JP5950726B2 - Video predictive encoding method, video predictive encoding device, video predictive encoding program, video predictive decoding method, video predictive decoding device, and video predictive decode program - Google Patents

Description

  The present invention relates to a moving picture predictive coding method, apparatus and program, and a moving picture predictive decoding method, apparatus and program, and particularly relates to a description in a buffer of a reference picture used for predictive coding between screens. It is.

  In order to efficiently transmit and store moving image data, a compression encoding technique is used. In the case of moving images, MPEG1-4 and H.264 are used. 261-H. H.264 is widely used.

  In these encoding methods, encoding / decoding processing is performed after an image to be encoded is divided into a plurality of blocks. In order to increase the encoding efficiency, the following predictive encoding method is used. In predictive coding within a screen, a predicted signal is generated using an adjacent reproduced image signal (reconstructed image data compressed in the past) in the same screen as the target block, and then the target signal is processed. The differential signal subtracted from the block signal is encoded. In predictive coding between screens, reference is made to a previously-reproduced image signal in a different screen from the target block, signal displacement is searched, the motion is compensated, and a predicted signal is generated, and the target block is generated. The difference signal subtracted from the signal is encoded. An already reproduced image that is referred to for motion search / compensation is referred to as a reference image.

  In the inter-screen predictive coding shown in Non-Patent Document 1, the prediction signal for the target block refers to a plurality of reference images encoded and reproduced in the past, and an image signal with the least error is obtained while performing motion search. Select as the optimal prediction signal. The difference between the pixel signal of the target block and the optimal prediction signal is obtained, subjected to discrete cosine transform, quantized, and entropy encoded. At the same time, information on which reference image an optimal prediction signal for the target block is acquired (referred to as “reference index”) and information on which region of the reference image the optimal prediction signal is acquired from (“motion vector”) Are also encoded. In Non-Patent Document 1, a plurality of reproduced images (for example, 4 to 5 images) are stored as reference images in a frame memory or a reproduced picture buffer (hereinafter also referred to as “DBP”).

  As a method of managing a plurality of reference images, an area occupied by the oldest reference image (that is, the one that has been in the buffer for the longest time) among a plurality of reproduced images is released from the buffer. Although there is a method of storing the decoded image as a reference image, Non-Patent Document 1 discloses a reference image management method that flexibly prepares a reference image optimal for a target image.

  According to Non-Patent Document 1, information describing a set of multiple reference images stored in a buffer (reference picture set, hereinafter referred to as “RPS”, also referred to as buffer description information) is added to the encoded data of each target image. To encode. In the RPS information, information related to picture numbers of a plurality of reference images required for processing (encoding or decoding) of the target image and subsequent images is described. In the encoding device or the decoding device, the buffer is managed so as to store the designated reproduced image in the buffer (frame memory) according to the RPS information. On the other hand, playback images that are not designated may be deleted from the buffer. In Non-Patent Document 1, since intra-screen coding / decoding and inter-screen coding / decoding can be switched in units called slices obtained by dividing the target image into one or more sections, RPS information is encoded using the header information of the slices. Convert / decrypt. The slice is described in Non-Patent Document 1.

  The RPS information is information indicating a relationship between a picture number for identifying a target image (picture output count, hereinafter referred to as “POC”) and a POC for identifying a plurality of reference images used for inter-screen prediction of the target screen. Consists of. This related information is the difference between the POC of each reference image and the POC of the target image, and is represented as DeltaPoc in this specification.

  An example of RPS information will be described with reference to FIGS. FIG. 9 shows a target image and a state of a plurality of reference images in the frame memory when each target image is processed. Each cell has a POC that identifies the image. For example, in row 1610, it means that reference images of POC = 18, 20, 22, 24 are stored in the frame memory when processing (encoding or decoding) a target image of POC = 32. FIG. 10 shows an RPS corresponding to FIG. 1701 indicates an identifier idx for identifying RPS information, and each cell below 1704 indicates a value of DeltaPoc which is an element of RPS information.

  There are two methods for encoding RPS information. One is a method called inter RPS (Inter RPS method), which refers to pre-encoded / decoded RPS and predictively encodes / decodes the relationship between the RPS to be encoded and the pre-encoded RPS. The second is called an intra RPS (Intra RPS method), which encodes / decodes the number and value of DeltaPoc included in the RPS to be encoded without reference. In this specification, a set of DeltaPocs included in one RPS is denoted as DeltaPoc [idx] [i]. Here, i indicates the i-th reference image stored in the frame memory, and idx indicates a number for identifying a specific RPS. In the following description, [i] may be omitted.

  In Asymmetric Literature 1, RPS information related to a plurality of slices is collected and encoded / decoded by being included in SPS (sequence parameter set) information carrying parameters of decoding processing applied in common. In the slice header, the identifier idx of the RPS information encoded / decoded by SPS is encoded / decoded, or new RPS information is encoded / decoded.

  FIG. 7 shows a syntax table short_term_ref_pic_set (idx) for encoding / decoding RPS information identified by an identifier idx. The number of RPS information encoded / decoded by SPS is encoded / decoded by SPS as num_short_term_ref_pic_sets. That is, the RPS identification information idx is identified by a value from 0 to num_short_term_ref_pic_sets-1.

  inter_ref_pic_set_prediction_flag (R100) is a syntax element for identifying whether the encoding / decoding method of the RPS information to be encoded / decoded identified by idx is intra RPS or inter RPS. When this flag is 0, DeltaPoc [idx] [i] is encoded / decoded by the intra RPS method. That is, the number of reference images included in the RPS to be encoded / decoded and the value of DeltaPoc corresponding to each reference image are encoded / decoded. For example, when RPS (1710) identified by idx = 0 in FIG. 10 is encoded / decoded with intra RPS, the number of DeltaPos is 4 and the value of 4 DeltaPocs (−14, −12, −10, -8) is encoded / decoded.

When inter_ref_pic_set_prediction_flag (R100) is 1, DeltaPoc [idx] [i] is encoded / decoded with inter RPS referring to RPS information of already encoded / decoded. delta_idx_minus1 (R110) is a syntax element for specifying the identifier RIdx of the RPS information referred to in the inter-RPS prediction process. RIdx is restored by equation (1).
RIdx = idx- (delta_idx_minus1 + 1) (1)

From the syntax elements delta_rps_sign and abs_delta_rps_minus1 (R120), the difference value DeltaRPS between the two RPSs is derived by equation (2). DeltaRPS indicates a difference value between a DeltaPoc set of RPS identified by RIdx and a DeltaPoc set identified by idx to be encoded / decoded. For example, in FIG. 10, when RIdx = 1 and idx = 2, the difference value 2 is encoded / decoded as DeltaRPS. That is, delta_rps_sign = 0 and abs_delta_rps_minus1 = 1 are encoded / decoded.
DeltaRPS = (1- (delta_rps_sign << 1)) * (abs_delta_rps_minus1 + 1) (2)

  In syntax element R130, RPS information identified by idx, that is, DeltaPoc [idx] [i] is derived. Specifically, NumDeltaPocs [RIdx] indicates the number of DeltaPocs (1702 in FIG. 10) included in the RPS information identified by RIdx, and DeltaPoc [idx] [0] to DeltaPoc [idx] [NumDeltaPocs [ RIdx]] is derived by iterative processing using a for statement.

used_by_curr_pic_flag [i] indicates whether or not the i-th reference image is used for encoding / decoding the target image, and use_delta_flag [i] is DeltaPoc [RIdx] [i] for derivation of the i-th DeltaPos Indicates whether or not to use. Here, when used_by_curr_pic_flag [i] is 1, use_delta_flag [i] is 1. When use_delta_flag [i] is 1, DeltaPoc [idx] [i] is derived from Equation (3), and when use_delta_flag [i] is 0, DeltaPoc [idx] [i] is derived from Equation (4). .
DeltaPoc [idx] [i] = DeltaPoc [RIdx] [i] + DeltaRPS (3)
DeltaPoc [idx] [i] = DeltaRPS (4)
For example, in FIG. 10, when RIdx = 1 and idx = 2, use_delta_flag [i] = 1 when i = 0, 1, 2, and use_delta_flag [i] = 0 when i = 3.

  When new RPS information is encoded / decoded in the slice header, num_short_term_ref_pic_sets which is an idx number not used in the SPS is used as an input value of the syntax table. That is, the syntax table short_term_ref_pic_set (num_short_term_ref_pic_sets) is encoded / decoded.

B. Bross et. Al., “High efficiency videocoding (HEVC) text specification draft 7”, Joint Collaborative Team on VideoCoding (JCT-VC) of ITU-T SG16 WP3 and ISO / IEC JTC1 / SC29 / WG11, JCTVC-I1003 , 9thMeeting: Geneva, Switzerland, 27th April -7th May, 2012.

  The RPS prediction method (inter-RPS) shown in the background art is a general and efficient method that can express any RPS pattern. On the other hand, in the decoding device, when restoring each element by analyzing the bit string of the compressed data, the process becomes simple if the bit string can be analyzed without being influenced by the data decoded in the past.

  In the inter-RPS shown in the background art, NumDeltaPocs [RIdx] is included in the syntax table shown in FIG. Since this value changes depending on RIdx, the number of elements (used_by_curr_pic_flag and use_delta_flag) to be decoded is not known unless the data analyzer acquires this RIdx. Therefore, although inter-RPS shown in the background art is a preferable method, in practice, analysis processing of a bit string of compressed data may be complicated.

  The present invention has been made in view of the above circumstances, and by simplifying the structure of encoded data by reducing the number of bits required for inter-RPS encoding, the analysis processing of the encoded data in the decoding apparatus is simplified. For the purpose.

The moving image predictive coding apparatus according to the present invention includes an input unit that inputs a plurality of images constituting a moving image, and a predictive code using a plurality of images decoded and reproduced after the images have been coded in the past as reference images. Encoding means for generating compressed image data, decoding means for decoding compressed image data and restoring it to a reproduced image, and one or more reproduced images as reference images used to encode subsequent images Image storage means for storing, and buffer management means for controlling the image storage means, the buffer management means being different from the target buffer description information related to a plurality of reference images used when predictively encoding an image The buffer description information similar to the target buffer description information is searched as reference buffer description information from a plurality of encoded buffer description information, and the reference buffer description information is identified. Generating different information, calculating a difference value between the picture number of the reference image of the reference buffer description information and the picture number of the target image of the target buffer description information, and predicting buffer description from each element and the difference value of the reference buffer description information Information is generated, mode information for generating target buffer description information is selected from three or more modes prepared for generating new buffer description information based on the prediction buffer description information, and the encoding means identifies The information, difference value, and mode information are encoded, and the three or more modes include at least three modes of a first mode, a second mode, and a third mode that perform different processes. Each of the three or more modes is characterized by indicating different processing methods for generating the target buffer description information from the prediction buffer description information .

  In this moving image predictive encoding device, it is not necessary to encode the instruction information related to each element of the RPS information as in the use_delta_flag shown in the background art, so that the compressed data of the RPS information can be encoded more efficiently. It becomes possible. Also, by preparing in advance a plurality of methods for generating the target buffer description information that are frequently generated as syntax elements, the target buffer description information can be efficiently encoded with a small number of code elements. Can do. Therefore, according to the present invention, the configuration of encoded data can be simplified by reducing the number of bits required for inter-RPS encoding.

  In the video predictive coding apparatus according to the present invention, it is preferable that one of the plurality of modes performs a process of adding a difference value as a new element to the prediction buffer description information.

  In the video predictive coding apparatus according to the present invention, one of the plurality of modes performs processing for replacing the element having the minimum value or the maximum value among the elements of the prediction buffer description information with the difference value. It is preferable.

  In the moving picture predictive coding apparatus according to the present invention, it is preferable that one of the plurality of modes performs processing using the prediction buffer description information as target buffer description information.

In addition, the video predictive decoding device according to the present invention includes, for each of a plurality of images constituting a video, data that is predictively encoded using a plurality of images decoded and reproduced in the past as reference images, Input means for inputting compressed image data including encoded data of buffer description information relating to a reference image, decoding means for decoding the compressed image data and restoring the reproduced image, and decoding the reproduced image and subsequent images An image storage means for storing one or more reference images used as the reference image, and a buffer management means for controlling the image storage means. The decoding means relates to a plurality of reference images used when decoding the reproduced image. In order to decode the target buffer description information, decoded buffer description information that is different from the target buffer description information and is used for decoding the target buffer description information. Prediction information generated by decoding identification information identifying information as reference buffer description information, decoding a difference value between a picture number related to reference buffer description information and a picture number related to target buffer description information, and the reference buffer description information and the difference value From the three or more modes prepared for generating new buffer description information based on the buffer description information, mode information used for restoring the target buffer description information is decoded, and based on the prediction buffer description information and the mode information, The buffer management means decodes the target buffer description information, and the buffer management means controls the image storage means based on the decoded target buffer description information . The three or more modes include at least a first mode for performing different processes from each other, Three modes of the second mode and the third mode are included, and three or more modes are respectively The decoding means indicates the different processing method for generating the target buffer description information from the measurement buffer description information, the decoding means decodes the compressed image data, decodes the mode information, and from the prediction buffer description information by the processing method indicated by the mode information. The target buffer description information is decoded .

  In this moving picture predictive decoding apparatus, compressed data related to buffer description information can be analyzed without obtaining the number of elements included in the target buffer description information from the prediction buffer description information. Also, by preparing a plurality of methods for generating the target buffer description information and having a high occurrence frequency as syntax elements in advance, the target buffer description information can be efficiently decoded with a small number of code elements. it can. Therefore, according to the present invention, the analysis processing of the encoded data in the decoding device can be simplified.

  In the video predictive decoding apparatus according to the present invention, it is preferable that one of the plurality of modes performs a process of adding a difference value as a new element to the prediction buffer description information.

  Further, in the video predictive decoding device according to the present invention, one of the plurality of modes performs processing for replacing the element having the minimum value or the maximum value among the elements of the prediction buffer description information with the difference value. Is preferred.

  In the video predictive decoding apparatus according to the present invention, it is preferable that one of the plurality of modes performs processing using the prediction buffer description information as target buffer description information.

The video predictive encoding method according to the present invention includes an input step of inputting a plurality of images constituting a video, and a plurality of images decoded and reproduced after encoding the images in the past as reference images. An encoding step for predictive encoding and generating compressed image data, a decoding step for decoding compressed image data and restoring it to a reproduced image, and a reproduced image as a reference image used for encoding subsequent images One or more image storage steps stored by the image storage means, and a buffer management step for controlling the image storage means. In the buffer management step, a plurality of reference images used when predictively encoding the image Buffer description information similar to the target buffer description information is referred to from a plurality of encoded buffer description information different from the target buffer description information. Search information as the buffer description information, generating identification information for identifying the reference buffer description information, calculating a difference value between the picture number of the reference image in the reference buffer description information and the picture number of the target image in the target buffer description information, Mode for generating target buffer description information from three or more modes prepared for generating prediction buffer description information from reference buffer description information and difference values and generating new buffer description information based on the prediction buffer description information In the encoding step, the identification information, the difference value, and the mode information are encoded, and the three or more modes include at least a first mode, a second mode, and a third mode that perform at least different processes. The three modes are included. Each of the three or more modes generates target buffer description information from the prediction buffer description information. Wherein the point to different processing methods that.

  The moving image predictive encoding program according to the present invention includes an input module that inputs a plurality of images constituting a moving image, and a plurality of images that have been decoded and reproduced after having previously encoded the images as reference images. An encoding module that performs predictive encoding and generates compressed image data, a decoding module that decodes compressed image data and restores the image to a reproduced image, and a reproduced image as a reference image used to encode subsequent images An image storage module that stores at least one image, and a buffer management module that controls the image storage module. The buffer management module includes target buffer description information relating to a plurality of reference images used when predictively encoding an image, and The buffer description information similar to the target buffer description information is referred to from a plurality of encoded buffer description information different from each other. Search information as the buffer description information, generating identification information for identifying the reference buffer description information, calculating a difference value between the picture number of the reference image in the reference buffer description information and the picture number of the target image in the target buffer description information, Mode information for generating target buffer description information from a plurality of modes prepared for generating prediction buffer description information from reference buffer description information and difference values, and generating new buffer description information based on the prediction buffer description information And the encoding module encodes the identification information, the difference value, and the mode information.

  The moving picture predictive coding method and the moving picture predictive coding program can achieve the same effects as the above-described moving picture predictive coding apparatus.

In addition, the moving picture predictive decoding method according to the present invention includes, for each of a plurality of pictures constituting a moving picture, a plurality of data that are predictively encoded using a plurality of pictures decoded and reproduced in the past as reference pictures, An input step for inputting compressed image data including encoded data of buffer description information relating to a reference image, a decoding step for decoding the compressed image data and restoring it to a reproduced image, and for decoding the reproduced image and subsequent images One or more reference images used for the image storage, an image storage step for storing by the image storage means, and a buffer management step for controlling the image storage means, and a plurality of reference images used for decoding the reproduced image in the decoding step In order to decode the target buffer description information related to the reference image, the decoded buffer description information is different from the target buffer description information. Decoding the identification information for identifying the buffer description information used for decoding the target buffer description information as the reference buffer description information, decoding the difference value between the picture number related to the reference buffer description information and the picture number related to the target buffer description information. Decoding mode information used for restoring the target buffer description information from three or more modes prepared for generating new buffer description information based on the buffer description information and the prediction buffer description information generated from the difference value; Based on the prediction buffer description information and the mode information, the target buffer description information is decoded. In the buffer management step, the image storage means is controlled based on the decoded target buffer description information. , A first mode, a second mode, and a third mode for performing different processes Three modes are included, and each of the three or more modes indicates different processing methods for generating the target buffer description information from the prediction buffer description information. In the decoding step, the compressed image data is decoded to decode the mode information. The target buffer description information is decoded from the prediction buffer description information by the processing method indicated by the mode information. The first mode is a mode in which the difference value is added as a new element to the prediction buffer description information, and the second mode is a predetermined element among the elements of the prediction buffer description information. The third mode may be a mode for performing processing using the prediction buffer description information as target buffer description information. In addition, the second mode may be a mode in which, among the elements of the prediction buffer description information, a process of replacing an element having a minimum value or a maximum value with the difference value. In the decoding step, a set of usage information indicating whether the reproduced image managed by the target buffer description information is used for prediction processing of the target image or for prediction processing of a future image. May be decoded as mode information. Each of the three or more modes is uniquely identified from information of 2 bits or 3 bits, and in the decoding step, at least 3 modes are selected from the information of 2 bits or 3 bits or more. May be used.

In addition, the moving picture predictive decoding program according to the present invention includes, for each of a plurality of pictures constituting a moving picture, a plurality of pieces of data that are predictively encoded using a plurality of pictures decoded and reproduced in the past as reference pictures, An input module for inputting compressed image data including encoded data of buffer description information relating to a reference image, a decoding module for decoding the compressed image data and restoring it to a reproduced image, and for decoding the reproduced image and subsequent images An image storage module for storing one or more reference images used for the image storage, and a buffer management module for controlling the image storage module, and the decoding module is related to a plurality of reference images used for decoding the reproduced image. In order to decode the target buffer description information, the decoded buffer description information is different from the target buffer description information. Decoding identification information for identifying buffer description information used for decoding buffer description information as reference buffer description information; decoding a difference value between a picture number related to reference buffer description information and a picture number related to the target buffer description information; and Decoding mode information used to restore the target buffer description information from three or more modes prepared for generating new buffer description information based on the description information and the prediction buffer description information generated from the difference value; The target buffer description information is decoded based on the prediction buffer description information and the mode information, and the buffer management module controls the image storage module based on the decoded target buffer description information . At least a first mode, a second mode, and a third mode for performing different processes from each other Three modes are included, and each of the three or more modes indicates different processing methods for generating the target buffer description information from the prediction buffer description information, and the decoding means decodes the compressed image data to obtain the mode information. And the target buffer description information is decoded from the prediction buffer description information by the processing method indicated by the mode information .

  The moving picture predictive decoding method and the moving picture predictive decoding program can achieve the same effects as the above-described moving picture predictive decoding apparatus.

  According to the reference picture set (RPS) encoding / decoding method of the present invention, the number of bits required for inter-RPS encoding is further reduced. In addition, since the configuration of the encoded data is simplified, the analysis processing of the encoded data in the decoding device is simplified.

It is a block diagram which shows the moving image predictive coding apparatus by embodiment of this invention. It is a block diagram which shows the moving image predictive decoding apparatus by embodiment of this invention. 5 is a flowchart illustrating a buffer management method and an RPS information encoding method in the video predictive encoding device according to the embodiment of the present invention. It is a flowchart which shows the detail of the buffer management method in the moving image predictive coding apparatus by embodiment of this invention. 5 is a flowchart showing a buffer management method and a RPS information decoding method in the video predictive decoding device according to the embodiment of the present invention. It is a flowchart which shows the detail of the buffer management method in the moving image predictive decoding apparatus by embodiment of this invention. FIG. 10 is a diagram illustrating a syntax table for encoding / decoding conventional RPS information. FIG. 6 is a diagram illustrating a syntax table for encoding / decoding RPS information according to an embodiment of the present invention. It is an example which shows the state of the reference image in a frame memory when processing a target image and each target image. 10 is a table showing RPS information obtained from the example of FIG. 9. It is a figure which shows the hardware constitutions of the computer for performing the program recorded on the recording medium. It is a perspective view of a computer for executing a program stored in a recording medium. It is a figure explaining the example of inter_rps_mode of FIG. It is a figure explaining another example of inter_rps_mode of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram showing a moving picture predictive coding apparatus 100 according to an embodiment of the present invention. As shown in FIG. 1, the moving image predictive encoding device 100 includes an input terminal 101, a block divider 102, a prediction signal generator 103, a frame memory 104, a subtractor 105, a converter 106, a quantizer 107, an inverse quantum, and the like. , An adder 110, an entropy encoder 111, an output terminal 112, and a buffer manager 114. The input terminal 101 corresponds to “input means” recited in the claims. The subtractor 105, the converter 106, the quantizer 107, and the entropy encoder 111 correspond to “encoding means” recited in the claims. The inverse quantizer 108, the inverse transformer 109, and the adder 110 correspond to “decoding means” recited in the claims. The frame memory 104 corresponds to “image storage means”, and the buffer manager 114 corresponds to “buffer management means”.

  The operation of the moving picture predictive coding apparatus 100 configured as described above will be described below. A moving image signal composed of a plurality of images is input to the input terminal 101. An image to be encoded is divided into a plurality of regions by the block divider 102. In the embodiment according to the present invention, the block is divided into 8 × 8 pixels, but may be divided into other block sizes or shapes. A plurality of block sizes and shapes may be mixed on one screen. Next, a prediction signal is generated for a region to be encoded (hereinafter referred to as a target block). In the embodiment according to the present invention, two types of prediction methods, inter-screen prediction and intra-screen prediction, are used.

  In inter-screen prediction, a reproduction image that has been encoded in the past and restored as a reference image is used as a reference image to obtain motion information that gives a prediction signal with the smallest error for the target block. Further, according to circumstances, the target block may be subdivided, and the inter-screen prediction method may be determined for the subdivided small area. In this case, the most efficient division method and the respective motion information are determined from the various division methods for the entire target block. In the embodiment according to the present invention, the prediction signal generator 103 inputs the target block via the line L102 and the reference image via L104. As the reference image, a plurality of images encoded and restored in the past are used as the reference image. For details, see the conventional technology H.264. H.264 or the method shown in Non-Patent Document 1. The motion information and the small area dividing method determined in this way are sent to the entropy encoder 111 via the line L112, encoded, and sent out from the output terminal 112. In addition, information (reference index) on which reference image the prediction signal is acquired from among a plurality of reference images is also sent to the entropy encoder 111 via the line L112. In the embodiment according to the present invention, 3 to 6 reproduced images are stored in the frame memory 104 and used as reference images. The prediction signal generator 103 acquires a reference image signal from the frame memory 104 based on the reference image and motion information corresponding to each small region dividing method and each small region, and generates a prediction signal. The inter-screen prediction signal generated in this way is sent to the subtractor 105 via the line L103.

  In intra-screen prediction, an intra-screen prediction signal is generated using already reproduced pixel values spatially adjacent to the target block. Specifically, the prediction signal generator 103 acquires already reproduced pixel signals in the same screen from the frame memory 104 and extrapolates these signals to generate an in-screen prediction signal. Information regarding the extrapolation method is sent to the entropy encoder 111 via the line L112, encoded, and sent from the output terminal 112. The intra-screen prediction signal generated in this way is sent to the subtractor 105. The prediction signal generation method in the screen in the prediction signal generator 103 is a conventional technique of H.264. H.264 or the method shown in Non-Patent Document 1. The inter-screen prediction signal and the intra-screen prediction signal obtained as described above are selected with the smallest error and sent to the subtractor 105.

  The subtractor 105 subtracts the prediction signal (via the line L103) from the signal of the target block (via the line L102) to generate a residual signal. The residual signal is subjected to discrete cosine transform by a transformer 106, and each transform coefficient is quantized by a quantizer 107. Finally, the transform coefficient quantized by the entropy encoder 111 is encoded and transmitted from the output terminal 112 together with information on the prediction method.

  In order to perform intra prediction or inter prediction for the subsequent target block, the compressed signal of the target block is inversely processed and restored. That is, the quantized transform coefficient is inversely quantized by the inverse quantizer 108 and then inverse discrete cosine transformed by the inverse transformer 109 to restore the residual signal. The residual signal restored by the adder 110 and the prediction signal sent from the line L103 are added, and the signal of the target block is reproduced and stored in the frame memory 104. In the present embodiment, converter 106 and inverse converter 109 are used, but other conversion processes in place of these converters may be used. In some cases, the converter 106 and the inverse converter 109 may be omitted.

  The frame memory 104 is finite and cannot store all reproduced images. Only the reproduced image used for encoding the subsequent image is stored in the frame memory 104. A buffer manager 114 controls the frame memory 104. Information (POC, picture output count) indicating the output order of each image and the type for encoding the image (intra-screen predictive coding, inter-screen predictive coding) are input from the input terminal 113, and the buffer is based on this information. The manager 114 operates. Reference picture set (RPS) information, which is information generated by the buffer manager 114 and describes a set of a plurality of reference images stored in the buffer, and POC information of each image are entropy via a line L114. The data is sent to the encoder 111 and output together with the encoded image data after being encoded. The processing method of the buffer manager 114 according to the present invention will be described later.

  Next, the video predictive decoding method according to the present invention will be described. FIG. 2 shows a block diagram of a video predictive decoding apparatus 200 according to an embodiment of the present invention. As shown in FIG. 2, the moving picture predictive decoding apparatus 200 includes an input terminal 201, a data analyzer 202, an inverse quantizer 203, an inverse transformer 204, an adder 205, a prediction signal generator 208, a frame memory 207, and an output. A terminal 206 and a buffer manager 209 are provided. The input terminal 201 corresponds to “input means” recited in the claims. The data analyzer 202, the inverse quantizer 203, and the inverse transformer 204 correspond to “decoding means” recited in the claims. A decoding means other than those described above may be used. Further, the inverse converter 204 may not be provided. The frame memory 207 corresponds to “image storage means”, and the buffer manager 209 corresponds to “buffer management means”.

  The operation of the video predictive decoding apparatus 200 configured as described above will be described below. The compressed data compressed and encoded by the method described above is input from the input terminal 201. The compressed data includes a residual signal encoded by predicting a target block obtained by dividing an image into a plurality of blocks, and information related to generation of a prediction signal. Information related to the generation of the prediction signal includes information related to block division (block size) in the case of inter-screen prediction, motion information and the above-mentioned POC information, and in the case of intra-screen prediction, the surrounding already reproduced pixels. Contains information on extrapolation methods. The compressed data also includes RPS information for controlling the frame memory 207.

  The data analyzer 202 extracts the residual signal of the target block, information related to generation of the prediction signal, the quantization parameter, and the POC information of the image from the compressed data. The residual signal of the target block is inversely quantized by the inverse quantizer 203 based on the quantization parameter (via the line L202). The result is subjected to inverse discrete cosine transform by an inverse transformer 204.

  Next, information related to the generation of the prediction signal is sent to the prediction signal generator 208 via the line L206b. The prediction signal generator 208 accesses the frame memory 207 based on information related to generation of a prediction signal, acquires a reference signal from a plurality of reference images, and generates a prediction signal. This prediction signal is sent to the adder 205 via the line L208, added to the restored residual signal, reproduces the target block signal, and is output via the line L205 and stored in the frame memory 207 at the same time.

  The frame memory 207 stores a reproduced image used for decoding / reproducing subsequent images. The buffer manager 209 controls the frame memory 207. The buffer manager 209 operates based on the RPS information sent via the line L206a and information on the image coding type. A method for controlling the buffer manager 209 according to the present invention will be described later.

  Next, the control method of the buffer manager (114 in FIG. 1 and 209 in FIG. 2) by the RPS information and the RPS information in the entropy encoder 111 and the data analyzer 202 will be described with reference to FIGS. The encoding / decoding method will be described, but RPS information and the concept of the data compression method will be described first in preparation for explaining the drawings.

  First, RPS information will be described. In the buffer manager 114 (209) according to the embodiment of the present invention, a reproduced picture buffer (also referred to as “DBP”), that is, a frame memory 104 (207), describes a set of a plurality of reference images stored therein. Management based on information (Reference picture set, hereinafter referred to as “RPS”, also referred to as buffer description information). That is, the RPS information functions as buffer management information. The RPS information is encoded / decoded by the entropy encoder 111 in FIG. 1 and the data analyzer in FIG.

  The RPS information is stored in the frame memory 207 and is a picture number (picture output count, hereinafter referred to as “POC”) that identifies a plurality of reference images used for inter-screen prediction of a target image or an image to be encoded / decoded in the future. This is information indicating a relationship (difference) between the POC number for identifying the target image.

  An example of RPS information will be described with reference to FIGS. In this specification, the relationship between the POC of one reference image and the POC of the target image is represented as DeltaPoc. FIG. 9 shows the state of a plurality of reference images in the frame memory 207 when the target image and each target image are processed. Each cell has a POC that identifies the image. For example, in row 1610, it means that reference images of POC = 18, 20, 22, 24 are stored in the frame memory when processing (encoding or decoding) a target image of POC = 32. FIG. 10 shows an RPS corresponding to FIG. 1701 indicates an identifier idx for identifying RPS information, and each cell below 1704 indicates a value of DeltaPoc which is an element of RPS information.

  Next, an outline of the concept of the data compression method of RPS information will be described. As shown in FIG. 9, the sets of reference images stored in the frame memory 207 are similar to each other across the frames. Therefore, in the encoding apparatus of the present embodiment, a plurality of RPS information for each of a plurality of target images is generated collectively, and SPS (sequence parameter set) information or PPS (picture parameter) that carries parameters for decoding processing to be applied in common. parameter set) sent as part of the information. In the decoding device, RPS information is extracted from SPS information or PPS information, and a reference image in the frame memory is prepared based on one RPS information specified in compressed data (for example, slice header data) of each target image. Decoding and playback processing is performed above. Reference images not described in the RPS information are erased from the frame memory and cannot be used as reference images thereafter.

  As described above, one RPS information is used for each target image for frame memory management. However, in the encoding / decoding method of Non-Patent Document 1, a slice obtained by dividing the target image into one or more sections (in this unit) One RPS information is indicated by the header information (switching between intra-screen encoding / decoding and inter-screen encoding / decoding). The slice is described in Non-Patent Document 1.

  In the present invention, the RPS information indicates one RPS information for each picture header or slice header. There are two methods for instructing RPS information used in the target image. One is instructed by encoding / decoding an identifier idx of RPS information encoded / decoded by SPS or PPS using a picture header or a slice header. Second, new RPS information is encoded / decoded by a picture header or a slice header.

  There are two methods for encoding / decoding new RPS information encoded / decoded by SPS / PPS or picture / slice header. One is a method called inter RPS (Inter RPS method), which refers to pre-encoded / decoded RPS and predictively encodes / decodes the relationship between the RPS to be encoded and the pre-encoded RPS. The second is called intra RPS (Intra RPS method), which encodes / decodes the number and value of DeltaPocs included in the RPS to be encoded / decoded without reference. In this specification, a set of DeltaPocs included in one RPS is denoted as DeltaPoc [idx] [i]. Here, i represents the i-th reference image stored in the frame memory, and idx represents a number (identifier) for identifying a specific RPS. In the following description, [i] may be omitted.

  Next, the control method of the buffer manager (114 in FIG. 1 and 209 in FIG. 2) by the RPS information and the RPS information in the entropy encoder 111 and the data analyzer 202 will be described with reference to FIGS. An encoding / decoding method will be described.

  FIG. 8 shows a syntax table short_term_ref_pic_set (idx) for encoding / decoding new RPS information identified by idx. The number of RPS information encoded / decoded by SPS or PPS is encoded / decoded by SPS or PPS as num_short_term_ref_pic_sets. That is, RPS information encoded / decoded by SPS or PPS is identified by an identifier idx (idx is an integer in the range of 0 to num_short_term_ref_pic_sets-1).

  inter_ref_pic_set_prediction_flag (R200) is a syntax element for identifying whether the encoding / decoding method of the RPS information to be encoded / decoded identified by idx is intra RPS or inter RPS. When this flag is 0, DeltaPoc [idx] is encoded / decoded by the intra RPS method. That is, the number of reference images included in the RPS to be encoded / decoded and the value of DeltaPoc corresponding to each reference image are encoded / decoded. For example, when RPS (1710) identified by idx = 0 in FIG. 10 is encoded / decoded with intra RPS, the number of DeltaPos is 4 and the value of 4 DeltaPocs (−14, −12, −10, -8) is encoded / decoded.

When inter_ref_pic_set_prediction_flag (R200) is 1, DeltaPoc [idx] [i] is encoded / decoded by inter-RPS that refers to RPS information of already encoded / decoded information. delta_idx_minus1 (R210) is a syntax element for specifying the identifier RIdx of the RPS information referred to in the inter-RPS prediction process. RIdx is restored by equation (5).
RIdx = idx- (delta_idx_minus1 + 1) (5)

The syntax element delta_rps (R220) is a positive or negative integer, and indicates a difference value DeltaRPS between the DeltaPoc set of RPS identified by RIdx and the DeltaPoc set identified by idx to be encoded / decoded. Note that delta_rps may be encoded / decoded separately as shown in the syntax element R120 (abs_delta_rps_minus1 and delta_rps_sign) in FIG.
DeltaRPS = delta_rps (6)
For example, in FIG. 10, when RIdx = 1 and idx = 2, the difference value 2 is encoded / decoded as delta_rps. Each RPS element DeltaPoc [idx] [i] and the number NumDeltaPocs [idx] of the target RPS are calculated as shown in equations (7) and (8). NumDeltaPocs [idx] indicates the number of DeltaPocs included in the RPS information identified by idx (1702 in FIG. 10). In addition, since the final target RPS information is determined by DeltaPoc [idx] [i] calculated by Expression (7) and inter_rps_mode described later, DeltaPoc [idx] [i] of Expression (7) is the target RPS. This is the positioning of predicted RPS information (predicted buffer description information) with respect to information (target buffer description information).
DeltaPoc [idx] [i] = DeltaPoc [RIdx] [i] + DeltaRPS (7)
Where i = 0 to (NumDeltaPocs [RIdx] -1)
NumDeltaPocs [idx] = NumDeltaPocs [RIdx] (8)

The syntax element inter_rps_mode (R230) is an important feature of the present invention. In the present invention, target RPS information (identified by idx, also called target RPS information or target buffer description information) is derived based on RPS to be referenced (identified by RIdx, also called reference RPS information or reference buffer description information). Prepare multiple methods to do this. More specifically, a plurality of methods for generating final target RPS information from Formula (7) and Formula (8) are prepared in advance. At this time, by preparing a method having a high occurrence frequency as inter_rps_mode, it is possible to efficiently encode / decode RPS information with fewer code elements than the syntax described in FIG. At this time, in the encoding / decoding of inter_rps_mode (R230), the number NumDeltaPocs [RIdx] of the reference RPS elements (DeltaPoc) is not required unlike the syntax element R130 of FIG.
Here, inter_rps_mode is a 1-bit signal (two modes).

When inter_rps_mode is 0, in addition to Expression (7) and Expression (8), Expression (9) and Expression (10) are performed, and one new DeltaPoc is added to the target RPS information.
DeltaPoc [idx] [NumDeltaPocs [RIdx]] = DeltaRPS (9)
NumDeltaPocs [idx] = NumDeltaPocs [RIdx] +1 (10)
For example, when RIdx = 1 in FIG. 10, the RPS information with idx = 2 can be realized by setting delta_idx_minus1 = 0, delta_rps = 2, and inter_rps_mode = 0.
When inter_rps_mode is 1, in addition to Expressions (7) and (8), the value of DeltaPoc [idx] [j] that satisfies a preset condition is replaced with DeltaRPS. As the condition j, for example, j that maximizes the value of DeltaPoc [idx] [j] is selected. The method for determining the condition j is not limited to this. The value of j may be encoded / decoded, the value of j may be determined in advance, or the value of j may be determined from information such as idx, delta_rps, and delta_idx_munus1.

  In the above, inter_rps_mode is a 1-bit signal (2 modes), but is not limited thereto. For example, as shown in 1300 in FIG. 13, 2-bit information (4 modes) is used, and a mode in which the value of DeltaPoc [idx] [j] is replaced with DeltaRPS for j where the value of DeltaPoc [idx] [j] is minimum, A mode in which the results of Expression (7) and Expression (8) are not changed and the target RPS information is used as it is may be added. Further, as shown by 1400 in FIG. 14, the mode in which the element having the maximum or minimum value (DeltaPoc) is deleted from the target RPS, the mode in which only the element having the maximum or minimum value is left in the target RPS, or the value is negative. A mode may be added in which only the DeltaPoc is left in the target RPS. The number of modes and mode drinking are not limited. Nine modes may be used, or some of the nine modes may be selected and used. The mode to be used may be instructed by including it in the SPS information or the PPS information.

  When new RPS information is encoded / decoded in the slice header, num_short_term_ref_pic_sets, which is an idx number not used in SPS or PPS, is used as an input value of the syntax table. That is, the syntax table short_term_ref_pic_set (num_short_term_ref_pic_sets) is encoded / decoded.

  Next, operations of the buffer manager (114 in FIG. 1 and 209 in FIG. 2), the entropy encoder 111, and the data analyzer 202 will be described with reference to FIGS.

  FIG. 3 is a flowchart showing one RPS information encoding method in the buffer manager 114 and the entropy encoder 111 of the video predictive encoding device 100 according to the embodiment of the present invention.

  In step 510 of FIG. 3, the buffer manager 114 determines whether there is a reference RPS suitable for encoding the target RPS using the inter-RPS method. Note that the reference RPS suitable for encoding the target RPS refers to a reference RPS having an RPS similar to the target RPS, and whether or not the RPS is similar depends on, for example, the number of DeltaPocs and the value of the DeltaPoc. Although similarity may be determined, the present invention is not limited to this, and it is preferable to select a reference RPS that increases coding efficiency. Details of step 510 will be described later with reference to FIG.

  If the buffer manager 114 determines in step 510 that there is no reference RPS suitable for encoding the target RPS using the inter RPS method (buffer description information predictive encoding), the process proceeds to step 570. In step 570, the buffer manager 114 sets inter_rps_prediction_flag to 0, and the entropy encoder 111 performs entropy encoding on inter_rps_prediction_flag. Next, at step 580, the buffer management 114 encodes the number and value of DeltaPocs included in the target RPS by the entropy encoder 111, and the process ends.

  If the buffer manager 114 determines in step 510 that there is a reference RPS suitable for encoding the target RPS using the inter-RPS method (buffer description information predictive coding method), the buffer manager 114 RIdx, DeltaRPS, and inter_rps_mode shown in FIG. 13 (shown as Mode in FIG. 4) are derived, and the process proceeds to step 520. Here, FIG. 13 is taken as an example, but the type of inter_rps_mode is not limited to FIG. 13. In step 520, the buffer manager 114 sets inter_rps_prediction_flag to 1, and the entropy encoder 111 entropy encodes inter_rps_prediction_flag. In Step 530, the difference value delta_idx_minus1 (= idx−RIdx−1) between the identifier RIdx for identifying the reference RPS selected by the buffer manager 114 as the RPS suitable for the inter-RPS method of the target RPS and the idx for identifying the target RPS. The identification information is encoded by the entropy encoder 111. In step 530, the difference value delta_idx_minus1 is encoded as the identification information. However, the identification information to be encoded is not limited to this, and any information that can identify the reference RPS may be used. The identifier RIdx for identifying may be encoded as identification information. In step 540, the entropy encoder 111 encodes delta_rps derived by the buffer manager 114 as DeltaRPS. Note that delta_rps may be encoded by dividing it into its absolute value and positive / negative sign as shown by the syntax element R120 (abs_delta_rps_minus1 and delta_rps_sign) in FIG. Finally, in step 550, the entropy encoder 111 encodes inter_rps_mode derived by the buffer manager 114. Note that the entropy encoding method of each encoding element in the entropy encoder 111 is not limited, but variable length encoding or arithmetic encoding can be applied.

  FIG. 4 is a flowchart showing details of the processing in step 510 of FIG. The process of the buffer manager 114 for deriving each encoding element of the syntax table used for encoding / decoding of RPS information is shown.

In step 610, it is determined whether there are unexamined RPS information among a plurality of reference RPS candidates used for inter-RPS prediction of the target RPS. If there is no unexamined reference RPS candidate, the process proceeds to step 680, and it is determined that there is no reference RPS suitable for encoding the target RPS using inter RPS prediction. Based on the result, the process proceeds to step 570 in FIG.
If unexamined reference RPS candidates remain, the process proceeds to step 620. In step 620, the identifier RIdx for identifying the next RPS candidate is acquired, and the difference value DeltaRPS between the RPS of the target image and the POC related to the reference RPS candidate is calculated by equation (11), and the process proceeds to step 630.
DeltaRPS = POCReference-POCCurrent (11)
Here, POCCurrent indicates the POC number related to the target RPS, and POCReference indicates the POC number of the reference RPS candidate. For example, when the target RPS is 1712 and the reference RPS candidate is 1711 in FIG. 10, POCCurrent = 26 (1612 in FIG. 9), POCReference = 28 (1611 in FIG. 9), and DeltaRPS = 2.
In step 630, DeltaPocPred [i] is calculated by Equation (12) as a predicted RPS (referred to as prediction buffer description information) that is a predicted value of the target RPS. Here, i varies from 0 to N−1, and the value of N is the number of reference RPSs NumDeltaPocs [RIdx].
DeltaPocPred [i] = DeltaPoc [RIdx] [i] + DeltaRPS (12)

  Next, in step 640, the predicted RPS and the target RPS are compared. If they match, Mode = inter_rps_mode = 3 is set in step 650, and the process proceeds to step 520 in FIG. If not, the process proceeds to step 631.

  In step 631, DeltaPocPred [N] = DeltaRPS is added as a new element to the predicted RPS. In step 641, the updated predicted RPS is compared with the target RPS, and if they match, Mode = inter_rps_mode = 0 is set in step 651, and the process proceeds to step 520 in FIG. If not, the process proceeds to Step 632.

  In step 632, the index corresponding to the DeltaPoc having the smallest value is detected from the predicted RPS, and the DeltaPoc detected as DeltaPocPred [index] = DeltaRPS is replaced with the value of DeltaRPS. In Step 642, the updated predicted RPS and the target RPS are compared. If they match, Mode = inter_rps_mode = 1 is set in Step 652, and the process proceeds to Step 520 in FIG. If not, the process proceeds to Step 632.

  In step 633, the index corresponding to the DeltaPoc having the maximum value is detected from the predicted RPS, and the DeltaPoc detected as DeltaPocPred [index] = DeltaRPS is replaced with the value of DeltaRPS. In step 643, the updated predicted RPS is compared with the target RPS, and if they match, Mode = inter_rps_mode = 2 is set in step 653, and the process proceeds to step 520 in FIG. If not, the process proceeds to step 610.

  In the entropy encoder 111, num_short_term_ref_pic_sets pieces of RPS information DeltaPoc [° k °] [° i °] (k = 0-num_short_term_ref_pic_sets-1, i = 0-NumDeltaPocs [k ] -1) is sent together with other compressed data as part of SPS information or PPS information. Based on one RPS information DeltaPoc [m] designated from the input terminal 113 in FIG. 1, the buffer manager 114 prepares a reference image in the frame memory 104 and performs an encoding process. On the receiving side, the buffer manager 209 prepares a reference image in the frame memory 207 based on the identifier m of RPS information added to the compressed data header (picture header or slice header) of each image, and then performs decoding processing. I do. When DeltaPoc [m] does not exist in num_short_term_ref_pic_sets RPS information, DeltaPoc [m] is encoded as new RPS information with the syntax indicated by short_term_ref_pic_set (num_short_term_ref_pic_sets). Therefore, in the embodiment of the present invention, a flag indicating whether to send new RPS information or RPS information identifier m is also sent in the slice header or picture header.

  FIG. 5 is a flowchart showing a method of decoding one RPS information in the buffer manager 209 and the data analyzer 202 of the moving picture predictive decoding apparatus 200 according to the embodiment of the present invention.

  In step 310, the data analyzer 209 decodes information inter_rps_prediction_flag indicating whether the target RPS is decoded by the intra RPS method or the inter RPS method (buffer description information predictive decoding method). When the decoded value of inter_rps_prediction_flag is 0, the process proceeds to step 380, and when the decoded value is 1, the process proceeds to step 330.

  In step 380, the data analyzer 202 and the buffer manager 209 restore the target RPS by the intra RPS method.

In steps 330, 340, and 350, the data analyzer 202 entropy-decodes delta_idx_minus1, delta_rps, and inter_rps_mode based on the inter RPS method, and sends the result to the buffer manager 209. At this time, as indicated by the syntax element R120 (abs_delta_rps_minus1 and delta_rps_sign) in FIG. 7, delta_rps may be decoded by dividing it into its absolute value and positive / negative sign. The entropy decoding method for each element is not limited, but variable length decoding or arithmetic decoding can be applied. Further, when the identifier RIdx is adopted as identification information on the encoding device side, the encoded identifier RIdx is decoded.
In step 360, the buffer manager 209 restores the target RPS from the decoded delta_idx_minus1, delta_rps, and inter_rps_mode. Details of step 360 will be described with reference to FIG.

  FIG. 6 is a flowchart showing details of the process in step 360 of FIG. The restoration process of the target RPS information in the buffer manager 209 is shown.

In step 410, the identifier RIdx that identifies the reference RPS is restored based on the equation (5) from the decoded delta_idx_minus1 and the identifier idx that identifies the target RPS information.
RIdx = idx- (delta_idx_minus1 + 1) (5)
Also, DeltaRPS is restored from the decoded delta_rps based on Equation (6).
DeltaRPS = delta_rps (6)
Further, the value of Mode is restored from the decoded inter_rps_mode.

Next, in step 420, N DeltaPocs are restored from the decoded DeltaRPS based on Equation (7) and Equation (8).
DeltaPoc [idx] [i] = DeltaPoc [RIdx] [i] + DeltaRPS (7)
Where i = 0 to N-1 (= NumDeltaPocs [RIdx] -1)
NumDeltaPocs [idx] = NumDeltaPocs [RIdx] (8)
Here, since the final target RPS information is determined by DeltaPoc [idx] [i] calculated in Equation (7) and Mode, DeltaPoc [idx] [i] in Equation (7) is the target RPS. This is the positioning of predicted RPS information (predicted buffer description information) with respect to information (target buffer description information).

In step 430, it is determined whether Mode is zero. If Mode is 0, the process proceeds to step 440, and DeltaPoc [idx] [N] = DeltaRPS is added to the target RPS as a new element of DeltaPoc [idx]. DeltaPoc [idx] [NumDeltaPocs [RIdx]] = DeltaRPS (9)
NumDeltaPocs [idx] = NumDeltaPocs [RIdx] +1 (10)
If Mode is not 0, the process proceeds to step 450.

  In step 450, it is determined whether Mode is 1. If Mode is 1, the process proceeds to step 460, and the element (DeltaPoc) having the smallest value among DeltaPoc [idx] [0] to DeltaPoc [idx] [N-1] is replaced with DeltaRPS. When the identifier for identifying the element having the smallest value is j, DeltaPoc [idx] [j] = DeltaRPS. If Mode is not 1, the process proceeds to step 470.

  In step 470, it is determined whether Mode is 2. When Mode is 2, the process proceeds to step 480, and the element (DeltaPoc) having the maximum value among DeltaPoc [idx] [0] to DeltaPoc [idx] [N-1] is replaced with DeltaRPS. When the identifier for identifying the element having the maximum value is j, DeltaPoc [idx] [j] = DeltaRPS. If Mode is not 2, the DeltaPoc [idx] and NumDeltaPocs [idx] restored in step 420 are output without change (Mode = 3).

  5 and FIG. 6, the data analyzer 202 in FIG. 2 can extract and decode data related to one RPS information from the compressed data. The data analyzer 202 and the buffer manager 209 calculate K pieces of RPS information DeltaPoc [k] [° i °] (k = 0−K−1, i = 0) from the SPS information or PPS information portion in the encoded data. -Decode NumDeltaPocs [k] -1). The value of K is decoded by SPS information or PPS information as num_short_term_ref_pic_sets, for example.

  When restoring each image, the buffer manager 209 uses the frame memory 207 based on DeltaPoc [idx] indicated by the identifier idx added to the header (picture header or slice header) of the compressed data of the target image. After the reference image inside is prepared, decoding / reproduction processing is performed. If there is no RPS information suitable for decoding the target image in the RPS information prepared in the SPS information, new RPS information is received by a slice header or a picture header. Therefore, in the embodiment of the present invention, the flag indicating whether to decode new RPS information or the identifier of RPS information is decoded first.

  As described above, according to the method for encoding / decoding the buffer description information (RPS information) according to the present invention, the method for generating the target RPS from the predicted RPS (generated from the reference RPS and the DeltaRPS) can be determined by inter_rps_mode. The analyzer 202 can analyze the compressed data related to the RPS information without acquiring the number of elements included in the reference RPS information. Further, since it is not necessary to encode the instruction information related to each element of the RPS information as in the use_delta_flag shown in the background art, it becomes possible to encode the compressed data of the RPS information more efficiently.

  Furthermore, in the present invention, used_by_curr_pic_flag [i] of the background art, that is, whether each reproduced image managed by the target RPS information is used for the target image prediction process or for the future image prediction process. It is also possible to extend inter_rps_mode so that the set of usage information shown can be encoded / decoded as mode information.

  Specifically, usage information used_by_curr_pic_flag is added to RPS information. When the identifier RIdx that identifies the reference RPS information is restored, the buffer manager copies the usage information of each playback image of the reference RPS identified by RIdx to the usage information of each playback image of the target RPS. Then, the usage information (the usage information of the reference image corresponding to the newly added DeltaPoc with Mode = 0 or the usage information corresponding to the specific DeltaPoc with Mode = 1 or 2 in FIG. 13) in which the value of DeltaPoc is DeltaRPS is inter_rps_mode. (In FIG. 13, encoding / decoding is performed when inter_rps_mode is 0, 1, 2). Alternatively, the mode in which the value of used_by_curr_pic_flag of the playback image corresponding to the newly added DeltaPoc is indicated by inter_rps_mode, or the used_by_curr_pic_flag of the playback image corresponding to a specific DeltaPoc (for example, the maximum DeltaPoc or the minimum DeltaPoc) A mode for changing the value may be prepared in combination with the original inter_rps_mode. Further, mode information indicating a pattern of usage information used_by_curr_pic_flag may be prepared separately from inter_rps_mode.

  A moving picture predictive coding program for causing a computer to function as the moving picture predictive coding apparatus 100 is stored in a recording medium and can be provided. Specifically, the moving image predictive encoding program predicts an input module for inputting a plurality of images constituting a moving image, and a plurality of images decoded and reproduced after encoding the images as reference images. An encoding module that encodes and generates compressed image data, a decoding module that decodes the compressed image data and restores it to a reproduced image, and a reproduced image as one reference image used to encode subsequent images An image storage module for storing the above, and a buffer management module for controlling the image storage module. The buffer management module is the target buffer description information related to a plurality of reference images used when predictively encoding an image. From different encoded buffer description information, the buffer description information similar to the target buffer description information is referred to as the reference buffer description information. And generating identification information for identifying the reference buffer description information, calculating a difference value between the picture number of the reference image of the reference buffer description information and the picture number of the target image of the target buffer description information, and the reference buffer description Generate prediction buffer description information from the information and the difference value, and select mode information for generating target buffer description information from a plurality of modes prepared for generating new buffer description information based on the prediction buffer description information. The encoding module is a video predictive encoding program characterized by encoding identification information, a difference value, and mode information.

  Similarly, a moving picture predictive decoding program for causing a computer to function as the moving picture predictive decoding apparatus 200 can be provided by being stored in a recording medium. Specifically, the moving image predictive decoding program performs prediction encoding on a plurality of images that have been decoded and reproduced in the past as reference images and a plurality of references for each of a plurality of images constituting the moving image. An input module for inputting compressed image data including encoded data of buffer description information relating to an image, a decoding module for decoding the compressed image data and restoring it to a reproduced image, and for decoding the reproduced image and subsequent images An image storage module that stores one or more reference images to be used, and a buffer management module that controls the image storage module. The decoding module is a target related to a plurality of reference images used when decoding a reproduction image. In order to decode the buffer description information, decoded buffer description information different from the target buffer description information, Decoding identification information for identifying buffer description information used for decoding buffer description information as reference buffer description information, decoding a difference value between a picture number related to reference buffer description information and a picture number related to target buffer description information, and a reference buffer description Decoding mode information used to restore the target buffer description information from a plurality of modes prepared to generate new buffer description information based on the prediction buffer description information generated from the information and the difference value, and the prediction buffer description The target buffer description information is decoded based on the information and the mode information, and the buffer management module controls the image storage module based on the decoded target buffer description information. . Examples of the recording medium include a recording medium such as a flexible disk, a CD-ROM, a DVD, or a ROM, or a semiconductor memory.

  FIG. 11 is a diagram illustrating a hardware configuration of a computer 30 for executing a program recorded on a recording medium. FIG. 12 is a perspective view of the computer 30 for executing a program stored on the recording medium. is there. The computer 30 here includes a wide range of DVD players, set-top boxes, mobile phones, and the like that have a CPU and perform information processing and control by software.

  As shown in FIG. 12, a computer 30 includes a reading device 12 such as a flexible disk drive device, a CD-ROM drive device, a DVD drive device, a working memory (RAM) 14 in which an operating system is resident, and a recording medium 10. A memory 16 for storing programs stored therein, a display device 18 such as a display, a mouse 20 and a keyboard 22 as input devices, a communication device 24 for transmitting and receiving data and the like, and a CPU 26 for controlling execution of the programs. And. When the recording medium 10 is inserted into the reading device 12, the computer 30 can access the moving image predictive encoding program stored in the recording medium 10 from the reading device 12, and the moving image predictive encoding program performs the above operation. It becomes possible to operate as the moving image predictive encoding device 100. Similarly, when the recording medium 10 is inserted into the reading device 12, the computer 30 can access the moving image predictive decoding program stored in the recording medium 10 from the reading device 12, and the moving image predictive decoding program performs the above operation. It becomes possible to operate as the moving picture predictive decoding apparatus 200.

  Next, the operational effects of the video predictive coding device 100 and the video predictive decoding device 200 according to the present invention will be described.

  In the video predictive encoding device 100, the buffer manager 114 searches the reference buffer description information for buffer description information similar to the target buffer description information from a plurality of encoded buffer description information. It is determined whether there is a reference RPS suitable for encoding the target RPS using the inter-RPS method. Then, the buffer management unit 114 generates identification information (difference value delta_idx_minus1 or identifier RIdx) for identifying the reference RPS (the reference buffer description information).

  Next, the buffer management unit 114 is a difference value between the POC (picture number) of the reference image of the reference RPS (reference buffer description information) and the POC (picture number) of the target image of the target PRS (target buffer description information). DeltaRPS is calculated, and predicted RPS (predicted buffer description information) is generated from each element of the reference RPS and the difference value DelatRPS. Then, MODE (mode information) for generating the target buffer description information is selected from a plurality of inter_rps_mode (mode information) prepared for generating new buffer description information based on the predicted RPS, and the entropy encoder 111 The difference value delta_idx_minus1 or the identifier RIdx (identification information), DeltaRPS (difference value), and MODE (mode information) are encoded.

  Thereby, unlike the use_delta_flag shown in the background art, it is not necessary to encode the instruction information related to each element of the RPS information, so that the compressed data of the RPS information can be encoded more efficiently. Also, by preparing in advance a plurality of methods for generating the target buffer description information that are frequently generated as syntax elements, the target buffer description information can be efficiently encoded with a small number of code elements. Can do. Therefore, according to the present invention, the configuration of encoded data can be simplified by reducing the number of bits required for inter-RPS encoding.

  In this video predictive decoding apparatus 200, the data analyzer 202 includes identification information for identifying a reference RPS (reference buffer description information), a POC (picture number) of a reference image of the reference RPS (reference buffer description information), and a target PRS. DeltaRPS (difference value) that is a difference value between the target image (target buffer description information) and the POC (picture number) of the target image, and MODE (mode information) that generates target buffer description information are decoded.

  Then, the data analyzer 202 decodes the target RPS (target buffer description information) based on the predicted RPS (predicted buffer description information) and MODE (mode information), and the buffer manager 114 reads the decoded target RPS. The frame memory 104 is controlled based on (target buffer description information).

  Accordingly, the compressed data related to the buffer description information can be analyzed without obtaining the number of elements included in the target buffer description information from the prediction buffer description information. Also, by preparing a plurality of methods for generating the target buffer description information and having a high occurrence frequency as syntax elements in advance, the target buffer description information can be efficiently decoded with a small number of code elements. it can. Therefore, according to the present invention, the analysis processing of the encoded data in the decoding device can be simplified.

DESCRIPTION OF SYMBOLS 100 ... Moving image predictive coding apparatus, 101 ... Input terminal, 102 ... Block divider, 103 ... Prediction signal generator, 104 ... Frame memory, 105 ... Subtractor, 106 ... Converter, 107 ... Quantizer, 108 ... Inverse quantizer 109 ... Inverse transformer 110 ... Adder 111 ... Entropy encoder 112 ... Output terminal 114 ... Buffer manager 200 ... Video predictive decoding device 201 ... Input terminal 202 ... Data Analyzer, 203 ... Inverse quantizer, 204 ... Inverse transformer, 205 ... Adder, 206 ... Output terminal, 207 ... Frame memory, 208 ... Predictive signal generator, 209 ... Buffer manager.

Claims (8)

For each of a plurality of images constituting a moving image, data that is predictively encoded using a plurality of images decoded and reproduced in the past as reference images, and encoded data of buffer description information related to the plurality of reference images An input step for inputting compressed image data;
A decoding step of decoding the compressed image data and restoring the reproduced image;
An image storage step of storing the reproduced image as one or more reference images used for decoding subsequent images by an image storage means;
A buffer management step for controlling the image storage means,
In the decoding step,
Decoded buffer description information different from the target buffer description information and used for decoding the target buffer description information in order to decode the target buffer description information related to a plurality of reference images used when decoding the reproduced image Decoding identification information identifying buffer description information as reference buffer description information;
Decoding a difference value between a picture number related to the reference buffer description information and a picture number related to the target buffer description information;
Mode information used to restore the target buffer description information from three or more modes prepared for generating new buffer description information based on the prediction buffer description information generated from the reference buffer description information and the difference value Decrypt
Decoding the target buffer description information based on the prediction buffer description information and the mode information;
In the buffer management step,
Controlling the image storage means based on the decoded target buffer description information;
The three or more modes include
At least three modes including a first mode, a second mode, and a third mode that perform different processes from each other are included.
The three or more modes are:
Each indicating a different processing method for generating the target buffer description information from the prediction buffer description information;
In the decoding step,
Decoding the compressed image data, decoding the mode information, and decoding the target buffer description information from the prediction buffer description information by the processing method indicated by the mode information. Method. The first mode is a mode for performing a process of adding the difference value as a new element to the prediction buffer description information,
The second mode is a mode for performing a process of replacing a predetermined element among the elements of the prediction buffer description information with the difference value;
The moving image predictive decoding method according to claim 1, wherein the third mode is a mode for performing processing using the prediction buffer description information as the target buffer description information.   3. The video predictive decoding according to claim 1, wherein the second mode is a mode for performing a process of replacing an element having a minimum value or a maximum value among the elements of the prediction buffer description information with the difference value. Method. In the decoding step,
A mode information is a set of usage information indicating whether the reproduced image managed by the target buffer description information is used for a target image prediction process or a future image prediction process. decoding, the moving picture prediction decoding method according to any one of claims 1 to 3. For each of a plurality of images constituting a moving image, data that is predictively encoded using a plurality of images decoded and reproduced in the past as reference images, and encoded data of buffer description information related to the plurality of reference images An input means for inputting compressed image data;
Decoding means for decoding the compressed image data and restoring the reproduced image;
Image storage means for storing one or more of the reproduced images as reference images used for decoding subsequent images;
Buffer management means for controlling the image storage means,
The decoding means includes
Decoded buffer description information different from the target buffer description information and used for decoding the target buffer description information in order to decode the target buffer description information related to a plurality of reference images used when decoding the reproduced image Decoding identification information identifying buffer description information as reference buffer description information;
Decoding a difference value between a picture number related to the reference buffer description information and a picture number related to the target buffer description information;
Mode information used to restore the target buffer description information from three or more modes prepared for generating new buffer description information based on the prediction buffer description information generated from the reference buffer description information and the difference value Decrypt
Decoding the target buffer description information based on the prediction buffer description information and the mode information;
The buffer management means includes
Controlling the image storage means based on the decoded target buffer description information;
The three or more modes include
At least three modes including a first mode, a second mode, and a third mode that perform different processes from each other are included.
The three or more modes are:
Each indicating a different processing method for generating the target buffer description information from the prediction buffer description information;
The decoding means includes
Decoding the compressed image data, decoding the mode information, and decoding the target buffer description information from the prediction buffer description information by the processing method indicated by the mode information. apparatus. For each of a plurality of images constituting a moving image, data that is predictively encoded using a plurality of images decoded and reproduced in the past as reference images, and encoded data of buffer description information related to the plurality of reference images An input module for inputting compressed image data;
A decoding module that decodes the compressed image data and restores the reproduced image;
An image storage module that stores one or more of the reproduced images as reference images used to decode subsequent images;
A buffer management module for controlling the image storage module;
The decryption module is
Decoded buffer description information different from the target buffer description information and used for decoding the target buffer description information in order to decode the target buffer description information related to a plurality of reference images used when decoding the reproduced image Decoding identification information identifying buffer description information as reference buffer description information;
Decoding a difference value between a picture number related to the reference buffer description information and a picture number related to the target buffer description information;
Mode information used to restore the target buffer description information from three or more modes prepared for generating new buffer description information based on the prediction buffer description information generated from the reference buffer description information and the difference value Decrypt
Decoding the target buffer description information based on the prediction buffer description information and the mode information;
The buffer management module includes:
Controlling the image storage module based on the decoded target buffer description information;
The three or more modes include
At least three modes including a first mode, a second mode, and a third mode that perform different processes from each other are included.
The three or more modes are:
Each indicating a different processing method for generating the target buffer description information from the prediction buffer description information;
The decryption module is
Decoding the compressed image data, decoding the mode information, and decoding the target buffer description information from the prediction buffer description information by the processing method indicated by the mode information. program. An input step for inputting a plurality of images constituting the moving image;
An encoding step for predictively encoding a plurality of images decoded and reproduced after being encoded in the past as reference images, and generating compressed image data;
A decoding step of decoding the compressed image data and restoring the reproduced image;
An image storage step of storing one or more of the reproduced images as reference images used to encode subsequent images by an image storage means;
A buffer management step for controlling the image storage means,
In the buffer management step,
Buffer description information similar to the target buffer description information from a plurality of encoded buffer description information different from target buffer description information related to a plurality of reference images used when predictively encoding the image is referred to as a reference buffer description Searching as information, generating identification information identifying the reference buffer description information,
Calculating a difference value between a picture number of a reference image of the reference buffer description information and a picture number of a target image of the target buffer description information;
The prediction buffer description information is generated from the reference buffer description information and the difference value, and the target buffer description information is obtained from three or more modes prepared for generating new buffer description information based on the prediction buffer description information. Select the mode information to generate,
In the encoding step,
Encode the identification information, the difference value, and the mode information,
The three or more modes include
At least three modes including a first mode, a second mode, and a third mode that perform different processes from each other are included.
The three or more modes are:
A moving picture predictive coding method characterized by indicating a different processing method for generating the target buffer description information from the prediction buffer description information. Input means for inputting a plurality of images constituting a moving image;
Encoding means for predictively encoding a plurality of images decoded and reproduced after being encoded in the past as reference images, and generating compressed image data;
Decoding means for decoding the compressed image data and restoring the reproduced image;
Image storage means for storing one or more of the reproduced images as reference images used to encode subsequent images;
Buffer management means for controlling the image storage means,
The buffer management means includes
Buffer description information similar to the target buffer description information from a plurality of encoded buffer description information different from target buffer description information related to a plurality of reference images used when predictively encoding the image is referred to as a reference buffer description Searching as information, generating identification information identifying the reference buffer description information,
Calculating a difference value between a picture number of a reference image of the reference buffer description information and a picture number of a target image of the target buffer description information;
The prediction buffer description information is generated from the reference buffer description information and the difference value, and the target buffer description information is obtained from three or more modes prepared for generating new buffer description information based on the prediction buffer description information. Select the mode information to generate,
The encoding means includes
Encode the identification information, the difference value, and the mode information,
The three or more modes include
At least three modes including a first mode, a second mode, and a third mode that perform different processes from each other are included.
The three or more modes are:
A moving picture predictive coding apparatus characterized by indicating a different processing method for generating the target buffer description information from the prediction buffer description information, respectively.

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