JP2013021505A - Moving image decoding device, moving image decoding method, and moving image decoding program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the code amount of indexes to prediction vector candidates increases.SOLUTION: A first prediction vector candidate list generation unit 130 generates a first predicted motion vector candidate list from the motion vectors of already decoded blocks adjacent to a block to be decoded. A second prediction vector candidate list generation unit 132 generates a second predicted motion vector candidate list from the motion vectors of a block at the same position as the block to be decoded and blocks adjacent to the block at the same position in an already decoded image. A coupling determination unit 131 compares the block size and a threshold size of the block to be decoded to determine whether or not to generate a third prediction vector candidate list which combines the first and the second prediction vector candidate lists. When the block size of the block to be decoded is larger than the threshold size thereof, a prediction vector candidate list determination unit 133 generates a third prediction vector candidate list from the first prediction vector candidate list, without combining the second prediction vector candidate list therewith.

Description

  The present invention relates to a moving picture decoding technique using motion compensated prediction, and more particularly to a motion vector decoding technique used in motion compensated prediction.

  In general video compression coding, motion compensation prediction is used. In motion compensated prediction, the target image is divided into fine blocks, the decoded image is used as a reference image, and a reference is made to the position moved from the same position as the target block of the target image by the amount of motion in the motion direction indicated by the motion vector. This is a technique for generating an image as a prediction signal. Some motion compensation predictions are performed unidirectionally using one motion vector, and others are performed bidirectionally using two motion vectors.

  As for the motion vector, the motion vector of the encoded block adjacent to the processing target block is used as a prediction motion vector (also simply referred to as “prediction vector”), and the difference between the motion vector of the processing target block and the prediction vector is obtained. The compression efficiency is improved by transmitting the difference vector as an encoded vector.

  MPEG-4AVC improves the efficiency of motion compensation prediction by making the block size of motion compensation prediction finer and more diversified than MPEG-2. On the other hand, since the number of motion vectors increases by making the block size fine, the code amount of the encoded vector becomes a problem.

  Therefore, in MPEG-2, the motion vector of the block adjacent to the left of the processing target block is simply used as the prediction vector (Non-Patent Document 1), but in MPEG-4 AVC, the median of the motion vectors of the plurality of adjacent blocks is used as the prediction vector. Thus, the accuracy of the prediction vector is improved and the increase in the code amount of the encoded vector is suppressed (Non-Patent Document 2). Further, in MPEG-4 AVC, a technique for improving the encoding efficiency of an encoded vector by using a motion vector of another encoded image is known.

ISO / IEC 13818-2 Information technology-Generic coding of moving pictures and associated audio information: Video ISO / IEC 14496-10 Information technology-Coding of audio-visual objects-Part 10: Advanced Video Coding

  In any of the methods described in Non-Patent Documents 1 and 2, since only one prediction vector is obtained, there is a problem that prediction accuracy is poor and encoding efficiency is not improved. The present inventors considered taking a method of using a plurality of prediction vector candidates, but in that case, it is necessary to encode an index for identifying the prediction vector candidate, and the code amount of the index increases. It came to recognize that there is a problem.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a moving picture decoding technique capable of improving motion vector prediction accuracy and encoding efficiency.

  In order to solve the above-described problem, a video decoding device according to an aspect of the present invention is a video decoding device that performs motion compensation prediction with a plurality of block sizes, and includes a prediction motion vector to be referred to in a prediction vector candidate list. A decoding unit (201) that decodes information indicating a position, and a first prediction vector candidate list including first prediction motion vector candidates from motion vectors of one or more decoded blocks adjacent to the decoding target block A first prediction vector candidate list generation unit (130) that performs the second prediction motion based on a motion vector of a block at the same position as the decoding target block in the decoded image and at least one block adjacent to the block at the same position A second prediction vector candidate list generation unit (132) for generating a second prediction vector candidate list including vector candidates; Whether to generate a third prediction vector candidate list obtained by combining the first prediction vector candidate list and the second prediction vector candidate list is determined based on a comparison result between the block size of the decoding target block and a predetermined threshold size. When the block size of the decoding target block is larger than the predetermined threshold size, the combination determination unit (131) and the third prediction vector candidate list are not combined, and the third prediction vector candidate list is not combined. A prediction motion of the decoding target block from the third prediction vector candidate list based on information indicating a position of the prediction motion vector to be referred to and a third prediction vector candidate list generation unit (133) that generates a prediction vector candidate list A prediction vector selection unit (221) for selecting a vector.

  Another aspect of the present invention is also a video decoding device. This apparatus is a moving picture decoding apparatus that performs motion compensation prediction with a plurality of block sizes, a decoding unit (201) that decodes information indicating the position of a predicted motion vector to be referenced in a prediction vector candidate list, and a decoding target A first prediction vector candidate list generation unit (130) for generating a first prediction vector candidate list including candidates for the first prediction motion vector from motion vectors of one or more decoded blocks adjacent to the block; A second prediction vector candidate list including a second prediction motion vector candidate is generated from motion vectors of a block at the same position as the decoding target block in the image and one or more blocks adjacent to the block at the same position. Prediction vector candidate list generation unit (132), block size of decoding target block and predetermined threshold size When the third predicted vector candidate list is generated by combining the first predicted vector candidate list and the second predicted vector candidate list, the second predicted vector candidate list is compared with the first predicted vector candidate list. And a combination determination unit (131) that determines whether or not to place a priority position on the third prediction vector candidate list, and when the block size of the decoding target block is larger than the predetermined threshold size, the first A third prediction vector candidate list generation unit (133) that generates the third prediction vector candidate list without giving priority to the two prediction vector candidate lists over the first prediction vector candidate list; and a prediction motion vector to be referred to Based on the information indicating the position, a prediction motion vector of the decoding target block is obtained from the third prediction vector candidate list. It comprises predictive vector selecting unit-option for the (221).

  Yet another aspect of the present invention is a video decoding method. This method is a moving picture decoding method that performs motion compensation prediction with a plurality of block sizes, and includes a decoding step for decoding information indicating the position of a predicted motion vector to be referred to in a prediction vector candidate list, and an adjacent to a decoding target block A first prediction vector candidate list generating step for generating a first prediction vector candidate list including first prediction motion vector candidates from motion vectors of one or more decoded blocks to be decoded; and the decoding target block in a decoded image A second prediction vector candidate list generating step for generating a second prediction vector candidate list including second prediction motion vector candidates from the motion vectors of the block at the same position and one or more blocks adjacent to the block at the same position And a comparison result between the block size of the decoding target block and a predetermined threshold size A combination determination step for determining whether or not to generate a third prediction vector candidate list obtained by combining the first prediction vector candidate list and the second prediction vector candidate list; and a block size of the decoding target block is the predetermined value A third predicted vector candidate list generating step for generating the third predicted vector candidate list from the first predicted vector candidate list without combining the second predicted vector candidate lists, A prediction vector selection step of selecting a prediction motion vector of the decoding target block from the third prediction vector candidate list based on information indicating the position of the prediction motion vector to be referred to.

  Yet another embodiment of the present invention is also a moving image decoding method. This method is a moving picture decoding method that performs motion compensation prediction with a plurality of block sizes, and includes a decoding step for decoding information indicating the position of a predicted motion vector to be referred to in a prediction vector candidate list, and an adjacent to a decoding target block A first prediction vector candidate list generating step for generating a first prediction vector candidate list including first prediction motion vector candidates from motion vectors of one or more decoded blocks to be decoded; and the decoding target block in a decoded image A second prediction vector candidate list generating step for generating a second prediction vector candidate list including second prediction motion vector candidates from the motion vectors of the block at the same position and one or more blocks adjacent to the block at the same position And a comparison result between the block size of the decoding target block and a predetermined threshold size Accordingly, when generating a third prediction vector candidate list obtained by combining the first prediction vector candidate list and the second prediction vector candidate list, the second prediction vector candidate list is more than the first prediction vector candidate list. A combination determination step for determining whether or not to place a priority position on the three prediction vector candidate lists; and when the block size of the decoding target block is larger than the predetermined threshold size, the second prediction vector candidate list is A third prediction vector candidate list generation step for generating the third prediction vector candidate list without giving priority over the first prediction vector candidate list, and the information indicating the position of the prediction motion vector to be referred to. A prediction vector for selecting a prediction motion vector of the decoding target block from the three prediction vector candidate lists And a-option step.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

  According to the present invention, motion vector prediction accuracy and coding efficiency can be improved.

It is a figure explaining the structure of the moving image encoder of 1st Embodiment. It is a figure explaining the management method of the motion vector and reference image index in the 1st motion information memory of FIG. 1, and a 2nd motion information memory. It is a figure explaining the structure of the motion information generation part of FIG. It is a figure explaining the 1st candidate block group. It is a figure explaining the 2nd candidate block group. It is a figure explaining the structure of the prediction vector candidate list production | generation part of FIG. It is a flowchart explaining the operation | movement of the encoding of the moving image encoder of 1st Embodiment. It is a flowchart explaining operation | movement of the motion information generation part of FIG. It is a flowchart explaining operation | movement of the prediction vector candidate list production | generation part of FIG. It is a flowchart explaining operation | movement of the 1st prediction vector candidate list production | generation part of FIG. 6, and a 2nd prediction vector candidate list production | generation part. It is a flowchart explaining operation | movement of the 2nd prediction vector candidate list production | generation part of FIG. It is a figure explaining the difference of an adjacent block by the size of the prediction block of a process target. It is a figure explaining the moving image decoding apparatus of 1st Embodiment. It is a figure explaining the structure of the motion information reproduction | regeneration part of FIG. It is a flowchart explaining the decoding operation | movement of the moving image decoding apparatus of 1st Embodiment. It is a flowchart explaining operation | movement of the motion information reproduction part of FIG. It is a figure explaining the structure of the prediction vector candidate list production | generation part of 2nd Embodiment. It is a flowchart explaining operation | movement of the prediction vector candidate list production | generation part of 2nd Embodiment. It is a figure explaining the structure of the prediction vector candidate list production | generation part of 3rd Embodiment. It is a flowchart explaining operation | movement of the prediction vector candidate list production | generation part 120 of 3rd Embodiment. It is a figure explaining an example of the predetermined threshold size by a POC difference. It is a figure explaining prediction coding mode. It is a figure explaining the example which divides | segments an image into the largest encoding block. It is a figure explaining an encoding block. It is a figure explaining a prediction block. It is a figure explaining prediction block size. It is a figure explaining an example of the syntax of a prediction block. It is a figure explaining the Truncated Unary code sequence.

  First, a technique that is a premise of the embodiment of the present invention will be described.

  Currently, apparatuses and systems that comply with an encoding method such as MPEG (Moving Picture Experts Group) are widely used. In such an encoding method, a plurality of images that are continuous on the time axis are handled as digital signal information. At that time, for the purpose of broadcasting, transmitting or storing highly efficient information, compression using motion compensation prediction using temporal redundancy and orthogonal transform such as discrete cosine transform using spatial redundancy Encode.

  In 1995, the MPEG-2 video (ISO / IEC 13818-2) encoding method was established as a general-purpose video compression encoding method, and a digital VTR of DVD (Digital Versatile Disk) and D-VHS (registered trademark) standards. Is widely used as an application for storage media such as magnetic tape and digital broadcasting.

  Furthermore, in 2003, joint work of the International Technical Organization (ISO) and the International Electrotechnical Commission (IEC) Joint Technical Committee (ISO / IEC) and the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) -4 AVC / H. An encoding method called H.264 (the ISO / IEC has a standard number of 14496-10 and ITU-T has an H.264 standard number, hereinafter referred to as MPEG-4AVC) has been established as an international standard.

  Coding currently called HEVC by the joint work of the International Technical Organization (ISO) and the International Electrotechnical Commission (IEC) Joint Technical Committee (ISO / IEC) and the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) Standardization of the method is being studied.

(Predictive coding mode)
In the embodiment of the present invention, the direction of motion compensation prediction and the number of encoded vectors can be switched with various block sizes.

  Here, an example of a predictive coding mode in which the direction of motion compensation prediction and the number of coding vectors are associated will be briefly described with reference to FIG.

  Unidirectional mode (UniPred) in which the direction of motion compensation prediction is unidirectional and the number of encoding vectors is 1, Bidirectional mode (BiPred) in which the direction of motion compensation prediction is bidirectional and the number of encoding vectors is 2. ), There are a temporal direct mode and a spatial direct mode in which the direction of motion compensation prediction is bidirectional and the number of encoding vectors is zero. There is also an intra mode (Intra) which is a predictive coding mode in which motion compensation prediction is not performed. In this embodiment, the temporal direct mode and the spatial direct mode are not used.

(Reference image index)
In the embodiment of the present invention, it is possible to select an optimal reference image from a plurality of reference images in motion compensation prediction in order to improve the accuracy of motion compensation prediction. Therefore, the reference image used in the motion compensation prediction is encoded in the encoded stream together with the encoded vector as a reference image index. The reference image index used for motion compensation prediction is a numerical value of 0 or more.

(Encoding block)
In the embodiment of the present invention, the input image signal is divided into maximum coding block units as shown in FIG. 23, and the divided coding blocks are processed in the raster scan order.

  The encoded block has a hierarchical structure, and can be made smaller encoded blocks by sequentially equally dividing into 4 in consideration of the encoding efficiency. Note that the encoded blocks divided into four are encoded in the zigzag scan order. An encoded block that cannot be further reduced is called a minimum encoded block. An encoded block is a unit of encoding, and the maximum encoded block is also an encoded block when the number of divisions is zero.

  In this embodiment, the maximum coding block is 64 pixels × 64 pixels, and the minimum coding block is 8 pixels × 8 pixels.

  FIG. 24 shows an example of division of the maximum coding block. In the example of FIG. 24, the encoding block is divided into ten. CU0, CU1, and CU9 are 32 × 32 pixel coding blocks, CU2, CU3, and CU8 are 16 × 16 pixel coding blocks, and CU4, CU5, and CU6 are 8 × 8 pixel coding blocks. Yes.

(Prediction block)
In the embodiment of the present invention, the encoded block is further divided into prediction blocks. A prediction block division pattern is shown in FIG. There are 2N × 2N which does not divide the encoded block, 2N × N which divides in the horizontal direction, N × 2N which divides in the vertical direction, and N × N which divides in the horizontal and vertical directions. That is, as shown in FIG. 26, the predicted block size is 0, and the maximum predicted block size is 64 pixels × 64 pixels, and the CU partition number is 3, and the minimum predicted block size is 4. There are 13 predicted block sizes of up to 4 pixels.

  In the embodiment of the present invention, the maximum encoding block is 64 pixels × 64 pixels and the minimum encoding block is 8 pixels × vertical 8. However, the present invention is not limited to this combination. Moreover, although the pattern of the prediction block division is shown in FIG. 25, the division is not limited to this as long as it is divided into one or more.

(Predicted vector index)
In HEVC, in order to further improve the accuracy of a prediction vector, it is considered to select an optimal prediction vector from among a plurality of prediction vector candidates and to encode a prediction vector index for indicating the selected prediction vector. ing. In addition, the use of a motion vector of another image as a prediction vector candidate is also under consideration. In the conventional moving image compression coding, a motion vector of another image is used in motion compensated prediction, but is not used as a prediction vector.

  In the embodiment of the present invention, the prediction vector index is introduced, and a motion vector of another image is used as a prediction vector candidate.

(Takeover direction index)
In HEVC, in order to further improve the encoding efficiency, an optimal adjacent block is selected from a plurality of adjacent block candidates, and a takeover direction index (merge index) for indicating the selected adjacent block is encoded and decoded. To be considered. In this method, the motion information (motion vector, reference image index, and motion compensation prediction direction) of the block indicated by the selected merge index is used as it is in the processing target block. Also in this method, it has been studied to use a processed block of another image in the same manner as the prediction vector index.

(Syntax)
An example of the syntax of the prediction block according to the present embodiment will be described with reference to FIG. Whether the prediction block is intra or inter is specified by a higher-order encoding block, and FIG. 33 shows syntax when the prediction block is inter. Takeover direction flag (merge_flag), takeover direction index (merge_idx), direction of motion compensation prediction (bipred_flag), reference index (ref_idx_l0 and ref_idx_l1), differential motion vector (mvd_l0 [0], mvd_l0 [1], mvd_l mvd_l1 [1]) and prediction vector indexes (mvp_idx_l0 and mvp_idx_l1) are installed.

  In FIG. 27, NumMvpCands (), which is a function for calculating the number of prediction vector candidates, is installed in the preceding stage of decoding (encoding) a prediction vector index. This is because the number of prediction vector candidates changes for each prediction block depending on the situation of the surrounding blocks.

  When the number of prediction vector candidates is 1, the prediction vector index is not decoded (encoded). This is because when the number of prediction vector candidates is 1, it can be uniquely determined without designation. Details of NumMvpCands () will be described later.

  A code string of the prediction vector index will be described with reference to FIG. In the present embodiment, a Truncated Unary code string is used as the code string of the prediction vector index. FIG. 28A shows a code vector of a predicted vector index based on a Truncated Unary code string when the number of prediction vector candidates is two, and FIG. 28B shows a Truncated Unary code when the number of prediction vector candidates is three. FIG. 28C shows a code string of a prediction vector index based on a Trunked Unary code string when the number of prediction vector candidates is four.

  It can be seen from FIG. 28 that even when the same prediction vector index value is encoded, the smaller the number of prediction vector candidates, the smaller the code bits assigned to the prediction vector index. For example, when the prediction vector index is 1, if the number of prediction vector candidates is 2, it is 1 bit of “1”, but if the number of prediction vector candidates is 3, it is 2 bits of “10”. Become.

  As described above, the encoding efficiency of the prediction vector index improves as the number of prediction vector candidates decreases. On the other hand, since the number of prediction vector candidates changes for each prediction block, it is necessary to calculate the number of prediction vector candidates in advance in order to decode a prediction vector index.

  In the conventional moving image coding, memory access to a motion vector of another image is only performed when motion compensation prediction is performed. However, in the embodiment of the present invention, the prediction vector index is calculated in advance as described above. Since it is necessary to calculate the number of prediction vector candidates, the amount of access to the motion vector memory greatly increases.

(POC)
In the embodiment of the present invention, POC (Picture Order Count) is used as time information (distance information) of an image. POC is a counter indicating the display order of images defined by MPEG-4 AVC. When the image display order is increased by 1, the POC is also increased by 1. Therefore, the time difference (distance) between images can be acquired from the POC difference between images.

(Characteristics of motion vectors of adjacent blocks)
In general, the degree of correlation between the motion vector of the processing target block and the motion vector of the block adjacent to the processing target block is high when the processing target block and the block adjacent to the processing target block have the same motion, for example, This is a case where the processing block and the area including the block adjacent to the processing block are moving in parallel.

(Characteristic of motion vector of another image)
On the other hand, a block having the same position as the processing target block (the same position block) on another decoded image that is generally used in the temporal direct mode or the spatial direct mode has a high degree of correlation. In this case, the same position block and the processing target block are in a stationary state, or the same position block and the processing target block are moving at a constant speed.

(Characteristics of small block motion vectors)
In general, the size of a block is reduced when the degree of correlation between the motion of the block to be processed (motion vector) and the motion of the adjacent block (motion vector) is low, that is, the motion in the image is complicated. Conceivable. In such a case, if the same position block of the processing target block and another image are in a stationary state, or if the same position block of the processing target block and another image are moving at a constant speed, The motion vector is valid.

  Hereinafter, preferred embodiments of a moving picture coding apparatus, a moving picture coding method, and a moving picture coding program according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

[First Embodiment]
(Configuration of moving picture coding apparatus 100)
FIG. 1 shows a configuration of a moving picture coding apparatus 100 according to the first embodiment of the present invention. The moving image encoding apparatus 100 is an apparatus that encodes a moving image signal in units of prediction blocks for performing motion compensation prediction. It is assumed that the coding block division, the prediction block size determination, and the prediction encoding mode determination are determined by the higher-order encoding control unit. The moving image encoding apparatus 100 is realized by hardware such as an information processing apparatus including a CPU (Central Processing Unit), a frame memory, and a hard disk. The moving image encoding apparatus 100 realizes functional components described below by operating the above components.

  Note that the position information, the prediction block size, the reference image index, and the motion compensation prediction direction of the prediction block to be processed are assumed to be shared in the video encoding device 100 and are not illustrated.

  The moving image encoding apparatus 100 according to the present embodiment includes a prediction block image acquisition unit 101, a subtraction unit 102, a prediction error encoding unit 103, a code string generation unit 104, a prediction error decoding unit 105, a motion compensation unit 106, and an addition unit. 107, a motion vector detection unit 108, a motion information generation unit 109, a frame memory 110, a first motion information memory 111, and a second motion information memory 112.

(Function of moving picture coding apparatus 100)
Hereinafter, functions of each unit will be described.
The prediction block image acquisition unit 101 acquires the image signal of the prediction block to be processed from the image signal supplied from the terminal 10 based on the position information and the prediction block size of the prediction block, and subtracts the image signal of the prediction block 102 and the motion vector detection unit 108.

  The subtraction unit 102 subtracts the image signal supplied from the prediction block image acquisition unit 101 and the prediction signal supplied from the motion compensation unit 106 to calculate a prediction error signal, and sends the prediction error signal to the prediction error encoding unit 103. Supply.

  The prediction error encoding unit 103 performs processing such as quantization and orthogonal transformation on the prediction error signal supplied from the subtraction unit 102 to generate prediction error encoded data, and the prediction error encoded data is converted into a code string generation unit 104. And supplied to the prediction error decoding unit 105.

  The code string generation unit 104 includes the prediction error encoded data supplied from the prediction error encoding unit 103 and the difference vector and the prediction vector index supplied from the motion information generation unit 109 together with the direction of motion compensation prediction and the reference index. Entropy encoding is performed according to the syntax to generate a code string, and the code string is supplied to the terminal 11.

  In the present embodiment, the Truncated Unary code string is used for encoding the prediction vector index as described above. However, if the prediction vector index is a code string that can be encoded with fewer bits as the number of prediction vector candidates is smaller. It is not limited to this.

  The prediction error decoding unit 105 performs processing such as inverse quantization or inverse orthogonal transform on the prediction error encoded data supplied from the prediction error encoding unit 103 to generate a prediction error signal, and adds the prediction error signal to the addition unit 107. To supply.

  The motion compensation unit 106 performs motion compensation on the reference image in the frame memory 110 by the motion vector supplied from the motion vector detection unit 108 to generate a prediction signal. If the direction of motion compensation prediction is bidirectional, the average of the prediction signals in the respective directions is used as a prediction signal, and the prediction signal is supplied to the adding unit 107.

  The adding unit 107 adds the prediction error signal supplied from the prediction error decoding unit 105 and the prediction signal supplied from the motion compensation unit 106 to generate a decoded image signal, and supplies the decoded image signal to the frame memory 110.

  The motion vector detection unit 108 detects a motion vector from the image signal that is different in time from the image signal supplied from the prediction block image acquisition unit 101, and supplies the motion vector to the motion compensation unit 106. If the direction of motion compensation prediction is bidirectional, the motion vector in each direction is detected and the motion vector is supplied to the motion compensation unit 106.

  In a general motion vector detection method, an error evaluation value is calculated for image signals at different positions moved by a predetermined movement amount from the same position as the image signal, and the movement amount that minimizes the error evaluation value is defined as a motion vector. To do. As the error evaluation value, SAD (Sum of Absolute Difference) indicating the sum of absolute differences, MSE (Mean Square Error) indicating the mean square error, or the like can be used.

  The motion information generation unit 109 includes the motion vector supplied from the motion vector detection unit 108, the first candidate block group supplied from the first motion information memory 111, and the second candidate supplied from the second motion information memory 112. A difference vector and a prediction vector index are generated from the candidate block group, and the difference vector and the prediction vector index are supplied to the code string generation unit 104.

  A detailed configuration of the motion information generation unit 109 will be described later.

  The frame memory 110 stores the decoded image signal supplied from the adding unit 107. In addition, a decoded image for which decoding of the entire image has been completed is stored as a reference image by a predetermined number of one or more, and a reference image signal is supplied to the motion compensation unit 106. A storage area for storing the reference image is controlled by a FIFO (First In First Out) method.

  The first motion information memory 111 stores the motion vector and the reference image index supplied from the motion vector detection unit 108 for each image in the minimum prediction block size unit, and stores information on adjacent blocks of the prediction block to be processed as the first information. To the motion information generating unit 109 as a candidate block group. The first motion information memory 111 moves the stored motion vector and reference image index to the second motion information memory 112 when the processing of the entire image is completed.

  The second motion information memory 112 stores a predetermined number of motion vectors and reference image indexes supplied from the first motion information memory 111, and the block on the ColPic at the same position as the prediction block to be processed and its peripheral blocks are stored. The second candidate block group is supplied to the motion information generation unit 109. The storage area for storing the motion vector and the reference image index is synchronized with the frame memory 110 and is controlled by a FIFO (First In First Out) method. ColPic is a decoded image different from the prediction block to be processed, and is stored in the frame memory 110 as a reference image. In the present embodiment, ColPic is a reference image decoded immediately before. In the present embodiment, ColPic is the reference image decoded immediately before, but the reference image immediately before in the display order, the reference image immediately after in the display order, or an arbitrary reference image is designated in the encoded stream. It is also possible.

  Here, a method of managing motion vectors and reference image indexes in the first motion information memory 111 and the second motion information memory 112 will be described with reference to FIG. The motion vector and the reference image index are stored in each memory area in units of the smallest prediction block. FIG. 2 shows a state where the predicted block size to be processed is 16 pixels × 16 pixels. In this case, the motion vector and the reference image index of this prediction block are stored in 16 memory areas indicated by hatching in FIG.

  When the predictive coding mode is the intra mode, (0, 0) is stored as the motion vector, and −1 is stored as the reference image index. It should be noted that −1 of the reference image index may be any value as long as it can be determined that the mode does not perform motion compensation prediction.

  From this point onward, unless expressed otherwise, the term “block” refers to the smallest predicted block unit when expressed simply as a block.

  Next, a detailed configuration of the motion information generation unit 109 that is a feature of the present embodiment will be described with reference to FIG. FIG. 3 shows the configuration of the motion information generation unit 109.

  The motion information generation unit 109 includes a prediction vector candidate list generation unit 120, a prediction vector selection unit 121, and a subtraction unit 122. The terminal 12 is connected to the first motion information memory 111, the terminal 13 is connected to the second motion information memory 112, the terminal 14 is connected to the motion vector detection unit 108, and the terminal 15 is connected to the code string generation unit 104.

  The prediction vector candidate list generation unit 120 is also installed in the moving picture decoding apparatus that decodes the code sequence generated by the moving picture encoding apparatus according to the present embodiment, and is installed in the moving picture encoding apparatus and the moving picture decoding apparatus. Thus, a predictive vector candidate list having no contradiction is generated.

  Note that NumMvpCands () described in the syntax returns the number of prediction vector candidates included in the prediction vector candidate list generated by the prediction vector candidate list generation unit 120.

  Hereinafter, functions of each unit will be described.

  The prediction vector candidate list generation unit 120 generates a prediction vector candidate list from the first candidate block group supplied from the terminal 12 and the second candidate block group supplied from the terminal 13, and converts the prediction vector candidate list into the prediction vector. This is supplied to the selector 121.

(Candidate block group)
Here, the first candidate block group will be described with reference to FIG. FIG. 4 shows a state where the predicted block size to be processed is 16 pixels × 16 pixels. As shown in FIG. 4, adjacent blocks of the prediction block to be processed are block A1, block A2, block A3, block A4 located on the left, block B1, block B2, block B3, block B4 located on the upper right, A block C, a block D located at the upper left, and a block E located at the lower left are defined as a first candidate block group.

Next, the second candidate block group will be described with reference to FIG. FIG. 5 shows a state where the predicted block size to be processed is 16 pixels × 16 pixels. As shown in FIG. 5, a block in a prediction block on ColPic located at the same position as the prediction block to be processed and its neighboring blocks are set as a second candidate block group.
Specifically, the block I in the prediction block on the ColPic at the same position as the prediction block to be processed, the block F positioned to the right of the prediction block on the ColPic at the same position as the prediction block to be processed, and the processing target The block G is located under the prediction block on the ColPic at the same position as the prediction block, and the block H is located at the lower right of the prediction block on the ColPic at the same position as the processing target prediction block. Let it be a second candidate block group.

  In the present embodiment, the second candidate block group is the block I, the block F, the block G, and the block H, but may be one or more blocks, for example, the block I2 to the block I16, and the block F2 to the block F4, block G2 may be added from block G2, or block I6 and block H may be added.

  The prediction vector selection unit 121 selects a prediction vector corresponding to the motion vector supplied from the terminal 14 from the prediction vector candidate list supplied from the prediction vector candidate list generation unit 120, and sends the prediction vector to the subtraction unit 122. At the same time, a prediction vector index, which is information indicating the selected prediction vector, is output to the terminal 15.

  The subtraction unit 122 subtracts the prediction vector supplied from the prediction vector selection unit 121 from the motion vector supplied from the terminal 14 to calculate a difference vector, and supplies the difference vector to the terminal 15.

  FIG. 6 shows a configuration of the prediction vector candidate list generation unit 120.

  The prediction vector candidate list generation unit 120 includes a first prediction vector candidate list generation unit 130, a combination determination unit 131, a second prediction vector candidate list generation unit 132, and a prediction vector candidate list determination unit 133. The terminal 16 is connected to the prediction vector selection unit 121.

  Hereinafter, functions of each unit will be described.

  The first prediction vector candidate list generation unit 130 generates a first prediction vector candidate list including one or more motion vectors from the first candidate block group supplied from the terminal 12, and selects the first prediction vector candidate list. This is supplied to the prediction vector candidate list determination unit 133.

  The combination determination unit 131 derives a combination determination result from the prediction block size of the processing target prediction block, and supplies the combination determination result to the prediction vector candidate list determination unit 133.

  The second prediction vector candidate list generation unit 132 generates a second prediction vector candidate list including zero or more motion vectors from the second candidate block group supplied from the terminal 13, and generates the second prediction vector candidate list. This is supplied to the prediction vector candidate list determination unit 133.

  The prediction vector candidate list determination unit 133 is based on the combination determination result supplied from the combination determination unit 131, and includes the first prediction vector candidate list and the second prediction vector candidate supplied from the first prediction vector candidate list generation unit 130. A third prediction vector candidate list is determined from the second prediction vector candidate list supplied from the list generation unit 132, and the third prediction vector candidate list is supplied to the terminal 16.

(Operation of moving picture coding apparatus 100)
Subsequently, an encoding operation in the moving image encoding apparatus 100 according to the present embodiment will be described with reference to a flowchart of FIG.

  The prediction block image acquisition unit 101 acquires the image signal of the prediction block to be processed from the image signal supplied from the terminal 10 based on the position information of the prediction block and the prediction block size (step S100).

  The motion vector detection unit 108 detects a motion vector from the image signal supplied from the predicted block image acquisition unit 101 and the reference image signal supplied from the frame memory 110 (step S101).

  The motion information generation unit 109 includes the motion vector supplied from the motion vector detection unit 108, the first candidate block group supplied from the first motion information memory 111, and the second candidate supplied from the second motion information memory 112. A difference vector and a prediction vector index are generated from the candidate block group (step S102).

  The motion compensation unit 106 performs motion compensation on the reference image in the frame memory 110 based on the motion vector supplied from the motion vector detection unit 108 to generate a prediction signal (step S103).

  The subtraction unit 102 calculates a prediction error signal by subtracting the image signal supplied from the prediction block image acquisition unit 101 and the prediction signal supplied from the motion compensation unit 106 (step S104).

  The prediction error encoding unit 103 performs processing such as quantization and orthogonal transform on the prediction error signal supplied from the subtraction unit 102 to generate prediction error encoded data (step S105).

  The code string generation unit 104 includes the prediction error encoded data supplied from the prediction error encoding unit 103 and the difference vector and the prediction vector index supplied from the motion information generation unit 109 together with the direction of motion compensation prediction and the reference index. Entropy encoding is performed according to the syntax to generate a code string (step S106).

  The adding unit 107 adds the prediction error signal supplied from the prediction error decoding unit 105 and the prediction signal supplied from the motion compensation unit 106 to generate a decoded image signal (step S107).

  The frame memory 110 stores the decoded image signal supplied from the adding unit 107 (step S108).

  The first motion information memory 111 stores the motion vector supplied from the motion vector detection unit 108 for one image in the minimum predicted block size unit (step S109).

  When the processing of the entire image is completed (step S110), the second motion information memory 112 stores a predetermined number of motion vectors supplied from the first motion information memory 111 (step S111). In the present embodiment, step S111 is performed when the processing of the entire image is completed. However, it may be performed for each prediction block to be processed.

  Subsequently, the operation of the motion information generation unit 109 will be described using the flowchart of FIG.

  The prediction vector candidate list generation unit 120 generates a prediction vector candidate list from the first candidate block group supplied from the terminal 12 and the second candidate block group supplied from the terminal 13 (step S120).

  The prediction vector selection unit 121 determines a prediction vector corresponding to the motion vector supplied from the terminal 14 from the prediction vector candidate list supplied from the prediction vector candidate list generation unit 120 (step S121). Here, a method for determining a prediction vector will be described. The absolute difference sum of the horizontal component and the vertical component of each prediction vector candidate included in the motion vector and the prediction vector candidate list is obtained, and the prediction vector candidate having the minimum absolute difference sum is determined as the prediction vector. This is because the code amount of the encoded vector can be expected to be minimized. The method is not limited to this method as long as the code amount of the encoded vector is minimized.

  The subtraction unit 122 calculates a difference vector by subtracting the prediction vector supplied from the prediction vector selection unit 121 from the motion vector supplied from the terminal 14 (step S122).

  Subsequently, the operation of the prediction vector candidate list generation unit 120 will be described using the flowchart of FIG.

  The first prediction vector candidate list generation unit 130 generates a first prediction vector candidate list including one or more motion vectors from the first candidate block group supplied from the terminal 12 (step S130).

  The second prediction vector candidate list generation unit 132 generates a second prediction vector candidate list including zero or more motion vectors from the second candidate block group supplied from the terminal 13 (step S131).

  The combination determination unit 131 derives a combination determination result from the prediction block size of the processing target prediction block and the predetermined threshold size (step S132).

  Derivation of the combination determination result is performed by comparing the predicted block size of the processing target block with a predetermined threshold size. If the predicted block size of the block to be processed is equal to or smaller than the predetermined threshold size, the combination determination result is set to 1, otherwise it is set to 0. In addition, since the combination determination of the present embodiment is performed by comparing the predicted block size of the processing target block with a predetermined threshold size set in advance, if the predicted block size of the processing target block is smaller than the predetermined threshold size, the combination is determined. The determination result may be 1 and may be 0 otherwise.

  In the present embodiment, a predetermined threshold size set in advance is set to 16 pixels × 16 pixels, which is 1/4 of the maximum predicted block size. The predetermined threshold size determined in advance is not limited to this, and may be set due to hardware restrictions or the like.

  If the combination determination result supplied from the combination determination unit 131 is 1, the prediction vector candidate list determination unit 133 determines the first prediction vector candidate list and the second prediction vector supplied from the first prediction vector candidate list generation unit 130. The second prediction vector candidate list supplied from the vector candidate list generation unit 132 is combined in the order of the first prediction vector candidate list and the second prediction vector candidate list to form a prediction vector candidate list (step S133). .

  The prediction vector candidate list determination unit 133 determines the first prediction vector candidate list supplied from the first prediction vector candidate list generation unit 130 as a prediction vector candidate if the combination determination result supplied from the combination determination unit 131 is 0. A list is formed (step S134).

  The prediction vector candidate list determination unit 133 sequentially checks the prediction vector candidates included in the prediction vector candidate list to detect the same motion vector, and deletes one of the prediction vector candidates detected as the same from the prediction vector candidate list. Thus, the prediction vector candidates are not overlapped, and the prediction vector candidate list is updated to delete redundant prediction vector candidates (step S135).

  In the present embodiment, step S135 is performed to improve the encoding efficiency of the prediction vector index, but step S135 can be omitted.

  In the present embodiment, step S131 is performed prior to step S132 for ease of explanation, but step S132 is performed first, and step S131 is omitted when the join determination result is 0. You can also.

  Subsequently, the operation of the first prediction vector candidate list generation unit 130 will be described using the flowchart of FIG.

  First, the first prediction vector candidate list is initialized by setting the number of registered first prediction vector candidate lists to 0 (step S140).

  Next, for the first candidate block group, two directions of a horizontal direction (direction 1) and a vertical direction (direction 2) are defined as inspection directions, and the following processing is performed (step S141). The inspection in each direction for the first candidate block group will be described with reference to FIG.

  The horizontal inspection is sequentially performed from block C to block B1, block B2, block B3, block B4, and block D. The vertical inspection is sequentially performed from the block E to the block A1, the block A2, the block A3, and the block A4.

  Next, the number of inspections to be inspected to be added to the first prediction vector candidate list is determined (step S142).

  In the present embodiment, the maximum number to be inspected in the horizontal direction is 10 which is half of the maximum predicted block size (block B1 to block B8) plus block C and block D, and inspects in the vertical direction. The maximum number is nine, which is eight (block A1 to block A8), which is half of the maximum predicted block size, plus block E. However, block C, block D, and block E may not exist depending on the position of the prediction block to be processed. When block C, block D, and block E do not exist, the number of non-existing blocks is subtracted from the maximum number to be inspected. When the number of candidate blocks in each direction included in the first candidate block group exceeds the maximum number to be inspected, the number of inspections is limited to the maximum number.

  Next, the following processing is repeatedly performed for each candidate block included in each direction of the first candidate block group for the number of inspections (step S143).

  It is determined whether the reference index of the candidate block is not −1, that is, whether it is not the intra mode (step S144).

  If the candidate block is not in the intra mode, it is determined whether the reference index of the candidate block is the same as the reference image index of the prediction block to be processed (step S145).

  If the reference index of the candidate block is the same as the reference image index of the prediction block to be processed, the motion vector of the candidate block is added to the first prediction vector candidate list (step S146).

  If the reference index of the candidate block is -1 or if the reference index of the candidate block is not the same as the reference image index of the prediction block to be processed, the next candidate block is examined (step S147).

  The above process is repeated until the reference index of the candidate block is the same as the reference image index of the prediction block to be processed or until the number of inspections in each direction is processed (step S148).

  Next, it is checked whether the number of registrations in the first prediction vector candidate list is 0 (step S149).

  If the number of registrations in the first prediction vector candidate list is 0, the motion vector (0, 0) is added to the first prediction vector candidate list (step S150). Note that S150 is performed to add one or more prediction vector candidates to the prediction vector candidate list, or one of the first prediction vector candidate list and the second prediction vector candidate list, and is not limited to this position.

  Subsequently, the operation of the second prediction vector candidate list generation unit 132 will be described using the flowchart of FIG. 11.

  First, the number of registered second prediction vector candidate lists is set to 0, and the second prediction vector candidate list is initialized (step S160).

  Next, the number of second candidate block groups is determined (step S161). In the present embodiment, the maximum number of second candidate block groups is four, block H, block I, block F, and block G. However, the block H, the block F, and the block G may not exist depending on the position of the prediction block to be processed. When the block H, the block F, and the block G do not exist, the number of nonexistent blocks is subtracted from the number to be inspected.

  Next, a test is performed on the second candidate block group. The inspection order of the second candidate block group will be described with reference to FIG. Block H, block I, block F, and block G are performed in this order (step S162).

  It is determined whether the reference index of the candidate block is not −1, that is, whether it is not the intra mode (step S163).

  If the candidate block is not the intra mode, it is determined whether the reference index of the candidate block is the same as the reference image index of the prediction block to be processed (step S164).

  If the reference index of the candidate block is the same as the reference image index of the prediction block to be processed, the motion vector of the candidate block is added to the second prediction vector candidate list (step S165).

  If the reference index of the candidate block is not the same as the reference image index of the prediction block to be processed, the motion vector of the candidate block indicates the time difference between the reference image indicated by the reference index of the candidate block and the image to be processed, and the prediction of the processing target. It is scaled by the time difference between the reference image indicated by the block reference index and the image to be processed and added to the second prediction vector candidate list (step S166).

  If the reference index of the candidate block is -1, the next candidate block is examined (step S167).

(Explanation of coupling control)
As described above, according to the video encoding device 100 according to the present embodiment, whether to add the second prediction vector candidate list to the prediction vector candidate list according to the size of the prediction block of the prediction block to be processed is determined. I have control.

  The reason why the second prediction vector candidate list is not added when the size of the prediction block of the prediction block to be processed is large will be described with reference to FIG. 12A shows a case where the size of the prediction block of the processing target prediction block is 16 × 16, and FIG. 12B shows a case where the size of the prediction block of the processing target prediction block is 8 × 8. FIG. 12C shows a case where the size of the prediction block to be processed is 4 × 4. When the size of the prediction block is 16 × 16, candidate blocks included in the first candidate block group are block C, block B1, block B2, block B3, block B4, block D, block E, block A1, and block A2. , Block A3 and block A4. When the size of the prediction block is 8 × 8, the number of candidate blocks included in the first candidate block group is block C, block B1, block B2, block D, block E, block A1, and block A2. When the size of the prediction block is 4 × 4, there are five candidate blocks, block C, block B1, block D, block E, and block A1, included in the first candidate block group. Although not shown in FIG. 12, there are 19 candidate blocks when the size of the prediction block is 32 × 32, and the number of candidate blocks when the size of the prediction block is 64 × 64 considers the maximum number to be inspected. Otherwise, the number is 35.

  That is, as the size of the prediction block increases, the number of candidate blocks included in the first candidate block group increases and the number of times of inspection may increase. However, the number of candidate blocks included in the first candidate block group Since the selection probability of candidate blocks that are not in the intra mode increases, the accuracy of the prediction vector is improved.

  On the other hand, when the size of the prediction block is small, the number of candidate blocks included in the first candidate block group is small. Therefore, there is a possibility that the selection probability of candidate blocks that are not in the intra mode is lower than when the size of the prediction block is large. Therefore, when the size of the prediction block is small, the second prediction vector candidate list is added to improve the accuracy of the prediction vector.

(Configuration of moving picture decoding apparatus 200)
Next, the moving picture decoding apparatus according to the present embodiment will be described. FIG. 13 shows a moving picture decoding apparatus 200 according to the present embodiment. The video decoding device 200 is a device that generates a playback image by decoding the code string encoded by the video encoding device 100.

  The moving picture decoding apparatus 200 is realized by hardware such as an information processing apparatus including a CPU (Central Processing Unit), a frame memory, and a hard disk. The moving picture decoding apparatus 200 realizes functional components described below by operating the above components.

  Note that the position information of the prediction block to be decoded, the prediction block size, the reference image index, and the direction of motion compensated prediction are assumed to be shared in the video decoding device 200 and are not illustrated.

  The moving picture decoding apparatus 200 according to the present embodiment includes a code string analysis unit 201, a prediction error decoding unit 202, an addition unit 203, a motion information reproduction unit 204, a motion compensation unit 205, a frame memory 206, a first motion information memory 207, The second motion information memory 208 is configured.

(Function of moving picture decoding apparatus 200)
Hereinafter, functions of each unit will be described.

  The code string analysis unit 201 decodes the code string supplied from the terminal 20, decodes the prediction error encoded data, the direction of motion compensation prediction, the reference image index, the difference vector, and the prediction vector index according to the syntax, and performs prediction. The error encoded data is supplied to the prediction error decoding unit 202, and the difference vector and the prediction vector index are supplied to the motion information reproducing unit 204.

  The prediction error decoding unit 202 performs a process such as inverse quantization or inverse orthogonal transform on the prediction error encoded data supplied from the code string analysis unit 201 to generate a prediction error signal, and the prediction error signal is sent to the addition unit 203. Supply.

  The addition unit 203 adds the prediction error signal supplied from the prediction error decoding unit 202 and the prediction signal supplied from the motion compensation unit 205 to generate a decoded image signal, and supplies the decoded image signal to the frame memory 206.

  The motion information reproduction unit 204 is supplied from the difference vector and the prediction vector index supplied from the code string analysis unit 201, the first candidate block group supplied from the first motion information memory 207, and the second motion information memory 208. The motion vector is reproduced from the second candidate block group, and the motion vector is supplied to the motion compensation unit 205.

  A detailed configuration of the motion information reproducing unit 204 will be described later.

  The motion compensation unit 205 performs motion compensation on the reference image in the frame memory 206 by a motion vector supplied from the motion information reproduction unit 204 to generate a prediction signal. If the direction of motion compensation prediction is bidirectional, the average of the prediction signals in the respective directions is used as the prediction signal, and the prediction signal is supplied to the adding unit 203.

  The frame memory 206, the first motion information memory 207, and the second motion information memory 208 have the same functions as the frame memory 110, the first motion information memory 111, and the second motion information memory 112, respectively.

  Next, a detailed configuration of the motion information reproducing unit 204 that is a feature of the present embodiment will be described with reference to FIG. FIG. 14 shows the configuration of the motion information playback unit 204.

  The motion information reproduction unit 204 includes a prediction vector candidate list generation unit 220, a prediction vector determination unit 221, and an addition unit 222. The terminal 22 is connected to the first motion information memory 207, the terminal 23 is connected to the second motion information memory 208, the terminal 24 is connected to the code string analysis unit 201, and the terminal 25 is connected to the motion compensation unit 205.

  Hereinafter, functions of each unit will be described.

  The prediction vector candidate list generation unit 220 has the same function as the prediction vector candidate list generation unit 120.

  The prediction vector determination unit 221 determines a prediction vector from the prediction vector candidate list supplied from the prediction vector candidate list generation unit 220 and the prediction vector index supplied from the terminal 24 and supplies the prediction vector to the addition unit 222.

  The adder 222 adds the difference vector supplied from the terminal 24 and the prediction vector supplied from the prediction vector determination unit 221 to calculate a motion vector, and supplies the motion vector to the terminal 25.

(Decryption device operation)
Next, the decoding operation in the moving picture decoding apparatus 200 according to the present embodiment will be described using the flowchart of FIG.

  The code string analysis unit 201 decodes the code string supplied from the terminal 20 and decodes the prediction error encoded data, the direction of motion compensation prediction, the reference image index, the difference vector, and the prediction vector index according to the syntax (Step S1). S200).

  The motion information reproduction unit 204 is supplied from the difference vector and the prediction vector index supplied from the code string analysis unit 201, the first candidate block group supplied from the first motion information memory 207, and the second motion information memory 208. A motion vector is reproduced from the second candidate block group to be reproduced (step S201).

  The motion compensation unit 205 performs motion compensation on the reference image in the frame memory 206 based on the motion vector supplied from the motion information reproduction unit 204 to generate a prediction signal (step S202).

  The prediction error decoding unit 202 performs a process such as inverse quantization or inverse orthogonal transform on the prediction error encoded data supplied from the code string analysis unit 201 to generate a prediction error signal (step S203).

  The adding unit 203 adds the prediction error signal supplied from the prediction error decoding unit 202 and the prediction signal supplied from the motion compensation unit 205 to generate a decoded image signal (step S204).

  The frame memory 206 stores the decoded image signal supplied from the adding unit 203 (step S205).

  The first motion information memory 207 stores the motion vector supplied from the motion information reproducing unit 204 for one image in the minimum predicted block size unit (step S206).

  When the processing of the entire image is completed (step S208), the second motion information memory 208 stores a predetermined number of motion vectors supplied from the first motion information memory 207 (step S209).

  Subsequently, the operation of the motion information reproducing unit 204 will be described with reference to the flowchart of FIG.

  The prediction vector candidate list generation unit 220 generates a prediction vector candidate list from the first candidate block group supplied from the terminal 22 and the second candidate block group supplied from the terminal 23 (step S220).

  The prediction vector determination unit 221 determines whether the number of prediction vector candidates in the prediction vector candidate list supplied from the prediction vector candidate list generation unit 220 is greater than 1 (step S221).

  If the number of prediction vector candidates is greater than 1, the prediction vector determination unit 221 acquires the prediction vector index supplied from the code string analysis unit 201 (step S222). Then, a prediction vector candidate indicated by the prediction vector index is selected from the prediction vector candidate list as a prediction vector (step S223).

  If the number of prediction vector candidates is 1, the prediction vector determination unit 221 selects a single prediction vector candidate included in the prediction vector candidate list as a prediction vector (step S224).

  The adder 222 adds the difference vector supplied from the terminal 24 and the prediction vector supplied from the prediction vector determination unit 221 to calculate a motion vector (step S225).

  As described above, according to the moving picture decoding apparatus 200 according to the present embodiment, it is possible to decode a moving picture by controlling the generation of a prediction vector candidate list in the same manner as the moving picture encoding apparatus 100. That is, according to the moving picture decoding apparatus 200 according to the present embodiment, the encoded stream encoded by the moving picture encoding apparatus 100 can be decoded.

(Extended example of the first embodiment)
This embodiment can be expanded as follows.

(Predetermined threshold size)
In the present embodiment, the predetermined threshold size set in advance is set to 16 pixels × 16 pixels, which is a quarter of the maximum predicted block size, but is not limited thereto. For example, the size may not depend on an asymmetric block such as 32 × 16 or 4 × 8 or a prediction block such as 6 × 6. Further, when the predetermined threshold size is equal to or smaller than the minimum prediction block size, the first prediction vector candidate list and the second prediction vector candidate list are combined so that the combination determination result is 0 for all prediction block sizes. You may make it not.

  In the present embodiment, the predetermined threshold size is defined in advance. However, by encoding the predetermined threshold size into a code string, the encoding apparatus can be adaptively set according to the characteristics of the moving image. For example, it can be installed adaptively so that it increases as the screen size increases and increases as the movement becomes more complex.

(Generation of prediction vector candidate list)
In the present embodiment, the horizontal inspection of the first prediction vector candidate list is performed by checking the block C positioned at the upper right of the processing target prediction block, the block B group positioned above the processing target prediction block, and the processing target prediction. The maximum number of blocks to be checked in the horizontal direction is performed on the block D located at the upper left of the block, and the vertical check is performed on the block E located at the lower left of the prediction block to be processed and the block located on the left of the prediction block to be processed It is assumed that the maximum number of inspections in the vertical direction is performed for the A group. However, in the present embodiment, the number of inspections in each direction of the first prediction vector candidate list may be one or more, and is not limited to this inspection method. In the present embodiment, the maximum number to be tested in each direction of the first prediction vector candidate list depends on the size of the prediction block to be processed. However, if the maximum number to be checked in each direction is 1 or more, It may be a fixed value such as 2.

  Specifically, the maximum number to be inspected in the horizontal direction is set to 3, and the maximum number to inspect in the vertical direction is set to 2, so that the candidate block to be inspected is located in another prediction block (sparse). By making sparse candidate blocks to be inspected, there is an effect of increasing motion vector choices of candidate blocks. For example, when the size of the prediction block is 16 × 16, the horizontal direction is block C, the block B group is one block (for example, block B1 or block B2), the block D, and the vertical direction is block E, block B One block (for example, block A1 or block A2) can be selected from the A group.

  In addition, the second prediction vector candidate list is checked by checking the block H located at the lower right of the prediction block on the ColPic at the same position as the processing target prediction block, and on the ColPic at the same position as the processing target prediction block. A block I in the prediction block, a block F located to the right of the prediction block on the ColPic at the same position as the prediction block to be processed, and a prediction block on the ColPic at the same position as the prediction block to be processed It is assumed that the process is performed in the order of block G.

  However, in the present embodiment, the number of inspections in the second prediction vector candidate list may be one or more, and is not limited to this inspection method.

  Specifically, it is possible to inspect only the block H located at the lower right of the prediction block on the ColPic with the number of inspections being 1, and the block H located at the lower right of the prediction block on the ColPic with the inspection number being 2, It is also possible to check in the order of the block I in the prediction block on the ColPic at the same position as the prediction block to be processed.

(Prediction vector join order)
In the present embodiment, if the combination determination result is 1, the prediction vector candidate list is generated by combining in the order of the first prediction vector candidate list and the second prediction vector candidate list. 1 may be combined in the order of the second prediction vector candidate list and the first prediction vector candidate list to generate a prediction vector candidate list.

(Encoding control)
In the present embodiment, if the combination determination result is 1, a prediction vector candidate list is generated by combining the first prediction vector candidate list and the second prediction vector candidate list, and if the combination determination result is 1. The prediction vector candidate list is generated only from the first prediction vector candidate list. This is a process performed to reduce the code amount of the prediction vector index by defining a common operation in encoding and decoding.

  If it is only for the purpose of reducing the amount of calculation, the prediction device candidate list is generated by combining the first prediction vector candidate list and the second prediction vector candidate list regardless of the combination determination result. If the combined determination result is 1 when the prediction vector index is selected, it is possible to control not to select a motion vector included in the second prediction vector candidate list. The moving picture encoding apparatus in this case has the following characteristics.

A video encoding apparatus that performs motion compensation prediction with a plurality of block sizes,
A first prediction vector candidate list generation unit that generates a first prediction vector candidate list including first prediction motion vector candidates from motion vectors of one or more encoded blocks adjacent to the encoding target block;
A second predicted vector candidate list including a second predicted motion vector candidate from a motion vector of a block at the same position as the current block in the encoded image and at least one block adjacent to the block at the same position; A second prediction vector candidate list generation unit to generate;
A third prediction vector candidate list generating unit that generates a third prediction vector candidate list obtained by combining the first prediction vector candidate list and the second prediction vector candidate list;
A combination determination unit that determines whether to use the second prediction vector candidate list based on a comparison result between a block size of the encoding target block and a predetermined threshold size;
When the block size of the encoding target block is larger than the predetermined threshold size, the second prediction vector candidate list in the third prediction vector candidate list is not selected, and the third prediction vector candidate list A prediction vector selection unit that selects a motion vector predictor from the first prediction vector candidate list;
An encoding unit that encodes information indicating a position of the selected prediction motion vector in the third prediction vector candidate list.

(Expansion of candidate list generation)
In the present embodiment, encoding and decoding of a prediction vector index have been described using a candidate list generation target as a motion vector. According to the present embodiment, the generation target of the candidate list is not limited to the motion vector, and the first candidate list is generated from the information of the processed block adjacent to the processing target block, and the processing target of the already processed image A second candidate list is generated from information of blocks adjacent to the same position as the block, a third candidate list generated from the first candidate list and the second candidate list is generated, and the third candidate list is generated. Any method for determining an index to be encoded and decoded may be used. For example, this embodiment can be applied to a takeover direction index (merge index) indicating a direction in which motion information is taken over.

  In this case, in the first candidate list, the second candidate list, and the third candidate list, the reference image index and the direction of motion compensation prediction are similarly managed in addition to the motion vector, and the block indicated by the takeover direction index As the motion information, a motion vector, a reference image index, and a direction of motion compensation prediction are used as motion information of the processing target block. That is, the prediction vector described in the present embodiment is used as it is as a motion vector. Note that NumMergeCands () described in the syntax returns the number of candidates included in the candidate list in the same manner as NumMvpCands (). In addition, a Truncated Unary code string is used as the code string of the takeover direction index in the same manner as the code string of the prediction vector index.

(Effects of the first embodiment)
As described above, according to the present embodiment, when the prediction block size of the prediction block to be processed is large, the motion vector of the prediction block on the image different from the prediction block to be processed is included in the prediction vector candidate list. When the prediction block size of the processing target prediction block is small without combining, the motion vector of the prediction block on the image different from the processing target prediction block is combined with the prediction vector candidate list, so that It is possible to improve the coding efficiency of the prediction vector index by reducing the amount of processing related to the motion vector evaluation of the prediction block and reducing the number of prediction vector candidates in advance.

[Second Embodiment]
A moving picture coding apparatus 300 according to the second embodiment of the present invention will be described. The configuration of the video encoding device 300 according to the second embodiment is the same as the configuration of the video encoding device 100 according to the first embodiment except for the prediction vector candidate list generation unit 120.

  Hereinafter, the difference between the prediction vector candidate list generation unit 120 in the present embodiment and the first embodiment will be described.

  FIG. 17 illustrates a configuration of the prediction vector candidate list generation unit 120 according to the second embodiment.

  The prediction vector candidate list generation unit 120 includes a first prediction vector candidate list generation unit 130, a combination priority determination unit 134, a second prediction vector candidate list generation unit 132, and a prediction vector candidate list determination unit 135.

  Hereinafter, functions of the combination priority determination unit 134 and the prediction vector candidate list determination unit 135 will be described.

  The combination priority determination unit 134 derives the combination priority determination result from the size of the prediction block of the processing target prediction block, and supplies the combination priority determination result to the prediction vector candidate list determination unit 135.

  The prediction vector candidate list determination unit 135 includes the first prediction vector candidate list and the first prediction vector candidate list supplied from the first prediction vector candidate list generation unit 130 based on the combination priority determination result supplied from the combination priority determination unit 134. A third prediction vector candidate list is determined from the second prediction vector candidate list supplied from the two prediction vector candidate list generation unit 132, and the third prediction vector candidate list is supplied to the terminal 16.

  Subsequently, the operation of the prediction vector candidate list generation unit 120 of the present embodiment will be described using the flowchart of FIG. Each process of step S130, step S131, and step S135 is the same as each process of the same sign by the prediction vector candidate list production | generation part 120 of 1st Embodiment shown in FIG.

  The combination priority determination unit 134 derives a combination priority determination result from the prediction block size of the processing target prediction block and the predetermined threshold size (step S132).

  Derivation of the combination priority determination result is performed by comparing the predicted block size of the processing target block with a predetermined threshold size. If the predicted block size of the processing target block is equal to or smaller than the predetermined threshold size, the combination priority determination result is set to 1, and otherwise it is set to 0.

  If the combination determination result supplied from the combination priority determination unit 134 is 1, the prediction vector candidate list determination unit 135 determines the first prediction vector candidate list and the first prediction vector candidate list supplied from the first prediction vector candidate list generation unit 130. The second prediction vector candidate list supplied from the two prediction vector candidate list generating unit 132 is combined in the order of the second prediction vector candidate list and the first prediction vector candidate list to form a prediction vector candidate list (step S136).

  The prediction vector candidate list determination unit 135 determines that the first prediction vector candidate list and the first prediction vector candidate list supplied from the first prediction vector candidate list generation unit 130 if the combination determination result supplied from the combination priority determination unit 134 is 0. The second prediction vector candidate list supplied from the two prediction vector candidate list generation unit 132 is combined in the order of the first prediction vector candidate list and the second prediction vector candidate list to form a prediction vector candidate list (step S137).

(Configuration of moving picture decoding apparatus 400)
Next, the moving picture decoding apparatus 400 of this Embodiment is demonstrated. The configuration of the moving picture decoding apparatus 400 of the present embodiment is the same as that of the moving picture decoding apparatus 200 of the first embodiment except for the prediction vector candidate list generation unit 220.

  The prediction vector candidate list generation unit 220 has the same function as the prediction vector candidate list generation unit 120 of the present embodiment, and a description thereof will be omitted.

(Effect of the second embodiment)
In general, the large predicted block size is selected as the processing target prediction block when the correlation between the processing target prediction block and the processed prediction block is high, and the small prediction block size is selected. This is a case where the correlation between the prediction block to be processed and the already processed prediction block is low.

  According to the present embodiment, when the prediction block size of the processing target prediction block is large, the motion vector of the prediction block on the image different from the processing target prediction block is combined behind the prediction vector candidate list, When the prediction block size of the prediction block to be processed is small, the prediction vector index is encoded by combining the motion vector of the prediction block on the image different from the prediction block to be processed before the prediction vector candidate list. Efficiency can be improved.

[Third Embodiment]
A video encoding apparatus 500 according to the third embodiment of the present invention will be described. The configuration of the video encoding device 500 according to the third embodiment is the same as the configuration of the video encoding device 300 according to the second embodiment except for the prediction vector candidate list generation unit 120.

  Hereinafter, the difference between the prediction vector candidate list generation unit 120 in the present embodiment and the second embodiment will be described.

  FIG. 19 illustrates a configuration of the prediction vector candidate list generation unit 120 according to the third embodiment. The configuration of the prediction vector candidate list generation unit 120 according to the third embodiment is the same as that of the prediction vector candidate list generation unit 120 according to the second embodiment except for the combination priority determination unit 134.

  The combination priority determination unit 134 of the present embodiment is connected to the terminal 17 and the terminal 18. The terminal 17 is supplied with time information of a processing target image having the first candidate block group, and the terminal 18 is supplied with time information of another decoded image having the second candidate block group.

  Hereinafter, the function of the combination priority determination unit 134 will be described.

  The combination priority determination unit 134 includes time information of the processing target image having the first candidate block group supplied from the terminal 17 and another decoded image having the second candidate block group supplied from the terminal 18. Based on the time information, the predetermined threshold size is set so that the predetermined threshold size decreases as the distance between images increases, and the combined priority determination result is derived from the predetermined threshold size and the predicted block size of the prediction block to be processed. Then, the combined priority determination result is supplied to the prediction vector candidate list determination unit 135.

  Subsequently, the operation of the prediction vector candidate list generation unit 120 of the present embodiment will be described using the flowchart of FIG. Each process of step S130 to step S137 is the same as each process of the same sign by the prediction vector candidate list production | generation part 120 of 2nd Embodiment shown in FIG.

  The combination priority determination unit 134 determines the distance between the images based on the time information of the processing target image supplied from the terminal 17 and the time information of another decoded image having the second candidate block group supplied from the terminal 18. The predetermined threshold size is set so that the predetermined threshold size becomes smaller as the value becomes larger (step S138).

  In this embodiment, POC is used as time information. FIG. 21 shows an example in which control is performed such that the predetermined threshold size decreases as the POC difference increases. Note that when the distance between the processing target image and another decoded image having the second candidate block group is longer than a predetermined distance, there is an implicit determination between the moving image encoding device and the moving image decoding device. Assuming that the threshold size is equal to or smaller than the minimum predicted block size, the combined determination result is 0 for all predicted block sizes, and the first predicted vector candidate list and the second predicted vector candidate list are not combined. Also good.

(Configuration of moving picture decoding apparatus 600)
Next, the moving picture decoding apparatus 600 of this Embodiment is demonstrated. The configuration of the moving picture decoding apparatus 600 of the present embodiment is the same as that of the moving picture decoding apparatus 400 of the second embodiment except for the prediction vector candidate list generation unit 220.

  The prediction vector candidate list generation unit 220 has the same function as the prediction vector candidate list generation unit 120 of the present embodiment, and a description thereof will be omitted.

(Effect of the third embodiment)
In general, as the distance between images increases, the correlation of motion between images decreases. Therefore, when the distance between images increases, the correlation between the processing target block and the second candidate block group also decreases.

  According to the present embodiment, control is performed such that the predetermined threshold size decreases as the distance between the processing target image and another decoded image having the second candidate block group increases. By reducing the priority of the motion vector of the prediction block on another image as the distance between the other decoded images having the two candidate block groups increases, the encoding efficiency of the prediction vector index can be improved. .

  The moving image encoded stream output from the moving image encoding apparatus of the embodiment described above has a specific data format so that it can be decoded according to the encoding method used in the embodiment. Therefore, the moving picture decoding apparatus corresponding to the moving picture encoding apparatus can decode the encoded stream of this specific data format.

  When a wired or wireless network is used to exchange an encoded stream between a moving image encoding device and a moving image decoding device, the encoded stream is converted into a data format suitable for the transmission form of the communication path. It may be transmitted. In that case, a video transmission apparatus that converts the encoded stream output from the video encoding apparatus into encoded data in a data format suitable for the transmission form of the communication channel and transmits the encoded data to the network, and receives the encoded data from the network Then, a moving image receiving apparatus that restores the encoded stream and supplies the encoded stream to the moving image decoding apparatus is provided.

  The moving image transmitting apparatus is a memory that buffers the encoded stream output from the moving image encoding apparatus, a packet processing unit that packetizes the encoded stream, and transmission that transmits the packetized encoded data via the network. Part. The moving image receiving apparatus generates a coded stream by packetizing the received data, a receiving unit that receives the packetized coded data via a network, a memory that buffers the received coded data, and packet processing. And a packet processing unit provided to the video decoding device.

  The above processing relating to encoding and decoding can be realized as a transmission, storage, and reception device using hardware, and is stored in a ROM (Read Only Memory), a flash memory, or the like. It can also be realized by firmware or software such as a computer. The firmware program and software program can be recorded on a computer-readable recording medium, provided from a server through a wired or wireless network, or provided as a data broadcast of terrestrial or satellite digital broadcasting Is also possible.

  The present invention has been described based on the embodiments. The embodiments are exemplifications, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are within the scope of the present invention. .

  DESCRIPTION OF SYMBOLS 100 moving image encoder, 101 prediction block image acquisition part, 102 subtraction part, 103 prediction error encoding part, 104 code stream production | generation part, 105 prediction error decoding part, 106 motion compensation part, 107 addition part, 108 motion vector detection , 109 motion information generation unit, 110 frame memory, 111 first motion information memory, 112 second motion information memory, 120 prediction vector candidate list generation unit, 121 prediction vector selection unit, 122 subtraction unit, 130 first prediction vector candidate List generation unit, 131 combination determination unit, 132 second prediction vector candidate list generation unit, 133 prediction vector candidate list determination unit, 134 combination priority determination unit, 135 prediction vector candidate list determination unit, 200 video decoding device, 201 code Column analysis section, 2 2 prediction error decoding unit, 203 addition unit, 204 motion information reproduction unit, 205 motion compensation unit, 206 frame memory, 207 first motion information memory, 208 second motion information memory, 220 prediction vector candidate list generation unit, 221 prediction vector A determination unit, 222 an addition unit.

Claims (6)

A video decoding device that performs motion compensation prediction with a plurality of block sizes,
A decoding unit that decodes information indicating a position of a motion vector predictor to be referred to in the prediction vector candidate list;
A first predictive vector candidate list generating unit that generates a first predictive vector candidate list including candidates for the first predictive motion vector from the motion vectors of one or more decoded blocks adjacent to the decoding target block;
A second prediction vector candidate list including a second prediction motion vector candidate is generated from a motion vector of a block at the same position as the decoding target block in the decoded image and one or more blocks adjacent to the block at the same position. A second prediction vector candidate list generation unit;
It is determined whether to generate a third prediction vector candidate list obtained by combining the first prediction vector candidate list and the second prediction vector candidate list based on a comparison result between the block size of the decoding target block and a predetermined threshold size. A combination determination unit to
When the block size of the decoding target block is larger than the predetermined threshold size, the third prediction vector candidate list is generated from the first prediction vector candidate list without combining the second prediction vector candidate lists. 3 prediction vector candidate list generation unit;
A video decoding device comprising: a prediction vector selection unit that selects a prediction motion vector of the block to be decoded from the third prediction vector candidate list based on information indicating a position of a prediction motion vector to be referred to . A video decoding device that performs motion compensation prediction with a plurality of block sizes,
A decoding unit that decodes information indicating a position of a motion vector predictor to be referred to in the prediction vector candidate list;
A first predictive vector candidate list generating unit that generates a first predictive vector candidate list including candidates for the first predictive motion vector from the motion vectors of one or more decoded blocks adjacent to the decoding target block;
A second prediction vector candidate list including a second prediction motion vector candidate is generated from a motion vector of a block at the same position as the decoding target block in the decoded image and one or more blocks adjacent to the block at the same position. A second prediction vector candidate list generation unit;
The second prediction vector candidate list is generated by combining the first prediction vector candidate list and the second prediction vector candidate list according to a comparison result between the block size of the decoding target block and a predetermined threshold size. A combination determination unit that determines whether or not to place a prediction vector candidate list at a position that is prioritized on the third prediction vector candidate list over the first prediction vector candidate list;
When the block size of the decoding target block is larger than the predetermined threshold size, the third prediction vector candidate list is generated without giving priority to the second prediction vector candidate list over the first prediction vector candidate list. 3 prediction vector candidate list generation unit;
A video decoding device comprising: a prediction vector selection unit that selects a prediction motion vector of the block to be decoded from the third prediction vector candidate list based on information indicating a position of a prediction motion vector to be referred to .   The moving image according to claim 1 or 2, wherein the combination determination unit controls the predetermined threshold size to increase as a time difference between the image including the decoding target block and the decoded image increases. Decoding device.   The third predicted vector candidate list generation unit deletes overlapping motion vectors when generating a third predicted vector candidate list obtained by combining the first predicted vector candidate list and the second predicted vector candidate list. The moving picture decoding apparatus according to any one of claims 1 to 3. A video decoding method for performing motion compensation prediction with a plurality of block sizes,
A decoding step of decoding information indicating a position of a prediction motion vector to be referred to in the prediction vector candidate list;
A first prediction vector candidate list generation step for generating a first prediction vector candidate list including a first prediction motion vector candidate from motion vectors of one or more decoded blocks adjacent to the decoding target block;
A second prediction vector candidate list including a second prediction motion vector candidate is generated from a motion vector of a block at the same position as the decoding target block in the decoded image and one or more blocks adjacent to the block at the same position. A second prediction vector candidate list generation step;
It is determined whether to generate a third prediction vector candidate list obtained by combining the first prediction vector candidate list and the second prediction vector candidate list based on a comparison result between the block size of the decoding target block and a predetermined threshold size. A combination determination step to
When the block size of the decoding target block is larger than the predetermined threshold size, the third prediction vector candidate list is generated from the first prediction vector candidate list without combining the second prediction vector candidate lists. 3 prediction vector candidate list generation step;
A video decoding method comprising: a prediction vector selection step of selecting a prediction motion vector of the decoding target block from the third prediction vector candidate list based on information indicating a position of the prediction motion vector to be referred to . A video decoding program for performing motion compensation prediction with a plurality of block sizes,
A decoding step of decoding information indicating a position of a prediction motion vector to be referred to in the prediction vector candidate list;
A first prediction vector candidate list generation step for generating a first prediction vector candidate list including a first prediction motion vector candidate from motion vectors of one or more decoded blocks adjacent to the decoding target block;
A second prediction vector candidate list including a second prediction motion vector candidate is generated from a motion vector of a block at the same position as the decoding target block in the decoded image and one or more blocks adjacent to the block at the same position. A second prediction vector candidate list generation step;
It is determined whether to generate a third prediction vector candidate list obtained by combining the first prediction vector candidate list and the second prediction vector candidate list based on a comparison result between the block size of the decoding target block and a predetermined threshold size. A combination determination step to
When the block size of the decoding target block is larger than the predetermined threshold size, the third prediction vector candidate list is generated from the first prediction vector candidate list without combining the second prediction vector candidate lists. 3 prediction vector candidate list generation step;
A moving image that causes a computer to execute a prediction vector selection step of selecting a prediction motion vector of the decoding target block from the third prediction vector candidate list based on information indicating a position of a prediction motion vector to be referred to Image decoding program.

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