagram illustrating an example of control point positions determined by the inter prediction parameter decoding unit 303 of the present embodiment. When the shape of the adjacent block is a square as shown in FIGS. 35A and 35B, the inter prediction parameter decoding unit 303 positions two vertices on the diagonal line of the adjacent block (for example, the upper left position of the adjacent block). The motion vectors of two control points (for example, V1 and V2) on the target block are derived by referring to the motion vectors of the point v0 and the point v3 located on the lower right), and the four-parameter affine processing is executed.

When the shape of the adjacent block is rectangular as shown in FIGS. 35C to 35F, the inter prediction parameter decoding unit 303 refers to the motion vectors of the two vertices sandwiching the long side of the adjacent block. Thus, motion vectors of two control points (for example, V1 and V2) on the target block are derived, and a 4-parameter affine process is executed. For example, as illustrated in FIGS. 35C and 35D, when the shape of the adjacent block is a rectangle longer in the height direction than the width direction, the inter prediction parameter decoding unit 303 determines the height of the adjacent block. The motion vectors of two points located at both ends of the side (for example, the point v1 located at the upper right and the point v3 located at the lower right of the adjacent block) are used. For example, as shown in FIGS. 35 (e) and 35 (f), when the shape of the adjacent block is a rectangle longer in the width direction than the height direction, the inter prediction parameter decoding unit 303 uses the side in the width direction of the adjacent block. Motion vectors of two points located at both ends (for example, the point v2 located at the lower left and the point v3 located at the lower right of the adjacent block) are used.

The inter prediction parameter decoding unit 303 of the present embodiment determines the position of the vertex in the adjacent block used for deriving the motion vectors of the two control points on the target block according to the shape of the adjacent block. Such an inter prediction parameter decoding unit 303 also improves the accuracy of motion vectors used by the inter prediction parameter decoding unit 303 for 4-parameter affine.

(Fifth embodiment)
The fifth embodiment of the present invention will be described below. In the fourth embodiment, the inter prediction parameter decoding unit 303 determines the positions of the vertices in the adjacent block used for deriving the motion vectors of the two control points on the target block based on the shape of the adjacent block. In the present embodiment, the inter prediction parameter decoding unit 303 determines the position of the control point in the target PU based on the shape of the adjacent block.

FIG. 36 is a flowchart of processing in which the inter prediction parameter decoding unit 303 determines the position of a control point from which a motion vector is derived based on the shape of an adjacent block. In the example illustrated in FIG. 36, in the inter prediction parameter decoding unit 303, the inter prediction parameter decoding control unit 3031 first determines whether the adjacent block is a square (SL1). When the adjacent block is a square (Y in SL1), the inter prediction parameter decoding control unit 3031 uses two vertices on the diagonal line of the target PU as control points (SL2). When the adjacent block is not square (N in SL1), the inter prediction parameter decoding control unit 3031 sets two vertices sandwiching the side of the target PU adjacent to the adjacent block as control points (SL3). Thereafter, the affine prediction unit 30372 (or AMVP prediction parameter decoding unit 3032) performs 4-parameter affine processing using the selected control point (SL4).

FIG. 37 is a diagram illustrating an example of the position of the control point determined by the inter prediction parameter decoding unit 303 of the present embodiment. When the shape of the adjacent block is square as shown in FIGS. 37A and 37B, the inter prediction parameter decoding unit 303 determines two vertices (for example, V0 and V3) on the diagonal line of the target PU. It is determined as a control point used for the 4-parameter affine.

When the shape of the adjacent block is a rectangle as shown in (c) to (f) of FIG. 37, the inter prediction parameter decoding unit 303 selects two vertices sandwiching the side of the target PU that is in contact with the adjacent block. It is determined as a control point used for the 4-parameter affine. For example, as illustrated in (c) and (e) of FIG. 37, when the adjacent block is in contact with the left side of the target PU, the inter prediction parameter decoding unit 303 determines the side of the target PU in contact with the adjacent block. Two points (point V1 located at the upper left of the target PU and point V3 located at the lower left of the target PU) are set as control points. For example, as illustrated in (d) or (f) of FIG. 37, when the adjacent block is in contact with the upper side of the target PU, the inter prediction parameter decoding unit 303 determines the side of the target PU in contact with the adjacent block. Two points (point V0 located at the upper left of the target PU and point V1 located at the upper right) of the target PU are set as control points.

The inter prediction parameter decoding unit 303 of the present embodiment determines the position of the control point in the adjacent block according to the shape of the adjacent block. Such an inter prediction parameter decoding unit 303 also improves the accuracy of motion vectors used by the inter prediction parameter decoding unit 303 for 4-parameter affine.

(Configuration of image encoding device)
Next, the configuration of the image encoding device 11 (moving image encoding device) according to the present embodiment will be described. FIG. 4 is a block diagram illustrating a configuration of the image encoding device 11 according to the present embodiment. The image encoding device 11 includes a prediction image generation unit 101, a subtraction unit 102, a DCT / quantization unit 103, an entropy encoding unit 104, an inverse quantization / inverse DCT unit 105, an addition unit 106, a loop filter 107, and a prediction parameter memory. (Prediction parameter storage unit, frame memory) 108, reference picture memory (reference image storage unit, frame memory) 109, encoding parameter determination unit 110, and prediction parameter encoding unit 111. The prediction parameter encoding unit 111 includes an inter prediction parameter encoding unit 112 (prediction image generation device) and an intra prediction parameter encoding unit 113.

The predicted image generation unit 101 generates, for each picture of the image T, a predicted image P of the prediction unit PU for each encoding unit CU that is an area obtained by dividing the picture. Here, the predicted image generation unit 101 reads a decoded block from the reference picture memory 109 based on the prediction parameter input from the prediction parameter encoding unit 111. The prediction parameter input from the prediction parameter encoding unit 111 is, for example, a motion vector in the case of inter prediction. The predicted image generation unit 101 reads a block at a position on the reference image indicated by the motion vector with the target PU as a starting point. In the case of intra prediction, the prediction parameter is, for example, an intra prediction mode. A pixel value of an adjacent PU used in the intra prediction mode is read from the reference picture memory 109, and a predicted image P of the PU is generated. The predicted image generation unit 101 generates a predicted image P of the PU using one prediction method among a plurality of prediction methods for the read reference picture block. The predicted image generation unit 101 outputs the generated predicted image P of the PU to the subtraction unit 102.

Note that the predicted image generation unit 101 performs the same operation as the predicted image generation unit 308 already described. For example, FIG. 6 is a schematic diagram illustrating a configuration of an inter predicted image generation unit 1011 included in the predicted image generation unit 101. The inter prediction image generation unit 1011 includes a motion compensation unit 10111 and a weight prediction unit 10112. Since the motion compensation unit 10111 and the weight prediction unit 10112 have the same configurations as the motion compensation unit 3091 and the weight prediction unit 3094 described above, description thereof is omitted here.

The prediction image generation unit 101 generates a prediction image P of the PU based on the pixel value of the reference block read from the reference picture memory, using the parameter input from the prediction parameter encoding unit. The predicted image generated by the predicted image generation unit 101 is output to the subtraction unit 102 and the addition unit 106.

The subtraction unit 102 subtracts the signal value of the predicted image P of the PU input from the predicted image generation unit 101 from the pixel value of the corresponding PU of the image T, and generates a residual signal. The subtraction unit 102 outputs the generated residual signal to the DCT / quantization unit 103.

The DCT / quantization unit 103 performs DCT on the residual signal input from the subtraction unit 102 and calculates a DCT coefficient. The DCT / quantization unit 103 quantizes the calculated DCT coefficient to obtain a quantization coefficient. The DCT / quantization unit 103 outputs the obtained quantization coefficient to the entropy coding unit 104 and the inverse quantization / inverse DCT unit 105.

The entropy encoding unit 104 receives the quantization coefficient from the DCT / quantization unit 103 and receives the encoding parameter from the prediction parameter encoding unit 111. Examples of input encoding parameters include codes such as a reference picture index refIdxLX, a prediction vector index mvp_LX_idx, a difference vector mvdLX, a prediction mode predMode, and a merge index merge_idx.

The entropy encoding unit 104 generates an encoded stream Te by entropy encoding the input quantization coefficient and encoding parameter, and outputs the generated encoded stream Te to the outside.

The inverse quantization / inverse DCT unit 105 inversely quantizes the quantization coefficient input from the DCT / quantization unit 103 to obtain a DCT coefficient. The inverse quantization / inverse DCT unit 105 performs inverse DCT on the obtained DCT coefficient to calculate a residual signal. The inverse quantization / inverse DCT unit 105 outputs the calculated residual signal to the addition unit 106.

The addition unit 106 adds the signal value of the prediction image P of the PU input from the prediction image generation unit 101 and the signal value of the residual signal input from the inverse quantization / inverse DCT unit 105 for each pixel, and performs decoding. Generate an image. The adding unit 106 stores the generated decoded image in the reference picture memory 109.

The loop filter 107 performs a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) on the decoded image generated by the adding unit 106.

The prediction parameter memory 108 stores the prediction parameter generated by the encoding parameter determination unit 110 at a predetermined position for each encoding target picture and CU.

The reference picture memory 109 stores the decoded image generated by the loop filter 107 at a predetermined position for each picture to be encoded and each CU.

The encoding parameter determination unit 110 selects one set from among a plurality of sets of encoding parameters. The encoding parameter is a parameter to be encoded that is generated in association with the above-described prediction parameter or the prediction parameter. The predicted image generation unit 101 generates a predicted image P of the PU using each of these encoding parameter sets.

The encoding parameter determination unit 110 calculates a cost value indicating the amount of information and the encoding error for each of a plurality of sets. The cost value is, for example, the sum of a code amount and a square error multiplied by a coefficient λ. The code amount is the information amount of the encoded stream Te obtained by entropy encoding the quantization error and the encoding parameter. The square error is the sum between pixels regarding the square value of the residual value of the residual signal calculated by the subtracting unit 102. The coefficient λ is a real number larger than a preset zero. The encoding parameter determination unit 110 selects a set of encoding parameters that minimizes the calculated cost value. As a result, the entropy encoding unit 104 outputs the selected set of encoding parameters to the outside as the encoded stream Te, and does not output the set of unselected encoding parameters. The encoding parameter determination unit 110 stores the determined encoding parameter in the prediction parameter memory 108.

The prediction parameter encoding unit 111 derives a format for encoding from the parameters input from the encoding parameter determination unit 110 and outputs the format to the entropy encoding unit 104. Deriving the format for encoding is, for example, deriving a difference vector from a motion vector and a prediction vector. Also, the prediction parameter encoding unit 111 derives parameters necessary for generating a prediction image from the parameters input from the encoding parameter determination unit 110 and outputs the parameters to the prediction image generation unit 101. The parameter necessary for generating the predicted image is, for example, a motion vector in units of sub-blocks.

The inter prediction parameter encoding unit 112 derives an inter prediction parameter such as a difference vector based on the prediction parameter input from the encoding parameter determination unit 110. The inter prediction parameter encoding unit 112 derives parameters necessary for generating a prediction image to be output to the prediction image generating unit 101, and an inter prediction parameter decoding unit 303 (see FIG. 5 and the like) derives inter prediction parameters. Some of the configurations are the same as the configuration to be performed. The configuration of the inter prediction parameter encoding unit 112 will be described later.

The intra prediction parameter encoding unit 113 derives a format (for example, MPM_idx, rem_intra_luma_pred_mode) for encoding from the intra prediction mode IntraPredMode input from the encoding parameter determination unit 110.

(Configuration of inter prediction parameter encoding unit)
Next, the configuration of the inter prediction parameter encoding unit 112 will be described. The inter prediction parameter encoding unit 112 is a unit corresponding to the inter prediction parameter decoding unit 303 in FIG. 12, and the configuration is shown in FIG.

The inter prediction parameter encoding unit 112 includes an inter prediction parameter encoding control unit 1121, an AMVP prediction parameter deriving unit 1122 (affine motion vector deriving unit, affine motion vector deriving device), a subtracting unit 1123, a sub-block prediction parameter deriving unit 1125, And a partition mode deriving unit, a merge flag deriving unit, an inter prediction identifier deriving unit, a reference picture index deriving unit, a vector difference deriving unit, etc. The deriving unit, the reference picture index deriving unit, and the vector difference deriving unit derive a PU partition mode part_mode, a merge flag merge_flag, an inter prediction identifier inter_pred_idc, a reference picture index refIdxLX, and a difference vector mvdLX, respectively. The inter prediction parameter encoding unit 112 outputs the motion vector (mvLX, subMvLX), the reference picture index refIdxLX, the PU partition mode part_mode, the inter prediction identifier inter_pred_idc, or information indicating these to the prediction image generating unit 101. Also, the inter prediction parameter encoding unit 112 entropy PU partition mode part_mode, merge flag merge_flag, merge index merge_idx, inter prediction identifier inter_pred_idc, reference picture index refIdxLX, prediction vector index mvp_LX_idx, difference vector mvdLX, sub-block prediction mode flag subPbMotionFlag. The data is output to the encoding unit 104.

The inter prediction parameter encoding control unit 1121 includes a merge index deriving unit 11211 and a vector candidate index deriving unit 11212. The merge index derivation unit 11211 compares the motion vector and reference picture index input from the encoding parameter determination unit 110 with the motion vector and reference picture index of the merge candidate PU read from the prediction parameter memory 108, and performs merge An index merge_idx is derived and output to the entropy encoding unit 104. A merge candidate is a reference PU (for example, a reference PU that touches the lower left end, upper left end, and upper right end of the encoding target block) within a predetermined range from the encoding target CU to be encoded. The PU has been processed. The vector candidate index deriving unit 11212 derives a prediction vector index mvp_LX_idx.

When the encoding parameter determination unit 110 determines to use the sub-block prediction mode, the sub-block prediction parameter derivation unit 1125 includes any of spatial sub-block prediction, temporal sub-block prediction, affine prediction, and matching prediction according to the value of subPbMotionFlag. A motion vector and a reference picture index for subblock prediction are derived. As described in the description of the image decoding apparatus, the motion vector and the reference picture index are derived by reading out the motion vector and the reference picture index such as the adjacent PU and the reference picture block from the prediction parameter memory 108. Specifically, the sub-block prediction parameter deriving unit 1125 has the same configuration as the above-described sub-block prediction parameter deriving unit 3037 (see FIG. 12).

The AMVP prediction parameter derivation unit 1122 has the same configuration as the AMVP prediction parameter derivation unit 3032 (see FIG. 12).

That is, when the prediction mode predMode indicates the inter prediction mode, the motion vector mvLX is input from the encoding parameter determination unit 110 to the AMVP prediction parameter derivation unit 1122. The AMVP prediction parameter derivation unit 1122 derives a prediction vector mvpLX based on the input motion vector mvLX. The AMVP prediction parameter derivation unit 1122 outputs the derived prediction vector mvpLX to the subtraction unit 1123. Note that the reference picture index refIdx and the prediction vector index mvp_LX_idx are output to the entropy encoding unit 104.

The subtraction unit 1123 subtracts the prediction vector mvpLX input from the AMVP prediction parameter derivation unit 1122 from the motion vector mvLX input from the coding parameter determination unit 110 to generate a difference vector mvdLX. The difference vector mvdLX is output to the entropy encoding unit 104.

Note that a part of the image encoding device 11 and the image decoding device 31 in the above-described embodiment, for example, the entropy decoding unit 301, the prediction parameter decoding unit 302, the loop filter 305, the predicted image generation unit 308, the inverse quantization / inverse DCT. Unit 311, addition unit 312, predicted image generation unit 101, subtraction unit 102, DCT / quantization unit 103, entropy encoding unit 104, inverse quantization / inverse DCT unit 105, loop filter 107, encoding parameter determination unit 110, The prediction parameter encoding unit 111 may be realized by a computer. In that case, the program for realizing the control function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read by a computer system and executed. Here, the “computer system” is a computer system built in either the image encoding device 11 or the image decoding device 31 and includes hardware such as an OS and peripheral devices. The “computer-readable recording medium” refers to a storage device such as a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a hard disk built in a computer system. Furthermore, the “computer-readable recording medium” is a medium that dynamically holds a program for a short time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, In such a case, a volatile memory inside a computer system serving as a server or a client may be included and a program that holds a program for a certain period of time. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

Further, part or all of the image encoding device 11 and the image decoding device 31 in the above-described embodiment may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each functional block of the image encoding device 11 and the image decoding device 31 may be individually made into a processor, or a part or all of them may be integrated into a processor. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. Further, in the case where an integrated circuit technology that replaces LSI appears due to progress in semiconductor technology, an integrated circuit based on the technology may be used.

As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the scope of the present invention. It is possible to

[Application example]
The image encoding device 11 and the image decoding device 31 described above can be used by being mounted on various devices that perform transmission, reception, recording, and reproduction of moving images. The moving image may be a natural moving image captured by a camera or the like, or an artificial moving image (including CG and GUI) generated by a computer or the like.

First, it will be described with reference to FIG. 38 that the image encoding device 11 and the image decoding device 31 described above can be used for transmission and reception of moving images.

(A) of FIG. 38 is a block diagram illustrating a configuration of a transmission device PROD_A in which the image encoding device 11 is mounted. As shown in (a) of FIG. 38, the transmission apparatus PROD_A modulates a carrier wave with an encoding unit PROD_A1 that obtains encoded data by encoding a moving image, and with the encoded data obtained by the encoding unit PROD_A1. Thus, a modulation unit PROD_A2 that obtains a modulation signal and a transmission unit PROD_A3 that transmits the modulation signal obtained by the modulation unit PROD_A2 are provided. The above-described image encoding device 11 is used as the encoding unit PROD_A1.

Transmission device PROD_A, as a source of moving images to be input to the encoding unit PROD_A1, a camera PROD_A4 that captures moving images, a recording medium PROD_A5 that records moving images, an input terminal PROD_A6 for inputting moving images from the outside, and An image processing unit A7 that generates or processes an image may be further provided. In FIG. 38A, a configuration in which all of these are provided in the transmission device PROD_A is illustrated, but a part may be omitted.

Note that the recording medium PROD_A5 may be a recording of a non-encoded moving image, or a recording of a moving image encoded by a recording encoding scheme different from the transmission encoding scheme. It may be a thing. In the latter case, a decoding unit (not shown) for decoding the encoded data read from the recording medium PROD_A5 in accordance with the recording encoding method may be interposed between the recording medium PROD_A5 and the encoding unit PROD_A1.

(B) of FIG. 38 is a block diagram showing a configuration of the receiving device PROD_B in which the image decoding device 31 is mounted. As shown in (b) of FIG. 38, the receiving device PROD_B includes a receiving unit PROD_B1 that receives a modulated signal, a demodulating unit PROD_B2 that obtains encoded data by demodulating the modulated signal received by the receiving unit PROD_B1, and a demodulator A decoding unit PROD_B3 that obtains a moving image by decoding the encoded data obtained by the unit PROD_B2. The above-described image decoding device 31 is used as the decoding unit PROD_B3.

The receiving device PROD_B is a display destination PROD_B4 for displaying a moving image, a recording medium PROD_B5 for recording a moving image, and an output terminal for outputting the moving image to the outside as a supply destination of the moving image output by the decoding unit PROD_B3 PROD_B6 may be further provided. FIG. 38B illustrates a configuration in which all of these are provided in the receiving device PROD_B, but some of them may be omitted.

Note that the recording medium PROD_B5 may be used for recording a non-encoded moving image, or is encoded using a recording encoding method different from the transmission encoding method. May be. In the latter case, an encoding unit (not shown) for encoding the moving image acquired from the decoding unit PROD_B3 according to the recording encoding method may be interposed between the decoding unit PROD_B3 and the recording medium PROD_B5.

Note that the transmission medium for transmitting the modulation signal may be wireless or wired. Further, the transmission mode for transmitting the modulated signal may be broadcasting (here, a transmission mode in which the transmission destination is not specified in advance) or communication (here, transmission in which the transmission destination is specified in advance). Refers to the embodiment). That is, the transmission of the modulation signal may be realized by any of wireless broadcasting, wired broadcasting, wireless communication, and wired communication.

For example, a terrestrial digital broadcast broadcasting station (broadcasting equipment, etc.) / Receiving station (such as a television receiver) is an example of a transmitting device PROD_A / receiving device PROD_B that transmits and receives a modulated signal by wireless broadcasting. A broadcasting station (such as broadcasting equipment) / receiving station (such as a television receiver) of cable television broadcasting is an example of a transmitting device PROD_A / receiving device PROD_B that transmits and receives a modulated signal by cable broadcasting.

In addition, a server (workstation, etc.) / Client (television receiver, personal computer, smartphone, etc.) such as a VOD (Video On Demand) service or a video sharing service using the Internet is a transmission device that transmits and receives modulated signals via communication. This is an example of PROD_A / receiving device PROD_B (normally, either a wireless or wired transmission medium is used in a LAN, and a wired transmission medium is used in a WAN). Here, the personal computer includes a desktop PC, a laptop PC, and a tablet PC. The smartphone also includes a multi-function mobile phone terminal.

In addition to the function of decoding the encoded data downloaded from the server and displaying it on the display, the video sharing service client has a function of encoding a moving image captured by the camera and uploading it to the server. That is, the client of the video sharing service functions as both the transmission device PROD_A and the reception device PROD_B.

Next, the fact that the above-described image encoding device 11 and image decoding device 31 can be used for recording and reproduction of moving images will be described with reference to FIG.

FIG. 39A is a block diagram showing a configuration of a recording apparatus PROD_C equipped with the image encoding device 11 described above. As shown in (a) of FIG. 39, the recording apparatus PROD_C includes an encoding unit PROD_C1 that obtains encoded data by encoding a moving image, and the encoded data obtained by the encoding unit PROD_C1 on the recording medium PROD_M. A writing unit PROD_C2 for writing. The above-described image encoding device 11 is used as the encoding unit PROD_C1.

The recording medium PROD_M may be of a type built into the recording device PROD_C, such as (1) HDD (Hard Disk Drive) or SSD (Solid State Drive), or (2) SD memory. It may be of the type connected to the recording device PROD_C, such as a card or USB (Universal Serial Bus) flash memory, or (3) DVD (Digital Versatile Disc) or BD (Blu-ray Disc: registration) Or a drive device (not shown) built in the recording device PROD_C.

In addition, the recording device PROD_C is a camera PROD_C3 that captures moving images as a source of moving images to be input to the encoding unit PROD_C1, an input terminal PROD_C4 for inputting moving images from the outside, and a reception for receiving moving images A unit PROD_C5 and an image processing unit PROD_C6 for generating or processing an image may be further provided. FIG. 39A illustrates a configuration in which the recording apparatus PROD_C includes all of these, but a part of the configuration may be omitted.

The receiving unit PROD_C5 may receive a non-encoded moving image, or may receive encoded data encoded by a transmission encoding scheme different from the recording encoding scheme. You may do. In the latter case, a transmission decoding unit (not shown) that decodes encoded data encoded by the transmission encoding method may be interposed between the reception unit PROD_C5 and the encoding unit PROD_C1.

Examples of such a recording device PROD_C include a DVD recorder, a BD recorder, an HDD (Hard Disk Drive) recorder, and the like (in this case, the input terminal PROD_C4 or the receiver PROD_C5 is a main source of moving images). . In addition, a camcorder (in this case, the camera PROD_C3 is a main source of moving images), a personal computer (in this case, the receiving unit PROD_C5 or the image processing unit C6 is a main source of moving images), a smartphone (this In this case, the camera PROD_C3 or the reception unit PROD_C5 is a main source of moving images), and the like is also an example of such a recording apparatus PROD_C.

FIG. 39 (b) is a block diagram showing the configuration of a playback device PROD_D equipped with the above-described image decoding device 31. As shown in FIG. 39 (b), the playback device PROD_D reads a moving image by decoding a read unit PROD_D1 that reads encoded data written to the recording medium PROD_M and a read unit PROD_D1 that reads the encoded data. A decoding unit PROD_D2. The above-described image decoding device 31 is used as the decoding unit PROD_D2.

The recording medium PROD_M may be of the type built into the playback device PROD_D, such as (1) HDD or SSD, or (2) such as an SD memory card or USB flash memory. It may be of the type connected to the playback device PROD_D, or (3) may be loaded into a drive device (not shown) built in the playback device PROD_D, such as a DVD or BD. Good.

In addition, the playback device PROD_D has a display unit PROD_D3 that displays a moving image as a supply destination of the moving image output by the decoding unit PROD_D2, an output terminal PROD_D4 that outputs the moving image to the outside, and a transmission unit that transmits the moving image. PROD_D5 may be further provided. FIG. 39B illustrates a configuration in which the playback apparatus PROD_D includes all of these, but a part of the configuration may be omitted.

The transmission unit PROD_D5 may transmit a non-encoded moving image, or transmits encoded data encoded by a transmission encoding scheme different from the recording encoding scheme. You may do. In the latter case, it is preferable to interpose an encoding unit (not shown) that encodes a moving image using a transmission encoding method between the decoding unit PROD_D2 and the transmission unit PROD_D5.

Examples of such a playback device PROD_D include a DVD player, a BD player, and an HDD player (in this case, an output terminal PROD_D4 to which a television receiver or the like is connected is a main moving image supply destination). . In addition, a television receiver (in this case, the display PROD_D3 is a main supply destination of moving images), a digital signage (also referred to as an electronic signboard or an electronic bulletin board), and the display PROD_D3 or the transmission unit PROD_D5 is the main supply of moving images Desktop PC (in this case, output terminal PROD_D4 or transmission unit PROD_D5 is the main video source), laptop or tablet PC (in this case, display PROD_D3 or transmission unit PROD_D5 is video) A smartphone (which is a main image supply destination), a smartphone (in this case, the display PROD_D3 or the transmission unit PROD_D5 is a main moving image supply destination), and the like are also examples of such a playback device PROD_D.

(Hardware implementation and software implementation)
Each block of the image decoding device 31 and the image encoding device 11 described above may be realized in hardware by a logic circuit formed on an integrated circuit (IC chip), or may be a CPU (Central Processing Unit). You may implement | achieve by software using.

In the latter case, each of the above devices includes a CPU that executes instructions of a program that realizes each function, a ROM (Read Memory) that stores the program, a RAM (RandomAccess Memory) that develops the program, the program, and various data. A storage device (recording medium) such as a memory for storing the. The object of the embodiment of the present invention is a record in which the program code (execution format program, intermediate code program, source program) of the control program for each of the above devices, which is software that realizes the above-described functions, is recorded in a computer-readable manner This can also be achieved by supplying a medium to each of the above devices, and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

Examples of the recording medium include tapes such as magnetic tapes and cassette tapes, magnetic disks such as floppy (registered trademark) disks / hard disks, CD-ROMs (Compact Disc Read-Only Memory) / MO discs (Magneto-Optical discs). ) / MD (Mini Disc) / DVD (Digital Versatile Disc) / CD-R (CD Recordable) / Blu-ray Disc (Blu-ray Disc: registered trademark) and other optical disks, IC cards (including memory cards) / Cards such as optical cards, Mask ROM / EPROM (Erasable Programmable Read-Only Memory) / EEPROM (Electrically Erasable and Programmable Read-Only Memory: registered trademark) / Semiconductor memories such as flash ROM, or PLD (Programmable logic device ) Or FPGA (Field Programmable Gate Gate Array) or the like.

Further, each of the above devices may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited as long as it can transmit the program code. For example, Internet, intranet, extranet, LAN (Local Area Network), ISDN (Integrated Services Digital Network), VAN (Value-Added Network), CATV (Community Area Antenna / television / Cable Television), Virtual Private Network (Virtual Private Network) Network), telephone line network, mobile communication network, satellite communication network, and the like. The transmission medium constituting the communication network may be any medium that can transmit the program code, and is not limited to a specific configuration or type. For example, IEEE (Institute of Electrical and Electronic Engineers) 1394, USB, power line carrier, cable TV line, telephone line, ADSL (Asymmetric Digital Subscriber Line) line, etc. wired such as IrDA (Infrared Data Association) or remote control , BlueTooth (registered trademark), IEEE802.11 wireless, HDR (High Data Rate), NFC (Near Field Communication), DLNA (Digital Living Network Alliance: registered trademark), mobile phone network, satellite line, terrestrial digital broadcasting network, etc. It can also be used wirelessly. The embodiment of the present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

The embodiments of the present invention are not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

(Cross-reference of related applications)
This application claims the benefit of priority over Japanese patent application: Japanese Patent Application No. 2016-188791 filed on September 27, 2016. Is included in this document.

Embodiments of the present invention can be preferably applied to an image decoding apparatus that decodes encoded data in which image data is encoded, and an image encoding apparatus that generates encoded data in which image data is encoded. it can. Further, the present invention can be suitably applied to the data structure of encoded data generated by an image encoding device and referenced by the image decoding device.

11 Image Encoding Device 31 Image Decoding Device 112 Inter Prediction Parameter Encoding Unit (Predicted Image Generating Device)
303 Inter prediction parameter decoding unit (predicted image generation device)
1122, 3032 AMVP prediction parameter deriving unit (affine motion vector deriving unit, affine motion vector deriving device)
30372 Affine prediction unit (affine motion vector deriving unit, affine motion vector deriving device)
309 inter prediction image generation unit (prediction image generation unit)

Claims (17)

In the affine motion vector deriving device for deriving the motion vector of each of the sub-blocks constituting the target PU,
The affine motion vector deriving device is:
The motion vector of each of the plurality of sub-blocks included in the target block is calculated with reference to the motion vector at the control point set in the reference block sharing the vertex with the target block,
Depending on at least one of the shape and size of the target block, motion vectors of two control points are calculated and 4-parameter affine processing is performed, or motion vectors of three control points are calculated and 6-parameter affine is calculated. An affine motion vector deriving device characterized by switching whether to perform the process. In a predicted image generation apparatus for generating a predicted image used for encoding or decoding a moving image,
An affine motion vector deriving unit;
A prediction image generation unit,
The affine motion vector derivation unit includes:
The motion vector of each of the plurality of sub-blocks included in the target block is calculated with reference to the motion vector at the control point set in the reference block sharing the vertex with the target block,
Depending on at least one of the shape and size of the target block, motion vectors of two control points are calculated and 4-parameter affine processing is performed, or motion vectors of three control points are calculated and 6-parameter affine is calculated. Switch whether to process
The predicted image generation unit
A predicted image generation apparatus that generates a predicted image by referring to a motion vector of the control point. The affine motion vector derivation unit includes:
The predicted image generation apparatus according to claim 2, wherein 6-parameter affine processing is performed when the target block is square, and 4-parameter affine processing is performed when the target block is not square. The affine motion vector derivation unit includes:
When the merge flag merge_flag indicates that the merge process is not performed, and the target block is not a square, a 4-parameter affine process is performed,
When the merge flag merge_flag indicates that the merge process is not performed, and the target block is a square, the PU affine mode flag pu_affine_mode_flag is decoded, and the PU affine mode flag pu_affine_mode_flag is a 6-parameter affine process. 6-parameter affine processing is performed, and when the PU affine mode flag pu_affine_mode_flag indicates that 4-parameter affine processing is performed, 4-parameter affine processing is performed. The predicted image generation apparatus according to claim 2 or 3. The affine motion vector derivation unit includes:
The 6-parameter affine processing is performed when the size of the target block is equal to or larger than a predetermined threshold, and the 4-parameter affine processing is performed when the size of the target block is not equal to or larger than the predetermined threshold. The predicted image generation apparatus described in 1. The affine motion vector derivation unit includes:
When the merge flag merge_flag indicates that the merge process is not performed, and the size of the target block is not equal to or greater than a predetermined threshold, a 4-parameter affine process is performed.
When the merge flag merge_flag indicates that the merge process is not performed and the size of the target block is equal to or greater than a predetermined threshold, the PU affine mode flag pu_affine_mode_flag is decoded, and the PU affine mode flag pu_affine_mode_flag is 6-parameter affine processing is performed when 6-parameter affine processing is indicated, and 4-parameter affine processing is performed when the PU affine mode flag pu_affine_mode_flag indicates 4-parameter affine processing. The predicted image generation apparatus according to claim 5, wherein: The affine motion vector derivation unit includes:
The predicted image generation apparatus according to claim 2, wherein a 6-parameter affine process is performed when the size of the target block is equal to or larger than a predetermined threshold and the target block is a square. The affine motion vector derivation unit includes:
When the merge flag merge_flag indicates that the merge process is not performed, and the size of the target block is not equal to or larger than a predetermined threshold and the target block is not a square, a 4-parameter affine process is performed. ,
(1) The merge flag merge_flag indicates that the merge process is not performed, and the size of the target block is equal to or larger than a predetermined threshold, or (2) the merge flag merge_flag does not perform the merge process. When the size of the target block is not equal to or greater than a predetermined threshold and the target block is a square, the PU affine mode flag pu_affine_mode_flag is decoded, and the PU affine mode flag pu_affine_mode_flag is 6 When the parameter affine processing is indicated, the six parameter affine processing is performed. When the PU affine mode flag pu_affine_mode_flag indicates the four parameter affine processing, the four parameter affine processing is performed. The prediction image generation apparatus according to claim 7, wherein the prediction image generation apparatus performs the prediction image generation apparatus. In a predicted image generation apparatus for generating a predicted image used for encoding or decoding a moving image,
An affine motion vector deriving unit;
A prediction image generation unit,
The affine motion vector derivation unit includes:
The motion vector of each of the plurality of sub-blocks included in the target block is calculated with reference to the motion vector at the control point set in the reference block sharing the vertex with the target block,
Depending on at least one of the shape and size of the reference block, motion vectors of two control points are calculated and 4-parameter affine processing is performed, or motion vectors of three control points are calculated and 6-parameter affine is calculated. Switch whether to process
The predicted image generation unit
A predicted image generation apparatus that generates a predicted image by referring to a motion vector of the control point. The affine motion vector derivation unit includes:
The predicted image generation apparatus according to claim 9, wherein 6-parameter affine processing is performed when the reference block is square, and 4-parameter affine processing is performed when the reference block is not square. The affine motion vector derivation unit includes:
The 6-parameter affine processing is performed when the size of the reference block is equal to or larger than a predetermined threshold, and the 4-parameter affine processing is performed when the size of the target block is not equal to or larger than the predetermined threshold. The predicted image generation apparatus described in 1. In a predicted image generation apparatus for generating a predicted image used for encoding or decoding a moving image,
An affine motion vector deriving unit;
A prediction image generation unit,
The affine motion vector derivation unit includes:
The motion vector of each of the plurality of sub-blocks included in the target block is calculated with reference to the motion vector at the control point set in the reference block sharing the vertex with the target block,
According to the shape of the target block or the shape of the reference block, the control point used for the processing of the four parameter affine is changed,
The predicted image generation unit
A predicted image generation apparatus that generates a predicted image by referring to a motion vector of the control point. The affine motion vector derivation unit includes:
When the target block is a square, a control point set in a reference block sharing each of two vertices on the diagonal of the target block is determined as the control point,
13. When the target block is not a square, a control point set in a reference block sharing each of two vertices sandwiching the long side of the target block is determined as the control point. The predicted image generation apparatus described in 1. The affine motion vector derivation unit includes:
When the reference block is a square, a control point set in a reference block sharing two vertices on the diagonal of the target block is determined as the control point,
The control point set in the reference block that shares two vertices sandwiching the long side of the target block is determined as the control point when the reference block is not a square. Prediction image generation apparatus. The affine motion vector derivation unit includes:
When the shape of the reference block is a square, two vertices on the diagonal of the reference block are determined as the control points,
The predicted image generation apparatus according to claim 12, wherein when the reference block is not a square, two vertices sandwiching a long side of the reference block are determined as the control points. A prediction image generation apparatus according to any one of claims 2 to 15,
A moving picture decoding apparatus, wherein a decoded picture is generated by adding or subtracting a residual signal to the predicted picture. A prediction image generation apparatus according to any one of claims 2 to 15,
A moving image encoding apparatus, wherein a residual signal between the prediction image and an encoding target image is encoded.

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