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WO2025261661A1 - Appareil, procédé et programme informatique pour le codage et le décodage de vidéos - Google Patents

Appareil, procédé et programme informatique pour le codage et le décodage de vidéos

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Publication number
WO2025261661A1
WO2025261661A1 PCT/EP2025/062976 EP2025062976W WO2025261661A1 WO 2025261661 A1 WO2025261661 A1 WO 2025261661A1 EP 2025062976 W EP2025062976 W EP 2025062976W WO 2025261661 A1 WO2025261661 A1 WO 2025261661A1
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WIPO (PCT)
Prior art keywords
samples
block
sample
determining
reference samples
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PCT/EP2025/062976
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English (en)
Inventor
Jani Lainema
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Nokia Technologies Oy
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Nokia Technologies Oy
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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/593—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving spatial prediction techniques
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/103—Selection of coding mode or of prediction mode
    • H04N19/105—Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/103—Selection of coding mode or of prediction mode
    • H04N19/11—Selection of coding mode or of prediction mode among a plurality of spatial predictive coding modes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock

Definitions

  • the present invention relates to an apparatus, a method and a computer program for video coding and decoding.
  • Matrix based intra prediction i.e. weighted intra prediction with matrix multiplication
  • other learning based intra prediction approaches are supported in contemporary video codecs, such as video codecs according to H.266/VVC standard.
  • Such methods apply a set of multipliers or other parameters to a predetermined set of reference samples to determine each predicted sample individually.
  • each predicted sample has a set of its own parameters, which can be trained to produce statistically good predictors for each predicted sample in a block. Similar concept is applied in typical neural network based intra prediction methods, where the learned multiplier values are substituted by a learned neural network consisting of both linear and nonlinear elements.
  • An apparatus comprises means for determining a block of samples to be predicted; means for determining a first set of reference samples for the block; means for determining a first predicted sample location within the block; means for determining a second set of reference samples using said first predicted sample location as a classification information for said reference samples; means for determining a predicted value for a first sample based on at least the first set of reference samples and the second set of reference samples; means for determining a second predicted sample location within the block; means for determining a third set of reference samples using said second predicted sample location as a classification information for said reference samples; and means for determining a predicted value for a second sample based on at least the first set of reference samples and the third set of reference samples.
  • the first set of reference samples comprises samples on a first row of samples immediately above the block and/or samples on a first column of samples immediately left of the block.
  • the first set of reference samples comprises all samples within a first predetermined window on the first row of samples immediately above the block and/or all samples within a second predetermined window on the first column of samples immediately left of the block.
  • the second set and the third set of reference samples comprise samples on a second row of samples above the block and/or samples on a second column of samples left of the block.
  • the apparatus comprises means for determining a classification mode for the block of samples; and means for determining at least one of said second and third sets of reference samples based on the classification mode and the first and/or the second predicted sample location.
  • the apparatus comprises means for determining the predicted value by multiplying values of the reference samples with a set of prediction parameters.
  • the set of prediction parameters comprises a set of predetermined values, multipliers, scalers, offsets, or a combination of those.
  • the apparatus comprises means for determining the predicted value by multiplying values of the reference samples with the determined set of prediction parameters.
  • the set of prediction parameters comprises parameters of a neural network.
  • the apparatus comprises means for determining the predicted value by applying the neural network, which uses at least the set of reference samples as its input.
  • the apparatus comprises means for selecting one or more of said reference sample sets so that the location of at least one of the reference sample sets depend on the position of the output sample location.
  • the apparatus comprises means for selecting at least one reference sample set so that its horizontal center is aligned with horizontal position of the output sample and another reference sample set is selected so that its vertical center is aligned with the vertical position of the output sample.
  • the apparatus comprises means for applying diagonal prediction direction for determining the predicted value for the sample at the determined location.
  • an apparatus comprising: at least one processor and at least one memory, said at least one memory stored with code thereon, which when executed by said at least one processor, causes the apparatus to perform at least: determine a block of samples to be predicted; determine a first set of reference samples for the block; determine a first predicted sample location within the block; determine a second set of reference samples using said first predicted sample location as a classification information for said reference samples; determine a predicted value for a first sample based on at least the first set of reference samples and the second set of reference samples; determine a second predicted sample location within the block; determine a third set of reference samples using said second predicted sample location as a classification information for said reference samples; and determine a predicted value for a second sample based on at least the first set of reference samples and the third set of reference samples.
  • a method comprises determining a block of samples to be predicted; determining a first set of reference samples for the block; determining a first predicted sample location within the block; determining a second set of reference samples using said first predicted sample location as a classification information for said reference samples; determining a predicted value for a first sample based on at least the first set of reference samples and the second set of reference samples; determining a second predicted sample location within the block; determining a third set of reference samples using said second predicted sample location as a classification information for said reference samples; and determining a predicted value for a second sample based on at least the first set of reference samples and the third set of reference samples.
  • Figures la and lb show schematically an encoder and a decoder, respectively, suitable for implementing embodiments of the invention
  • Figure 2 shows a flow chart of a method according to a first aspect
  • Figure 3 shows an example of a reference sample arrangement according to an embodiment
  • Figure 4 shows an example of a reference sample arrangement according to an embodiment
  • Figure 5 shows an example of a reference sample arrangement according to an embodiment
  • Figure 6 shows an example of a reference sample arrangement according to an embodiment
  • Figure 7 shows an example of a reference sample arrangement according to an embodiment
  • Figure 8 shows an example of a reference sample arrangement according to an embodiment
  • Figure 9 shows a flow chart of a method according to a second aspect
  • Figure 10 shows an example of a reference sample arrangement according to an embodiment
  • Figure 11 shows an example of a reference sample arrangement according to an embodiment
  • Figure 12 shows an example of a reference sample arrangement according to an embodiment
  • Figure 13 shows a flow chart of a method according to a third aspect
  • Figure 14 shows an example of a reference sample arrangement according to an embodiment
  • Figure 15 shows an example of a reference sample arrangement according to an embodiment
  • Figure 16 shows schematically an electronic device suitable for employing embodiments of the invention
  • Figure 17 shows schematically a user equipment suitable for employing embodiments of the invention.
  • Figure 19 shows a schematic diagram of an example multimedia communication system within which various embodiments may be implemented.
  • Video codec consists of an encoder that transforms the input video into a compressed representation suited for storage/transmission and a decoder that can uncompress the compressed video representation back into a viewable form.
  • a video encoder and/or a video decoder may also be separate from each other, i.e. need not form a codec.
  • an encoder discards some information in the original video sequence in order to represent the video in a more compact form (that is, at lower bitrate).
  • Typical hybrid video encoders for example many encoder implementations of ITU-T H.263 and H.264, encode the video information in two phases. Firstly, pixel values in a certain picture area (or “block”) are predicted for example by motion compensation means (finding and indicating an area in one of the previously coded video frames that corresponds closely to the block being coded) or by spatial means (using the pixel values around the block to be coded in a specified manner). Secondly the prediction error, i.e. the difference between the predicted block of pixels and the original block of pixels, is coded. This is typically done by transforming the difference in pixel values using a specified transform (e.g.
  • inter prediction In temporal prediction, the sources of prediction are previously decoded pictures (a.k.a. reference pictures).
  • IBC intra block copy
  • inter-block-copy prediction prediction is applied similarly to temporal prediction but the reference picture is the current picture and only previously decoded samples can be referred in the prediction process.
  • Interlayer or inter-view prediction may be applied similarly to temporal prediction, but the reference picture is a decoded picture from another scalable layer or from another view, respectively.
  • inter prediction may refer to temporal prediction only, while in other cases inter prediction may refer collectively to temporal prediction and any of intra block copy, inter-layer prediction, and inter-view prediction provided that they are performed with the same or similar process than temporal prediction.
  • Inter prediction or temporal prediction may sometimes be referred to as motion compensation or motion-compensated prediction.
  • Motion compensation can be performed either with full sample or sub-sample accuracy.
  • motion can be represented as a motion vector with integer values for horizontal and vertical displacement and the motion compensation process effectively copies samples from the reference picture using those displacements.
  • motion vectors are represented by fractional or decimal values for the horizontal and vertical components of the motion vector.
  • a sub-sample interpolation process is typically invoked to calculate predicted sample values based on the reference samples and the selected sub-sample position.
  • the sub-sample interpolation process typically consists of horizontal filtering compensating for horizontal offsets with respect to full sample positions followed by vertical filtering compensating for vertical offsets with respect to full sample positions.
  • the vertical processing can be also be done before horizontal processing in some environments.
  • One outcome of the coding procedure is a set of coding parameters, such as motion vectors and quantized transform coefficients.
  • Many parameters can be entropy-coded more efficiently if they are predicted first from spatially or temporally neighboring parameters.
  • a motion vector may be predicted from spatially adjacent motion vectors and only the difference relative to the motion vector predictor may be coded.
  • Prediction of coding parameters and intra prediction may be collectively referred to as in-picture prediction.
  • FIGs, la and lb show an encoder and a decoder suitable for employing embodiments of the invention.
  • a video codec consists of an encoder that transforms an input video into a compressed representation suited for storage/transmission and a decoder that can decompress the compressed video representation back into a viewable form.
  • the encoder discards and/or loses some information in the original video sequence in order to represent the video in a more compact form (that is, at lower bitrate).
  • An example of an encoding process is illustrated in Figure la.
  • Figure 4a illustrates an image to be encoded (I n ); a predicted representation of an image block (P' n ); a prediction error signal (D n ); a reconstructed prediction error signal (D' n ); a preliminary reconstructed image (I' n ); a final reconstructed image (R' n ); a transform (T) and inverse transform (T -1 ); a quantization (Q) and inverse quantization (Q 1 ); entropy encoding (E); a reference frame memory (RFM); inter prediction (Pinter); intra prediction (Pintra); mode selection (MS) and filtering (F).
  • pixel values in a certain picture area are predicted for example by motion compensation means (finding and indicating an area in one of the previously coded video frames that corresponds closely to the block being coded) or by spatial means (using the pixel values around the block to be coded in a specified manner).
  • the prediction error i.e. the difference between the predicted block of pixels and the original block of pixels. This is typically done by transforming the difference in pixel values using a specified transform (e.g. Discrete Cosine Transform (DCT) or a variant of it), quantizing the coefficients and entropy coding the quantized coefficients.
  • DCT Discrete Cosine Transform
  • Video codecs may also provide a transform skip mode, which the encoders may choose to use.
  • the prediction error is coded in a sample domain, for example by deriving a sample-wise difference value relative to certain adjacent samples and coding the sample-wise difference value with an entropy coder.
  • the phrase along the bitstream may be defined to refer to out-of-band transmission, signalling, or storage in a manner that the out-of-band data is associated with the bitstream.
  • the phrase decoding along the bitstream or alike may refer to decoding the referred out-of-band data (which may be obtained from out-of-band transmission, signalling, or storage) that is associated with the bitstream.
  • an indication along the bitstream may refer to metadata in a container file that encapsulates the bitstream.
  • the H.264/AVC standard was developed by the Joint Video Team (JVT) of the Video Coding Experts Group (VCEG) of the Telecommunications Standardization Sector of International Telecommunication Union (ITU-T) and the Moving Picture Experts Group (MPEG) of International Organisation for Standardization (ISO) / International Electrotechnical Commission (IEC).
  • JVT Joint Video Team
  • VCEG Video Coding Experts Group
  • MPEG Moving Picture Experts Group
  • ISO International Organization for Standardization
  • ISO International Electrotechnical Commission
  • the H.264/AVC standard is published by both parent standardization organizations, and it is referred to as ITU-T Recommendation H.264 and ISO/IEC International Standard 14496-10, also known as MPEG-4 Part 10 Advanced Video Coding (AVC).
  • ITU-T Recommendation H.264 and ISO/IEC International Standard 14496-10 also known as MPEG-4 Part 10 Advanced Video Coding (AVC).
  • AVC MPEG-4 Part 10 Advanced Video Coding
  • H.265/HEVC a.k.a. HEVC High Efficiency Video Coding
  • JCT-VC Joint Collaborative Team - Video Coding
  • the standard was published by both parent standardization organizations, and it is referred to as ITU-T Recommendation H.265 and ISO/IEC International Standard 23008-2, also known as MPEG-H Part 2 High Efficiency Video Coding (HEVC).
  • HEVC High Efficiency Video Coding
  • VVC Versatile Video Coding
  • MPEG Moving Picture Experts Group
  • VCEG Video Coding Experts Group
  • ITU International Telecommunication Union
  • bitstream and coding structures, and concepts of H.264/ AVC and HEVC are described in this section for providing background for a video encoder, decoder, encoding method, decoding method, and a bitstream structure, wherein the embodiments may be implemented.
  • Some of the key definitions, bitstream and coding structures, and concepts of H.264/AVC are the same as in HEVC - hence, they are described below jointly.
  • bitstream syntax and semantics as well as the decoding process for error-free bitstreams are specified in H.264/AVC and HEVC.
  • the encoding process is not specified, but encoders must generate conforming bitstreams.
  • bitstream and decoder conformance can be verified with the Hypothetical Reference Decoder (HRD).
  • HRD Hypothetical Reference Decoder
  • the standards contain coding tools that help in coping with transmission errors and losses, but the use of the tools in encoding is optional and no decoding process has been specified for erroneous bitstreams.
  • the elementary unit for the input to an H.264/AVC or HEVC encoder and the output of an H.264/AVC or HEVC decoder, respectively, is a picture.
  • a picture given as an input to an encoder may also be referred to as a source picture, and a picture decoded by a decoded may be referred to as a decoded picture.
  • the source and decoded pictures are each comprised of one or more sample arrays, such as one of the following sets of sample arrays:
  • Arrays representing other unspecified monochrome or tri-stimulus color samplings for example, YZX, also known as XYZ).
  • each of the two chroma arrays has half the height and half the width of the luma array.
  • each of the two chroma arrays has the same height and half the width of the luma array.
  • each of the two chroma arrays has the same height and width as the luma array.
  • a partitioning may be defined as a division of a set into subsets such that each element of the set is in exactly one of the subsets.
  • a coding tree unit may be defined as a coding tree block of luma samples, two corresponding coding tree blocks of chroma samples of a picture that has three sample arrays, or a coding tree block of samples of a monochrome picture or a picture that is coded using three separate color planes and syntax structures used to code the samples.
  • a coding unit may be defined as a coding block of luma samples, two corresponding coding blocks of chroma samples of a picture that has three sample arrays, or a coding block of samples of a monochrome picture or a picture that is coded using three separate color planes and syntax structures used to code the samples.
  • a CU with the maximum allowed size may be named as LCU (largest coding unit) or coding tree unit (CTU) and the video picture is divided into non-overlapping LCUs.
  • a CU consists of one or more prediction units (PU) defining the prediction process for the samples within the CU and one or more transform units (TU) defining the prediction error coding process for the samples in the said CU.
  • PU prediction units
  • TU transform units
  • a CU consists of a square block of samples with a size selectable from a predefined set of possible CU sizes.
  • Each PU and TU can be further split into smaller PUs and TUs in order to increase granularity of the prediction and prediction error coding processes, respectively.
  • Each PU has prediction information associated with it defining what kind of a prediction is to be applied for the pixels within that PU (e.g. motion vector information for inter predicted PUs and intra prediction directionality information for intra predicted PUs).
  • Each TU can be associated with information describing the prediction error decoding process for the samples within the said TU (including e.g. DCT coefficient information). It is typically signalled at CU level whether prediction error coding is applied or not for each CU. In the case there is no prediction error residual associated with the CU, it can be considered there are no TUs for the said CU.
  • the division of the image into CUs, and division of CUs into PUs and TUs is typically signalled in the bitstream allowing the decoder to reproduce the intended structure of these units.
  • a slice header is defined to be the slice segment header of the independent slice segment that is a current slice segment or is the independent slice segment that precedes a current dependent slice segment
  • a slice segment header is defined to be a part of a coded slice segment containing the data elements pertaining to the first or all coding tree units represented in the slice segment.
  • the decoder reconstructs the output video by applying prediction means similar to the encoder to form a predicted representation of the pixel blocks (using the motion or spatial information created by the encoder and stored in the compressed representation) and prediction error decoding (inverse operation of the prediction error coding recovering the quantized prediction error signal in spatial pixel domain). After applying prediction and prediction error decoding means the decoder sums up the prediction and prediction error signals (pixel values) to form the output video frame.
  • the decoder (and encoder) can also apply additional filtering means to improve the quality of the output video before passing it for display and/or storing it as prediction reference for the forthcoming frames in the video sequence.
  • a color palette based coding can be used.
  • Palette based coding refers to a family of approaches for which a palette, i.e. a set of colors and associated indexes, is defined and the value for each sample within a coding unit is expressed by indicating its index in the palette.
  • Palette based coding can typically achieve good coding efficiency in coding units with a relatively small number of colors (such as image areas which are representing computer screen content, like text or simple graphics).
  • palette index prediction approaches In order to improve the coding efficiency of palette coding different kinds of palette index prediction approaches can be utilized, or the palette indexes can be run-length coded to be able to represent larger homogenous image areas efficiently. Also, in the case the CU contains sample values that are not recurring within the CU, escape coding can be utilized. Escape coded samples are transmitted without referring to any of the palette indexes. Instead, their values are indicated individually for each escape coded sample.
  • the filtering may for example include one more of the following: deblocking, sample adaptive offset (SAG), and/or adaptive loop filtering (ALF).
  • deblocking sample adaptive offset (SAG)
  • ALF adaptive loop filtering
  • H.264/AVC includes a deblocking
  • HEVC includes both deblocking and SAG.
  • the motion information is indicated with motion vectors associated with each motion compensated image block, such as a prediction unit.
  • Each of these motion vectors represents the displacement of the image block in the picture to be coded (in the encoder side) or decoded (in the decoder side) and the prediction source block in one of the previously coded or decoded pictures.
  • those are typically coded differentially with respect to block specific predicted motion vectors.
  • the predicted motion vectors are created in a predefined way, for example calculating the median of the encoded or decoded motion vectors of the adjacent blocks.
  • Another way to create motion vector predictions is to generate a list of candidate predictions from adjacent blocks and/or co-located blocks in temporal reference pictures and signalling the chosen candidate as the motion vector predictor.
  • this prediction information may be represented for example by a reference index of previously coded/ decoded picture.
  • the reference index is typically predicted from adjacent blocks and/or co-located blocks in temporal reference picture.
  • typical high efficiency video codecs employ an additional motion information coding/decoding mechanism, often called merging/merge mode, where all the motion field information, which includes motion vector and corresponding reference picture index for each available reference picture list, is predicted and used without any modification/correction.
  • predicting the motion field information is carried out using the motion field information of adjacent blocks and/or co-located blocks in temporal reference pictures and the used motion field information is signalled among a list of motion field candidate list filled with motion field information of available adjacent/co-located blocks.
  • Video coding standards and specifications may allow encoders to divide a coded picture to coded slices or alike. In-picture prediction is typically disabled across slice boundaries. Thus, slices can be regarded as a way to split a coded picture to independently decodable pieces. In H.264/AVC and HEVC, in-picture prediction may be disabled across slice boundaries. Thus, slices can be regarded as a way to split a coded picture into independently decodable pieces, and slices are therefore often regarded as elementary units for transmission. In many cases, encoders may indicate in the bitstream which types of in-picture prediction are turned off across slice boundaries, and the decoder operation takes this information into account for example when concluding which prediction sources are available. For example, samples from a neighboring CU may be regarded as unavailable for intra prediction, if the neighboring CU resides in a different slice.
  • NAL Network Abstraction Layer
  • H.264/AVC and HEVC For transport over packet-oriented networks or storage into structured files, NAL units may be encapsulated into packets or similar structures.
  • a bytestream format has been specified in H.264/AVC and HEVC for transmission or storage environments that do not provide framing structures. The bytestream format separates NAL units from each other by attaching a start code in front of each NAL unit.
  • NAL units consist of a header and payload.
  • the NAL unit header indicates the type of the NAL unit
  • a sub-layer or a temporal sub-layer may be defined to be a temporal scalable layer (or a temporal layer, TL) of a temporal scalable bitstream, consisting of VCL NAL units with a particular value of the Temporalld variable and the associated non-VCL NAL units.
  • nuh layer id can be understood as a scalability layer identifier.
  • NAL units can be categorized into Video Coding Layer (VCL) NAL units and non- VCL NAL units.
  • VCL NAL units are typically coded slice NAL units.
  • VCL NAL units contain syntax elements representing one or more CU.
  • a non-VCL NAL unit may be for example one of the following types: a sequence parameter set, a picture parameter set, a supplemental enhancement information (SEI) NAL unit, an access unit delimiter, an end of sequence NAL unit, an end of bitstream NAL unit, or a filler data NAL unit.
  • SEI Supplemental Enhancement Information
  • Parameter sets may be needed for the reconstruction of decoded pictures, whereas many of the other non-VCL NAL units are not necessary for the reconstruction of decoded sample values.
  • Parameters that remain unchanged through a coded video sequence may be included in a sequence parameter set.
  • the sequence parameter set may optionally contain video usability information (VUI), which includes parameters that may be important for buffering, picture output timing, rendering, and resource reservation.
  • VUI video usability information
  • a sequence parameter set RBSP includes parameters that can be referred to by one or more picture parameter set RBSPs or one or more SEI NAL units containing a buffering period SEI message.
  • a picture parameter set contains such parameters that are likely to be unchanged in several coded pictures.
  • a picture parameter set RBSP may include parameters that can be referred to by the coded slice NAL units of one or more coded pictures.
  • a video parameter set may be defined as a syntax structure containing syntax elements that apply to zero or more entire coded video sequences as determined by the content of a syntax element found in the SPS referred to by a syntax element found in the PPS referred to by a syntax element found in each slice segment header.
  • a video parameter set RBSP may include parameters that can be referred to by one or more sequence parameter set RBSPs.
  • VPS resides one level above SPS in the parameter set hierarchy and in the context of scalability and/or 3D video.
  • VPS may include parameters that are common for all slices across all (scalability or view) layers in the entire coded video sequence.
  • SPS includes the parameters that are common for all slices in a particular (scalability or view) layer in the entire coded video sequence, and may be shared by multiple (scalability or view) layers.
  • PPS includes the parameters that are common for all slices in a particular layer representation (the representation of one scalability or view layer in one access unit) and are likely to be shared by all slices in multiple layer representations.
  • VPS may provide information about the dependency relationships of the layers in a bitstream, as well as many other information that are applicable to all slices across all (scalability or view) layers in the entire coded video sequence.
  • VPS may be considered to comprise two parts, the base VPS and a VPS extension, where the VPS extension may be optionally present.
  • Out-of-band transmission, signaling or storage can additionally or alternatively be used for other purposes than tolerance against transmission errors, such as ease of access or session negotiation.
  • a sample entry of a track in a file conforming to the ISO Base Media File Format may comprise parameter sets, while the coded data in the bitstream is stored elsewhere in the file or in another file.
  • the phrase along the bitstream (e.g.
  • indicating along the bitstream or along a coded unit of a bitstream (e.g. indicating along a coded tile) may be used in claims and described embodiments to refer to out-of-band transmission, signaling, or storage in a manner that the out-of-band data is associated with the bitstream or the coded unit, respectively.
  • decoding along the bitstream or along a coded unit of a bitstream or alike may refer to decoding the referred out-of-band data (which may be obtained from out-of-band transmission, signaling, or storage) that is associated with the bitstream or the coded unit, respectively.
  • a SEI NAL unit may contain one or more SEI messages, which are not required for the decoding of output pictures but may assist in related processes, such as picture output timing, rendering, error detection, error concealment, and resource reservation.
  • a coded picture is a coded representation of a picture.
  • a coded picture may be defined as a coded representation of a picture containing all coding tree units of the picture.
  • an access unit (AU) may be defined as a set of NAL units that are associated with each other according to a specified classification rule, are consecutive in decoding order, and contain at most one picture with any specific value of nuh layer id.
  • an access unit may also contain non-VCL NAL units. Said specified classification rule may for example associate pictures with the same output time or picture output count value into the same access unit.
  • a bitstream may be defined as a sequence of bits, in the form of a NAL unit stream or a byte stream, that forms the representation of coded pictures and associated data forming one or more coded video sequences.
  • a first bitstream may be followed by a second bitstream in the same logical channel, such as in the same file or in the same connection of a communication protocol.
  • An elementary stream (in the context of video coding) may be defined as a sequence of one or more bitstreams.
  • the end of the first bitstream may be indicated by a specific NAL unit, which may be referred to as the end of bitstream (EOB) NAL unit and which is the last NAL unit of the bitstream.
  • EOB NAL unit In HEVC and its current draft extensions, the EOB NAL unit is required to have nuh layer id equal to 0.
  • a coded video sequence is defined to be a sequence of consecutive access units in decoding order from an IDR access unit, inclusive, to the next IDR access unit, exclusive, or to the end of the bitstream, whichever appears earlier.
  • a coded video sequence may be defined, for example, as a sequence of access units that consists, in decoding order, of an IRAP access unit with NoRaslOutputFlag equal to 1, followed by zero or more access units that are not IRAP access units with NoRaslOutputFlag equal to 1, including all subsequent access units up to but not including any subsequent access unit that is an IRAP access unit with NoRaslOutputFlag equal to 1.
  • An IRAP access unit may be defined as an access unit in which the base layer picture is an IRAP picture.
  • NoRaslOutputFlag is equal to 1 for each IDR picture, each BLA picture, and each IRAP picture that is the first picture in that particular layer in the bitstream in decoding order, is the first IRAP picture that follows an end of sequence NAL unit having the same value of nuh layer id in decoding order.
  • HandleCraAsBlaFlag may be set to 1 for example by a player that seeks to a new position in a bitstream or tunes into a broadcast and starts decoding and then starts decoding from a CRA picture.
  • HandleCraAsBlaFlag is equal to 1 for a CRA picture, the CRA picture is handled and decoded as if it were a BLA picture.
  • a coded video sequence may additionally or alternatively (to the specification above) be specified to end, when a specific NAL unit, which may be referred to as an end of sequence (EOS) NAL unit, appears in the bitstream and has nuh layer id equal to 0.
  • EOS end of sequence
  • a group of pictures (GOP) and its characteristics may be defined as follows.
  • a GOP can be decoded regardless of whether any previous pictures were decoded.
  • An open GOP is such a group of pictures in which pictures preceding the initial intra picture in output order might not be correctly decodable when the decoding starts from the initial intra picture of the open GOP.
  • pictures of an open GOP may refer (in inter prediction) to pictures belonging to a previous GOP.
  • An HEVC decoder can recognize an intra picture starting an open GOP, because a specific NAL unit type, CRA NAL unit type, may be used for its coded slices.
  • a closed GOP is such a group of pictures in which all pictures can be correctly decoded when the decoding starts from the initial intra picture of the closed GOP. In other words, no picture in a closed GOP refers to any pictures in previous GOPs.
  • a closed GOP may start from an IDR picture.
  • a closed GOP may also start from a BLA W RADL or a BLA N LP picture.
  • An open GOP coding structure is potentially more efficient in the compression compared to a closed GOP coding structure, due to a larger flexibility in selection of reference pictures.
  • a Decoded Picture Buffer may be used in the encoder and/or in the decoder. There are two reasons to buffer decoded pictures, for references in inter prediction and for reordering decoded pictures into output order. As H.264/AVC and HEVC provide a great deal of flexibility for both reference picture marking and output reordering, separate buffers for reference picture buffering and output picture buffering may waste memory resources. Hence, the DPB may include a unified decoded picture buffering process for reference pictures and output reordering. A decoded picture may be removed from the DPB when it is no longer used as a reference and is not needed for output.
  • the reference picture for inter prediction is indicated with an index to a reference picture list.
  • the index may be coded with variable length coding, which usually causes a smaller index to have a shorter value for the corresponding syntax element.
  • two reference picture lists (reference picture list 0 and reference picture list 1) are generated for each bi-predictive (B) slice, and one reference picture list (reference picture list 0) is formed for each inter-coded (P) slice.
  • a reference picture index may be coded by an encoder into the bitstream is some inter coding modes or it may be derived (by an encoder and a decoder) for example using neighboring blocks in some other inter coding modes.
  • HEVC comprises 35 intra prediction modes, including a DC, a planar, and 33 angular (directional) prediction modes.
  • the DC and the planar mode are targeted at flat areas (i.e., the DC mode representing a block whose pixel values are constant across the block) or areas with few structure (i.e., the planar mode representing a block with pixel values gradually changing with a small planar gradient).
  • the angular modes provide directional prediction in a very granular way.
  • Motion parameter types or motion information may include but are not limited to one or more of the following types: an indication of a prediction type (e.g. intra prediction, uni-prediction, bi-prediction) and/or a number of reference pictures; an indication of a prediction direction, such as inter (a.k.a.
  • interlayer prediction inter- view prediction
  • view synthesis prediction VSP
  • intercomponent prediction which may be indicated per reference picture and/or per prediction type and where in some embodiments inter-view and view-synthesis prediction may be jointly considered as one prediction direction
  • an indication of a reference picture type such as a short-term reference picture and/or a long-term reference picture and/or an inter-layer reference picture (which may be indicated e.g. per reference picture) a reference index to a reference picture list and/or any other identifier of a reference picture (which may be indicated e.g.
  • a horizontal motion vector component (which may be indicated e.g. per prediction block or per reference index or alike); a vertical motion vector component (which may be indicated e.g. per prediction block or per reference index or alike); one or more parameters, such as picture order count difference and/or a relative camera separation between the picture containing or associated with the motion parameters and its reference picture, which may be used for scaling of the horizontal motion vector component and/or the vertical motion vector component in one or more motion vector prediction processes (where said one or more parameters may be indicated e.g.
  • coordinates of a block to which the motion parameters and/or motion information applies e.g. coordinates of the top-left sample of the block in luma sample units; extents (e.g. a width and a height) of a block to which the motion parameters and/or motion information applies.
  • H.266/VVC standard supports matrix based intra prediction (i.e. weighted intra prediction with matrix multiplication) or other learning based intra prediction approaches.
  • matrix based intra prediction i.e. weighted intra prediction with matrix multiplication
  • Such methods apply a set of multipliers or other parameters to a predetermined set of reference samples to determine each predicted sample individually.
  • each predicted sample has a set of its own parameters, which can be trained to produce statistically good predictors for each predicted sample in a block.
  • larger blocks of predicted samples can use a subsampled prediction approach where only certain initial prediction samples are generated using matrix operations and the resulting block is further upsampled to produce a full set of predicted samples.
  • reference samples for matrix based intra prediction or other learning based intra prediction are selected by classifying prediction blocks to different categories, wherein the classification may be based on bitstream signaling or an analysis-based categorization.
  • the reference samples may be selected using multiple reference sample groups distributed in different ways using the classification information. By selecting the most relevant reference samples via the classification, significant memory and computational complexity reduction may be achieved compared to the known reference line based approaches.
  • a method comprises determining (200) a block of samples to be predicted; determining (202) a classification mode for the block of samples; determining (204) a location of a sample within the block of samples; determining (206) one or more sets of reference samples based on the classification mode and the location of the sample; wherein at least one set of reference samples includes (206a) a first set of samples on a first row of samples immediately above the block with a first set of horizontal coordinates and the set of reference samples includes a second set of samples on a second row of samples above the block with a second set of horizontal coordinates, where the first set of horizontal coordinates and the second set of horizontal coordinates differ from each other; or at least one set of reference samples includes (206b) a first set of samples on a first column of samples immediately left of the block with a first set of vertical coordinates and the set of reference samples includes a second set of samples on a second column of samples left of the block with a second set of vertical
  • predicted samples of a block are generated from one or more reference sample groups using a learning based intra prediction process, where the reference samples of at least one reference sample group selected from the first and second reference line are not aligned with each other.
  • the first reference line refers to a first row of samples immediately above the block and/or a first column of samples immediately left of the block.
  • the second reference line refers to a second row of samples above the block and/or a second column of samples left of the block, correspondingly. Based on the location of the sample to predicted (i.e.
  • Reference samples can be selected from a predetermined window or range of reconstructed samples in the vicinity of the block to be predicted.
  • the reference samples on the first reference line above the block can include samples within a first predetermined window with coordinates (x, y-1) to (x+W-1, y-1), or (x-1, y-1) to (x+W-1, y-1), or (x, y-1) to (x+2W-l, y-1), or (x-1, y-1) to (x+2W- 1, y-1), where (x, y) corresponds to the top-left corner of the prediction block.
  • the reference samples on the first reference line left of the block may include samples within a second predetermined window, such as (x-1, y) to (x-1, y+H-1), or (x-1, y-1) to (x-1, y+H-1), or (x-1, y) to (x-1, y+2H-l) or (x-1, y-1) to (x-1, y+2H-l).
  • the first and second predetermined windows may comprise an equal or a different number of samples.
  • the method comprises applying diagonal prediction direction for determining the predicted value for the sample at the determined location.
  • the method comprises determining the predicted value by multiplying values of the reference samples with the determined set of prediction parameters.
  • Samples belonging to a block of samples can be predicted using matrix based intra prediction that convolves a set of reference sample values with specific set of multipliers that depend on the position of the output sample within a block.
  • Output of the operation is a predicted sample value p x , y at a position x, y in a prediction block and can be given as a function of the multipliers for that position q(x, y) and the reference sample values for that position n(x, y): [0113] Same can be expressed in a vector form collecting all multipliers in a vector c(x, y) and all reference samples in a vector r(x, y) as:
  • the set of prediction parameters comprises a set of predetermined values, multipliers, scalers, offsets, or a combination of those.
  • the prediction parameters may comprise predetermined values, such as the location of the current sample, and various filter parameters, such as multipliers, scalers, offsets.
  • the prediction parameters may relate, for example, to various kinds of predictions or corrective operations between a current block and its prediction block expressed as a function between current sample/block and reference sample/block.
  • the parameters of the function can be denoted by a scale a and an offset 0, which forms a linear equation, that is, a*p[x]+0 to carry out the prediction or the corrective operation, where p[x] is a reference sample pointed to by a motion vector at a location x on reference picture.
  • the method comprises determining the predicted value by applying a neural network, which uses at least the set of reference samples as its input.
  • a neural network can be used to determine the predicted samples using the determined set of reference samples n(x, y) or a vector consisting of the determined reference samples r(x, y).
  • any function f with parameters 0 can be used to determine the output samples of the prediction process from the reference sample vector:
  • the set of prediction parameters comprises parameters of the neural network.
  • the set of prediction parameters may be used as input parameters of the neural network.
  • the method comprises determining the classification mode based on bitstream signaling; based on parsing at least one syntax element from a bitstream, or by an encoder decision.
  • classifications can be used to select which set of filter parameters and which set of reference samples are used to determine predicted sample values. Classification can be done, and the classification mode can be determined, explicitly or implicitly. For example, a syntax element in a bitstream can be used to explicitly indicate the class or category of filter parameters and corresponding reference sample positions. As another example, the class or category of filter parameters can be derived from available information, such as the intra prediction mode or intra prediction direction that has been indicated for the block. As a further example, gradients or other measures such as the ones used in typical decoder side intra prediction mode derivation (DIMD) systems can be used to determine a class or a category of filter parameters and corresponding reference sample positions.
  • DIMD decoder side intra prediction mode derivation
  • Figure 3 shows an example of a reference sample arrangement for a diagonal (45 degrees) prediction direction or a category corresponding to a diagonal (45 degrees) prediction direction.
  • Reference samples are selected in the reference sample area, depicted with gray background, which is located above and left of the current block as those areas are typically processed before the current block and thus their sample values are available in both encoders and decoders to be used as reference values for the current block.
  • reference sample set 0, illustrated with circles is selected from the above reference area projecting from the location of the current sample at 45 degrees angle towards up-right direction and selecting some number of (herein 3) horizontally adjacent samples from both reference lines to be able to generalize the filter with a relatively large input window.
  • FIG. 4 shows another example of a reference sample arrangement for a diagonal (45 degrees) prediction direction. In comparison to the example of Figure 3, there is only one sample on the second reference line in both reference sample sets 0 and 1 (i.e.
  • Figure 5 shows yet another example of reference sample arrangement, where a different directional classification (i.e. 30 degrees prediction direction) is applied.
  • a different directional classification i.e. 30 degrees prediction direction
  • there are two samples on the second reference line in both reference sample sets 0 and 1 i.e. two samples on the second row of samples above the block and two samples on the second column of samples left of the block.
  • the 30 degrees prediction direction introduces some ambiguity about reference samples that should be used for the current sample. Therefore, the locations of these two samples on the second reference line in both reference sample sets 0 and 1 are selected such that they are approximately on the 30 degrees projection line from the current sample, thus being the most relevant reference samples on the second reference line.
  • Figure 6 shows yet another example of reference sample arrangement, which is a further implementation of the example in Figure 4.
  • reference sample sets are selected for two output sample locations in the same horizontal line.
  • the horizontal distance between the output sample locations is the same as the horizontal distance between the two reference sample sets in the above reference area.
  • the method further comprises selecting one or more of said reference sample sets so that the location of at least one of the reference sample sets depends on the horizontal and/or vertical location of the sample.
  • At least one reference sample set being selected such that the samples from the first and second reference line are not aligned with each other, there may be one or more further reference sample sets having their location depending on the horizontal and/or vertical location of the sample. In such reference sample sets, the samples from the first and second reference line may also be aligned with each other.
  • the method further comprises selecting at least one reference sample set so that its horizontal center is aligned with horizontal location of the sample and another reference sample set is selected so that its vertical center is aligned with the vertical location of the sample.
  • the widest input window of reference samples is provided for a filter, if the reference sample sets have their horizontal/vertical center aligned with the horizontal/vertical location of the current sample.
  • Figure 7 shows an example of reference sample arrangement, where three reference sample sets are provided for the current sample, one being determined based on the classification result and two being determined based on the horizontal/vertical location of the current sample.
  • the samples from the first and second reference line are not aligned with each other, thus being adjusted, based on the classification result, for diagonal prediction direction.
  • the reference sample set 1 has its location depending on the horizontal location of the current sample, thus being adjusted for vertical prediction direction.
  • the reference sample set 2 has its location depending on the vertical location of the current sample, thus being adjusted for horizontal prediction direction.
  • Figure 8 illustrates shows an example of reference sample arrangement, where four reference sample sets are provided for the current sample, two being determined based on the classification result and two being determined based on the horizontal/vertical location of the current sample.
  • reference sample sets 0 and 1 can be determined based on classification result
  • reference sample set 2 can be determined based horizontal coordinate of the output sample
  • reference sample set 3 can be determined based on the vertical coordinate of the output sample.
  • Filter parameters such as multiplier coefficients q(x, y)
  • each block position (x, y) can have separate sets of multipliers specific for that position for all its reference sample sets s and all available prediction classes g.
  • a predicted sample p g , x , y for class g can be calculated as a sum of the impacts of different reference sample sets when the total number of sample sets is denoted by S: where c g , s ,i(x, y) is the i th predetermined multiplier in prediction class g for output block position (x, y) in reference sample set s.
  • r g , s ,i(x, y) is the i th reference sample value in prediction class g for output block position (x, y) in reference sample set s.
  • the actual computations can be implemented using fixed point, integer or floating point numbers and include different scaling, rounding or weighting operations. The same can also be represented in vector form:
  • each block position can be associated with an output from a neural network or other linear or non-linear system that may have parameters impacting predicted values in multiple block positions.
  • the multipliers can be substituted by a non-linear or linear function fe, s that may be trained or determined by other means for intra prediction class g and reference sample set s:
  • Predicted samples can be determined based on a first set of coefficients that is fixed for a given reference sample set on one line of the prediction block and a second set of coefficients that is fixed for another line of the prediction block. This kind of design can significantly reduce the number of parameters that need to be trained and stored.
  • a method according to a second aspect can be implemented either independently or in combination with one or more of the above or below embodiments.
  • the method according to the second aspect is shown in Figure 9, where the method comprises determining (900) a block of samples to be predicted; determining (902) a first set of reference samples for the block; determining (904) a first predicted sample location within the block; determining (906) a second set of reference samples using said first predicted sample location as a classification information for said reference samples; determining (908) a predicted value for a first sample based on at least the first set of reference samples and the second set of reference samples; determining (910) a second predicted sample location within the block; determining (912) a third set of reference samples using said second predicted sample location as a classification information for said reference samples; and determining (914) a predicted value for a second sample based on at least the first set of reference samples and the third set of reference samples.
  • predicted samples of a block are generated from one or more reference sample groups using a learning based intra prediction process, where the reference samples of the reference sample groups are selected so that some reference samples, such as the first set of reference samples, are the same for all the locations of sample values to be predicted while some reference samples, such as the further sets of reference samples, change based on the location of sample values to be predicted.
  • the classification mode is not necessarily needed (but not excluded either), but rather the location of the current sample can be used as the classification information for the reference samples.
  • the first set of reference samples comprises samples on a first row of samples immediately above the block and/or samples on a first column of samples immediately left of the block.
  • the first set of reference samples which may herein be considered common for all the locations of sample values, comprises sample from the first reference line, i.e. from the first row of samples immediately above the block and/or the first column of samples immediately left of the block.
  • the samples from the first reference line, being the closest to the block, are typically more relevant for prediction, and therefore it is beneficial to select the common reference samples from the first reference line.
  • the first set of reference samples comprises all samples within a first predetermined window on the first row of samples immediately above the block and/or all samples within a second predetermined window on the first column of samples immediately left of the block.
  • the reference sample sets can be selected from a predetermined window or range of reconstructed samples in the vicinity of the block to be predicted. There may be a first predetermined window for the samples on the first row immediately above the block and a second predetermined window for the samples on the first column immediately left of the block.
  • the first and second predetermined windows may comprise an equal or a different number of samples.
  • the first set of reference samples may thus comprise all samples within the first and second predetermined windows of the first reference line.
  • the second set and the third set of reference samples comprise samples on a second row of samples above the block and/or samples on a second column of samples left of the block.
  • the further sets of reference samples such as the second, third, fourth, etc. set of reference samples, may be selected at least from the second reference line, being further away from the block, wherein selecting the samples to the further sets of reference samples may be more precisely adjusted based on the location of the current sample.
  • the method comprises determining a classification mode for the block of samples; and determining at least one of said second and third sets of reference samples based on the classification mode and the first and/or the second predicted sample location.
  • the classification mode such as an indication of diagonal prediction direction, may thus be utilized in selecting the samples in the second and third sets of reference samples.
  • Figure 10 shows an example of a reference sample arrangement, where a first set of reference samples (reference sample set 0, denoted with star symbols) locate on the first reference line, i.e. comprising samples on the first row of samples immediately above the block and on the first column of samples immediately left of the block.
  • the first set of reference samples is common for all output samples of the block.
  • the first set of reference samples is shown to comprise all samples of the first reference line, but in practical implementations, the number of samples could be limited by the first and second predetermined windows. The same applies to the following examples, as well.
  • the second and the third set of reference samples may be determined based on e.g. the classification mode indicating the diagonal prediction direction to applied for predicting the specific output sample.
  • the second and the third set of reference samples are thus output sample-specific, and for another output sample in the block there may be different second and/or third set of reference samples, or there may be only one, or even none, further set of reference samples.
  • Figure 11 shows another example of a reference sample arrangement, where, similarly to the example in Figure 10, a first set of reference samples (reference sample set 0, denoted with star symbols) locate on the first reference line, i.e. comprising samples on the first row of samples immediately above the block and on the first column of samples immediately left of the block.
  • the first set of reference samples is common for all output samples of the block.
  • there are a second set of reference samples (reference sample set 1, denoted with triangles) locating on the second row of samples above the block and a third set of reference samples (reference sample set 2, denoted with squares) locating on the second column of samples left to the block.
  • the second and the third set of reference samples may be determined based on either horizontal or vertical coordinates of the specific output sample, respectively.
  • Figure 12 shows yet another example of a reference sample arrangement, which is a combination of the examples in Figures 10 and 11.
  • a first set of reference samples (reference sample set 0, denoted with star symbols) locate on the first reference line, i.e. comprising samples on the first row of samples immediately above the block and on the first column of samples immediately left of the block.
  • the first set of reference samples is common for all output samples of the block.
  • the second set of reference samples (reference sample set 1, denoted with circles) locates on the second row of samples above the block and the third set of reference samples (reference sample set 2, denoted with shaded circles) locates on the second column of samples left to the block.
  • the second and the third set of reference samples may be determined based on e.g. the classification mode indicating the diagonal prediction direction to applied for predicting the specific output sample.
  • the fourth set of reference samples locates on the second row of samples above the block and the fifth set of reference samples (reference sample set 4, denoted with squares) locates on the second column of samples left to the block.
  • the fourth and the fifth set of reference samples may be determined based on either horizontal or vertical coordinates of the specific output sample, respectively.
  • a method according to a third aspect can be implemented either independently or in combination with one or more of the above or below embodiments.
  • the method according to the third aspect is shown in Figure 13, where the method comprises determining (1300) a block of samples to be predicted; determining (1302) a first set of reference samples, wherein the reference samples are derived from a first row of samples immediately above the block and a first column of samples immediate left of the block; determining (1304) a second row of samples above the first row of samples and a second column of samples left of the first column of samples; determining (1306) a second set of reference samples, wherein the reference samples are derived from the second row of samples and the second column of samples; wherein the number of samples in the second set of reference samples is smaller than the number of samples in the first set of reference samples; and determining (1308) a predicted value for a sample within the block using the first set of reference samples and the second set of reference samples.
  • the multiple reference sample sets are utilised such that the number of reference samples in a set, selected from a reference sample line, depends on the distance of the reference sample line from the block border. Accordingly, the distance of a reference line (a row of reference samples above the block or a column of reference samples left of the block) from the block border can be advantageously used to determine the set of reference samples n(x, y).
  • the principle here is that the further away from the block the reference line is, the less significant the reference samples on said reference line are for predicting an output sample in the block. Thus, the further away from the block the reference line is, the smaller number of reference samples are selected from said reference line.
  • the first set of reference samples comprises all samples within a first predetermined window on the first row of samples immediately above the block and/or all samples within a second predetermined window on the first column of samples immediately left of the block.
  • all the reference samples within the first and second predetermined windows in the first reference line closest to the prediction sample block can be included in the set of reference samples.
  • the first and second predetermined windows may comprise an equal or a different number of samples.
  • the second set of reference samples comprises every second sample on the second row of samples above the block and/or every second sample on the second column of samples left of the block.
  • the reference samples of the second reference line may be subsampled such that every second sample may be included from the second reference line to the second set of reference samples. It is noted that the second reference line may refer to any reference line other than the first reference immediately above and/or left to the block.
  • the method comprises determining a plurality of sets of reference samples including said first and second sets of reference sample, wherein a L th set of reference samples is derived from a L th row of samples and a L th column of samples; wherein the number of samples in the L th set of reference samples comprises every 2 1 ' -1 sample on the L th row of samples above the block and/or every 2 , _
  • the L th set of reference samples is derived from the first predetermined window within the L th row of samples and the second predetermined window within the L th column of samples.
  • the above generalization may be limited to applied within the first and second predetermined window of samples, wherein the first and second predetermined windows may be defined for the first line of reference samples, thereby reducing the number of samples from which subsampling for reference sample sets on further reference lines is carried out.
  • any other kind of reduction of selected reference samples as function of the distance of the reference sample line from the block border can be used.
  • every third sample may be selected from the second reference line. It is also possible to select every sample from the first and second reference lines and every other sample from the reference lines three and four.
  • the method comprises applying an offset to the reference samples of the second or any further reference sample set.
  • an offset may be applied to adjust the location of the reference samples in said reference sample set to better aligned with prediction to applied to output samples of the block.
  • Figure 14 shows an example of a reference sample arrangement, where a first set of reference samples (reference sample set 0, denoted with star symbols) locate on the first reference line, i.e. comprising samples on the first row of samples immediately above the block and on the first column of samples immediately left of the block.
  • the first set of reference samples is common for all output samples of the block.
  • the first set of reference samples is shown to comprise all samples of the first reference line, but in practical implementations, the number of samples could be limited by the first and second predetermined windows. The same applies to the following example, as well.
  • a second set of reference samples locate on the second reference line, i.e.
  • the second set of reference samples may be common for all output samples of the block.
  • subsampling has been applied to the second set of reference samples such that the second set of reference samples comprises every second sample on the second row of samples above the block and every second sample on the second column of samples left of the block.
  • Figure 15 shows another example of a reference sample arrangement otherwise similar to that of the example of Figure 14, but herein an offset is applied to the second set of reference samples.
  • the subsampled reference samples of the second set of reference samples are displaced by a half sample distance from the reconstructed neighboring samples and can be determined by a subsampling filter using the reconstructed neighboring samples as an input.
  • the examples shown in Figures 10 - 12 also comply with method according to a third aspect and the underlying principle that the further away from the block the reference line is, the smaller number of reference samples are selected from said reference line.
  • the examples according to the third aspect illustrate how the most relevant reference samples are selected from the second and further reference lines, while at the same time, the number of reference samples is further reduced, thereby contributing to memory and computational complexity reductions.
  • An apparatus comprises means for determining a block of samples to be predicted; means for determining a first set of reference samples for the block; means for determining a first predicted sample location within the block; means for determining a second set of reference samples using said first predicted sample location as a classification information for said reference samples; means for determining a predicted value for a first sample based on at least the first set of reference samples and the second set of reference samples; means for determining a second predicted sample location within the block; means for determining a third set of reference samples using said second predicted sample location as a classification information for said reference samples; and means for determining a predicted value for a second sample based on at least the first set of reference samples and the third set of reference samples.
  • the first set of reference samples comprises samples on a first row of samples immediately above the block and/or samples on a first column of samples immediately left of the block.
  • the first set of reference samples comprises all samples within a first predetermined window on the first row of samples immediately above the block and/or all samples within a second predetermined window on the first column of samples immediately left of the block.
  • the second set and the third set of reference samples comprise samples on a second row of samples above the block and/or samples on a second column of samples left of the block.
  • the apparatus comprises means for determining a classification mode for the block of samples; and means for determining at least one of said second and third sets of reference samples based on the classification mode and the first and/or the second predicted sample location.
  • the apparatus comprises means for determining the predicted value by multiplying values of the reference samples with a set of prediction parameters.
  • the set of prediction parameters comprises a set of predetermined values, multipliers, scalers, offsets, or a combination of those.
  • the apparatus comprises means for determining the predicted value by multiplying values of the reference samples with the determined set of prediction parameters.
  • the set of prediction parameters comprises parameters of a neural network.
  • the apparatus comprises means for determining the predicted value by applying the neural network, which uses at least the set of reference samples as its input.
  • the apparatus comprises means for selecting one or more of said reference sample sets so that the location of at least one of the reference sample sets depend on the position of the output sample location.
  • the apparatus comprises means for selecting at least one reference sample set so that its horizontal center is aligned with horizontal position of the output sample and another reference sample set is selected so that its vertical center is aligned with the vertical position of the output sample.
  • the apparatus comprises means for applying diagonal prediction direction for determining the predicted value for the sample at the determined location.
  • an apparatus comprising: at least one processor and at least one memory, said at least one memory stored with code thereon, which when executed by said at least one processor, causes the apparatus to perform at least: determine a block of samples to be predicted; determine a first set of reference samples for the block; determine a first predicted sample location within the block; determine a second set of reference samples using said first predicted sample location as a classification information for said reference samples; determine a predicted value for a first sample based on at least the first set of reference samples and the second set of reference samples; determine a second predicted sample location within the block; determine a third set of reference samples using said second predicted sample location as a classification information for said reference samples; and determine a predicted value for a second sample based on at least the first set of reference samples and the third set of reference samples.
  • the first set of reference samples comprises samples on a first row of samples immediately above the block and/or samples on a first column of samples immediately left of the block.
  • the first set of reference samples comprises all samples within a first predetermined window on the first row of samples immediately above the block and/or all samples within a second predetermined window on the first column of samples immediately left of the block.
  • the second set and the third set of reference samples comprise samples on a second row of samples above the block and/or samples on a second column of samples left of the block.
  • the apparatus comprises code configured to cause the apparatus to determine a classification mode for the block of samples; and determine at least one of said second and third sets of reference samples based on the classification mode and the first and/or the second predicted sample location.
  • the apparatus comprises code configured to cause the apparatus to determine the predicted value by multiplying values of the reference samples with a set of prediction parameters.
  • the set of prediction parameters comprises a set of predetermined values, multipliers, scalers, offsets, or a combination of those.
  • the apparatus comprises code configured to cause the apparatus to determine the predicted value by multiplying values of the reference samples with the determined set of prediction parameters.
  • the set of prediction parameters comprises parameters of a neural network.
  • the apparatus comprises code configured to cause the apparatus to determine the predicted value by applying the neural network, which uses at least the set of reference samples as its input.
  • the apparatus comprises code configured to cause the apparatus to select at least one reference sample set so that its horizontal center is aligned with horizontal position of the output sample and another reference sample set is selected so that its vertical center is aligned with the vertical position of the output sample.
  • the apparatus comprises code configured to cause the apparatus to apply diagonal prediction direction for determining the predicted value for the sample at the determined location.
  • Such apparatuses may comprise e.g. all or a subset of the functional units disclosed in any of the appended Figures la, lb, and 16 - 19 for implementing the embodiments.
  • Such an apparatus further comprises code, stored in said at least one memory, which when executed by said at least one processor, causes the apparatus to perform one or more of the embodiments disclosed herein.
  • Figure 16 shows a schematic block diagram of an exemplary apparatus or electronic device 50, which may incorporate a codec according to an embodiment of the invention.
  • Figure 17 shows a layout of an apparatus according to an example embodiment.
  • the electronic device 50 may for example be a mobile terminal or user equipment of a wireless communication system. However, it would be appreciated that embodiments of the invention may be implemented within any electronic device or apparatus which may require encoding and decoding or encoding or decoding video images.
  • the apparatus 50 may comprise a housing 30 for incorporating and protecting the device.
  • the apparatus 50 further may comprise a display 32 in the form of a liquid crystal display.
  • the display may be any suitable display technology suitable to display an image or video.
  • the apparatus 50 may further comprise a keypad 34.
  • any suitable data or user interface mechanism may be employed.
  • the user interface may be implemented as a virtual keyboard or data entry system as part of a touch-sensitive display.
  • the apparatus may comprise a microphone 36 or any suitable audio input which may be a digital or analogue signal input.
  • the apparatus 50 may further comprise an audio output device which in embodiments of the invention may be any one of: an earpiece 38, speaker, or an analogue audio or digital audio output connection.
  • the apparatus 50 may also comprise a battery (or in other embodiments of the invention the device may be powered by any suitable mobile energy device such as solar cell, fuel cell or clockwork generator).
  • the apparatus may further comprise a camera capable of recording or capturing images and/or video.
  • the apparatus 50 may further comprise an infrared port for short range line of sight communication to other devices. In other embodiments the apparatus 50 may further comprise any suitable short range communication solution such as for example a Bluetooth wireless connection or a USB/firewire wired connection.
  • the apparatus 50 may comprise a controller 56, processor or processor circuitry for controlling the apparatus 50.
  • the controller 56 may be connected to memory 58 which in embodiments of the invention may store both data in the form of image and audio data and/or may also store instructions for implementation on the controller 56.
  • the controller 56 may further be connected to codec circuitry 54 suitable for carrying out coding and decoding of audio and/or video data or assisting in coding and decoding carried out by the controller.
  • the apparatus 50 may further comprise a card reader 48 and a smart card 46, for example a UICC and UICC reader for providing user information and being suitable for providing authentication information for authentication and authorization of the user at a network.
  • a card reader 48 and a smart card 46 for example a UICC and UICC reader for providing user information and being suitable for providing authentication information for authentication and authorization of the user at a network.
  • the apparatus 50 may comprise radio interface circuitry 52 connected to the controller and suitable for generating wireless communication signals for example for communication with a cellular communications network, a wireless communications system or a wireless local area network.
  • the apparatus 50 may further comprise an antenna 44 connected to the radio interface circuitry 52 for transmitting radio frequency signals generated at the radio interface circuitry 52 to other apparatus(es) and for receiving radio frequency signals from other apparatus(es).
  • the apparatus 50 may comprise a camera capable of recording or detecting individual frames which are then passed to the codec 54 or the controller for processing.
  • the apparatus may receive the video image data for processing from another device prior to transmission and/or storage.
  • the apparatus 50 may also receive either wirelessly or by a wired connection the image for coding/decoding.
  • the structural elements of apparatus 50 described above represent examples of means for performing a corresponding function.
  • the system 10 comprises multiple communication devices which can communicate through one or more networks.
  • the system 10 may comprise any combination of wired or wireless networks including, but not limited to a wireless cellular telephone network (such as a GSM, UMTS, CDMA network etc.), a wireless local area network (WLAN) such as defined by any of the IEEE 802.x standards, a Bluetooth personal area network, an Ethernet local area network, a token ring local area network, a wide area network, and the Internet.
  • a wireless cellular telephone network such as a GSM, UMTS, CDMA network etc.
  • WLAN wireless local area network
  • the system 10 may include both wired and wireless communication devices and/or apparatus 50 suitable for implementing embodiments of the invention.
  • the system shown in Figure 18 shows a mobile telephone network 11 and a representation of the internet 28.
  • Connectivity to the internet 28 may include, but is not limited to, long range wireless connections, short range wireless connections, and various wired connections including, but not limited to, telephone lines, cable lines, power lines, and similar communication pathways.
  • the example communication devices shown in the system 10 may include, but are not limited to, an electronic device or apparatus 50, a combination of a personal digital assistant (PDA) and a mobile telephone 14, a PDA 16, an integrated messaging device (IMD) 18, a desktop computer 20, a notebook computer 22.
  • PDA personal digital assistant
  • IMD integrated messaging device
  • the apparatus 50 may be stationary or mobile when carried by an individual who is moving.
  • the apparatus 50 may also be located in a mode of transport including, but not limited to, a car, a truck, a taxi, a bus, a train, a boat, an airplane, a bicycle, a motorcycle or any similar suitable mode of transport.
  • the embodiments may also be implemented in a set-top box; i.e. a digital TV receiver, which may/may not have a display or wireless capabilities, in tablets or (laptop) personal computers (PC), which have hardware or software or combination of the encoder/decoder implementations, in various operating systems, and in chipsets, processors, DSPs and/or embedded systems offering hardware/software based coding.
  • a set-top box i.e. a digital TV receiver, which may/may not have a display or wireless capabilities, in tablets or (laptop) personal computers (PC), which have hardware or software or combination of the encoder/decoder implementations, in various operating systems, and in chipsets, processors, DSPs and/or embedded systems offering hardware/software based coding.
  • Some or further apparatus may send and receive calls and messages and communicate with service providers through a wireless connection 25 to a base station 24.
  • the base station 24 may be connected to a network server 26 that allows communication between the mobile telephone network 11 and the internet 28.
  • the system may include additional communication devices and communication devices of various types.
  • the communication devices may communicate using various transmission technologies including, but not limited to, code division multiple access (CDMA), global systems for mobile communications (GSM), universal mobile telecommunications system (UMTS), time divisional multiple access (TDMA), frequency division multiple access (FDMA), transmission control protocol-internet protocol (TCP-IP), short messaging service (SMS), multimedia messaging service (MMS), email, instant messaging service (IMS), Bluetooth, IEEE 802.11 and any similar wireless communication technology.
  • CDMA code division multiple access
  • GSM global systems for mobile communications
  • UMTS universal mobile telecommunications system
  • TDMA time divisional multiple access
  • FDMA frequency division multiple access
  • TCP-IP transmission control protocol-internet protocol
  • SMS short messaging service
  • MMS multimedia messaging service
  • email instant messaging service
  • Bluetooth IEEE 802.11 and any similar wireless communication technology.
  • a communications device involved in implementing various embodiments of the present invention may communicate using various media including, but not limited to, radio, infrared, laser, cable connections, and any suitable connection.
  • FIG 19 is a graphical representation of an example multimedia communication system within which various embodiments may be implemented.
  • a data source 1510 provides a source signal in an analog, uncompressed digital, or compressed digital format, or any combination of these formats.
  • An encoder 1520 may include or be connected with a preprocessing, such as data format conversion and/or filtering of the source signal.
  • the encoder 1520 encodes the source signal into a coded media bitstream. It should be noted that a bitstream to be decoded may be received directly or indirectly from a remote device located within virtually any type of network. Additionally, the bitstream may be received from local hardware or software.
  • the encoder 1520 may be capable of encoding more than one media type, such as audio and video, or more than one encoder 1520 may be required to code different media types of the source signal.
  • the encoder 1520 may also get synthetically produced input, such as graphics and text, or it may be capable of producing coded bitstreams of synthetic media. In the following, only processing of one coded media bitstream of one media type is considered to simplify the description. It should be noted, however, that typically real-time broadcast services comprise several streams (typically at least one audio, video and text sub-titling stream). It should also be noted that the system may include many encoders, but in the figure only one encoder 1520 is represented to simplify the description without a lack of generality. It should be further understood that, although text and examples contained herein may specifically describe an encoding process, one skilled in the art would understand that the same concepts and principles also apply to the corresponding decoding process and vice versa.
  • the coded media bitstream may be transferred to a storage 1530.
  • the storage 1530 may comprise any type of mass memory to store the coded media bitstream.
  • the format of the coded media bitstream in the storage 1530 may be an elementary self-contained bitstream format, or one or more coded media bitstreams may be encapsulated into a container file, or the coded media bitstream may be encapsulated into a Segment format suitable for DASH (or a similar streaming system) and stored as a sequence of Segments. If one or more media bitstreams are encapsulated in a container file, a file generator (not shown in the figure) may be used to store the one more media bitstreams in the file and create file format metadata, which may also be stored in the file.
  • the encoder 1520 or the storage 1530 may comprise the file generator, or the file generator is operationally attached to either the encoder 1520 or the storage 1530.
  • Some systems operate “live”, i.e. omit storage and transfer coded media bitstream from the encoder 1520 directly to the sender 1540.
  • the coded media bitstream may then be transferred to the sender 1540, also referred to as the server, on a need basis.
  • the format used in the transmission may be an elementary self-contained bitstream format, a packet stream format, a Segment format suitable for DASH (or a similar streaming system), or one or more coded media bitstreams may be encapsulated into a container file.
  • the encoder 1520, the storage 1530, and the server 1540 may reside in the same physical device or they may be included in separate devices.
  • the encoder 1520 and server 1540 may operate with live real-time content, in which case the coded media bitstream is typically not stored permanently, but rather buffered for small periods of time in the content encoder 1520 and/or in the server 1540 to smooth out variations in processing delay, transfer delay, and coded media bitrate.
  • the server 1540 sends the coded media bitstream using a communication protocol stack.
  • the stack may include but is not limited to one or more of Real-Time Transport Protocol (RTP), User Datagram Protocol (UDP), Hypertext Transfer Protocol (HTTP), Transmission Control Protocol (TCP), and Internet Protocol (IP).
  • RTP Real-Time Transport Protocol
  • UDP User Datagram Protocol
  • HTTP Hypertext Transfer Protocol
  • TCP Transmission Control Protocol
  • IP Internet Protocol
  • the server 1540 encapsulates the coded media bitstream into packets.
  • RTP Real-Time Transport Protocol
  • UDP User Datagram Protocol
  • HTTP Hypertext Transfer Protocol
  • TCP Transmission Control Protocol
  • IP Internet Protocol
  • the sender 1540 may comprise or be operationally attached to a "sending file parser" (not shown in the figure).
  • a sending file parser locates appropriate parts of the coded media bitstream to be conveyed over the communication protocol.
  • the sending file parser may also help in creating the correct format for the communication protocol, such as packet headers and payloads.
  • the multimedia container file may contain encapsulation instructions, such as hint tracks in the ISOBMFF, for encapsulation of the at least one of the contained media bitstream on the communication protocol.
  • the server 1540 may or may not be connected to a gateway 1550 through a communication network, which may e.g. be a combination of a CDN, the Internet and/or one or more access networks.
  • the gateway may also or alternatively be referred to as a middle-box.
  • the gateway may be an edge server (of a CDN) or a web proxy. It is noted that the system may generally comprise any number gateways or alike, but for the sake of simplicity, the following description only considers one gateway 1550.
  • the gateway 1550 may perform different types of functions, such as translation of a packet stream according to one communication protocol stack to another communication protocol stack, merging and forking of data streams, and manipulation of data stream according to the downlink and/or receiver capabilities, such as controlling the bit rate of the forwarded stream according to prevailing downlink network conditions.
  • the gateway 1550 may be a server entity in various embodiments.
  • the system includes one or more receivers 1560, typically capable of receiving, demodulating, and de-capsulating the transmitted signal into a coded media bitstream.
  • the coded media bitstream may be transferred to a recording storage 1570.
  • the recording storage 1570 may comprise any type of mass memory to store the coded media bitstream.
  • the recording storage 1570 may alternatively or additively comprise computation memory, such as random access memory.
  • the format of the coded media bitstream in the recording storage 1570 may be an elementary self-contained bitstream format, or one or more coded media bitstreams may be encapsulated into a container file. If there are multiple coded media bitstreams, such as an audio stream and a video stream, associated with each other, a container file is typically used and the receiver 1560 comprises or is attached to a container file generator producing a container file from input streams. Some systems operate “live,” i.e. omit the recording storage 1570 and transfer coded media bitstream from the receiver 1560 directly to the decoder 1580. In some systems, only the most recent part of the recorded stream, e.g., the most recent 10-minute excerption of the recorded stream, is maintained in the recording storage 1570, while any earlier recorded data is discarded from the recording storage 1570.
  • the coded media bitstream may be transferred from the recording storage 1570 to the decoder 1580. If there are many coded media bitstreams, such as an audio stream and a video stream, associated with each other and encapsulated into a container file or a single media bitstream is encapsulated in a container file e.g. for easier access, a file parser (not shown in the figure) is used to decapsulate each coded media bitstream from the container file.
  • the recording storage 1570 or a decoder 1580 may comprise the file parser, or the file parser is attached to either recording storage 1570 or the decoder 1580. It should also be noted that the system may include many decoders, but here only one decoder 1580 is discussed to simplify the description without a lack of generality.
  • the coded media bitstream may be processed further by a decoder 1580, whose output is one or more uncompressed media streams.
  • a Tenderer 1590 may reproduce the uncompressed media streams with a loudspeaker or a display, for example.
  • the receiver 1560, recording storage 1570, decoder 1580, and Tenderer 1590 may reside in the same physical device or they may be included in separate devices.
  • a sender 1540 and/or a gateway 1550 may be configured to perform switching between different representations e.g. for switching between different viewports of 360-degree video content, view switching, bitrate adaptation and/or fast start-up, and/or a sender 1540 and/or a gateway 1550 may be configured to select the transmitted representation(s). Switching between different representations may take place for multiple reasons, such as to respond to requests of the receiver 1560 or prevailing conditions, such as throughput, of the network over which the bitstream is conveyed. In other words, the receiver 1560 may initiate switching between representations.
  • a request from the receiver can be, e.g., a request for a Segment or a Subsegment from a different representation than earlier, a request for a change of transmitted scalability layers and/or sub-layers, or a change of a rendering device having different capabilities compared to the previous one.
  • a request for a Segment may be an HTTP GET request.
  • a request for a Subsegment may be an HTTP GET request with a byte range.
  • bitrate adjustment or bitrate adaptation may be used for example for providing so-called fast start-up in streaming services, where the bitrate of the transmitted stream is lower than the channel bitrate after starting or random-accessing the streaming in order to start playback immediately and to achieve a buffer occupancy level that tolerates occasional packet delays and/or retransmissions.
  • Bitrate adaptation may include multiple representation or layer up-switching and representation or layer down-switching operations taking place in various orders.
  • a decoder 1580 may be configured to perform switching between different representations e.g. for switching between different viewports of 360-degree video content, view switching, bitrate adaptation and/or fast start-up, and/or a decoder 1580 may be configured to select the transmitted representation(s). Switching between different representations may take place for multiple reasons, such as to achieve faster decoding operation or to adapt the transmitted bitstream, e.g. in terms of bitrate, to prevailing conditions, such as throughput, of the network over which the bitstream is conveyed.
  • Faster decoding operation might be needed for example if the device including the decoder 1580 is multi-tasking and uses computing resources for other purposes than decoding the video bitstream.
  • faster decoding operation might be needed when content is played back at a faster pace than the normal playback speed, e.g. twice or three times faster than conventional real-time playback rate.
  • user equipment may comprise a video codec such as those described in embodiments of the invention above. It shall be appreciated that the term user equipment is intended to cover any suitable type of wireless user equipment, such as mobile telephones, portable data processing devices or portable web browsers.
  • elements of a public land mobile network may also comprise video codecs as described above.
  • the various embodiments of the invention may be implemented in hardware or special purpose circuits, software, logic or any combination thereof.
  • some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto.
  • firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto.
  • While various aspects of the invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.
  • the embodiments of this invention may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware.
  • any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions.
  • the software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD.
  • the memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.
  • the data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multi-core processor architecture, as non-limiting examples.
  • Embodiments of the inventions may be practiced in various components such as integrated circuit modules.
  • the design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.
  • Programs such as those provided by Synopsys, Inc. of Mountain View, California and Cadence Design, of San Jose, California automatically route conductors and locate components on a semiconductor chip using well established rules of design as well as libraries of pre-stored design modules.
  • the resultant design in a standardized electronic format (e.g., Opus, GDSII, or the like) may be transmitted to a semiconductor fabrication facility or "fab" for fabrication.
  • a standardized electronic format e.g., Opus, GDSII, or the like

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Abstract

L'invention concerne un procédé consistant à : déterminer un bloc d'échantillons à prédire ; déterminer un premier ensemble d'échantillons de référence pour le bloc ; déterminer un premier emplacement d'échantillon prédit à l'intérieur du bloc ; déterminer un deuxième ensemble d'échantillons de référence à l'aide dudit premier emplacement d'échantillon prédit en tant qu'informations de classification pour lesdits échantillons de référence ; déterminer une valeur prédite pour un premier échantillon sur la base au moins du premier ensemble d'échantillons de référence et du deuxième ensemble d'échantillons de référence ; déterminer un deuxième emplacement d'échantillon prédit à l'intérieur du bloc ; déterminer un troisième ensemble d'échantillons de référence à l'aide dudit deuxième emplacement d'échantillon prédit en tant qu'informations de classification pour lesdits échantillons de référence ; et déterminer une valeur prédite pour un deuxième échantillon sur la base au moins du premier ensemble d'échantillons de référence et du troisième ensemble d'échantillons de référence.
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US20230362353A1 (en) * 2016-05-04 2023-11-09 Microsoft Technology Licensing, Llc Intra-picture prediction using non-adjacent reference lines of sample values
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