JP2004289808A - Image encoding method and image decoding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image coding method and an image decoding method which prevent a malfunction caused by a retransmission of a command. <P>SOLUTION: The image coding method for preventing a malfunction includes an adding step (step S203) of coding a memory management command for a first picture of a predetermined picture number and adding the command to a second picture different from the first picture (step S203) and a readding step of recoding the memory management command and readding the command to an addition target portion other than the second picture of an image coding stream VSt (steps S205 to S208). In the readding step, when the first picture is not disposed immediately before among pictures of predetermined picture numbers included in the image coding stream VSt, the readdition of the memory management command is inhibited. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image encoding method for encoding a moving image signal for each picture, and an image decoding method for decoding the encoded signal.

  In recent years, the multimedia era, in which voices, images, and other pixel values are integrated, has been approached, and the traditional information media, that is, means for transmitting information such as newspapers, magazines, televisions, radios, and telephones, to humans, has been developed. It has been taken up as an object. Generally, multimedia means not only characters, but also figures, sounds, and especially images, etc., that are simultaneously associated with each other. Is an essential condition.

  However, when the amount of information of each of the above information media is estimated as a digital information amount, the amount of information per character is 1 to 2 bytes in the case of characters, while 64 kbits per second in the case of voice (telephone quality). In addition, for a moving image, an information amount of 100 Mbits per second (current television reception quality) or more is required, and it is not realistic to handle the vast amount of information in the above-mentioned information medium in a digital form. For example, videophones have already been put into practical use by the Integrated Services Digital Network (ISDN) having a transmission rate of 64 kbps to 1.5 Mbps, but it is impossible to send video from a video camera directly through ISDN. It is possible.

  Therefore, information compression technology is required. For example, in the case of a videophone, H.264 standardized internationally by ITU-T (International Telecommunication Union Telecommunication Standardization Sector). 261 and H.E. H.263 video compression technology is used. In addition, according to the information compression technology of the MPEG-1 standard, it is possible to store image information together with audio information in a normal music CD (compact disc).

  Here, MPEG (Moving Picture Experts Group) is an international standard for digital compression of moving image signals, and MPEG-1 converts moving image signals up to 1.5 Mbps, that is, information of television signals by about 1/100. It is a standard that compresses up to. In addition, since the transmission rate for the MPEG-1 standard is mainly limited to about 1.5 Mbps, the moving picture signal is 2 to 2 in MPEG-2, which is standardized to meet the demand for higher image quality. It is compressed to 15 Mbps.

  Further, at present, MPEG-4, which has a higher compression ratio, has been standardized by a working group (ISO / IEC JTC1 / SC29 / WG11) that has been standardizing MPEG-1 and MPEG-2. MPEG-4 initially introduced a powerful error resilience technique that not only enables highly efficient encoding at a low bit rate, but also reduces subjective image quality degradation even if a transmission path error occurs. . In addition, ISO / IEC and ITU-T have jointly developed ITU H.264 as a next-generation image coding system by JVT (Joint Video Team). H.264 | AVC has been advancing a standardization activity, and at present, a study called FCD (SoFCD) is the latest (for example, see Non-Patent Document 1).

H. Unlike H.264 | AVC, unlike conventional video coding, an arbitrary picture can be selected as a forward reference picture from a plurality of pictures. Here, a picture represents a frame or a field.
Reference pictures and the like are stored in the memory.
The memory includes a short-term storage memory and a long-term storage memory. The short-term storage memory stores a plurality of pictures decoded immediately before, and is a so-called MPEG-1 or MPEG-2 P picture (forward predictive coded picture) and B picture (bidirectional predictive coded picture). Is stored. The long-term storage memory is used for storing pictures for a longer time than the short-term storage memory.

  Normally, the short-term storage memory is a FIFO (first-in, first-out) memory, and when a picture is filled in the storage area and a picture is further stored in the short-term storage memory, the shortest-time storage memory is most frequently used. The picture saved at the old time is removed and the new image is saved in the removed area. Therefore, when it is necessary to refer to a reference picture that is usually removed from the short-term storage memory for a long time, the reference picture is moved from the short-term storage memory to the long-term storage memory in advance and stored in the long-term storage memory. To save. This enables long-term reference. The long-term storage memory stores a picture in a specified area. As a result, the picture stored in the area can be referred to unless the same area is designated and overwritten.

Further, the decoded picture is temporarily stored in the display memory until it is displayed. This display memory has a FIFO configuration in which the oldest pictures are overwritten in the order of display.
In order to use such memory efficiently, advanced memory management is required. 264 | AVC.

The memory management commands used for the management include, for example, the following commands.
1. 1. A command to select a referenceable picture 2. A command to release a memory area in which a picture that is no longer required as a reference picture for predictive encoding is stored in the short-time storage memory. 3. Command to move pictures from short-term storage memory to long-term storage memory Command to release all pictures in the memory and initialize information related to picture decoding In image coding / decoding, in order to select a picture having a small prediction error in a block unit from referenceable pictures as a reference picture, A signal (reference picture indication signal) indicating a reference picture in block units is required. By selecting a picture that can be referred to in advance, the number of reference picture candidates can be narrowed down to an appropriate value, and the number of bits of the reference image indication signal required for each block can be saved.

When a picture is moved from the short-term storage memory to the long-term storage memory, it is useless to store the same picture in both the short-term storage memory and the long-term storage memory. Pictures in memory are removed.
In such an image encoding method and an image decoding method, a memory management command for instructing removal of unnecessary pictures from a memory and a memory for instructing movement of pictures from a short-term storage memory to a long-term storage memory are provided. The management command is encoded and output by the image encoding device, and transmitted to the image decoding device for decoding. Such a memory management command is transmitted by being added to the encoded picture. If the picture accompanying the memory management command is lost due to a transmission error or the like, the image in the memory of the image decoding apparatus side is deleted. Since the arrangement cannot be correctly restored, the picture cannot be decoded.

In consideration of such a problem, retransmission of the memory management command (MMCO) can be considered. By retransmitting the memory management command in this way, when a picture accompanying the memory management command is lost due to a transmission error or the like, the retransmitted memory management command correctly restores the image arrangement in the memory.
In order to indicate the picture to which the memory management command is applied (the picture to be managed by the memory management command) or the picture to which the memory management command added when retransmitting the memory management command is to be retransmitted , A picture number is assigned to each picture. The picture number indicates a picture to be managed or a picture to which a memory management command is first added.

The picture number is a number assigned in ascending order (encoding order) in the image encoding stream, and is also used to derive the display order of the pictures in the display memory. Since the picture number becomes very large as the number of pictures increases, the picture number is encoded as a remainder of a predetermined number MaxFrameNum.
On the other hand, even if the picture rate or the like of an image coded stream is switched in the middle, an IDR picture is introduced to ensure that the subsequent image coded stream can be correctly decoded. The IDR picture is a picture for preventing reference to a picture ahead of the IDR picture. When the IDR picture is coded, the picture in the memory is released and the picture is decoded. Is initialized. For this reason, the pictures stored in the memory before and after the encoding and decoding of the IDR picture are different. An initialization command may be used instead of an IDR picture. An IDR picture initializes decoding information about all pictures including a picture number, whereas an initialization command initializes only some information (such as a picture number).

When the image encoded stream is edited, that is, when a part of each of the plurality of image encoded streams is extracted and combined and another image encoded stream is newly generated, the combining unit ( At the edit point), a mismatch such as a picture number occurs.
"Study of Final Committee Draft of Joint Video Specification", Joint Video Team (JVT) of ISO / IEC and ITU-T VCEG, JVT-F100, 15 Feb., 2003

However, in the above-described image encoding method and image decoding method, even if the retransmitted memory management command indicates a picture to be managed by a picture number, the image decoding apparatus that has received the retransmitted memory management command does not However, it is unclear which picture the memory management command is for, which may cause a malfunction.
That is, the same picture number is assigned to different pictures by expressing the picture number as a predetermined remainder, or by initializing the picture number to 0 by an IDR picture or an initialization command. In addition, it becomes difficult to specify one picture by the picture number, which causes a malfunction.

  For example, the display memory removes each picture in ascending order of display order based on information on the display order of each picture, and secures a new area necessary for display. When the IDR picture or the picture number after the initialization command is reset to the minimum value 0, the information indicating the display order is also initialized. As a result, even if the image encoding apparatus retransmits a memory management command for managing a picture in front of an IDR picture or the like after encoding the IDR picture or the initialization command, the image decoding apparatus that has received it Causes a malfunction because there is no picture to which the memory management command is applied.

  The present invention has been made in view of such a problem, and has as its object to provide an image encoding method and an image decoding method for preventing occurrence of a malfunction due to retransmission of a command.

  In order to achieve the above object, the image encoding method of the present invention assigns a picture number to each picture included in a moving image signal in the order of encoding in units of a predetermined number of pictures, and performs encoding for each picture. An image encoding method for generating an image encoded signal by using a memory management command indicating management contents in a memory for a first picture of a predetermined picture number, the second picture being different from the first picture And a re-adding step of re-adding the memory management command to an additional target portion other than the second picture in the image coded signal, wherein the re-adding step comprises: Out of the pictures of the predetermined picture number included in the coded image signals up to, the first picture is immediately before the addition target portion in coding order. A determining sub-step of judging whether said if it is determined that no previously on that determination substep is characterized in that it comprises a prohibition substep of prohibiting the re-addition of the memory management command.

  As a result, since the picture to be managed by the re-added memory management command is always the immediately preceding picture, the image decoding apparatus that has obtained the re-added and re-transmitted memory management command has the memory Even if there are a plurality of pictures having a predetermined picture number indicated by the management command, the immediately preceding picture can be specified as a picture to be managed by the memory management command, and image decoding caused by the retransmitted memory management command It is possible to prevent occurrence of a malfunction on the conversion device side.

Further, in the determining sub-step, it is further determined whether or not the first picture is ahead of a reference point in an image coded signal in coding order. When it is determined in the determination sub-step that the memory management command is located ahead, re-addition of the memory management command may be prohibited. For example, in the determination sub-step, an edit point at which the continuity of the image coded signal is lost by editing is treated as the reference point. Alternatively, in the determination sub-step, a picture encoded including information prompting to initialize a memory is treated as the reference point.

  As a result, since the memory management command that manages the picture located ahead of the reference point is not re-added, the image decoding apparatus that has obtained the re-added and re-transmitted memory management command as described above uses the reference point. The later picture can be treated as the management target of the memory management command, and the occurrence of a malfunction caused by applying the memory management command to a picture that is before the reference point and has already been erased, for example, can be prevented. Can be prevented.

  In order to achieve the above object, an image decoding method according to the present invention further comprises: converting an image coded signal in which a moving image signal is coded on a picture basis in a decoding order for each picture in a predetermined picture number unit. An image decoding method for decoding using an assigned picture number, comprising: determining whether a memory management command indicating management content on a memory for a picture having a predetermined picture number is added to the image code signal. A determining step of determining, and when it is determined in the determining step that the memory management command is added, decoding is performed from among the pictures having the predetermined picture number included in the image coded signal up to the memory management command. A selecting step of selecting a picture immediately before the memory management command in order, and selecting a picture selected in the selecting step. , Characterized in that it comprises an execution step of executing the management contents indicated by the memory management command.

  As a result, even if there are a plurality of pictures having a predetermined picture number indicated by the memory management command, the memory management command is applied to the immediately preceding picture. Is retransmitted from the image encoding device, the management targets can be matched on the encoding side and the decoding side, and the occurrence of malfunction due to the memory management command retransmitted from the image encoding device can be prevented. be able to.

  It should be noted that the present invention can be realized not only as such an image encoding method and an image decoding method, but also as an image encoding apparatus and an image decoding apparatus using such a method. It can be realized as a recording medium on which an image encoded stream encoded by the encoding method is recorded, or as a program for causing a computer to execute each step in the image encoding method and the image decoding method. Needless to say, such a program can be distributed via a recording medium such as a CD-ROM or a transmission medium such as the Internet.

  The image encoding method and the image decoding method according to the present invention have an effect of being able to prevent occurrence of a malfunction due to retransmission of a command.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a block diagram illustrating a configuration of an image encoding device for implementing the image encoding method according to the present embodiment.
The image encoding device 100 includes a memory information control unit 101, a short-term storage memory management unit 102, a long-term storage memory management unit 103, a non-storage memory management information unit 104, a management information encoding unit 105, An image selection unit 106, a storage area designation unit 107, a reference area designation unit 108, an image memory 109, an image decoding unit 111, an image encoding unit 110, a variable length encoding unit 112, a counter 113, , A counter 114 and the like.

The reference image selection unit 106 selects a reference picture candidate from the importance level indication signal Pri and the picture type information PT input from the outside, and notifies the memory information control unit 101 of the selection result.
The memory information control unit 101 determines whether one of the front and rear pictures, or both pictures, can be referred to based on the picture type information PT. Further, the memory information control unit 101 instructs the reference area designating unit 108 to output a reference picture corresponding to the determination result from the image memory 109 to the image encoding unit 110.

  The image encoding unit 110 encodes the input image signal Vin for each picture with reference to the reference picture output from the image memory 109. The variable length coding unit 112 further performs variable length coding on the output from the image coding unit 110 and outputs a coded image stream VSt. Further, when the coded video stream VSt is edited, the variable length coding unit 112 also codes information indicating an editing point of the edited coded video stream VSt. The output of the image encoding unit 110 is decoded by the image decoding unit 111 to become a decoded image, and is stored in the image memory 109 as a reference picture.

  At this time, the memory area in the image memory 109 in which the decoded image can be stored is determined by an instruction from the storage area specifying unit 107. That is, the memory information control unit 101 inquires of the short-term storage memory management unit 102 to specify a memory area in the short-term storage memory in the image memory 109 from which pictures have been removed. The storage area specifying unit 107 issues an instruction to the image memory 109 to record the decoded image in the specified memory area.

  The short-term storage memory management unit 102 detects unnecessary (unreferenced) pictures in the short-term storage memory, manages the pictures, and removes them (releases the memory). The management command is notified to the memory information control unit 101. Further, the long-term storage memory management unit 103 manages a picture in the short-term storage memory, and issues a memory management command having a content for instructing the picture to be moved to the long-term storage memory in the image memory 109. Notify section 101. Such a memory management command is encoded by the management information encoding unit 105 to become a memory management information stream CSt. Further, the memory management command included in such a memory management information stream CSt is added to the coded image stream VSt and transmitted to the image decoding device.

The counter 113 for the short-term storage memory and the counter 114 for the long-term storage memory include a memory management command for removing unnecessary pictures and an instruction for moving a picture in the short-term storage memory to the long-term storage memory. The number of times the memory management command to be coded is counted.
The non-storage memory management information unit 104 encodes a memory management command that instructs removal of unnecessary pictures and a memory management command that instructs to move a picture in the short-term storage memory to the long-term storage memory. It manages whether or not it has been added to a picture of low importance in the encoded stream VSt that is difficult to decode. Then, when the non-preserved memory management information unit 104 is added to a picture with low importance, the non-stored memory management information unit 104 instructs the memory information control unit 101 to re-encode the memory management command and to add it to the coded image stream VSt. .

Accordingly, the image encoding device 100 transmits the memory management command a plurality of times as necessary, thereby preventing the memory management command of the memory management information stream CSt from being lost due to a transmission path error.
Further, when the memory management command is transmitted for the second or subsequent time (at the time of retransmission), the picture (the picture to be managed) stored in the memory to which the memory management command is applied is more than the IDR picture. It is detected whether the picture is coded before, and if the picture is coded before the IDR picture, the memory management command is not coded and retransmitted. In addition, the memory information control unit 101 detects whether or not the management target picture is the latest picture in coding order among pictures having the same picture number (because a cyclic number is assigned). Only when the picture is the latest picture, the memory management command is encoded and retransmitted. Further, the memory information control unit 101 detects whether or not the picture to be managed precedes in the coding order from the editing point that has become discontinuous due to the editing of the coded image stream VSt. In some cases, the memory management command is not encoded and retransmitted.

Here, features of the present embodiment will be described.
FIG. 2A is a diagram showing each encoded picture.
As shown in FIG. 2A, each picture is assigned a picture number in the order of encoding. When the picture number reaches a predetermined maximum value (for example, 15), it is returned to 0 again. As described above, the picture numbers are cyclic.

It is assumed that the picture to be coded at this point (the picture to be coded) is picture A. In the present embodiment, when a memory management command (MMCO) attached to a picture coded before picture A is coded again and added at the position of picture A, the following is performed.
Each picture coded before picture A is referred to as picture B0, B1... B15, C0, C1. The picture numbers of the pictures B0 to B15 are 0 to 15, and the picture numbers of the pictures C0 to C11 are 0 to 11. The pictures C0, C1,..., C11 are closer to the picture A in coding order than the pictures B0, B1,. Therefore, the image coding apparatus 100 according to the present embodiment re-encodes the memory management command applied to the pictures C0, C1,. Are not re-encoded.

  For example, even if a memory management command indicating that the memory in which the picture B2 of the picture number 2 is stored is released (reusable) has been previously encoded, the image encoding according to the present embodiment is performed. The apparatus 100 does not re-encode the memory management command with the picture A, and if the memory management command indicating that the memory area storing the picture C2 of the picture number 2 is to be released has been previously encoded. , Is re-encoded (re-added) at the location of picture A.

  By doing so, the image decoding apparatus decodes the memory management command for instructing the release of the memory area, and when decoding the memory management command, the picture B2 and the picture C2 to which the same picture number 2 is assigned are stored. Which one should be opened can be uniquely determined. That is, the image decoding apparatus can specify the memory area in which the picture C2 encoded at the time closest to the encoding target picture A is stored as the memory area to be released. As a result, there is no occurrence of a mismatch between the states of the memories in the image encoding device and the image decoding device, and it is possible to prevent the image decoding device from malfunctioning due to retransmission of the memory management command.

Further, other features of the present embodiment will be described.
FIG. 2B is a diagram showing each picture when picture C4 in FIG. 2A is an IDR picture.
The IDR picture means that even if decoding of the image coded stream VSt is started from that point, the image coded stream VSt can be correctly decoded, or the picture rate of the image coded stream VSt is switched immediately before. , IDR pictures and subsequent pictures are introduced to ensure that the stream can be correctly decoded. The IDR picture is prevented from referring to a picture ahead of the IDR picture. At the time when the IDR picture is encoded, all the pictures in the memory are released and information on decoding is initialized. .

In the present embodiment, when a memory management command (MMCO) attached to a picture coded earlier than picture A to be coded at the present time is coded again and coded at picture A, the IDR picture is used before To avoid re-encoding a memory management command to be applied to a picture encoded as follows.
For example, if a memory management command indicating that the memory in which the picture C1 before the picture C4 that is an IDR picture is stored is released (reusable) has been encoded before, the present embodiment will be described. The image encoding device 100 does not encode the memory management command again.

  The IDR picture initializes the picture and the picture number stored in the memory at that time. Therefore, when the picture to be managed by the memory management command to be retransmitted is a picture before the IDR picture, the memory management command is already stored in the memory of the image decoding apparatus when the memory management command is retransmitted. There is no picture to be managed by the command. At this time, in the image decoding device, a picture that is lost as an error is newly generated and stored in the memory, and as a result, there is a possibility that a malfunction such that another picture in the memory is lost may occur.

For this reason, the image coding apparatus 100 according to the present embodiment can prevent the occurrence of a malfunction by preventing the memory management command applied to the picture coded before the IDR picture from being coded again. it can.
Further, still another feature of the present embodiment will be described with reference to FIG.
FIG. 3 is an explanatory diagram for describing editing of the image encoded stream VSt.

For example, as shown in FIG. 3, an image encoded stream including pictures E0 to E13 and an image encoded stream including pictures F0 to F13 are combined (edited) in the middle of each. It should be noted that such editing of the image encoded stream is performed when editing a DVD or the like.
The coded image stream including the pictures E0 to E13 is divided between the pictures E11 and E12, and the coded image stream including the pictures F0 to F13 is divided between the pictures F11 and F12. The picture coded streams of the pictures E0 to E11 and the picture coded streams of the pictures F12 to F13 are connected and edited into one picture coded stream Y. The part where the picture numbers are discontinuous due to the connection of the picture E11 and the picture F12 is called an editing point H.

  The image coding apparatus 100 according to the present embodiment attempts to re-encode a memory management command (MMCO) attached to a picture encoded before the picture F13 to be encoded at the present time and attach it to the picture F13. In this case, it is determined whether the picture to be managed by the memory management command is a picture coded before the edit point H. If the picture is coded before the edit point H, the image coding apparatus 100 prohibits the memory management command from being coded again.

For example, when a memory management command indicating that the memory in which the picture F1 before the edit point H is stored is released (reusable) is previously attached to the picture F10 of the picture number m-2 and encoded. If so, the image encoding device 100 does not encode the memory management command again.
That is, since the coded image stream including the picture F13 has been edited into the coded image stream Y, the pictures F0 to F11 before the editing point H do not exist in the memory in the pictures stored in the memory. Therefore, if the memory management command applied to the pictures F0 to F11 that are the pictures before the edit point H is encoded again, the image decoding apparatus applies the memory management command when executing the memory management command. Since there is no picture, there is a possibility that a malfunction such as newly generating a lost picture, saving it in the memory, and erasing other pictures from the memory may occur. Therefore, the image encoding device 100 of the present embodiment prohibits re-encoding such a memory management command.

Here, the operation of the image coding apparatus 100 according to the present embodiment will be described.
FIG. 4 is a flowchart showing an operation in which the image encoding device 100 of the present embodiment re-encodes a memory management command based on an IDR picture.
First, the image encoding unit 110 of the image encoding device 100 starts encoding the input image signal Vin (Step S100). During the encoding processing of the image encoding unit 110, the short-term storage memory management unit 102 and the long-term storage memory management unit 103 investigate unnecessary areas (pictures that will not be referred to in future encoding) in the memory (step S101). ), It is determined whether or not there is an unnecessary memory area (step S102). Here, when the short-term storage memory management unit 102 and the long-term storage memory management unit 103 determine that there is an unnecessary memory area (Yes in step S102), the management information encoding unit 105 of the image encoding device 100 A memory management command for instructing to release an unnecessary memory area is encoded (step S103). Then, the short-term storage memory management unit 102 and the long-term storage memory management unit 103 release the unnecessary memory area (step S104). When the short-term storage memory management unit 102 and the long-term storage memory management unit 103 determine that there is no unnecessary memory area (No in step S102), the image encoding device 100 performs the operations in steps S103 and S104. Do not execute.

  Next, based on the operation of the non-reserved memory management information unit 104, the memory information control unit 101 encodes a memory management command instructing to release an unnecessary memory area, and encodes a previously encoded picture (code It is determined whether or not the memory management command is added to the picture (picture before the current picture to be coded) (step S105). If it is determined that the memory management command is not coded (No in step S105), the image coding apparatus 100 The process ends.

  On the other hand, when it is determined that the memory management command has been encoded (Yes in step S105), the memory information control unit 101 determines whether the picture to be managed by the memory management command (stored in the unnecessary memory area that has been released). Is determined before the IDR picture in the coding order (step S106). Here, when it is determined that the memory management command is present (Yes in step S106), the memory information control unit 101 ends the process without re-encoding (re-adding) the memory management command, and determines that the memory management command is not before. In some cases (No in step S106), the memory management command is re-encoded (re-added) (step S107), and the process ends.

FIG. 5 is a flowchart showing an operation in which the image encoding apparatus 100 of the present embodiment re-encodes a memory management command based on an IDR picture and whether or not it is recent.
First, the image coding apparatus 100 performs the same operation as Steps S100 to S106 shown in FIG. 4 (Steps S200 to S206).
When the memory information control unit 101 determines that the picture to be managed by the memory management command does not precede the IDR picture (No in step S206), the same picture number as the picture to be managed is further assigned. Then, it is determined whether the management target picture is the latest picture among the pictures (step S207). That is, the memory information control unit 101 determines that the pictures to be managed in the pictures assigned the same picture number as the pictures to be managed are in coding order, and the memory management command in the image encoded stream VSt is re-executed. It is determined whether or not it is immediately before the part to be added.

As a result, when the memory information control unit 101 determines that the picture is not the latest picture (No in step S207), the process ends without re-encoding (re-adding) the memory management command, and determines that the picture is the latest picture. If this has been done (Yes in step S207), the memory management command is re-encoded (re-added) (step S208), and the process ends.
FIG. 6 is a flowchart showing an operation in which the image encoding device 100 of the present embodiment edits an image encoded signal.

First, the image encoding device 100 edits the encoded image stream VSt (Step S300).
Next, the memory information control unit 101 of the image encoding device 100 determines whether the memory management command has been encoded and added to the edited image encoded stream VSt (Step S301).

Here, when it is determined that the memory management command is coded (Yes in step S301), the image coding apparatus 100 further moves the picture to be managed by the memory management command from the editing point in the coding order. It is determined whether or not there is also before (step S302).
On the other hand, when it is determined in step S301 that the memory management command is not encoded (added) (No in step S301), or when it is determined in step S302 that the picture to be managed is located before the edit point. (Yes in step S302), the image encoding device 100 ends the editing process of the image encoded stream VSt.

  When the memory information control unit 101 of the image encoding device 100 determines in step S302 that the picture to be managed is not before the editing point (No in step S302), the memory management command is again transmitted to the management information. The image is encoded by the encoding unit 105 and re-added to the encoded image stream VSt (step S303).

  FIG. 7 is a flowchart showing an operation in which the image encoding device 100 of the present embodiment re-encodes a memory management command based on an IDR picture, whether or not it is recent, and an editing point.

First, the image coding apparatus 100 performs the same operation as Steps S200 to S207 shown in FIG. 5 (Steps S400 to S407).
When the memory information control unit 101 determines that the picture to be managed by the memory management command is not the latest picture (No in step S407), the process ends, but when it is determined that the picture is the latest picture (step S407). Yes), it is further determined whether or not the picture to be managed by the memory management command is before the edit point in the coding order (step S408).

  When the memory information control unit 101 determines that it is before the edit point (Yes in step S408), it ends the process, and when it determines that it is not before the edit point (No in step S408), The management command is re-encoded (re-added) (step S409), and the process ends.

  As described above, in the present embodiment, the memory management command instructing to release the memory area (remove the picture in the memory area) is repeatedly encoded. Even if the data disappears, the other memory management command transmits the instruction to the image decoding apparatus, so that the picture can be correctly decoded in the image decoding apparatus even if there is a transmission path error.

  Furthermore, the image coding apparatus 100 according to the present embodiment, when the picture to which the memory management command is applied is before the edit point, before the IDR picture, or when it is not a recent picture, Since the memory management command is not re-encoded, the image decoding apparatus prevents a malfunction that occurs when the memory management command is executed, for example, because there is no picture to be managed by the memory management command.

  In the present embodiment, a memory management command having a content for instructing release of unnecessary memory has been described as an example. It may be a memory management command having an instruction to move the picture stored in the storage memory to the long-term storage memory.

  Further, in the present embodiment, when the picture to be managed by the memory management command is earlier than the IDR picture in the coding order, retransmission of the memory management command is prohibited. The retransmission may be prohibited when it is before the memory initialization command in order. The memory initialization command is a command for erasing all pictures stored in the memory, initializing the memory, and resetting the picture number to 0.

  Further, in the flowchart of FIG. 7, the description has been given assuming that the image coding apparatus 100 executes all the processes of step S406, step S407, and step S408 in this order, but these steps may be performed in any order and the order of execution may be changed. Some steps may be omitted for simplicity.

  Furthermore, in the flowcharts of FIGS. 4 to 7, an example has been shown in which a memory management command that is not retransmitted is coded before a memory management command to be retransmitted. May be encoded first, and then a memory management command that is not a retransmission may be encoded.

(Embodiment 2)
Next, a second embodiment of the present invention will be described.
FIG. 8 is a block diagram of an image decoding device for realizing the image decoding method according to the second embodiment.
The image decoding apparatus 200 includes a memory information control unit 201, a short-term storage memory management unit 202, a long-term storage memory management unit 203, a management information decoding unit 205, a storage area designation unit 207, and a reference area designation. It comprises a unit 208, an image memory 209, an image decoding unit 210, a variable length decoding unit 212 and the like.

  Based on the picture type information PT, the memory information control unit 201 determines whether one or both of the front and rear pictures or both pictures can be referred to the decoding target picture. Further, the memory information control unit 201 instructs the reference area specifying unit 208 to output a reference picture corresponding to the determination result from the image memory 209 to the image decoding unit 210.

The variable length decoding unit 212 performs variable length decoding on the coded image stream VSt. Image decoding section 210 further decodes the output from variable length decoding section 212 to output decoded image signal Vout, and stores the output in image memory 209 as a reference picture.
At this time, the memory area in which the reference picture can be stored in the image memory 209 is determined by an instruction from the storage area specifying unit 207. That is, the memory information control unit 201 inquires of the short-term storage memory management unit 202 to specify a memory area in the short-term storage memory in the image memory 209 from which pictures have been removed. The storage area designating unit 207 instructs the image memory 209 to record the reference picture in the specified memory area.

The edit detection unit 215 detects an edit point of the encoded video stream VSt based on the output of the variable length decoding unit 212, and outputs information indicating the edit point to the memory information control unit 201.
The management information decoding unit 205 decodes the memory management information stream CSt and, through the memory information control unit 201, a memory management command having a content instructing to remove unnecessary (unreferenced) pictures in the short-term storage memory. Is notified to the short-term storage memory management unit 202. In addition, the management information decoding unit 205 notifies the long-term storage memory management unit 203 of a memory management command that instructs the picture in the short-term storage memory to be moved to the long-term storage memory in the image memory 209.

  Here, if the picture to be managed by the retransmitted memory management command precedes the IDR picture in the decoding order, the memory information control unit 201 invalidates the memory management command. If the picture to be managed by the memory management command is located before the editing point in the decoding order, the memory information control unit 201 invalidates the memory management command. Also, the memory information control unit 201 manages the most recently decoded picture among the pictures assigned the same picture number as the picture number indicated by the memory management command, and performs memory management on that picture. Apply command management contents.

The features of the image decoding device 200 according to the present embodiment will be described with reference to FIG. 2B used in the first embodiment.
For example, the image decoding apparatus 200 releases the memory area where the decoded memory management command is retransmitted and the picture (for example, C1) decoded before the IDR picture (C4) is stored. In the case of giving an instruction to make it reusable, the memory management command is invalidated. That is, the image decoding apparatus 200 does not execute the management content specified by the memory management command for the picture C1.

  The IDR picture initializes the picture stored in the memory at the time of decoding. Therefore, when the picture to be managed by the memory management command to be retransmitted is a picture before the IDR picture, the picture is already stored in the memory of the image decoding apparatus at the time of executing the retransmitted memory management command. A situation occurs in which there is no picture to be managed by the memory management command. At this time, in the image decoding apparatus, a picture that is lost as an error is newly generated and stored in the memory, and as a result, a malfunction may occur that another picture in the memory is lost.

Therefore, the image decoding apparatus 200 according to the present embodiment regards the resending of the memory management command as an error even if the memory management command for which the picture decoded before the IDR picture is to be managed is regarded as an error. Do not execute the management contents of the memory management command. As a result, the above-described malfunction can be prevented.
The image encoding apparatus 100 according to the first embodiment generates an image encoded stream so as not to retransmit such a memory management command. The stream can be decoded without causing the malfunction as described above. However, the conventional image decoding device performs the above-described malfunction when decoding the image encoded stream generated by the conventional image encoding device. Therefore, the image decoding apparatus according to the present embodiment can decode an image encoded stream generated by a conventional image encoding apparatus without causing a malfunction.

Other features of the present embodiment will be described.
Further, the image decoding apparatus 200 according to the present embodiment assigns the most recently decoded picture among the pictures assigned the same picture number as the picture number of the picture to be managed by the retransmitted memory management command. Apply that memory management command. Such operations need to be matched between the image encoding device and the image decoding device. Therefore, even when the image encoding apparatus 100 according to Embodiment 1 inhibits retransmission of a memory management command that does not manage a recent picture as described above and creates an image encoded stream, A form operation is required.

The features of the image decoding apparatus 200 according to the present embodiment will be described with reference to FIG. 2A used in the first embodiment.
If the decoded memory management command is a retransmitted memory management command, for example, if the decoded memory management command is a memory management command instructing to release the memory area in which the picture with the picture number 2 is stored, the decoding is performed. The memory area where the picture C2 whose conversion order is closest to the current time is released, and the memory where the picture B2 is stored is not released.

  Accordingly, when decoding the memory management command indicating that the memory area storing the picture of picture number 2 is to be released, the image decoding apparatus 200 of the present embodiment is given the same picture number 2. It is possible to easily determine which one of the memory areas in which the pictures B2 and C2 are stored should be opened. That is, the image decoding apparatus 200 can specify the memory area in which the picture C2 decoded at the time closest to the decoding target picture A is stored as the memory area to be released. Here, the picture C2 is the immediately preceding picture in the decoding order of the retransmitted memory management command among the pictures of the picture number 2.

In addition, if the picture to be managed by the retransmitted memory management command is decoded before the edit point, the image decoding apparatus 200 according to the present embodiment applies the memory management command to that picture. do not do.
The characteristic operation of the image decoding device 200 according to the present embodiment will be described with reference to FIG.

In the case where the decoded memory management command is retransmitted and the picture stored in the memory to which the memory management command is applied is a picture decoded before the edit point H, the image decoding apparatus 200 Does not execute the management contents of the memory management command.
For example, if the decoded memory management command is a retransmitted memory management command and instructs to release the memory area where the picture F1 before the edit point H is stored, Do not release.

  That is, since the coded image stream including the picture F13 has been edited into the coded image stream Y, the pictures F0 to F11 before the editing point H do not exist in the memory in the pictures stored in the memory. Therefore, if the image decoding apparatus executes a memory management command applied to pictures F0 to F11, which are pictures before the edit point H, the picture to be managed is stored in the memory when the memory management command is executed. Since they do not exist, there is a possibility that a malfunction such as newly generating a lost picture, saving it in the memory, and erasing other pictures from the memory may occur. Also, if a picture having the same picture number as the picture to be executed exists in the memory when the memory management command is executed, the memory management command is erroneously applied to a picture which is not originally applied (not operated by the memory management command). As a result, the image encoded stream after the edit point may not be correctly decoded. Therefore, the image decoding apparatus 200 of the present embodiment does not execute a memory management command for managing a picture located before the edit point.

Here, the operation of the image decoding device 200 according to the present embodiment will be described.
FIG. 9 is a flowchart illustrating an operation in which the image decoding apparatus 200 according to the present embodiment handles a memory management command based on a determination as to whether or not it is recent.
First, the management information decoding unit 205 of the image decoding device 200 decodes a memory management command included in the memory management information stream CSt (Step S500). In this memory management command decoding step (step S500), both the retransmitted memory management command and the first received (non-retransmitted) memory management command are decoded. Next, the variable length decoding unit 212 and the image decoding unit 210 decode the coded image stream VSt (Step S501).

  Next, the memory information control unit 201 determines whether or not the decrypted memory management command includes a retransmitted memory management command (for example, a memory management command having an instruction to release an unnecessary memory). A determination is made (step S502). When it is determined that there is no retransmitted memory management command (No in step S502), the memory information control unit 201 executes another memory management command that is not retransmitted (step S503). On the other hand, when it is determined that there is a retransmitted memory management command (Yes in step S502), the memory information control unit 201 replaces the retransmitted memory management command with the same picture number as the picture number indicated by the memory management command. Is performed on the most recent picture in the decoding order among the pictures to which is added (step S504). That is, the memory information control unit 201 performs a memory management on the picture immediately before the memory management command among the pictures of the picture numbers included in the decoding order up to the memory management command of the image encoded stream VSt. Execute a command.

FIG. 10 is a flowchart showing an operation in which the image decoding apparatus 200 according to the present embodiment handles a memory management command based on an IDR picture and whether or not it is recent.
The image decoding device 200 performs the same operation as Steps S500 to S503 shown in FIG. 9 (Steps S600 to S603).
When the memory information control unit 201 of the image decoding device 200 determines in step S602 that there is a retransmitted memory management command (Yes in step S602), the picture to be managed by the retransmitted memory management command is an IDR. It is determined whether or not the picture has been decoded before the picture (step S604). The picture to be managed by the retransmitted memory management command is released when the retransmitted memory management command is, for example, a command instructing release of an unnecessary memory area (to enable reuse). Picture stored in a memory area.

  Here, when the memory information control unit 201 determines that it is before the IDR picture (Yes in step S604), it ends the process without executing the retransmitted memory management command. On the other hand, when it is determined that the picture number is not before the IDR picture (No in step S604), the memory information control unit 201 determines the same picture number as the picture number indicated by the retransmitted memory management command as in step S504 shown in FIG. The memory management command is executed for the most recent picture in the decoding order among the pictures to which is added (step S605), and the process ends.

FIG. 11 is a flowchart showing an operation in which the image decoding apparatus 200 according to the present embodiment handles a memory management command based on an IDR picture, an edit point, and whether or not it is recent.
The image decoding device 200 performs the same operation as Steps S600 to S604 shown in FIG. 10 (Steps S700 to S704).

  When the memory information control unit 201 of the image decoding apparatus 200 determines in step S704 that the picture to be managed by the retransmitted memory management command does not precede the IDR picture in decoding order (step S704). No), it is further determined whether or not the picture to be managed is before the editing point in the decoding order (step S705). That is, the memory information control unit 201 determines whether the picture to be managed is a picture decoded before the edit point.

  Here, when the memory information control unit 201 determines that it is before the edit point (Yes in step S705), the process ends without executing the retransmitted memory management command. On the other hand, when it is determined that it is not before the edit point (No in step S705), the memory information control unit 201 determines the same as the picture number indicated by the retransmitted memory management command as in step S504 shown in FIG. The memory management command is executed for the most recent picture in the decoding order among the pictures to which the picture numbers have been assigned (step S706), and the process ends.

  As described above, the image decoding apparatus 200 according to the present embodiment, when the picture to be managed by the retransmitted memory management command is before the edit point or before the IDR picture, Since the memory management command is not applied (executed), it is possible to prevent the occurrence of malfunction due to the absence of a picture to be managed by the memory management command.

In addition, the image decoding apparatus 200 according to the present embodiment applies the memory management command to the most recent picture up to the current picture to be coded among the pictures assigned the same picture number. Can be reliably specified.
In the present embodiment, a memory management command having a content for instructing release of unnecessary memory has been described as an example. It may be a memory management command having an instruction to move the picture stored in the storage memory to the long-term storage memory.

  Further, in the present embodiment, when the picture to be managed by the retransmitted memory management command is before the IDR picture in the coding order, the application of the memory management command is prohibited. May be prohibited when is in the encoding order before the memory initialization command. The memory initialization command is a command for erasing all pictures stored in the memory, initializing the memory, and resetting the picture number to 0.

  Further, in the flowchart of FIG. 11, it has been described that steps S704, S705, and S706 are all executed in this order. However, these steps may be executed in any order and the order of execution may be changed. Some steps may be omitted.

(Embodiment 3)
Next, a third embodiment of the present invention will be described.

  In the present embodiment, a program for realizing the configuration of the image encoding method or the image decoding method shown in Embodiments 1 and 2 is recorded on a storage medium such as a flexible disk. Accordingly, the processing described in the above embodiment can be easily performed in an independent computer system.

  FIG. 12 is an explanatory diagram of a case where the image encoding method or the image decoding method according to the above embodiment is implemented by a computer system using a flexible disk storing the image encoding method or the image decoding method.

  FIG. 12B shows the appearance, cross-sectional structure, and flexible disk as viewed from the front of the flexible disk, and FIG. 12A shows an example of the physical format of the flexible disk that is the recording medium body. The flexible disk FD1 is built in the case F, and a plurality of tracks Tr are formed concentrically from the outer circumference toward the inner circumference on the surface of the disk, and each track is divided into 16 sectors Se in an angular direction. ing. Therefore, in the flexible disk storing the program, an image encoding method as the program is recorded in an area allocated on the flexible disk FD1.

  FIG. 12C shows a configuration for recording and reproducing the program on the flexible disk FD1. When the above program is recorded on the flexible disk FD1, the image encoding method or the image decoding method as the above program is written from the computer system Cs via the flexible disk drive FDD. When the image encoding method is constructed in a computer system using the program in the flexible disk FD1, the program is read from the flexible disk FD1 by the flexible disk drive FDD and transferred to the computer system Cs.

In the above description, the description has been made using a flexible disk as a recording medium. However, the same description can be made using an optical disk. Further, the recording medium is not limited to this, and the present invention can be similarly implemented as long as the program can be recorded, such as an IC card or a ROM cassette.
In addition, the image encoding method and the image decoding method described in the above-described embodiment can be applied to a mobile communication device such as a mobile phone or a car navigation system or a photographing device such as a digital video camera or a digital still camera by using a semiconductor such as an LSI. It is possible to implement. In addition, as a mounting format, in addition to a transmission / reception type terminal having both an encoder and a decoder, three types of a transmission terminal including only an encoder and a reception terminal including only a decoder can be considered.

Further, here, application examples of the image encoding method and the image decoding method described in the above embodiment and a system using the same will be described.
FIG. 13 is a block diagram illustrating an overall configuration of a content supply system ex100 that realizes a content distribution service. A communication service providing area is divided into desired sizes, and base stations ex107 to ex110, which are fixed wireless stations, are installed in each cell.

  The content supply system ex100 includes, for example, a computer ex111, a PDA (personal digital assistant) ex112, a camera ex113, a mobile phone ex114, and a camera via the Internet service provider ex102 and the telephone network ex104, and the base stations ex107 to ex110. Each device such as a mobile phone ex115 with a tag is connected.

However, the content supply system ex100 is not limited to the combination as shown in FIG. 13, and may be connected in any combination. Further, each device may be directly connected to the telephone network ex104 without going through the base stations ex107 to ex110 which are fixed wireless stations.
The camera ex113 is a device capable of shooting moving images, such as a digital video camera. In addition, a mobile phone is a PDC (Personal Digital Communications) system, a CDMA (Code Division Multiple Access) system, a W-CDMA (Wideband-Code Division Multiple Access) system, or a GSM (Global System for Mobile Communications) system. Or PHS (Personal Handyphone System) or the like, and either may be used.

  The streaming server ex103 is connected from the camera ex113 to the base station ex109 and the telephone network ex104, and enables live distribution and the like based on the encoded data transmitted by the user using the camera ex113. The encoding process of the captured data may be performed by the camera ex113, or may be performed by a server or the like that performs the data transmission process. Also, moving image data captured by the camera ex116 may be transmitted to the streaming server ex103 via the computer ex111. The camera ex116 is a device such as a digital camera capable of shooting still images and moving images. In this case, encoding of the moving image data may be performed by the camera ex116 or the computer ex111. The encoding process is performed by the LSI ex117 included in the computer ex111 and the camera ex116. The image encoding / decoding software may be incorporated in any storage medium (CD-ROM, flexible disk, hard disk, or the like) that is a recording medium readable by the computer ex111 or the like. Further, the moving image data may be transmitted by a mobile phone with camera ex115. The moving image data at this time is data that has been encoded by the LSI included in the mobile phone ex115.

  In the content supply system ex100, the content (for example, a video of a live music shot) captured by the user with the camera ex113, the camera ex116, or the like is encoded and transmitted to the streaming server ex103 in the same manner as in the above embodiment. On the other hand, the streaming server ex103 stream-distributes the content data to the requesting client. Examples of the client include a computer ex111, a PDA ex112, a camera ex113, a mobile phone ex114, and the like, which are capable of decoding the encoded data. In this way, the content providing system ex100 can receive and reproduce the encoded data on the client, and further, can receive, decode, and reproduce the encoded data on the client in real time, thereby realizing personal broadcasting. It is a system that becomes possible.

  The encoding and decoding of each device constituting this system may be performed using the image encoding device or the image decoding device described in each of the above embodiments.

A mobile phone will be described as an example.
FIG. 14 is a diagram illustrating the mobile phone ex115 using the image encoding method and the image decoding method described in the above embodiment. The mobile phone ex115 includes an antenna ex201 for transmitting and receiving radio waves to and from the base station ex110, a video image of a CCD camera or the like, a camera unit ex203 capable of taking a still image, a video image captured by the camera unit ex203, and an antenna ex201. A display unit ex202 such as a liquid crystal display for displaying data obtained by decoding a received video or the like, a main unit including a group of operation keys ex204, an audio output unit ex208 such as a speaker for outputting audio, and audio input. Input unit ex205 such as a microphone for storing encoded or decoded data, such as data of captured moving images or still images, received mail data, moving image data or still image data, etc. Recording medium ex207, and a slot ex20 for allowing the recording medium ex207 to be attached to the mobile phone ex115. The it has. The recording medium ex207 stores a flash memory element which is a kind of EEPROM (Electrically Erasable and Programmable Read Only Memory) which is a nonvolatile memory which can be electrically rewritten and erased, in a plastic case such as an SD card.

  Further, the mobile phone ex115 will be described with reference to FIG. The mobile phone ex115 has a power supply circuit unit ex310, an operation input control unit ex304, an image encoding unit, and a main control unit ex311 that integrally controls each unit of a main unit including a display unit ex202 and operation keys ex204. Unit ex312, camera interface unit ex303, LCD (Liquid Crystal Display) control unit ex302, image decoding unit ex309, demultiplexing unit ex308, recording / reproducing unit ex307, modulation / demodulation circuit unit ex306, and audio processing unit ex305 via a synchronous bus ex313. Connected to each other.

The power supply circuit unit ex310 activates the camera-equipped digital mobile phone ex115 in an operable state by supplying power to each unit from the battery pack when the call end and the power key are turned on by a user operation. .
The mobile phone ex115 converts an audio signal collected by the audio input unit ex205 into digital audio data by the audio processing unit ex305 in the audio communication mode based on the control of the main control unit ex311 including a CPU, a ROM, a RAM, and the like. This is spread-spectrum processed by a modulation / demodulation circuit unit ex306, subjected to digital-analog conversion processing and frequency conversion processing by a transmission / reception circuit unit ex301, and then transmitted via an antenna ex201. The mobile phone ex115 amplifies the received data received by the antenna ex201 in the voice call mode, performs frequency conversion processing and analog-to-digital conversion processing, performs spectrum despreading processing in the modulation / demodulation circuit unit ex306, and performs analog voice decoding in the voice processing unit ex305. After the data is converted, the data is output via the audio output unit ex208.

  Further, when an e-mail is transmitted in the data communication mode, text data of the e-mail input by operating the operation key ex204 of the main body is sent to the main control unit ex311 via the operation input control unit ex304. The main control unit ex311 performs spread spectrum processing on the text data in the modulation / demodulation circuit unit ex306, performs digital / analog conversion processing and frequency conversion processing on the transmission / reception circuit unit ex301, and transmits the text data to the base station ex110 via the antenna ex201.

  When transmitting image data in the data communication mode, the image data captured by the camera unit ex203 is supplied to the image encoding unit ex312 via the camera interface unit ex303. When the image data is not transmitted, the image data captured by the camera unit ex203 can be directly displayed on the display unit ex202 via the camera interface unit ex303 and the LCD control unit ex302.

  The image encoding unit ex312 includes the image encoding device described in the present invention, and uses the image data supplied from the camera unit ex203 in the encoding method used in the image encoding device described in the above embodiment. The image data is converted into encoded image data by compression encoding, and is transmitted to the demultiplexing unit ex308. Further, at this time, the mobile phone ex115 simultaneously transmits the voice collected by the voice input unit ex205 during imaging by the camera unit ex203 to the demultiplexing unit ex308 as digital voice data via the voice processing unit ex305.

  The demultiplexing unit ex308 multiplexes the encoded image data supplied from the image encoding unit ex312 and the audio data supplied from the audio processing unit ex305 by a predetermined method, and modulates and outputs the resulting multiplexed data. The signal is subjected to spread spectrum processing in ex306 and subjected to digital / analog conversion processing and frequency conversion processing in the transmission / reception circuit unit ex301, and then transmitted via the antenna ex201.

When data of a moving image file linked to a homepage or the like is received in the data communication mode, the data received from the base station ex110 via the antenna ex201 is subjected to spectrum despreading processing by the modulation / demodulation circuit unit ex306, and the resulting multiplexed data The demultiplexed data is sent to the demultiplexing unit ex308.
To decode the multiplexed data received via the antenna ex201, the demultiplexing unit ex308 separates the multiplexed data into a bit stream of image data and a bit stream of audio data, and performs synchronization. The coded image data is supplied to the image decoding unit ex309 via the bus ex313, and the audio data is supplied to the audio processing unit ex305.

  Next, the image decoding unit ex309 is configured to include the image decoding device described in the present invention, and decodes a bit stream of image data by a decoding method corresponding to the encoding method described in the above embodiment. Thereby, reproduced moving image data is generated and supplied to the display unit ex202 via the LCD control unit ex302, whereby, for example, moving image data included in a moving image file linked to a homepage is displayed. At this time, at the same time, the audio processing unit ex305 converts the audio data into analog audio data, and then supplies the analog audio data to the audio output unit ex208, whereby, for example, the audio data included in the moving image file linked to the homepage is reproduced. You.

  It should be noted that the present invention is not limited to the example of the above system, and digital broadcasting using satellites and terrestrial waves has recently become a hot topic. As shown in FIG. Any of the decoding devices can be incorporated. Specifically, at the broadcasting station ex409, the bit stream of the video information is transmitted to the communication or the broadcasting satellite ex410 via radio waves. The broadcasting satellite ex410 receiving this transmits a radio wave for broadcasting, receives this radio wave with a home antenna ex406 having satellite broadcasting receiving equipment, and outputs the radio wave to a television (receiver) ex401 or a set-top box (STB) ex407 or the like. The device decodes the bit stream and reproduces it. In addition, the image decoding device described in the above embodiment can be mounted on a reproducing device ex403 that reads and decodes a bit stream recorded on a storage medium ex402 such as a CD or DVD, which is a recording medium. In this case, the reproduced video signal is displayed on the monitor ex404. A configuration is also conceivable in which an image decoding device is mounted in a set-top box ex407 connected to a cable ex405 for cable television or an antenna ex406 for satellite / terrestrial broadcasting, and this is reproduced on a monitor ex408 of the television. At this time, the image decoding device may be incorporated in the television instead of the set-top box. In addition, a car ex412 having an antenna ex411 can receive a signal from the satellite ex410 or a base station ex107 or the like, and can reproduce a moving image on a display device such as a car navigation ex413 included in the car ex412.

  Further, an image signal can be encoded by the image encoding device described in the above embodiment and recorded on a recording medium. As a specific example, there is a recorder ex420 such as a DVD recorder for recording an image signal on a DVD disc ex421 or a disc recorder for recording on a hard disk. Furthermore, it can be recorded on the SD card ex422. If the recorder ex420 includes the image decoding device described in the above embodiment, the image signal recorded on the DVD disc ex421 or the SD card ex422 can be reproduced and displayed on the monitor ex408.

  The configuration of the car navigation ex413 may be, for example, a configuration excluding the camera unit ex203, the camera interface unit ex303, and the image encoding unit ex312 from the configuration illustrated in FIG. 15, and the same applies to the computer ex111 and the television (receiver). ) Ex401 and the like are also conceivable.

  In addition, the terminal such as the above-mentioned mobile phone ex114 has three mounting formats, in addition to a transmitting / receiving terminal having both an encoder and a decoder, a transmitting terminal having only an encoder and a receiving terminal having only a decoder. Can be considered.

As described above, the image encoding method or the image decoding method described in the above embodiment can be used for any of the devices and systems described above, and by doing so, the effects described in the above embodiment can be obtained. Obtainable.
Further, the present invention is not limited to the above embodiment, and various changes or modifications can be made without departing from the scope of the present invention.

  The image encoding method and the image decoding method according to the present invention can prevent the occurrence of a malfunction due to retransmission of a command, and can encode an image by the image encoding method, for example, a video camera or a mobile phone with a recording function. The present invention can be applied to an image encoding device such as a telephone, or an image decoding device such as a personal computer or a mobile phone that decodes an encoded signal by the image decoding method.

FIG. 1 is a block diagram illustrating a configuration of an image encoding device that implements an image encoding method according to Embodiment 1 of the present invention. (A) and (b) are diagrams each showing a picture used for explaining the first embodiment of the present invention. FIG. 3 is a diagram showing pictures used to explain stream editing in Embodiment 1 of the present invention. 5 is a flowchart showing an operation of the image encoding device in Embodiment 1 of the present invention for re-encoding a memory management command based on an IDR picture. 5 is a flowchart showing an operation of the image encoding apparatus in Embodiment 1 of the present invention for re-encoding a memory management command based on an IDR picture and whether or not it is recent. 6 is a flowchart showing an operation of the image encoding device in Embodiment 1 of the present invention for editing an image encoded signal. 6 is a flowchart showing an operation of the image encoding device in Embodiment 1 of the present invention for re-encoding a memory management command based on an IDR picture, whether or not it is recent, and an editing point. FIG. 13 is a block diagram illustrating a configuration of an image decoding device that implements an image decoding method according to Embodiment 2 of the present invention. 15 is a flowchart showing an operation of the image decoding apparatus according to Embodiment 2 of the present invention for handling a memory management command based on a determination as to whether or not it is recent. 15 is a flowchart showing an operation of the image decoding apparatus according to Embodiment 2 of the present invention for handling a memory management command based on an IDR picture and whether or not it is recent. 15 is a flowchart showing an operation of the image decoding apparatus according to the second embodiment of the present invention for handling a memory management command based on an IDR picture, an edit point, and a determination as to whether or not it is recent. (a), (b) and (c) are illustrations of a storage medium according to Embodiment 3 of the present invention. FIG. 13 is a block diagram illustrating an overall configuration of a content supply system according to Embodiment 4 of the present invention. FIG. 14 is an external view showing an example of a mobile phone according to Embodiment 4 of the present invention. FIG. 13 is a block diagram illustrating a configuration of a mobile phone according to a fourth embodiment of the present invention. FIG. 14 is a configuration diagram illustrating a configuration of a digital broadcasting system according to a fourth embodiment of the present invention.

Explanation of reference numerals

REFERENCE SIGNS LIST 100 Image encoding device 101 Memory information control unit 102 Short-term storage memory management unit 103 Long-term storage memory management unit 104 Non-storage memory management information unit 105 Management information encoding unit 106 Reference image selection unit 107 Storage region designation unit 108 Reference region Designating unit 109 Image memory 110 Image encoding unit 111 Image decoding unit 112 Variable length encoding unit 113 Counter 114 Counter 200 Image decoding device 201 Memory information control unit 202 Short-time storage memory management unit 203 Long-time storage memory management unit 205 Management information decoding section 207 storage area specifying section 208 reference area specifying section 209 image memory 210 image decoding section 212 variable length decoding section 215 edit detection section CSt memory management information stream H editing point PT picture type information Pri importance indication signal VSt image Image encoded stream Vin Input image signal Vout Decoded image signal Y Image encoded stream

Claims (12)

An image encoding method for generating a picture encoded signal by assigning a picture number to each picture included in a moving image signal in a coding order in a predetermined picture number unit and performing encoding for each picture,
An adding step of adding, to a second picture different from the first picture, a memory management command indicating the management content on the memory for the first picture of the predetermined picture number;
Re-adding the memory management command to an addition target portion other than the second picture in the image coded signal,
The re-adding step includes:
A determination sub-determine for determining whether or not the first picture is immediately before the addition target portion in the coding order among pictures of the predetermined picture number included in the image coded signal up to the addition target portion; Steps and
A prohibition sub-step of prohibiting the re-addition of the memory management command when it is determined in the determination sub-step that it is not immediately before the image coding method. In the determining sub-step, further,
Determining whether the first picture is ahead of the reference point in the image coded signal in coding order,
The prohibition sub-step further includes:
The image encoding method according to claim 1, wherein when it is determined in the determination sub-step that the memory management command is located ahead, re-addition of the memory management command is prohibited. In the determining sub-step,
The image encoding method according to claim 2, wherein an edit point at which continuity of the image encoded signal is lost by editing is treated as the reference point. In the determining sub-step,
The image encoding method according to claim 2, wherein a picture encoded including information prompting to initialize a memory is treated as the reference point. An image decoding method for decoding an image coded signal in which a moving image signal is coded in picture units, using a picture number assigned in a decoding order to each picture in a predetermined picture number unit,
A determination step of determining whether or not a memory management command indicating management content on a memory for a picture having a predetermined picture number is added to the image code signal;
When it is determined in the determining step that the memory management command is added, the memory management command is decoded in the decoding order from among the pictures of the predetermined picture number included in the image coded signal up to the memory management command. A selection step of selecting a picture immediately before
Executing the management content indicated by the memory management command on the picture selected in the selection step. The image decoding method further includes:
When it is determined in the determining step that the memory management command is added, it is determined whether or not the picture targeted by the memory management command is ahead of the reference point in the image coded signal in the decoding order. A reference point determining step of determining;
A management invalidating step of invalidating the management content indicated by the memory management command when the first picture is determined to be ahead of the reference point in the reference point determining step. The image decoding method according to claim 5, wherein In the reference point determining step,
The image decoding method according to claim 6, wherein an edit point at which continuity of the image coded signal is lost by editing is treated as the reference point. In the reference point determining step,
7. The image decoding method according to claim 6, wherein a picture encoded including information prompting to initialize a memory is treated as the reference point. An image encoding apparatus that assigns a picture number to each picture included in a moving image signal in an encoding order in a predetermined picture number unit and generates an encoded image signal by performing encoding for each picture,
Adding means for adding a memory management command indicating the management content on the memory for the first picture of the predetermined picture number to a second picture different from the first picture;
Re-adding means for re-adding the memory management command to an addition target portion other than the second picture in the image encoded signal,
The re-adding means,
Judging means for judging whether or not the first picture is immediately before the addition target portion in a coding order among pictures of the predetermined picture number included in the image coded signal up to the addition target portion; When,
An image encoding apparatus, comprising: a prohibition unit that prohibits re-addition of the memory management command when the determination unit determines that it is not the first. An image decoding apparatus for decoding an image coded signal in which a moving image signal is coded in units of pictures, using picture numbers assigned in a decoding order to each picture in a predetermined number of pictures,
Determining means for determining whether or not a memory management command indicating management content on a memory for a picture having a predetermined picture number is added to the image code signal;
When the determining means determines that the memory management command is added, the memory management command is decoded in the decoding order from among the pictures having the predetermined picture number included in the image coded signal up to the memory management command. Selecting means for selecting a picture immediately before
Executing means for executing the management content indicated by the memory management command with respect to the picture selected by the selecting means. A program for generating a picture coded signal by assigning a picture number to each picture included in the moving picture signal in a coding order in a predetermined picture number unit and performing coding for each picture,
An adding step of adding, to a second picture different from the first picture, a memory management command indicating the management content on the memory for the first picture of the predetermined picture number;
Re-adding the memory management command to an addition target portion other than the second picture in the image coded signal.
In the re-adding step,
A determination sub-determine for determining whether or not the first picture is immediately before the addition target portion in the coding order among pictures of the predetermined picture number included in the image coded signal up to the addition target portion; Steps and
And a prohibition sub-step of prohibiting re-attachment of the memory management command when it is determined in the determination sub-step that the current time is not immediately before. A program for decoding an image coded signal in which a moving image signal is coded in units of pictures, using a picture number assigned to each picture in a decoding order in a predetermined number of pictures,
A determining step of determining whether or not a memory management command indicating a management content on a memory for a first picture of a predetermined picture number is added to the image code signal;
When it is determined in the determining step that the memory management command is added, the memory management command is decoded in the decoding order from among the pictures of the predetermined picture number included in the image coded signal up to the memory management command. A selection step of selecting a picture immediately before
And (c) executing a management content indicated by the memory management command on the picture selected in the selection step.

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