JP2013074468A - Moving image decoder, moving image decoding method, and moving image decoding program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of an image decoding method using motion compensation prediction in which reduction in a total code amount is required by compressing encoding information.SOLUTION: A moving image decoder includes: a prediction motion vector candidate generation section 221 for generating a plurality of prediction motion vector candidates in accordance with prediction based on any one of motion vectors of a decoding object block and a decoded block adjacent to the decoding object block, both of the blocks being in the same picture; a prediction motion vector candidate registration section 222 for registering the prediction motion vector candidates by associating information on a distance between pictures with a prediction motion vector value before scaling calculation processing; a prediction motion vector scaling calculation section 226 for performing a scaling calculation of a prediction vector value of a selected prediction motion vector in accordance with a distance between pictures; and an addition section 227 for adding a prediction motion vector after scaling calculation processing to a differential motion vector in order to calculate the motion vector of the decoding object block.

Description

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

  As a typical moving image compression encoding method, MPEG-4 AVC / H. There are H.264 standards. MPEG-4 AVC / H. In H.264, motion compensation is used in which a picture is divided into a plurality of rectangular blocks, a picture that has already been encoded / decoded is used as a reference picture, and motion from the reference picture is predicted. A technique for predicting motion by this motion compensation is called inter prediction. MPEG-4 AVC / H. In the inter prediction in H.264, a plurality of pictures can be used as reference pictures, and the most suitable reference picture is selected for each block from the plurality of reference pictures to perform motion compensation. Therefore, a reference index is assigned to each reference picture, and the reference picture is specified by this reference index. Note that, for B pictures, a maximum of two reference pictures that have been encoded and decoded can be selected and used for inter prediction. The predictions from these two reference pictures are distinguished as L0 prediction (list 0 prediction) mainly used as forward prediction and L1 prediction (list 1 prediction) mainly used as backward prediction.

  Furthermore, bi-prediction using two inter predictions of L0 prediction and L1 prediction at the same time is also defined. In the case of bi-prediction, bi-directional prediction is performed, the inter-predicted signals of L0 prediction and L1 prediction are multiplied by a weighting coefficient, an offset value is added and superimposed, and a final inter-predicted image signal is obtained. Generate. As weighting coefficients and offset values used for weighted prediction, representative values are set for each reference picture in each list and encoded. The encoding information related to inter prediction includes, for each block, a prediction mode for distinguishing between L0 prediction and L1 prediction and bi-prediction, a reference index for specifying a reference picture for each reference list for each block, and a moving direction and a moving amount of the block. There is a motion vector that expresses and encodes and decodes the encoded information.

  In a moving picture coding system that performs motion compensation, a prediction process is performed on a motion vector in order to reduce the amount of code of the motion vector generated in each block. MPEG-4 AVC / H. In H.264, using the fact that the motion vector to be encoded has a strong correlation with the motion vectors of neighboring neighboring blocks, a prediction motion vector is calculated by performing prediction from neighboring neighboring blocks, and the coding target motion vector is calculated. A difference motion vector that is a difference between the motion vector and the predicted motion vector is calculated, and the difference motion vector is encoded to reduce the amount of codes.

  Specifically, as shown in FIG. 34A, a median value is calculated from the motion vectors of neighboring blocks A, B, and C in the vicinity to obtain a predicted motion vector, and the difference between the motion vector and the predicted motion vector By taking this, the amount of code of the motion vector is reduced. However, if the size and shape of the encoding target block and the adjacent block are different as shown in FIG. 34 (b), if there are multiple adjacent blocks on the left, When there is an adjacent block, the leftmost block is set as the prediction block, and the encoding target block is divided into 16 × 8 pixels or 8 × 16 pixels as shown in FIGS. 34 (c) and 34 (d). In this case, instead of taking the median value of the motion vectors of neighboring neighboring blocks, each area divided as indicated by the white arrows in FIGS. 31 (c) and 31 (d) according to the arrangement of the motion compensation blocks. Then, the prediction block of the reference destination is determined, and the prediction is performed from the motion vector of the determined prediction block.

JP 2011-147172 A

  However, in the conventional method, since only one prediction vector is obtained, the prediction accuracy of the prediction motion vector may be lowered depending on the image, and the encoding efficiency may not be improved.

  Under such circumstances, the present inventors have come to recognize the necessity of further compressing the encoded information and reducing the overall code amount in the moving image encoding method using motion compensation prediction.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a moving picture decoding technique for improving the coding efficiency by calculating the prediction motion vector candidates and thereby reducing the code amount of the difference motion vector. Is to provide. Another object is to provide a moving picture decoding technique that improves encoding efficiency by calculating encoding information candidates to reduce the amount of encoded information.

  In order to solve the above problems, a moving picture decoding apparatus according to an aspect of the present invention decodes a coded bit string obtained by coding the moving picture using motion compensation in units of blocks obtained by dividing each picture of the moving picture. A decoding unit (202) that decodes information indicating an index of a predicted motion vector to be selected in a predicted motion vector candidate list together with an elementary motion vector, and the decoding in the same picture as the decoding target block A prediction motion vector candidate generation unit (221) that generates a plurality of prediction motion vector candidates by predicting from any motion vector of a decoded block adjacent to the target block, and the generated prediction motion vector candidates Information about the inter-picture distance required for the scaling calculation process to the predicted motion vector value before the scaling calculation process. In association with the prediction motion vector candidate registration unit (222) for registering in the prediction motion vector candidate list and information indicating the index of the prediction motion vector to be selected in the decoded prediction motion vector candidate list, A prediction motion vector selection unit (225) that selects a prediction motion vector from the prediction motion vector candidate list, and prediction that performs a scaling operation on the prediction vector value before the scaling operation processing of the selected prediction motion vector according to the inter-picture distance. A motion vector scaling operation unit (226); and an addition unit (227) that calculates the motion vector of the decoding target block by adding the predicted motion vector after the scaling operation processing and the difference motion vector.

  Another aspect of the present invention is a video decoding method. This method is a moving picture decoding method for decoding a coded bit sequence in which the moving picture is coded by using motion compensation in units of blocks obtained by dividing each picture of the moving picture, and is selected in the predicted motion vector candidate list. A decoding step for decoding information indicating an index of a predicted motion vector together with a prime motion vector, and prediction from a motion vector of a decoded block adjacent to the decoding target block in the same picture as the decoding target block A prediction motion vector candidate generation step for generating a plurality of prediction motion vector candidates, and the generated prediction motion vector candidates are converted into predicted motion vector values before the scaling calculation processing, and the inter-picture distance required for the scaling calculation processing Prediction associated with information and registered in the predicted motion vector candidate list A motion vector candidate registration step and prediction motion vector selection for selecting a motion vector predictor from the motion vector predictor candidate list based on information indicating an index of the motion vector predictor to be selected in the decoded motion vector predictor candidate list A predicted motion vector scaling operation step for performing a scaling operation on the predicted vector value before the scaling operation processing of the selected predicted motion vector according to the inter-picture distance; and the predicted motion vector and the difference after the scaling operation processing Adding a motion vector to calculate a motion vector of the decoding target block.

  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, a plurality of prediction motion vectors are calculated, an optimal prediction motion vector is selected from the plurality of prediction motion vectors, and the amount of generated code of the difference motion vector is reduced, thereby improving the encoding efficiency. Can be made.

It is a block diagram which shows the structure of the moving image encoder which performs the motion vector prediction method which concerns on embodiment. It is a block diagram which shows the structure of the moving image decoding apparatus which performs the motion vector prediction method which concerns on embodiment. It is a figure explaining a tree block and an encoding block. It is a figure explaining the division mode of a prediction block. It is a figure explaining a prediction block group. It is a figure explaining a prediction block group. It is a figure explaining a prediction block group. It is a figure explaining a prediction block group. It is a figure explaining a prediction block group. It is a figure explaining the syntax of the bit stream in the slice level regarding the prediction method of a motion vector. It is a figure explaining the syntax of the bit stream in the prediction block level regarding the prediction method of a motion vector. It is a figure explaining an example of the entropy code of the syntax element of a prediction motion vector index. It is a block diagram which shows the detailed structure of the difference motion vector calculation part of FIG. FIG. 3 is a block diagram illustrating a detailed configuration of a motion vector calculation unit in FIG. 2. It is a flowchart which shows the difference motion vector calculation process procedure of the difference motion vector calculation part of FIG. It is a flowchart which shows the motion vector calculation process procedure of the motion vector calculation part of FIG. It is a flowchart which shows the process of derivation | leading-out of the motion vector predictor candidate, and a motion vector predictor list construction process. It is a flowchart which shows the candidate derivation | leading-out process procedure of a motion vector predictor. It is a flowchart which shows the candidate derivation | leading-out process procedure of a motion vector predictor. It is a flowchart which shows the candidate derivation | leading-out process procedure of a motion vector predictor. It is a flowchart which shows the candidate derivation | leading-out process procedure of a motion vector predictor. It is a flowchart which shows the derivation | leading-out process of the picture of a different time. It is a flowchart which shows the derivation | leading-out process procedure of the prediction block of the picture of a different time. It is a flowchart which shows the candidate derivation | leading-out process procedure of a motion vector predictor. It is a flowchart which shows the candidate derivation | leading-out process procedure of a motion vector predictor. It is a flowchart which shows the registration process procedure of the candidate of a motion vector predictor to a motion vector predictor candidate list. It is a flowchart which shows the deletion process procedure of the redundant motion vector predictor candidate from a motion vector predictor candidate list. It is a flowchart which shows the restriction | limiting process procedure of the number of prediction motion vector candidates. It is a flowchart which shows the scaling calculation process procedure of a motion vector. It is a flowchart which shows the scaling calculation process procedure of the motion vector by integer calculation. It is a flowchart which shows the candidate derivation | leading-out process procedure of a motion vector predictor. It is a flowchart which shows the candidate derivation | leading-out process procedure of a motion vector predictor. It is a flowchart which shows the candidate derivation | leading-out process procedure of a motion vector predictor. It is a figure explaining the calculation method of the conventional prediction motion vector.

  In the present embodiment, with regard to moving picture coding, in particular, to improve coding efficiency in moving picture coding in which a picture is divided into rectangular blocks of an arbitrary size and shape and motion compensation is performed in units of blocks between pictures. In addition, by calculating a plurality of predicted motion vectors from the motion vectors of the surrounding blocks that have been encoded, and calculating and encoding a difference vector between the motion vector of the block to be encoded and the selected predicted motion vector Reduce the amount of code. Alternatively, the amount of code is reduced by estimating the encoding information of the encoding target block by using the encoding information of the surrounding blocks that have already been encoded. Also, in the case of decoding a moving image, a plurality of predicted motion vectors are calculated from the motion vectors of the peripheral blocks that have been decoded, and a decoding target is calculated from the difference vector decoded from the encoded stream and the selected predicted motion vector. The motion vector of the block is calculated and decoded. Alternatively, the encoding information of the decoding target block is estimated by using the encoding information of the peripheral blocks that have been decoded.

  First, techniques used in the present embodiment and technical terms are defined.

(About tree blocks and coding blocks)
In the embodiment, as shown in FIG. 3, the picture is equally divided into square units of any same size. This unit is defined as a tree block, and is an encoding / decoding target block in a picture (an encoding target block in the encoding process and a decoding target block in the decoding process. Hereinafter, unless otherwise specified, It is used as a basic unit of address management for specifying. Except for monochrome, the tree block is composed of one luminance signal and two color difference signals. The size of the tree block can be freely set to a power of 2 depending on the picture size and the texture in the picture. In order to optimize the encoding process according to the texture in the picture, the tree block divides the luminance signal and chrominance signal in the tree block hierarchically into four parts (two parts vertically and horizontally) as necessary, The block can be made smaller in block size. Each block is defined as a coding block, and is a basic unit of processing when performing coding and decoding. Except for monochrome, the coding block is also composed of one luminance signal and two color difference signals. The maximum size of the coding block is the same as the size of the tree block. An encoded block having the minimum size of the encoded block is called a minimum encoded block, and can be freely set to a power of 2.

  In FIG. 3, the encoding block A is a single encoding block without dividing the tree block. The encoding block B is an encoding block formed by dividing a tree block into four. The coding block C is a coding block obtained by further dividing the block obtained by dividing the tree block into four. The coding block D is a coding block obtained by further dividing the block obtained by dividing the tree block into four parts and further dividing the block into four twice hierarchically, and is a coding block of the minimum size.

(About prediction mode)
Encoded / decoded in units of coding blocks (used in encoded processing for encoded picture, predicted block, image signal, etc., and used in decoded processing for decoded picture, predicted block, image signal, etc.) (Used in this sense unless otherwise noted.) Intra prediction (MODE_INTRA) in which prediction is performed from surrounding image signals, and inter prediction (MODE_INTER) in which prediction is performed from encoded / decoded picture image signals Switch. A mode for identifying the intra prediction (MODE_INTRA) and the inter prediction (MODE_INTER) is defined as a prediction mode (PredMode). The prediction mode (PredMode) has intra prediction (MODE_INTRA) or inter prediction (MODE_INTER) as a value, and can be selected and encoded.

(About split mode, prediction block, prediction unit)
When performing intra prediction (MODE_INTRA) and inter prediction (MODE_INTER) by dividing the picture into blocks, the coded block is divided as necessary to reduce the unit for switching the intra prediction and inter prediction methods. Make predictions. A mode for identifying the division method of the luminance signal and the color difference signal of the coding block is defined as a division mode (PartMode). Furthermore, this divided block is defined as a prediction block. As shown in FIG. 4, four types of partition modes (PartMode) are defined according to the method of dividing the luminance signal of the coding block. The division mode (PartMode) of what is regarded as one prediction block without dividing the luminance signal of the coding block (FIG. 4A) is 2N × 2N division (PART_2Nx2N), and the luminance signal of the coding block is horizontally The division mode (PartMode) of the two prediction blocks (FIG. 4B) is divided into 2N × N divisions (PART_2NxN), the luminance signal of the encoded block is divided in the vertical direction, and the encoded block is The division mode (PartMode) of the two prediction blocks (FIG. 4 (c)) is N × 2N division (PART_Nx2N), and the luminance signal of the encoded block is divided into four prediction blocks by horizontal and vertical equal divisions. The division mode (PartMode) of (FIG. 4D) is defined as N × N division (PART_NxN), respectively. Except for N × N division (PART_NxN) of intra prediction (MODE_INTRA), the color difference signal is also divided for each division mode (PartMode) in the same manner as the vertical / horizontal division ratio of the luminance signal.

  In order to specify each prediction block within the coding block, a number starting from 0 is assigned to the prediction block existing inside the coding block in the coding order. This number is defined as a split index PartIdx. A number described in each prediction block of the encoded block in FIG. 4 represents a partition index PartIdx of the prediction block. In the 2N × N division (PART_2NxN) shown in FIG. 4B, the division index PartIdx of the upper prediction block is set to 0, and the division index PartIdx of the lower prediction block is set to 1. In the N × 2N division (PART_Nx2N) shown in FIG. 4C, the division index PartIdx of the left prediction block is set to 0, and the division index PartIdx of the right prediction block is set to 1. In the N × N partition (PART_NxN) shown in FIG. 4D, the partition index PartIdx of the upper left prediction block is 0, the partition index PartIdx of the upper right prediction block is 1, and the partition index PartIdx of the lower left prediction block is 2. And the division index PartIdx of the prediction block at the lower right is set to 3.

  When the prediction mode (PredMode) is inter prediction (MODE_INTER), except for the coding block D which is the smallest coding block, the partition mode (PartMode) is 2N × 2N partition (PART_2Nx2N), 2N × N partition (PART_2NxN), and N × 2N partition (PART_Nx2N) is defined, and only the coding block D which is the smallest coding block, the partition mode (PartMode) is 2N × 2N partition (PART_2Nx2N), 2N × N partition (PART_2NxN), and N × 2N In addition to the division (PART_Nx2N), N × N division (PART_NxN) is defined. The reason why N × N division (PART_NxN) is not defined other than the smallest coding block is that, except for the smallest coding block, the coding block can be divided into four to represent a small coding block.

(Position of tree block, coding block, prediction block, transform block)
The position of each block including the tree block, the encoding block, the prediction block, and the transform block according to the present embodiment has the position of the pixel of the luminance signal at the upper left of the luminance signal screen as the origin (0, 0). The pixel position of the upper left luminance signal included in each block area is represented by two-dimensional coordinates (x, y). The direction of the coordinate axis is a right direction in the horizontal direction and a downward direction in the vertical direction, respectively, and the unit is one pixel unit of the luminance signal. Of course, the luminance signal and the color difference signal have the same image size (number of pixels) and the color difference format is 4: 4: 4. Of course, the luminance signal and the color difference signal have a different color size format of 4: 4. Even in the case of 2: 0, 4: 2: 2, the position of each block of the color difference signal is represented by the coordinates of the pixel of the luminance signal included in the block area, and the unit is one pixel of the luminance signal. In this way, not only can the position of each block of the color difference signal be specified, but also the relationship between the positions of the luminance signal block and the color difference signal block can be clarified only by comparing the coordinate values.

(About prediction block groups)
A group composed of a plurality of prediction blocks is defined as a prediction block group. 5, FIG. 6, FIG. 7 and FIG. 8 are diagrams for explaining a prediction block group adjacent to a prediction block to be encoded / decoded within the same picture as the prediction block to be encoded / decoded. FIG. 9 shows an already encoded / decoded picture that exists at the same position as or near the predicted block to be encoded / decoded in a picture that has been encoded / decoded that is temporally different from the predicted block to be encoded / decoded It is a figure explaining this prediction block group. The prediction block group will be described with reference to FIGS. 5, 6, 7, 8, and 9.

  As shown in FIG. 5, the prediction block A1 adjacent to the left side of the prediction block to be encoded / decoded within the same picture as the prediction block to be encoded / decoded, and the prediction block to be encoded / decoded A first prediction block group including a prediction block A0 adjacent to the lower left vertex is defined as a prediction block group adjacent to the left side.

  As shown in FIG. 6, even when the size of the prediction block adjacent to the left side of the prediction block to be encoded / decoded is larger than the prediction block to be encoded / decoded, the prediction adjacent to the left side according to the above condition is used. If the block A is adjacent to the left side of the prediction block to be encoded / decoded, the prediction block A1 is used. If the block A is adjacent to the lower left vertex of the prediction block to be encoded / decoded, the prediction block A0 is set. . In the example of FIG. 6, the prediction block A0 and the prediction block A1 are the same prediction block.

  In addition, as shown in FIG. 7, when the size of the prediction block adjacent to the left side of the prediction block to be encoded / decoded is smaller than the prediction block to be encoded / decoded and there are a plurality of prediction blocks, this embodiment In the embodiment, only the lowest prediction block A10 among the prediction blocks adjacent to the left side is set as the prediction block A1 adjacent to the left side.

  A prediction block B1 adjacent to the upper side of the prediction block to be encoded / decoded within the same picture as the prediction block to be encoded / decoded, and a prediction block adjacent to the upper right vertex of the prediction block to be encoded / decoded A second prediction block group composed of B0 and a prediction block B2 adjacent to the top left vertex of the prediction block to be encoded / decoded is defined as a prediction block group adjacent to the upper side.

  In addition, as shown in FIG. 8, even when the size of the prediction block adjacent to the upper side of the prediction block to be encoded / decoded is larger than the prediction block to be encoded / decoded, the prediction adjacent to the upper side according to the above condition. If the block B is adjacent to the upper side of the prediction block to be encoded / decoded, the prediction block B1 is set. If the block B is adjacent to the upper right vertex of the prediction block to be encoded / decoded, the prediction block B0 is set. If it is adjacent to the top left vertex of the prediction block to be encoded / decoded, the prediction block is B2. In the example of FIG. 8, the prediction block B0, the prediction block B1, and the prediction block B2 are the same prediction block.

  As shown in FIG. 7, when the size of the prediction block adjacent to the upper side of the prediction block to be encoded / decoded is smaller than the prediction block to be encoded / decoded, and there are a plurality of prediction blocks, the embodiment In FIG. 4, only the rightmost prediction block B10 among the prediction blocks adjacent on the upper side is set as the prediction block B1 adjacent on the upper side.

  As shown in FIG. 9, in an encoded / decoded picture that is temporally different from the prediction block to be encoded / decoded, an existing code that exists at the same position as the prediction block to be encoded / decoded or a position in the vicinity thereof. A third prediction block group composed of prediction / decoding prediction block groups T0 and T1 is defined as a prediction block group at different times.

(Inter prediction mode, reference list)
In the embodiment of the present invention, in inter prediction in which prediction is performed from an image signal of a coded / decoded picture, a plurality of decoded pictures can be used as reference pictures. In order to identify a reference picture selected from a plurality of reference pictures, a reference index is attached to each prediction block. In the B slice, any two reference pictures can be selected for each prediction block and inter prediction can be performed. As inter prediction modes, there are L0 prediction (Pred_L0), L1 prediction (Pred_L1), and bi-prediction (Pred_BI). The reference picture is managed by L0 (reference list 0) and L1 (reference list 1) of the list structure, and the reference picture can be specified by specifying the reference index of L0 or L1. L0 prediction (Pred_L0) is inter prediction that refers to a reference picture managed in L0, L1 prediction (Pred_L1) is inter prediction that refers to a reference picture managed in L1, and bi-prediction (Pred_BI) is This is inter prediction in which both L0 prediction and L1 prediction are performed and one reference picture managed by each of L0 and L1 is referred to. Only L0 prediction can be used in inter prediction of P slice, and L0 prediction, L1 prediction, and bi-prediction (Pred_BI) that averages or weights and adds L0 prediction and L1 prediction can be used in inter prediction of B slice. In the subsequent processing, regarding constants and variables with subscript LX (X is 0 or 1) in the output, it is assumed that processing is performed for each of L0 and L1.

(About POC)
POC is a variable associated with the picture to be encoded, and is set to a value that increases by 1 in the picture output / display order. Based on the POC value, it is possible to determine whether they are the same picture, to determine the front-to-back relationship between pictures in the output / display order, or to derive the distance between pictures. For example, if the POCs of two pictures have the same value, it can be determined that they are the same picture. When the POCs of two pictures have different values, it can be determined that the picture with the smaller POC value is a picture that is output / displayed earlier in time, and the difference between the POCs of the two pictures is the time axis direction. Indicates the distance between pictures.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a moving picture coding apparatus according to an embodiment of the present invention. The moving image encoding apparatus according to the embodiment includes an image memory 101, a motion vector detection unit 102, a difference motion vector calculation unit 103, an inter prediction information estimation unit 104, a motion compensation prediction unit 105, a prediction method determination unit 106, a residual signal. Generation unit 107, orthogonal transform / quantization unit 108, first encoded bit string generation unit 109, second encoded bit string generation unit 110, multiplexing unit 111, inverse quantization / inverse orthogonal transform unit 112, decoded image signal A superimposing unit 113, an encoded information storage memory 114, and a decoded image memory 115 are provided.

  The image memory 101 temporarily stores the image signal of the encoding target picture supplied in the order of shooting / display time. The image memory 101 supplies the stored image signal of the picture to be encoded to the motion vector detection unit 102, the prediction method determination unit 106, and the residual signal generation unit 107 in units of predetermined pixel blocks. At this time, the image signals of the pictures stored in the order of shooting / display time are rearranged in the encoding order and output from the image memory 101 in units of pixel blocks.

  The motion vector detection unit 102 uses the motion vector of each prediction block size and each prediction mode by block matching between the image signal supplied from the image memory 101 and the reference picture supplied from the decoded image memory 115 for each prediction block. Detection is performed in units, and the detected motion vector is supplied to the motion compensation prediction unit 105, the difference motion vector calculation unit 103, and the prediction method determination unit 106.

  The difference motion vector calculation unit 103 calculates a plurality of motion vector predictor candidates by using the encoded information of the already encoded image signal stored in the encoded information storage memory 114, and will be described later. The motion vector detection unit 102 selects an optimal motion vector predictor from a plurality of motion vector predictor candidates registered in the motion vector list and registered in the motion vector predictor list, and a motion vector difference is detected from the motion vector detected by the motion vector detection unit 102 and the motion vector predictor. And the calculated difference motion vector is supplied to the prediction method determination unit 106. Furthermore, a prediction motion vector index that identifies a prediction motion vector selected from prediction motion vector candidates registered in the prediction motion vector list is supplied to the prediction method determination unit 106. The detailed configuration and operation of the difference motion vector calculation unit 103 will be described later.

  The inter prediction information estimation unit 104 estimates inter prediction information in merge mode. The merge mode refers to inter prediction information such as a prediction mode of the prediction block, a reference index (information for specifying a reference picture used for motion compensation prediction from a plurality of reference pictures registered in the reference list), a motion vector, and the like. Is a mode in which inter prediction information of an adjacent inter-predicted prediction block that has been encoded or an inter-predicted prediction block of a different picture is used. A plurality of merge candidates (inter prediction information candidates) are calculated using the encoded information of the already encoded prediction block stored in the encoded information storage memory 114, registered in the merge candidate list, and merged. An optimal merge candidate is selected from a plurality of merge candidates registered in the candidate list, and inter prediction information such as a prediction mode, a reference index, and a motion vector of the selected merge candidate is supplied to the motion compensation prediction unit 105. The merge index that identifies the selected merge candidate is supplied to the prediction method determination unit 106.

  The motion compensation prediction unit 105 generates a prediction image signal by motion compensation prediction from a reference picture using the motion vectors detected by the motion vector detection unit 102 and the inter prediction information estimation unit 104, and uses the prediction image signal as a prediction method determination unit. 106. In L0 prediction and L1 prediction, one-way prediction is performed. In the case of bi-prediction (Pred_BI), bi-directional prediction is performed, the inter-predicted signals of L0 prediction and L1 prediction are adaptively multiplied by weighting factors, offset values are added and superimposed, and finally A predicted image signal is generated.

  The prediction method determination unit 106 evaluates the code amount of the difference motion vector, the distortion amount between the prediction image signal and the image signal, and the like, so that inter prediction (in an optimal coding block unit) is selected from a plurality of prediction methods. In the merge mode, the prediction mode PredMode and the partition mode PartMode are determined to determine whether the prediction mode is PRED_INTER) or intra prediction (PRED_INTRA). In the inter prediction (PRED_INTER), the prediction method such as whether the mode is the merge mode or not is determined for each prediction block. Is a merge index, and when not in the merge mode, an inter prediction flag, a prediction motion vector index, L0 and L1 reference indexes, a difference motion vector, and the like are determined, and encoded information corresponding to the determination is determined as a first encoded bit string generation unit 109.

  Further, the prediction method determination unit 106 stores information indicating the determined prediction method and encoded information including a motion vector according to the determined prediction method in the encoded information storage memory 114. The encoded information stored here is the motion of the reference indexes refIdxL0, refIdxL1, L0, and L1 of the flags predFlagL0, predFlagL1, L0, and L1 indicating whether to use the prediction mode PredMode, the partition mode PartMode, the L0 prediction, and the L1 prediction. Vectors mvL0, mvL1, etc. Here, when the prediction mode PredMode is inter prediction (MODE_INER), the flag predFlagL0 indicating whether to use L0 prediction and the flag predFlagL1 indicating whether to use L1 prediction are both 0. On the other hand, when the prediction mode PredMode is inter prediction (MODE_INTER) and the inter prediction mode is L0 prediction (Pred_L0), a flag predFlagL0 indicating whether to use L0 prediction is 1, and a flag predFlagL1 indicating whether to use L1 prediction Is 0. When the inter prediction mode is L1 prediction (Pred_L1), the flag predFlagL0 indicating whether to use L0 prediction is 0, and the flag predFlagL1 indicating whether to use L1 prediction is 1. When the inter prediction mode is bi-prediction (Pred_BI), a flag predFlagL0 indicating whether to use L0 prediction and a flag predFlagL1 indicating whether to use L1 prediction are both 1. The prediction method determination unit 106 supplies a prediction image signal corresponding to the determined prediction mode to the residual signal generation unit 107 and the decoded image signal superposition unit 113.

  The residual signal generation unit 107 generates a residual signal by performing subtraction between the image signal to be encoded and the predicted image signal, and supplies the residual signal to the orthogonal transform / quantization unit 108.

  The orthogonal transform / quantization unit 108 performs orthogonal transform and quantization on the residual signal in accordance with the quantization parameter to generate an orthogonal transform / quantized residual signal, and a second encoded bit string generation unit 110 and the inverse quantization / inverse orthogonal transform unit 112. Further, the orthogonal transform / quantization unit 108 stores the quantization parameter in the encoded information storage memory 114.

  The first encoded bit string generation unit 109 adds information corresponding to the prediction method determined by the prediction method determination unit 106 for each encoding block and prediction block, in addition to the information in units of sequences, pictures, slices, and encoding blocks. Encoding information is encoded. Specifically, in the prediction mode PredMode, partition mode PartMode, and inter prediction (PRED_INTER) for each coding block, a flag that determines whether or not the mode is merge mode, merge index in the case of merge mode, and inter prediction in the case of not in merge mode Encoding information such as information on the mode, the predicted motion vector index, and the difference motion vector is encoded in accordance with a predetermined syntax rule described later to generate a first encoded bit string, and the encoded information is supplied to the multiplexing unit 111.

  The second encoded bit string generation unit 110 generates a second encoded bit string by entropy-encoding the orthogonally transformed and quantized residual signal according to a prescribed syntax rule, and supplies the second encoded bit string to the multiplexing unit 111. The multiplexing unit 111 multiplexes the first encoded bit string and the second encoded bit string in accordance with a prescribed syntax rule, and outputs a bit stream.

  The inverse quantization / inverse orthogonal transform unit 112 calculates a residual signal by performing inverse quantization and inverse orthogonal transform on the orthogonal transform / quantized residual signal supplied from the orthogonal transform / quantization unit 108 to perform decoding. This is supplied to the image signal superimposing unit 113. The decoded image signal superimposing unit 113 superimposes the predicted image signal according to the determination by the prediction method determining unit 106 and the residual signal that has been inverse quantized and inverse orthogonal transformed by the inverse quantization / inverse orthogonal transform unit 112 to decode the decoded image. Is generated and stored in the decoded image memory 115. The decoded image may be stored in the decoded image memory 115 after filtering processing for reducing distortion such as block distortion due to encoding.

  FIG. 2 is a block diagram showing the configuration of the moving picture decoding apparatus according to the embodiment of the present invention corresponding to the moving picture encoding apparatus of FIG. The moving picture decoding apparatus according to the embodiment includes a separation unit 201, a first encoded bit string decoding unit 202, a second encoded bit string decoding unit 203, a motion vector calculation unit 204, an inter prediction information estimation unit 205, and a motion compensation prediction unit 206. , An inverse quantization / inverse orthogonal transform unit 207, a decoded image signal superimposing unit 208, an encoded information storage memory 209, and a decoded image memory 210.

  The decoding process of the moving picture decoding apparatus in FIG. 2 corresponds to the decoding process provided in the moving picture encoding apparatus in FIG. 1, so the motion compensation prediction unit 206 in FIG. The configurations of the inverse orthogonal transform unit 207, the decoded image signal superimposing unit 208, the encoded information storage memory 209, and the decoded image memory 210 are the same as those of the motion compensation prediction unit 105, the inverse quantization / inverse of the moving image encoding device in FIG. The orthogonal transform unit 112, the decoded image signal superimposing unit 113, the encoded information storage memory 114, and the decoded image memory 115 have functions corresponding to the respective configurations.

  The bit stream supplied to the separation unit 201 is separated according to a rule of a prescribed syntax, and the separated encoded bit string is supplied to the first encoded bit string decoding unit 202 and the second encoded bit string decoding unit 203.

  The first encoded bit string decoding unit 202 decodes the supplied encoded bit string to obtain sequence, picture, slice, encoded block unit information, and predicted block unit encoded information. Specifically, in the prediction mode PredMode for determining whether the prediction is inter prediction (PRED_INTER) or intra prediction (PRED_INTRA) for each coding block, split mode PartMode, and inter prediction (PRED_INTER), a flag for determining whether the mode is merge mode, When the merge mode is selected, the merge index is decoded. When the merge mode is not selected, the encoded information related to the inter prediction mode, the predicted motion vector index, the difference motion vector, and the like is decoded according to a predetermined syntax rule to be described later, and the encoded information is a motion vector calculation unit 204 or the inter prediction information estimation unit 205.

  The second encoded bit string decoding unit 203 calculates a residual signal that has been orthogonally transformed / quantized by decoding the supplied encoded bit string, and dequantized / inverted the residual signal that has been orthogonally transformed / quantized. This is supplied to the orthogonal transform unit 207.

  When the prediction block to be decoded is not in the merge mode, the motion vector calculation unit 204 uses the encoded information of the already decoded image signal stored in the encoded information storage memory 209 to generate a plurality of prediction motion vector candidates. And the motion vector is registered in a motion vector predictor list, which will be described later, and a motion vector predictor that is decoded and supplied from the plurality of motion vector predictor candidates registered in the motion vector predictor list by the first encoded bit string decoding unit 202. A prediction motion vector corresponding to the index is selected, a motion vector is calculated from the difference vector decoded by the first encoded bit string decoding unit 202 and the selected prediction motion vector, and the motion compensated prediction unit 206 together with other encoded information. And is stored in the encoded information storage memory 209. Here, the encoding information of the prediction block to be supplied / stored includes the prediction indexes PredFlagL0, predFlagL1, L0, and L1 reference indexes refIdxL0, refIdxL1, indicating whether to use the prediction mode PredMode, the partition mode PartMode, the L0 prediction, and the L1 prediction L0, L1 motion vectors mvL0, mvL1, etc. Here, when the prediction mode PredMode is inter prediction (MODE_INTER), the flag predFlagL0 indicating whether to use the L0 prediction and the flag predFlagL1 indicating whether to use the L1 prediction are both 0. On the other hand, when the prediction mode PredMode is inter prediction (MODE_INTER) and the inter prediction mode is L0 prediction (Pred_L0), a flag predFlagL0 indicating whether to use L0 prediction is 1, and a flag predFlagL1 indicating whether to use L1 prediction Is 0. When the inter prediction mode is L1 prediction (Pred_L1), the flag predFlagL0 indicating whether to use L0 prediction is 0, and the flag predFlagL1 indicating whether to use L1 prediction is 1. When the inter prediction mode is bi-prediction (Pred_BI), a flag predFlagL0 indicating whether to use L0 prediction and a flag predFlagL1 indicating whether to use L1 prediction are both 1. The detailed configuration and operation of the motion vector calculation unit 204 will be described later.

  The inter prediction information estimation unit 205 estimates the inter prediction information in the merge mode when the prediction block to be decoded is in the merge mode. Using the encoded information of the already decoded prediction block stored in the encoded information storage memory 114, a plurality of merge candidates are calculated and registered in the merge candidate list, and the plurality of merge candidates registered in the merge candidate list The merge candidate corresponding to the merge index decoded and supplied by the first encoded bit string decoding unit 202 is selected from the merge candidates, and the prediction mode PredMode, split mode PartMode, L0 prediction, and L1 prediction of the selected merge candidate are selected. Inter prediction information such as a flag indicating whether or not to use, reference indexes of L0 and L1, motion vectors of L0 and L1, and the like are supplied to the motion compensation prediction unit 206 and stored in the encoded information storage memory 209.

  The motion compensation prediction unit 206 generates a prediction image signal by motion compensation prediction from the reference picture using the motion vector calculated by the motion vector calculation unit 204, and supplies the prediction image signal to the decoded image signal superimposition unit 208. In the case of bi-prediction (Pred_BI), a weighted coefficient is adaptively multiplied and superimposed on the two motion-compensated predicted image signals of L0 prediction and L1 prediction to generate a final predicted image signal.

  The inverse quantization / inverse orthogonal transform unit 207 performs inverse orthogonal transform and inverse quantization on the orthogonal transform / quantized residual signal decoded by the first encoded bit string decoding unit 202, and performs inverse orthogonal transform / An inverse quantized residual signal is obtained.

  The decoded image signal superimposing unit 208 superimposes the predicted image signal subjected to motion compensation prediction by the motion compensation prediction unit 206 and the residual signal subjected to inverse orthogonal transform / inverse quantization by the inverse quantization / inverse orthogonal transform unit 207. As a result, the decoded image signal is decoded and stored in the decoded image memory 210. When stored in the decoded image memory 210, the decoded image may be stored in the decoded image memory 210 after filtering processing for reducing block distortion or the like due to encoding is performed on the decoded image.

(About syntax)
Next, a syntax that is a common rule for encoding and decoding a bit stream of a moving image that is encoded by a moving image encoding device including the motion vector prediction method according to the present embodiment and decoded by the decoding device explain.

  FIG. 10 shows a first syntax structure described in the slice header in units of slices of the bitstream generated according to the present embodiment. However, only syntax elements relevant to the present embodiment are shown. When the slice type is B, a picture colPic at a different time used when calculating a motion vector prediction candidate or merge candidate in the temporal direction is a reference list of L0 or a reference of L1 of a picture including a prediction block to be processed. A flag collocated_from_l0_flag indicating which reference picture registered in which list is used is set. Details of the flag collocated_from_l0_flag will be described later.

  Note that the above syntax elements may be placed in a picture parameter set describing syntax elements set in units of pictures.

  FIG. 11 shows a syntax pattern described in units of prediction blocks. When the value of the prediction mode PredMode of the prediction block is inter prediction (MODE_INTER), merge_flag [x0] [y0] indicating whether the mode is the merge mode is set. Here, x0 and y0 are indices indicating the position of the upper left pixel of the prediction block in the picture of the luminance signal, and merge_flag [x0] [y0] is the prediction block located at (x0, y0) in the picture It is a flag indicating whether or not merge mode.

  Next, when merge_flag [x0] [y0] is 1, it indicates merge mode, and a merge list index syntax element merge_idx [x0] [y0] is set, which is a list of merge candidates to be referred to. . Here, x0 and y0 are indices indicating the position of the upper left pixel of the prediction block in the picture, and merge_idx [x0] [y0] is the merge index of the prediction block located at (x0, y0) in the picture. is there.

  On the other hand, when merge_flag [x0] [y0] is 0, this indicates that the mode is not merge mode. When the slice type is B, a syntax element inter_pred_flag [x0] [y0] for identifying the inter prediction mode is installed. The L0 prediction (Pred_L0), L1 prediction (Pred_L1), and bi-prediction (Pred_BI) are identified by the tax element. For each of L0 and L1, syntax elements ref_idx_l0 [x0] [y0] and ref_idx_l1 [x0] [y0] of the reference index for specifying the reference picture, the motion vector and prediction of the prediction block obtained by motion vector detection The differential motion vector syntax elements mvd_l0 [x0] [y0] [j] and mvd_l1 [x0] [y0] [j], which are the differences from the motion vector, are provided. Here, x0 and y0 are indexes indicating the position of the upper left pixel of the prediction block in the picture, and ref_idx_l0 [x0] [y0] and mvd_l0 [x0] [y0] [j] are respectively (x0 , y0) is the reference index of L0 of the prediction block and the differential motion vector, and ref_idx_l1 [x0] [y0] and mvd_l1 [x0] [y0] [j] are respectively (x0, y0) in the picture It is the reference index of L1 of the prediction block located, and a difference motion vector. Further, j represents a differential motion vector component, j represents 0 as an x component, and j represents 1 as a y component. Next, syntax elements mvp_idx_l0 [x0] [y0] and mvp_idx_l1 [x0] [y0] of an index of a predicted motion vector list that is a list of predicted motion vector candidates to be referred to are set. Here, x0 and y0 are indices indicating the position of the upper left pixel of the prediction block in the picture, and mvp_idx_l0 [x0] [y0] and mvp_idx_l1 [x0] [y0] are in (x0, y0) in the picture It is the prediction motion vector index of L0 and L1 of the prediction block located. FIG. 12 is an example of entropy codes of the syntax elements mvp_idx_l0 [x0] [y0] and mvp_idx_l1 [x0] [y0] of the predicted motion vector index for each number of defined predicted motion vector candidates. When the number of motion vector predictor candidates is 2, when the motion vector predictor index is 0, the signs of the motion vector index syntax elements mvp_idx_l0 [x0] [y0] and mvp_idx_l1 [x0] [y0] are “0”. When the predicted motion vector index is 1, the signs of the syntax elements mvp_idx_l0 [x0] [y0] and mvp_idx_l1 [x0] [y0] of the predicted motion vector index are “1”. When the number of motion vector predictor candidates is 3, when the motion vector predictor index is 0, the signs of the motion vector index syntax elements mvp_idx_l0 [x0] [y0] and mvp_idx_l1 [x0] [y0] are “0”. When the motion vector predictor index is 1, the syntax elements mvp_idx_l0 [x0] [y0] and mvp_idx_l1 [x0] [y0] of the motion vector predictor index are “10” and when the motion vector predictor index is 2, The signs of the syntax elements mvp_idx_l0 [x0] [y0] and mvp_idx_l1 [x0] [y0] of the predicted motion vector index are “11”. In the embodiment of the present invention, the number of motion vector predictor candidates is set to the same value as the final candidate number finalNumMVPCand defined below, and the value of the number of candidates is set to 2.

  The motion vector prediction method according to the embodiment is implemented in the difference motion vector calculation unit 103 of the video encoding device in FIG. 1 and the motion vector calculation unit 204 of the video decoding device in FIG.

  A motion vector prediction method according to an embodiment will be described with reference to the drawings. The motion vector prediction method is performed in any of the encoding and decoding processes for each prediction block constituting the encoding block. When the prediction mode of the prediction block is inter prediction (MODE_INTER) and not the merge mode, in the case of encoding, the encoded motion vector used when calculating the differential motion vector to be encoded from the motion vector to be encoded is used. In the case of deriving the predicted motion vector, the decoding is performed when the predicted motion vector is derived using the decoded motion vector used when calculating the motion vector to be decoded.

(Prediction of motion vector in encoding)
The operation of the motion vector prediction method according to the embodiment in the video encoding device that encodes a video bitstream based on the above-described syntax will be described. The motion vector prediction method is a method in which motion compensated prediction is performed in units of slices, that is, when the slice type is a P slice (unidirectional prediction slice) or a B slice (bidirectional prediction slice). The prediction mode is an inter prediction (MODE_INTER) and is applied to a prediction block that encodes or decodes a differential motion vector that is not a merge mode.

  FIG. 13 is a diagram showing a detailed configuration of the differential motion vector calculation unit 103 of the moving picture encoding device of FIG. A portion surrounded by a thick frame line in FIG. 13 indicates the differential motion vector calculation unit 103.

  Further, the part surrounded by a thick dotted line inside thereof shows an operation unit of a motion vector prediction method described later, and is similarly installed in a video decoding device corresponding to the video encoding device of the embodiment, The same determination result that does not contradict between encoding and decoding can be obtained. Hereinafter, a motion vector prediction method in encoding will be described with reference to FIG.

  The difference motion vector calculation unit 103 includes a prediction motion vector candidate generation unit 121, a prediction motion vector candidate registration unit 122, a prediction motion vector redundant candidate deletion unit 123, a prediction motion vector candidate number limit unit 124, and a prediction motion vector candidate code amount calculation unit. 125, a predicted motion vector selection unit 126, a predicted motion vector scaling calculation unit 127, and a motion vector subtraction unit 128.

  In the differential motion vector calculation processing in the differential motion vector calculation unit 103, the differential motion vector of the motion vector used in the inter prediction method selected in the encoding target block is calculated for each of L0 and L1. Specifically, when the prediction mode PredMode of the encoding target block is inter prediction (MODE_INTER) and the inter prediction mode of the encoding target block is L0 prediction (Pred_L0), the prediction motion vector list mvpListL0 of L0 is calculated and predicted. A motion vector mvpL0 is selected, and a differential motion vector mvdL0 of the L0 motion vector is calculated. When the inter prediction mode (Pred_L1) of the encoding target block is L1 prediction, the L1 predicted motion vector list mvpListL1 is calculated, the predicted motion vector mvpL1 is selected, and the differential motion vector mvdL1 of the L1 motion vector is calculated. When the inter prediction mode of the encoding target block is bi-prediction (Pred_BI), both L0 prediction and L1 prediction are performed, a prediction motion vector list mvpListL0 of L0 is calculated, a prediction motion vector mvpL0 of L0 is selected, and L0 A difference motion vector mvdL0 of the L1 motion vector mvLL, a prediction motion vector list mvpListL1 of the L1, a prediction motion vector mvpL1 of the L1, and a difference motion vector mvdL1 of the motion vector mvL1 of the L1. .

  Difference motion vector calculation processing is performed for each of L0 and L1, but both L0 and L1 are common processing. Therefore, in the following description, L0 and L1 are represented as a common LX. In the process of calculating the differential motion vector of L0, X is 0, and in the process of calculating the differential motion vector of L1, X is 1. Further, when referring to the information of the other list instead of LX during the process of calculating the differential motion vector of LX, the other list is represented as LY.

  For each of L0 and L1, the motion vector predictor candidate generation unit 121 has a prediction block group adjacent to the upper side (a prediction block group adjacent to the left side of the prediction block in the same picture as the prediction block to be encoded: A0 in FIG. 5). , A1), prediction block group adjacent to the left side (prediction block group adjacent to the upper side of the prediction block in the same picture as the prediction block to be encoded: B0, B1, B2 in FIG. 5), prediction blocks at different times Three predictions of a group (predicted block group that has already been encoded and exists at the same position as the prediction block in a picture temporally different from the prediction block to be encoded or a position near the prediction block: T0 and T1 in FIG. 9) From the block group, one motion vector mvLXA, mvLXB, mvLXCol for each prediction block group Out as a predicted motion vector candidates, their motion vectors mvLXA, MvLXB, each picture distance distA corresponding to MvLXCol, DISTB, with DistCol, supplies the predicted motion vector candidate registration unit 122. Details of the inter-picture distances distA, distB, and distCol will be described later. Hereinafter, mvLXA and mvLXB are referred to as spatial prediction motion vectors, and mvLXCol is referred to as a temporal prediction motion vector. When selecting the prediction motion vector candidate, encoding information such as the prediction mode of the encoded prediction block stored in the encoding information storage memory 114, the reference index for each reference list, the POC of the reference picture, the motion vector, etc. Is used.

  The motion vector predictor candidate generation unit 121 performs a later-described condition determination on the prediction blocks in each prediction block group in a predetermined order for each prediction block group. A motion vector is selected and set as the predicted motion vector candidates mvLXA, mvLXB, and mvLXCol.

  When calculating a prediction motion vector from a prediction block group adjacent to the left side, predictions adjacent to the upper side in the order from the bottom to the top of the prediction block group adjacent to the left side (order of A0 to A0 and A1 in FIG. 5). When calculating a prediction motion vector from a block group, prediction is performed from prediction block groups at different times in the order from right to left of the prediction block group adjacent to the upper side (order B0 to B0, B1, and B2 in FIG. 5). When calculating the motion vector, condition determination to be described later is performed for each prediction block in the order of T0 to T0 and T1 in FIG. 9, and the motion vector of the prediction block that first matches the condition is selected. Predicted motion vector candidates are mvLXA, mvLXB, and mvLXCol, respectively.

  That is, in the left adjacent prediction block group, the lowest prediction block has the highest priority, and the priority is given from the bottom to the top. In the upper adjacent prediction block group, the rightmost prediction block Blocks have the highest priority and are prioritized from right to left. In the prediction block group at different times, the prediction block of T0 has the highest priority, and the priority is given in the order of T0 and T1.

(Explanation of loop for condition judgment of spatial prediction block)
For each of the adjacent prediction blocks of the left adjacent prediction block group and the upper adjacent prediction block group, in the scanning methods 1, 4, 5, and 6 to be described later, the following condition determinations 1, 2, 3, and 4 are prioritized. Each condition decision is applied in order.
Condition determination 1: Prediction using the same reference index, that is, the same reference picture is performed in the adjacent prediction block with the same reference list LX as the motion vector of the LX that is the difference motion vector calculation target of the prediction block to be encoded / decoded. Yes.
Condition determination 2: Although the reference list LY is different from the LX motion vector of the differential motion vector calculation target of the prediction block to be encoded / decoded, prediction using the same reference picture is performed in the adjacent prediction block.
Condition determination 3: Prediction using a different reference picture is performed in the adjacent prediction block in the same reference list LX as the LX motion vector of the differential motion vector calculation target of the prediction block to be encoded / decoded.
Condition determination 4: Prediction using a different reference picture in a reference list LY different from a motion vector of an LX that is a difference motion vector calculation target of a prediction block to be encoded / decoded is performed in an adjacent prediction block.

In scanning method 2 and scanning method 3, which will be described later, condition determination 5 that satisfies either condition determination 1 or condition determination 3 and condition determination 6 that satisfies either condition determination 2 or condition determination 4 are applied.
Condition determination 5: Prediction using the same reference list LX as the motion vector of the LX that is the difference motion vector calculation target of the prediction block to be encoded / decoded is also performed in the adjacent prediction block. (Condition judgment 5 does not distinguish whether the reference pictures are the same)
Condition determination 6: Prediction using the reference list LY that is different from the motion vector of the LX that is the difference motion vector calculation target of the prediction block to be encoded / decoded is also performed in the adjacent prediction block. (Condition 6 does not distinguish whether the reference pictures are the same)

  If any of these conditions is met, it is determined that there is a motion vector that matches the condition in the prediction block, and the subsequent condition determination is not performed.

  The following six methods can be set as the method of loop scanning of the spatial prediction block depending on the above-described four conditions. The appropriateness of the prediction vector and the maximum processing amount differ depending on each method, and these are selected and set in consideration of them. The scanning method 1 and the scanning method 2 will be described in detail later with reference to the flowcharts of FIGS. 18 to 20 and FIGS. 31 to 33, respectively. Since this is a matter that can be appropriately designed according to the procedure for performing 1 and scanning method 2, detailed description thereof will be omitted. In addition, although the loop process of the scan of the spatial prediction block in a moving image encoder is demonstrated here, the same process is also possible in a moving image decoder.

Scanning method 1:
Priority is given to the determination of a prediction motion vector that does not require scaling operation using the same reference picture, and two condition determinations are performed for each prediction block among the four condition determinations. If the condition is not satisfied, the condition determination of the adjacent prediction block is performed. Move on. Condition determination 1 and condition determination 2 are performed in the first round, and condition determination 3 and condition determination 4 are performed in the next round of prediction blocks.

Specifically, the condition determination is performed in the following priority order. (However, N is A or B)
1. Condition determination 1 of the prediction block N0 (same reference list LX, same reference picture)
2. Prediction block N0 condition determination 2 (different reference list LY, same reference picture)
3. Condition determination 1 of the prediction block N1 (same reference list LX, same reference picture)
4). Condition determination 2 of the prediction block N1 (different reference list LY, same reference picture)
5. 5. Condition determination 1 of the prediction block N2 (the same reference list LX, the same reference picture), only the prediction block group adjacent on the upper side 6. Condition determination 2 of the prediction block N2 (different reference list LY, the same reference picture), only the prediction block group adjacent on the upper side Condition determination 3 of the prediction block N0 (same reference list LX, different reference pictures)
8). Prediction block N0 condition decision 4 (different reference list LY, different reference picture)
9. Condition determination 3 of the prediction block N1 (same reference list LX, different reference pictures)
10. Prediction block N1 condition determination 4 (different reference list LY, different reference picture)
11. 11. Condition determination 3 of the prediction block N2 (same reference list LX, different reference pictures), only the prediction block group adjacent on the upper side Predictive block N2 condition decision 4 (different reference list LY, different reference picture), upper adjacent prediction block group only

  According to the scanning method 1, since a prediction motion vector that does not require a scaling operation using the same reference picture is easily selected, there is an effect that the possibility that the code amount of the difference motion vector is reduced is increased. In addition, since the maximum number of rounds for condition determination is two, the number of memory accesses to the encoded information of the prediction block is reduced compared to the scan method 4 described later when considering implementation in hardware, and complexity is increased. Is reduced.

Scanning method 2:
Prioritizing the determination of the motion vector predictor using the same list, two condition determinations are performed for each prediction block among the four condition determinations. If the condition is not satisfied, the process proceeds to the condition determination for the adjacent prediction block. Condition determination 1 and condition determination 3 are performed in the first round, and condition determination 2 and condition determination 4 are performed in the next round of prediction blocks. At this time, it is not determined whether the reference pictures are the same or different.

Specifically, the condition determination is performed in the following priority order. (However, N is A or B)
1. Prediction block N0 condition decision 5 (same reference list LX, same or different reference pictures)
2. Prediction block N1 condition decision 5 (same reference list LX, same or different reference pictures)
3. 3. Condition determination 5 of the prediction block N2 (the same reference list LX, the same or different reference pictures), only the prediction block group adjacent on the upper side Prediction block N0 condition decision 6 (different reference lists LY, same or different reference pictures)
5. Condition determination 6 of the prediction block N1 (different reference lists LY, same or different reference pictures)
6). Condition determination 6 of the prediction block N2 (different reference lists LY, the same or different reference pictures), only the prediction block group adjacent on the upper side

  According to the scanning method 2, it becomes easy to select a motion vector predictor using the same list LX. In addition, since it is not necessary to determine whether the reference pictures are the same, the condition determination complexity is reduced.

Scan method 3:
Similar to the scan method 2, the determination of the motion vector predictor using the same list is given priority. However, priority is given to the condition determination of the same prediction block, and two condition determinations are performed within one prediction block. If all the conditions are not met, it is determined that there is no motion vector matching the condition in the prediction block. Then, the condition of the next prediction block is determined.

Specifically, the condition determination is performed in the following priority order. (However, N is A or B)
1. Prediction block N0 condition decision 5 (same reference list LX, same or different reference pictures)
2. Prediction block N0 condition decision 6 (different reference lists LY, same or different reference pictures)
3. Prediction block N1 condition decision 5 (same reference list LX, same or different reference pictures)
4). Condition determination 6 of the prediction block N1 (different reference lists LY, same or different reference pictures)
5. 5. Condition determination 5 of the prediction block N2 (the same reference list LX, the same or different reference pictures), only the prediction block group adjacent on the upper side Condition determination 6 of the prediction block N2 (different reference lists LY, the same or different reference pictures), only the prediction block group adjacent on the upper side

  According to the scanning method 3, it is not necessary to determine whether the reference pictures are the same or different as in the scanning method 2, so that the complexity is reduced. In addition, since the number of rounds of condition determination is at most one, the number of memory accesses to the encoded information of the prediction block is smaller than that of the scanning method 1 and the scanning method 2 when considering implementation in hardware. , Complexity is reduced.

Scanning method 4:
Of the four condition determinations, one condition determination is performed for each prediction block. If the condition is not satisfied, the process proceeds to the condition determination for the adjacent prediction block. If the condition determination is performed four times for each prediction block, the process is terminated.

Specifically, the condition determination is performed in the following priority order. (However, N is A or B)
1. Condition determination 1 of the prediction block N0 (same reference list LX, same reference picture)
2. Condition determination 1 of the prediction block N1 (same reference list LX, same reference picture)
3. 3. Condition determination 1 of the prediction block N2 (same reference list LX, same reference picture), only the prediction block group adjacent on the upper side Prediction block N0 condition determination 2 (different reference list LY, same reference picture)
5. Condition determination 2 of the prediction block N1 (different reference list LY, same reference picture)
6). 6. Condition determination 2 of the prediction block N2 (different reference list LY, the same reference picture), only the prediction block group adjacent on the upper side Condition determination 3 of the prediction block N0 (same reference list LX, different reference pictures)
8). Condition determination 3 of the prediction block N1 (same reference list LX, different reference pictures)
9. 9. Condition determination 3 of the prediction block N2 (same reference list LX, different reference pictures), only the prediction block group adjacent on the upper side Prediction block N0 condition decision 4 (different reference list LY, different reference picture)
11. Prediction block N1 condition determination 4 (different reference list LY, different reference picture)
12 Predictive block N2 condition decision 4 (different reference list LY, different reference picture), upper adjacent prediction block group only

  According to the scan method 4, since a prediction motion vector that does not require a scaling operation using the same reference picture is easily selected, there is an effect that the possibility that the code amount of the difference motion vector is reduced is increased. In addition, the number of rounds for condition determination is four times, and the number of memory accesses to the encoded information of the prediction block is larger than that in the scanning method 1 when considering implementation in hardware, but the prediction of the same reference list is performed. A motion vector is easily selected.

Scanning method 5:
In the first round, the condition determination of condition determination 1 is performed for each prediction block. In the next lap, condition determination is performed in order of condition determination 2, condition determination 3 and condition determination 4 for each prediction block, and then the process proceeds to the next.

Specifically, the condition determination is performed in the following priority order. (However, N is A or B)
1. Condition determination 1 of the prediction block N0 (same reference list LX, same reference picture)
2. Condition determination 1 of the prediction block N1 (same reference list LX, same reference picture)
3. 3. Condition determination 1 of the prediction block N2 (same reference list LX, same reference picture), only the prediction block group adjacent on the upper side Prediction block N0 condition determination 2 (different reference list LY, same reference picture)
5. Condition determination 3 of the prediction block N0 (same reference list LX, different reference pictures)
6). Prediction block N0 condition decision 4 (different reference list LY, different reference picture)
7). Condition determination 2 of the prediction block N1 (different reference list LY, same reference picture)
8). Condition determination 3 of the prediction block N1 (same reference list LX, different reference pictures)
9. Prediction block N1 condition determination 4 (different reference list LY, different reference picture)
10. 10. Condition determination 2 of the prediction block N2 (different reference list LY, same reference picture), only the prediction block group adjacent on the upper side 11. Condition determination 3 of the prediction block N2 (same reference list LX, different reference pictures), only the prediction block group adjacent on the upper side Predictive block N2 condition decision 4 (different reference list LY, different reference picture), upper adjacent prediction block group only

  According to the scan method 5, a prediction motion vector that does not require a scaling operation using the same reference picture in the same reference list is easily selected, so that there is an effect that the possibility that the code amount of the difference motion vector is reduced is increased. In addition, since the maximum number of condition determination cycles is two, the number of memory accesses to the encoded information of the prediction block is less than that of the scan method 4 when considering implementation in hardware, and complexity is reduced. Is done.

Scanning method 6:
Priority is given to condition determination of the same prediction block, and four condition determinations are performed within one prediction block. If all the conditions are not met, it is determined that there is no motion vector matching the condition in the prediction block. The condition of the next prediction block is determined.

Specifically, the condition determination is performed in the following priority order. (However, N is A or B)
1. Condition determination 1 of the prediction block N0 (same reference list LX, same reference picture)
2. Prediction block N0 condition determination 2 (different reference list LY, same reference picture)
3. Condition determination 3 of the prediction block N0 (same reference list LX, different reference pictures)
4). Prediction block N0 condition decision 4 (different reference list LY, different reference picture)
5. Condition determination 1 of the prediction block N1 (same reference list LX, same reference picture)
6). Condition determination 2 of the prediction block N1 (different reference list LY, same reference picture)
7). Condition determination 3 of the prediction block N1 (same reference list LX, different reference pictures)
8). Prediction block N1 condition determination 4 (different reference list LY, different reference picture)
9. 9. Condition determination 1 of the prediction block N2 (the same reference list LX, the same reference picture), only the prediction block group adjacent on the upper side 10. Condition determination 2 of the prediction block N2 (different reference list LY, same reference picture), only the prediction block group adjacent on the upper side 11. Condition determination 3 of the prediction block N2 (same reference list LX, different reference pictures), only the prediction block group adjacent on the upper side Condition determination 4 of the prediction block N2 (different reference list LY, different reference picture), only the prediction block group adjacent on the upper side According to the scan method 6, as in the scan method 3, the number of rounds of the condition determination is at most once. Therefore, when considering implementation in hardware, the number of memory accesses to the encoded information of the prediction block is smaller than that of scan method 1, scan method 2, scan method 4, and scan method 5, and complexity is reduced. Is done.

  Next, the motion vector predictor candidate registration unit 122 stores the motion vector predictor candidates mvLXA, mvLXB, and mvLXCol in the order of the motion vector predictor candidates mvpListLX.

  Next, the motion vector predictor redundant candidate deletion unit 123 compares the motion vector values of the motion vector predictor candidates stored in the motion vector list mvpListLX of the LX, and selects the same motion vector candidate from the motion vector predictor candidates. Judgment of motion vector values, leave one candidate motion vector candidate determined to have the same motion vector value, delete the rest from the motion vector predictor list mvpListLX, The predicted motion vector list mvpListLX is updated so that the candidates do not overlap. When deletion of a candidate is determined based only on the motion vector value of the predicted motion vector candidate, predicted motion vector candidates that have the same motion vector but different inter-picture distances are deleted from the predicted motion vector list. Therefore, in addition to the motion vector value of each predicted motion vector candidate stored in the predicted motion vector list mvpListLX, the inter-picture distance value is also compared, and the same inter-picture distance and motion are selected from the predicted motion vector candidates. Predicts those with vector values, leaves one candidate for the predicted motion vector determined to have the same inter-picture distance and motion vector value, and deletes the others from the predicted motion vector list mvpListLX for prediction Prevent motion vector candidates from overlapping, and update the motion vector predictor list mvpListLX to prevent deletion of motion vector candidates that have the same motion vector but different inter-picture distances from the motion vector predictor list You can also. However, when the motion vector value of the motion vector predictor candidate is (0, 0), the motion vector value is (0, 0) even if the scaling calculation is performed according to the inter-picture distance. When there are a plurality of motion vector predictor candidates whose vector value is (0, 0), regardless of the inter-picture distance value, one candidate can be left and other candidates can be regarded as redundant and deleted. .

  In the motion vector predictor candidate number limiting unit 124, the number of motion vector predictor candidates registered in the motion vector list mvpListLX of LX is counted, and the motion vector candidate number numMVPCandLX of LX is set to the counted candidate value. Is done.

  Further, the motion vector predictor candidate number limiting unit 124 limits the motion vector candidate number numMVPCandLX of LX registered in the motion vector list mvpListLX of LX to the defined final candidate number finalNumMVPCand.

  In the present embodiment, the final candidate number finalNumMVPCand is defined. This is because if the number of motion vector predictor candidates registered in the motion vector predictor list fluctuates according to the state of construction of the motion vector predictor list, the motion vector list on the decoding side must be constructed before the motion vector predictor list is constructed. This is because entropy decoding cannot be performed. Furthermore, if entropy decoding depends on the construction state of the motion vector predictor list including the motion vector candidate mvLXCol derived from the prediction block of the picture at different time, when an error occurs when decoding the encoded bit string of another picture The encoded bit string of the current picture is also affected by this, and there is a problem that entropy decoding cannot be continued normally. If the final candidate number finalNumMVPCand is defined as a fixed number, the prediction motion vector index can be entropy-decoded independently of the construction of the prediction motion vector list, and an error occurs when decoding the encoded bit string of another picture. However, it is possible to continue the entropy decoding of the coded bit string of the current picture without being affected by this.

  When the number of predicted motion vector candidates numMVPCandLX is smaller than the specified final candidate number finalNumMVPCand, the predicted motion vector candidate number limit unit 124 (0 until the predicted motion vector candidate number numMVPCandLX becomes the same value as the final candidate number finalNumMVPCand. , 0) is added to the motion vector list mvpListLX to limit the number of motion vector predictor candidates to a specified value. In this case, a motion vector having a value of (0, 0) may be added in duplicate, but on the decoding side, how the predicted motion vector index falls within the range from 0 to (the number of specified candidates −1). Even if a large value is taken, the predicted motion vector can be determined. On the other hand, when the number of predicted motion vector candidates for LX numMVPCandLX is larger than the final number of final candidates defined, finalNumMVPCand, all the elements registered in the index larger than finalNumMVPCand-1 are deleted from the predicted motion vector list mvpListLX. By setting the number of candidates numMVPCandLX to the same value as the final candidate number finalNumMVPCand, the number of motion vector predictor candidates is limited to a specified value. The updated prediction motion vector list mvpListLX is supplied to the prediction motion vector candidate code amount calculation unit 125 and the prediction motion vector selection unit 126.

  On the other hand, a motion vector mvLX of LX (X = 0 or 1) is detected for each prediction block by the motion vector detection unit 102 in FIG. These motion vectors mvLX are supplied to the prediction motion vector candidate code amount calculation unit 125 together with the prediction motion vector candidates of the updated prediction motion vector list mvpListLX.

  The motion vector predictor candidate code amount calculation unit 125 calculates the difference from the motion vector mvLX for each motion vector candidate mvpListLX [i] stored in the motion vector list mvpListLX of LX (X = 0 or 1). The motion vectors are calculated, the code amounts when the differential motion vectors are encoded are calculated, and supplied to the predicted motion vector selection unit 126. When calculating the differential motion vector, the value obtained by actually scaling each predicted motion vector candidate may be used as needed, or the division required for the scaling operation may be substituted with a bit shift operation. An approximate value calculated as above may be used. The predicted motion vector scaling calculator 127 can also be used for this scaling calculation.

  The motion vector predictor selection unit 126 corresponds to a motion vector predictor candidate mvpListLX [i] having the smallest code amount for each motion vector predictor candidate among the elements registered in the motion vector list mvpListLX of LX. The inter-picture distance is selected as the LX predicted motion vector mvpLX and the inter-picture distance distLX. In the case where there are a plurality of motion vector predictor candidates having the smallest generated code amount in the motion vector predictor list mvpListLX, the motion vector predictor candidates represented by the index i in the motion vector list mvpListLX with a small number mvpListLX [i] is selected as the LX optimum predicted motion vector mvpLX. The selected predicted motion vector mvpLX and inter-picture distance distLX are supplied to the predicted motion vector scaling calculator 127. Further, the index i in the predicted motion vector list corresponding to the selected predicted motion vector mvpLX is output as a predicted motion vector index mvpIdxLX of LX.

  The predicted motion vector scaling calculator 127 performs a scaling operation on the selected predicted motion vector mvpLX according to the inter-picture distance distLX, and supplies the scaled predicted motion vector mvpLX to the motion vector subtractor 128. Note that, when the motion vector predictor candidate code amount calculation unit 125 actually performs a scaling operation on each motion vector predictor candidate, the value may be used. Details of the scaling operation will be described later with reference to FIGS.

Finally, the motion vector subtracting unit 128 calculates an LX differential motion vector mvdLX by subtracting the LX predicted motion vector mvpLX selected from the LX motion vector mvLX and scaled according to the inter-picture distance distLX. Outputs motion vector mvdLX.
mvdLX = mvLX-mvpLX

  Returning to FIG. 1, the motion compensation prediction unit 105 refers to the image signal of the decoded picture stored in the decoded image memory 115, and the motion vector of LX (X = 0 or 1) supplied from the motion vector detection unit 102. Motion compensation is performed according to mvLX to obtain a predicted image signal, which is supplied to the prediction method determination unit 106.

  The prediction method determination unit 106 determines a prediction method. The code amount and the coding distortion are calculated for each prediction mode, and the prediction block size and the prediction mode for the smallest generated code amount and coding distortion are determined. The LX differential motion vector mvdLX supplied from the motion vector subtraction unit 128 of the differential motion vector calculation unit 103 and the LX prediction motion vector index mvpIdxLX representing the prediction motion vector supplied from the prediction motion vector selection unit 126 are encoded. The code amount of motion information is calculated. Further, the code amount of the prediction residual signal obtained by encoding the prediction residual signal between the prediction image signal supplied from the motion compensation prediction unit 105 and the image signal to be encoded supplied from the image memory 101 is calculated. The total generated code amount obtained by adding the code amount of the motion information and the code amount of the prediction residual signal is calculated and used as the first evaluation value.

  Further, after encoding such a prediction residual signal, it is decoded for distortion amount evaluation, and the encoding distortion is calculated as a ratio representing an error from the original image signal caused by the encoding. By comparing the total generated code amount and the coding distortion for each motion compensation, the prediction block size and the prediction mode that generate the least generated code amount and the coding distortion are determined. The motion vector prediction method described above is performed on the motion vector mvLX corresponding to the prediction mode of the determined prediction block size, and the index mvpIdxLX representing the prediction motion vector is a second syntax pattern in units of prediction blocks. It is encoded as the represented syntax element mvp_idx_lX [i]. The generated code amount calculated here is preferably a simulation of the encoding process, but can be approximated or approximated easily.

(Prediction of motion vector in decoding)
The operation of the motion vector prediction method according to the present invention in the video decoding device that decodes the encoded video bitstream based on the above-described syntax will be described.

  When the motion vector prediction method according to the embodiment is performed, processing is performed by the motion vector calculation unit 204 of the video decoding device in FIG. FIG. 14 is a diagram illustrating a detailed configuration of the motion vector calculation unit 204 of the video decoding device of FIG. 2 corresponding to the video encoding device of the embodiment. A portion surrounded by a thick frame line in FIG. 14 indicates the motion vector calculation unit 204. Further, the part surrounded by the thick dotted line inside shows the operation part of the motion vector prediction method described later, which is also installed in the corresponding moving picture coding apparatus in the same way and has the same consistency between coding and decoding. Judgment results are obtained. Hereinafter, a motion vector prediction method in decoding will be described with reference to FIG.

  The motion vector calculation unit 204 includes a predicted motion vector candidate generation unit 221, a predicted motion vector candidate registration unit 222, a predicted motion vector redundant candidate deletion unit 223, a predicted motion vector candidate number limit unit 224, a predicted motion vector selection unit 225, a predicted motion A vector scaling calculation unit 226 and a motion vector addition unit 227 are included.

  In the motion vector calculation process in the motion vector calculation unit 204, a motion vector used in inter prediction is calculated for each of L0 and L1. Specifically, when the prediction mode PredMode of the encoding target block is inter prediction (MODE_INTER) and the inter prediction mode of the encoding target block is L0 prediction (Pred_L0), the prediction motion vector list mvpListL0 of L0 is calculated and predicted. A motion vector mvpL0 is selected, and a motion vector mvL0 of L0 is calculated. When the inter prediction mode of the encoding target block is L1 prediction (Pred_L1), the L1 predicted motion vector list mvpListL1 is calculated, the predicted motion vector mvpL1 is selected, and the L1 motion vector mvL1 is calculated. When the inter prediction mode of the encoding target block is bi-prediction (Pred_BI), both L0 prediction and L1 prediction are performed, a prediction motion vector list mvpListL0 of L0 is calculated, a prediction motion vector mvpL0 of L0 is selected, and L0 Motion vector mvL0, L1 predicted motion vector list mvpListL1 is calculated, L1 predicted motion vector mvpL1 is calculated, and L1 motion vector mvL1 is calculated.

  Similar to the encoding side, the motion vector calculation processing is performed for each of L0 and L1 on the decoding side, but both L0 and L1 are common processing. Therefore, in the following description, L0 and L1 are represented as a common LX. X is 0 in the process of calculating the L0 motion vector, and X is 1 in the process of calculating the L1 motion vector. When the information of the other list is referred to instead of LX during the process of calculating the LX motion vector, the other list is represented as LY.

  The motion vector calculation unit 204 includes a motion vector predictor candidate generation unit 221, a motion vector predictor candidate registration unit 222, a motion vector motion redundancy candidate deletion unit 223, a motion vector motion vector candidate number limiting unit 224, and a motion vector predictor scaling calculation unit 226. The prediction motion vector candidate generation unit 121, the prediction motion vector candidate registration unit 122, the prediction motion vector redundant candidate deletion unit 123, the prediction motion vector candidate number restriction unit 124, and the prediction motion in the differential motion vector calculation unit 103 on the encoding side. By defining the same operation as that of the vector scaling operation unit 127, it is possible to obtain the same motion vector predictor candidates that are consistent in encoding and decoding on the encoding side and decoding side.

  The motion vector predictor candidate generation unit 221 performs the same processing as that of the motion vector predictor candidate generation unit 121 on the encoding side in FIG. The same position as or near the decoded prediction block adjacent to the decoding target block in the same picture as the decoding target block and the decoding target block in a different picture recorded in the encoded information storage memory 209 after decoding. Are read out from the encoded information storage memory 209. Predicted motion vector candidates mvLXA, mvLXB, mvLXCol are selected for each predicted block group from the motion vectors of other decoded blocks read from the encoded information storage memory 209, and the corresponding inter-picture distances distA, distB, distCol are selected. At the same time, the predicted motion vector candidate registration unit 222 is supplied.

  Since the motion vector predictor candidate generation unit 221 performs the same processing as that of the motion vector predictor candidate generation unit 121 on the encoding side in FIG. 13, the motion vector predictor candidate generation unit 121 on the encoding side in FIG. The condition determination of the scan methods 1, 2, 3, 4, 5, and 6 for calculating the predicted motion vector can be applied also by the predicted motion vector candidate generation unit 221, and detailed description thereof is omitted here.

  Next, the motion vector predictor candidate registration unit 222 performs the same processing as that of the motion vector predictor candidate registration unit 122 on the encoding side in FIG. The calculated motion vector candidates mvLXA, mvLXB, and mvLXCol are stored in the LX motion vector predictor list mvpListLX in this order.

  Next, the motion vector redundancy candidate deletion unit 223 performs the same process as the motion vector redundancy candidate deletion unit 123 on the encoding side in FIG. The motion vector values of the motion vector predictor candidates stored in the motion vector list mvpListLX of the LX are compared, and the motion vector values of the motion vector predictor candidates that have the same motion vector value are determined. Predictive motion vector list mvpListLX is created by removing one candidate for the predicted motion vector determined to have motion vector values and deleting the other from the predicted motion vector list mvpListLX so that the predicted motion vector candidates do not overlap. Update. In this case, prediction motion vector candidates that have the same motion vector but different inter-picture distances are deleted from the prediction motion vector list mvpListLX. Therefore, in addition to the motion vector value of each predicted motion vector candidate stored in the predicted motion vector list mvpListLX, the inter-picture distance value is also compared, and the same inter-picture distance distN is selected from the predicted motion vector candidates. Judgments with motion vector values are made, leaving one of the predicted motion vector candidates determined to have the same inter-picture distance distN and motion vector values, and deleting the others from the motion vector predictor list mvpListLX The predicted motion vector candidates are not duplicated, and the predicted motion vector list mvpListLX is updated so that the predicted motion vector candidates that have the same motion vector but different inter-picture distances are deleted from the predicted motion vector list. Can also be prevented.

  Next, the motion vector predictor candidate number limiting unit 224 performs the same processing as the motion vector predictor candidate number limiting unit 124 on the encoding side in FIG. In the motion vector predictor candidate number limiting unit 224, the number of elements registered in the motion vector predictor list mvpListLX is counted, and the motion vector candidate number numMVPCandLX of LX is set to the value of the counted candidate number.

  Furthermore, the motion vector predictor candidate number limiting unit 224 limits the number of predicted motion vector candidates numMVPCandLX of LX registered in the motion vector predictor list mvpListLX to the specified final candidate number finalNumMVPCand for the reason described on the encoding side. When the number of predicted motion vector candidates for LX numMVPCandLX is smaller than the specified final candidate number finalNumMVPCand, a motion vector having a value of (0, 0) is obtained until the predicted motion vector candidate number numMVPCandLX becomes the same value as the final candidate number finalNumMVPCand. By adding to the motion vector predictor list mvpListLX, the number of motion vector predictor candidates is limited to a specified value. In this case, a motion vector having a value of (0, 0) may be added in duplicate, but on the decoding side, any value within the range of the predicted motion vector index from 0 to the specified value −1 is taken. The predicted motion vector can be determined. On the other hand, when the number of predicted motion vector candidates for LX numMVPCandLX is larger than the final number of final candidates defined, finalNumMVPCand, all the elements registered in the index larger than finalNumMVPCand-1 are deleted from the predicted motion vector list mvpListLX. By setting the number of candidates numMVPCandLX to the same value as the final candidate number finalNumMVPCand, the number of motion vector predictor candidates is limited to a specified value. The updated motion vector predictor list mvpListLX is supplied to the motion vector predictor selection unit 225.

  On the other hand, the LX (X = 0 or 1) differential motion vector mvdLX for each prediction block decoded by the first encoded bit string decoding unit 202 is supplied to the motion vector addition unit 227. The predicted motion vector index mvpIdxLX of the LX predicted motion vector decoded by the first encoded bit string decoding unit 202 is supplied to the predicted motion vector selection unit 225.

  The motion vector predictor selection unit 225 is supplied with the LX motion vector predictor index mvpIdxLX decoded by the first encoded bit stream decoder 202, and the motion vector predictor candidate mvpListLX [corresponding to the supplied motion vector predictor index mvpIdxLX The inter-picture distance corresponding to mvpIdxLX] is extracted from the LX predicted motion vector list mvpListLX as the selected LX predicted motion vector mvpLX and inter-picture distance distLX. The supplied candidate motion vector predictor is supplied to the motion vector adding unit 227 as a motion vector predictor mvpLX.

  The predicted motion vector scaling calculator 226 performs the same processing as that of the predicted motion vector scaling calculator 127 on the encoding side in FIG. The predicted motion vector scaling calculator 226 performs a scaling operation on the selected predicted motion vector mvpLX according to the inter-picture distance distLX, and supplies the scaled predicted motion vector mvpLX to the motion vector adder 227. Details of the scaling operation will be described later with reference to FIGS.

Finally, the motion vector adding unit 227 adds the LX differential motion vector mvdLX decoded and supplied by the first encoded bit string decoding unit 202 and the LX predicted motion vector mvpLX scaled according to the inter-picture distance distN. As a result, the LX motion vector mv is calculated, and the motion vector mvLX is output.
mvLX = mvpLX + mvdLX

  As described above, the LX motion vector mvLX is calculated for each prediction block. A predicted image signal is generated by motion compensation using this motion vector, and is added to the decoded prediction residual signal to generate a decoded image signal.

  Processing procedures of the difference motion vector calculation unit 103 of the moving image encoding device and the motion vector calculation unit 204 of the moving image decoding device will be described with reference to flowcharts of FIGS. 15 and 16, respectively. FIG. 15 is a flowchart showing a difference motion vector calculation processing procedure by the moving image encoding device, and FIG. 16 is a flowchart showing a motion vector calculation processing procedure by the moving image decoding device.

  The difference motion vector calculation processing procedure on the encoding side will be described with reference to FIG. On the encoding side, the differential motion vector calculation unit 103 calculates the differential motion vector of the motion vector used in the inter prediction selected in the encoding target block for each of L0 and L1 (S101 to S107). Specifically, when the prediction mode PredMode of the encoding target block is inter prediction (MODE_INTER) and the inter prediction mode is L0 prediction (Pred_L0), a prediction motion vector list mvpListL0 of L0 is calculated and a prediction motion vector mvpL0 is selected. Then, the differential motion vector mvdL0 of the motion vector mvL0 of L0 is calculated. When the inter prediction mode of the block to be encoded is L1 prediction (Pred_L1), the prediction motion vector list mvpListL1 of L1 is calculated, the prediction motion vector mvpL1 is selected, and the differential motion vector mvdL1 of the motion vector mvL1 of L1 is calculated. . When the inter prediction mode of the encoding target block is bi-prediction (Pred_BI), both L0 prediction and L1 prediction are performed, a prediction motion vector list mvpListL0 of L0 is calculated, a prediction motion vector mvpL0 of L0 is selected, and L0 A difference motion vector mvdL0 of the L1 motion vector mvLL, a prediction motion vector list mvpListL1 of the L1, a prediction motion vector mvpL1 of the L1, and a difference motion vector mvdL1 of the motion vector mvL1 of the L1. .

  Difference motion vector calculation processing is performed for each of L0 and L1, but both L0 and L1 are common processing. Therefore, in the following description, L0 and L1 are represented as a common LX. In the process of calculating the differential motion vector of L0, X is 0, and in the process of calculating the differential motion vector of L1, X is 1. Further, when referring to the information of the other list instead of LX during the process of calculating the differential motion vector of LX, the other list is represented as LY.

  When the LX differential motion vector mvdLX is calculated (YES in S102), the LX predicted motion vector candidates are calculated to construct the LX predicted motion vector list mvpListLX (S103). The motion vector predictor candidate generation unit 121 in the motion vector difference calculation unit 103 calculates a plurality of motion vector predictor candidates, and the motion vector predictor candidate registration unit 122 calculates the motion vector predictor candidates calculated in the motion vector predictor list mvpListLX. In addition, the motion vector redundancy candidate deletion unit 123 deletes unnecessary motion vector predictor candidates, and the motion vector predictor candidate number limiting unit 124 registers the number of motion vector motion vector candidates numMVPCandLX in the motion vector list mvpListLX. Is set and the predicted motion vector list mvpListLX is constructed by limiting the number of predicted motion vector candidates numMVPCandLX of LX registered in the predicted motion vector list mvpListLX to the final number of final candidates finalNumMVPCand. The detailed processing procedure of step S103 will be described later with reference to the flowchart of FIG.

  Subsequently, the predicted motion vector candidate code amount calculation unit 125 and the predicted motion vector selection unit 126 select the LX predicted motion vector mvpLX from the LX predicted motion vector list mvpListLX (S104). First, the prediction motion vector candidate code amount calculation unit 125 calculates a difference motion vector from the motion vector mvLX for each prediction motion vector candidate mvpListLX [i] stored in the prediction motion vector list mvpListLX, The code amount when the differential motion vector is encoded is calculated. When calculating the difference motion vector, the value obtained by actually scaling each predicted motion vector candidate may be used as necessary, or the division required for the scaling operation by simplifying the scaling operation An approximate value calculated by substituting with a bit shift operation may be used. Furthermore, among the elements registered in the motion vector predictor list mvpListLX by the motion vector predictor selection unit 126, it corresponds to a motion vector candidate mvpListLX [i] that has the smallest code amount for each motion vector predictor candidate. The inter-picture distances are selected as the LX predicted motion vector mvpLX and the inter-picture distance distLX, respectively. In the case where there are a plurality of motion vector predictor candidates having the smallest generated code amount in the motion vector predictor list mvpListLX, the motion vector predictor candidates represented by the index i in the motion vector list mvpListLX with a small number Select mvpListLX [i] as the optimal prediction motion vector mvpLX.

  Subsequently, the motion vector scaling calculator 127 performs a scaling operation on the selected motion vector mvpLX according to the inter-picture distance distLX (S105). The detailed processing procedure of step S105 will be described later with reference to the flowcharts of FIGS.

Subsequently, the motion vector subtraction unit 128 calculates the LX differential motion vector mvdLX by subtracting the LX predicted motion vector mvpLX scaled according to the inter-picture distance distN from the LX motion vector mvLX (S106).
mvdLX = mvLX-mvpLX
However, when the accurate difference motion vector is already calculated by the scaling operation in step S104, the processing of step S105 and step S106 may be omitted, and the value of the difference motion vector mvdLX calculated in step S104 may be used.

  Next, the decoding-side motion vector calculation processing procedure will be described with reference to FIG. On the decoding side, the motion vector calculation unit 204 calculates motion vectors used for inter prediction for each of L0 and L1 (S201 to S207). Specifically, when the prediction mode PredMode of the encoding target block is inter prediction (MODE_INTER) and the inter prediction mode of the encoding target block is L0 prediction (Pred_L0), the prediction motion vector list mvpListL0 of L0 is calculated and predicted. A motion vector mvpL0 is selected, and a motion vector mvL0 of L0 is calculated. When the inter prediction mode of the encoding target block is L1 prediction (Pred_L1), the L1 predicted motion vector list mvpListL1 is calculated, the predicted motion vector mvpL1 is selected, and the L1 motion vector mvL1 is calculated. When the inter prediction mode of the encoding target block is bi-prediction (Pred_BI), both L0 prediction and L1 prediction are performed, a prediction motion vector list mvpListL0 of L0 is calculated, a prediction motion vector mvpL0 of L0 is selected, and L0 Motion vector mvL0, L1 predicted motion vector list mvpListL1 is calculated, L1 predicted motion vector mvpL1 is calculated, and L1 motion vector mvL1 is calculated.

  Similar to the encoding side, the motion vector calculation processing is performed for each of L0 and L1 on the decoding side, but both L0 and L1 are common processing. Therefore, in the following description, L0 and L1 are represented as a common LX. X is 0 in the process of calculating the L0 motion vector, and X is 1 in the process of calculating the L1 motion vector. When the information of the other list is referred to instead of LX during the process of calculating the LX motion vector, the other list is represented as LY.

  When calculating the LX motion vector mvdLX (YES in S202), the LX predicted motion vector candidates are calculated to construct the LX predicted motion vector list mvpListLX (S203). The motion vector calculation unit 204 includes a motion vector predictor candidate generation unit 221 that calculates a plurality of motion vector predictor candidates, and the motion vector predictor candidate registration unit 222 adds the motion vector predictor candidates calculated to the motion vector predictor list mvpListLX. Then, the motion vector redundancy candidate deletion unit 223 deletes unnecessary motion vector predictor candidates, and the motion vector predictor candidate number limit unit 224 stores the number of motion vector motion vector candidates numMVPCandLX registered in the motion vector predictor list mvpListLX. The predicted motion vector list mvpListLX is constructed by limiting the set number of predicted motion vector candidates numMVPCandLX of LX registered in the predicted motion vector list mvpListLX to the final number of final candidates finalNumMVPCand. The detailed processing procedure of step S203 will be described later using the flowchart of FIG.

  Subsequently, a predicted motion vector candidate mvpListLX [mvpIdxLX] corresponding to the predicted motion vector index mvpIdxLX decoded by the first encoded bit string decoding unit 202 from the LX predicted motion vector list mvpListLX by the predicted motion vector selection unit 225 and The inter-picture distance is extracted as the selected predicted motion vector mvpLX and inter-picture distance distLX (S204).

  Subsequently, the motion vector scaling calculator 127 performs a scaling operation on the selected motion vector mvpLX according to the inter-picture distance distLX (S205). The detailed processing procedure of step S105 will be described later with reference to the flowcharts of FIGS.

Subsequently, the motion vector adding unit 227 calculates the LX motion vector mvLX by adding the LX differential motion vector mvdLX decoded and supplied by the first encoded bit string decoding unit 202 and the LX predicted motion vector mvpLX. (S206).
mvLX = mvpLX + mvdLX

  Next, a procedure for derivation of a prediction motion vector candidate common to S103 of FIG. 15 and S203 of FIG. 16 and a prediction motion vector list construction process will be described in detail with reference to the flowchart of FIG.

(Motion vector prediction method)
FIG. 17 shows prediction motion vector candidate generation units 121 and 221 having a function common to the difference motion vector calculation unit 103 of the moving image encoding device and the motion vector calculation unit 204 of the moving image decoding device, and a prediction motion vector candidate registration unit 122. And 222, and the motion vector redundancy candidate deletion units 123 and 223 and the motion vector predictor candidate number limiting units 124 and 224 are flowcharts.

  The motion vector predictor candidate generation units 121 and 221 derive motion vector predictor candidates from the prediction block adjacent on the left side, a flag availableFlagLXA indicating whether the motion vector candidate of the prediction block adjacent on the left side can be used, and motion A vector mvLXA, a reference index refIdxA, and a list ListA are derived (S301 in FIG. 17). Note that X is 0 when L0 and X is 1 when L1 (the same applies hereinafter). Subsequently, the motion vector predictor candidate generation units 121 and 221 derive a motion vector predictor candidate from the upper adjacent prediction block, and a flag availableFlagLXB indicating whether the motion vector predictor candidate of the upper adjacent prediction block can be used. , And a motion vector mvLXB, a reference index refIdxB, and a list ListB are derived (S302 in FIG. 17). The processes of S301 and S302 in FIG. 17 are common except that the positions and numbers of adjacent blocks to be referenced are different, and a flag availableFlagLXN indicating whether or not a predicted motion vector candidate of a prediction block can be used, a motion vector mvLXN, and a reference index A common derivation procedure for deriving refIdxN, ListN, and inter-picture distance distN (N is A or B, the same applies hereinafter) will be described in detail later with reference to the flowcharts of FIGS.

  Subsequently, the motion vector predictor candidate generation units 121 and 221 derive motion vector predictor candidates from the prediction blocks of the pictures at different times, and indicate whether the motion vector predictor candidates of the motion pictures at different times can be used. The flag availableFlagLXCol, the motion vector mvLXCol, the reference index refIdxCol, the list ListCol, and the inter-picture distance distCol are derived (S303 in FIG. 17). The derivation processing procedure of step S303 will be described in detail later with reference to the flowcharts of FIGS.

  Subsequently, the motion vector predictor candidate registration units 122 and 222 create an LX motion vector predictor list mvpListLX, and add respective motion vector candidates mvLXA, mvLXB, and mvLXCol for LX (S304 in FIG. 17). At this time, the inter-picture distances distA, distB, and distCol corresponding to the respective prediction vector candidates mvLXA, mvLXB, and mvLXCol of LX are also managed in association with each other using the prediction motion vector list mvpListLX. The registration processing procedure in step S304 will be described in detail later using the flowchart of FIG.

  Subsequently, when the motion vector redundancy candidate deletion units 123 and 223 have the same inter-picture distance distN and motion vector values from a plurality of motion vector candidates in the motion vector predictor list mvpListLX, It is determined that the candidate is a redundant motion vector, and redundant motion vector candidates are removed except for the motion vector candidate with the smallest order, that is, the smallest index i (S305 in FIG. 17). The deletion processing procedure in step S305 will be described in detail later using the flowchart of FIG.

  Subsequently, the motion vector predictor candidate number limiting units 124 and 224 count the number of elements added in the motion vector predictor list mvpListLX, and the number is set as the motion vector vector candidate number numMVPCandLX of the LX. The number of predicted motion vector candidates for LX numMVPCandLX registered in mvpListLX is limited to the specified final candidate number finalNumMVPCand. (S306 in FIG. 17). The restriction processing procedure in step S306 will be described in detail later using the flowchart of FIG.

  A procedure for deriving motion vector predictor candidates from prediction blocks adjacent to the left or upper side of S301 and S302 in FIG. 17 will be described in detail.

  As shown in FIGS. 5, 6, 7, and 8, a prediction block (in FIG. 5, FIG. 6, FIG. 7, and FIG. 8) that is defined for motion compensation within a coding block in the same picture. A motion vector predictor candidate is derived from surrounding prediction blocks adjacent to the processing target prediction block.

  The motion vector predictor candidates are the prediction block Ak (k = 0, 1) adjacent to the left side of the prediction block to be processed, that is, the prediction block group A composed of A0 and A1, and the prediction block Bk (k) adjacent above. = 0, 1, 2), that is, predictive motion vector candidates are selected from the prediction block group B composed of B0, B1, and B2.

  Next, a method for deriving prediction motion vector candidates from the prediction block group N adjacent on the left and upper sides, which is the processing procedure of S301 and S302 in FIG. 17, will be described. FIG. 18 is a flowchart showing a predicted motion vector candidate derivation process procedure of S301 and S302 of FIG. Subscript X contains 0 or 1 representing the reference list, and N represents A (left side) or B (upper side) representing the area of the adjacent prediction block group.

  In order to derive motion vector predictor candidates from the left prediction block (S301 in FIG. 17), N is assumed to be A in FIG. 18, and prediction is performed from prediction blocks A0 and A1 adjacent to the left side of the prediction block to be encoded / decoded. In order to derive a motion vector candidate from the upper prediction block (S302 in FIG. 17), a motion vector predictor is predicted from the B0, B1, and B2 prediction blocks adjacent to the upper side with N as B in FIG. The candidates are calculated according to the following procedure.

  First, a prediction block adjacent to a prediction block to be encoded / decoded is specified, and encoding is performed when each prediction block Nk (k = 0, 1, 2, where 2 is only the upper prediction block group) can be used. The encoded information stored in the information storage memory 114 or the encoded information storage memory 209 is acquired. The encoding information of the adjacent prediction block Nk acquired here includes the flags predFlagLX [xNk] [yNk] indicating whether to use the prediction modes PredMode and LX, the LX reference indexes refIdxLX [xNk] [yNk], and LX. The motion vector mvLX [xNk] [yNk]. In the case of a prediction block group (N = A) adjacent to the left side of the prediction block to be encoded / decoded (YES in S1101), the prediction block A0 adjacent to the lower left and the prediction block A1 adjacent to the left are specified and encoded. Information is acquired (S1102, S1103), and in the case of a prediction block group (N = B) adjacent to the upper side of the prediction block to be encoded / decoded (NO in S1101), adjacent to the prediction block B0 adjacent to the upper right Coding information is acquired by specifying the prediction block B1 to be predicted and the prediction block B2 adjacent to the upper left (S1104, S1105, S1106). It can be used when the adjacent prediction block Nk is located inside the slice including the prediction block to be encoded / decoded, and cannot be used when located outside.

  Next, a flag availableFlagLXN indicating whether or not a prediction motion vector is selected from the prediction block group N is set to 0, and a motion vector mvLXN representing the prediction block group N is set to (0, 0) (S1107).

  Subsequently, a motion vector predictor candidate that matches the aforementioned condition determination 1 or condition determination 2 is selected (S1108). Reference list that is currently targeted by the prediction block to be encoded / decoded in the adjacent prediction blocks N0, N1, and N2 (N2 is only the upper adjacent prediction block group B) of the prediction block group N (N is A or B) The same reference list LX as LX, or the reference list LY opposite to the reference list LX that is the current target in the encoding / decoding target prediction block (Y =! X: the opposite reference list when the current target reference list is L0) Is L1, and when the current reference list is L1, the opposite reference list is L0), and the motion vector of the same reference picture is searched for and the motion vector is set as a motion vector predictor candidate.

  FIG. 19 is a flowchart showing the derivation process procedure of step S1108 of FIG. For the adjacent prediction block Nk (k = 0, 1, 2, where 2 is only the upper adjacent prediction block group), the following processing is performed in the order of k, 0, 1, 2 (S1201 to S1207). ). When N is A, the following processing is performed in the order of A0 and A1 from bottom to top, and when N is B, the following processing is performed in the order of B0, B1, and B2 from right to left.

  When the adjacent prediction block Nk can be used and the prediction mode PredMode of the prediction block Nk is not intra (MODE_INTRA) (YES in S1202), the condition determination of the above-described condition determination 1 is performed (S1203). The flag predFlagLX [xNk] [yNk] indicating whether or not to use the LX of the adjacent prediction block Nk is 1, that is, the adjacent prediction block Nk is inter-predicted using the same LX motion vector as the calculation target and adjacent When the LX reference index refIdxLX [xNk] [yNk] of the prediction block Nk and the index refIdxLX of the prediction block to be processed are the same, that is, when adjacent prediction blocks Nk are inter-predicted using the same reference picture in LX prediction ( If YES in step S1203, the process advances to step S1204. If not (NO in step S1203), the condition determination in step S1205 is performed.

  When step S1203 is YES, the flag availableFlagLXN is set to 1, the prediction motion vector mvLXN of the prediction block group N is set to the same value as the LX motion vector mvLX [xNk] [yNk] of the adjacent prediction block Nk, and prediction is performed. The reference index refIdxN of the block group N is set to the same value as the LX reference index refIdxLX [xNk] [yNk] of the adjacent prediction block Nk, the reference list ListN of the prediction block group N is set to LX (S1204), step The process proceeds to S1208.

  On the other hand, when step S1203 is NO, the condition determination of the above-described condition determination 2 is performed (S1205). The flag predFlagLY indicating whether to use the LY of the adjacent prediction block Nk is 1, that is, the adjacent prediction block Nk is inter-predicted using a motion vector of LY different from the calculation target, and the current target of the adjacent prediction block Nk Inter prediction using the same reference picture in the LY prediction where the POC of the reference picture in the reference list LY opposite to the reference list LX is the same as the POC of the reference picture of the LX of the prediction block to be processed If YES in step S1205, the process advances to step S1206, the flag availableFlagLXN is set to 1, and the prediction motion vector mvLXN of the prediction block group N is the LY motion vector mvLY [xNk] [yNk] of the adjacent prediction block Nk. And the reference index refIdxN of the prediction block group N is It is set to the same value as the LY reference index refIdxLY [xNk] [yNk] of the adjacent prediction block Nk, the reference list ListN of the prediction block group N is set to LY (S1206), and the process proceeds to step S1208.

Subsequently, when availableFlagLXN is 1 (YES in S1208), the inter-picture distance distN is calculated by subtracting the POC of the reference picture referenced by the reference list ListN of the adjacent prediction block from the POC of the current encoding / decoding target picture. (S1209), and the prediction vector candidate selection process ends. When the reference picture referred to in the adjacent prediction block list ListN is earlier in the display order than the current encoding / decoding target picture, the inter-picture distance distN is a positive value, and the current encoding / decoding target When the reference picture referenced in the reference list ListN of the adjacent prediction block is later in the display order than the picture, the inter-picture distance distN is a negative value.
distN = POC of current encoding / decoding target picture—POC of reference picture referenced in reference list ListN of adjacent prediction block

  If these conditions are not met, that is, if NO in S1203 or NO in S1205, k is incremented by 1 and the next adjacent prediction block processing (S1201 to S1207) is performed, and availableFlagLXN becomes 1 or adjacent block Repeat until A1 or B2 is finished.

  Subsequently, returning to the flowchart of FIG. 18, when availableFlagLXN is 0 (YES in S1109), that is, when a motion vector predictor candidate cannot be calculated in step S1108, prediction that matches the above-described condition determination 3 or condition determination 4 Motion vector candidates are calculated (S1110). The reference list LX that is currently targeted by the prediction block to be encoded / decoded among the adjacent blocks N0, N1, and N2 (N2 is only the upper adjacent prediction block group B) of the prediction block group N (N is A or B) Or the reference list LY opposite to the current reference list LX in the encoding / decoding target prediction block (Y =! X: when the current target reference list is L0, the opposite reference list is L1, when the current target reference list is L1, the opposite reference list is L0), and a prediction block having a motion vector of a different reference picture is searched and the motion vector is set as a motion vector predictor candidate.

  FIG. 20 is a flowchart showing the derivation process procedure of step S1110 of FIG. For adjacent prediction blocks Nk (k = 0, 1, 2, where 2 is only the upper adjacent prediction block group), the following processing is performed in the order of k, 0, 1, 2 (S1301 to S1307). ). When N is A, the following processing is performed in the order of A0 and A1 from bottom to top, and when N is B, the following processing is performed in the order of B0, B1, and B2 from right to left.

  When the adjacent prediction block Nk can be used and the prediction mode PredMode of the prediction block Nk is not intra (MODE_INTRA) (YES in S1302), the condition determination of the above-described condition determination 3 is performed (S1303). When the flag predFlagLX [xNk] [yNk] indicating whether or not to use the LX of the adjacent prediction block Nk is 1, that is, when the adjacent prediction block Nk is inter-predicted using the same LX motion vector as the calculation target, step The process proceeds to S1304, and if not (NO in S1303), the condition is determined in Step S1305.

  When step S1303 is YES, the flag availableFlagLXN is set to 1, the mvLXN of the prediction block group N is set to the same value as the LX motion vector mvLX [xNk] [yNk] of the adjacent prediction block Nk, and the prediction block group N Is set to the same value as the LX reference index refIdxLX [xNk] [yNk] of the adjacent prediction block Nk, the reference list ListN of the prediction block group N is set to LX (S1304), and the process proceeds to step S1308. .

  When step S1303 is NO, the condition determination of the above-described condition determination 4 is performed (S1305). When the flag predFlagLY indicating whether to use the LY of the adjacent prediction block Nk is 1, that is, when the adjacent prediction block Nk is inter-predicted using a motion vector of LY different from the calculation target (YES in S1305), the flag availableFlagLXN Is set to 1, the prediction motion vector mvLXN of the prediction block group N is set to the same value as the LY motion vector mvLY [xNk] [yNk] of the adjacent prediction block Nk, and the prediction motion vector mvLXN of the prediction block group N is The LY motion vector mvLY [xNk] [yNk] of the adjacent prediction block Nk is set to the same value, and the reference index refIdxN of the prediction block group N is the LY reference index refIdxLY [xNk] [yNk] of the adjacent prediction block Nk , The reference list ListN of the prediction block group N is set to LY (S1306), step The process proceeds to S1308.

  On the other hand, if these conditions are not met (NO in S1303 or NO in S1305), k is incremented by 1, and the next adjacent prediction block is processed (S1301 to S1307), and availableFlagLXN becomes 1, The process is repeated until the processing of the adjacent block A1 or B2 is completed, and the process proceeds to step S1308.

Subsequently, when availableFlagLXN is 1 (YES in S1308), the inter-picture distance distN is calculated by subtracting the POC of the reference picture referenced in the reference list ListN of the adjacent prediction block from the POC of the current encoding / decoding target picture. In step S1309, the prediction vector candidate selection process is terminated.
distN = POC of current encoding / decoding target picture—POC of reference picture referenced in reference list ListN of adjacent prediction block

  Next, a method for deriving motion vector predictor candidates from the prediction blocks of pictures at different times in S303 in FIG. 17 will be described in detail. FIG. 21 is a flowchart for explaining the predicted motion vector candidate derivation processing procedure in step S303 in FIG.

  First, a picture colPic at a different time is derived based on the slice type slice_type and the aforementioned flag collocated_from_l0_flag (S2101 in FIG. 21).

  FIG. 22 is a flowchart for explaining the procedure for deriving the picture colPic at different times in step S2101 of FIG. When the slice type slice_type is B and the aforementioned flag collocated_from_l0_flag is 0 (YES in S2201 in FIG. 22, YES in S2202), RefPicList1 [0], that is, the picture colPic at which the pictures with the reference index 0 in the reference list L1 have different times (S2203 in FIG. 22). Otherwise, that is, when the above-described flag collocated_from_l0_flag is 1 (NO in S2201, NO in S2202, NO in S2204 in FIG. 22), RefPicList0 [0], that is, pictures with a reference index 0 in the reference list L0 are different times. The picture is colPic (S2205 in FIG. 22).

  Next, returning to the flowchart in FIG. 21, a prediction block colPU at a different time is derived, and encoded information is acquired (S2102 in FIG. 21).

  FIG. 23 is a flowchart for explaining the procedure for deriving the prediction block colPU of the picture colPic at different times in step S2102 of FIG.

  First, a prediction block located in the lower right (outside) of the same position as the processing target prediction block in a picture colPic at a different time is set as a prediction block colPU at a different time (S2301 in FIG. 23). This prediction block corresponds to the prediction block T0 in FIG.

  Next, the encoding information of the prediction block colPU at different times is acquired (S2302 in FIG. 23). When a prediction block colPU at a different time cannot be used or when PredMode of a prediction block colPU at a different time is MODE_INTRA (YES in S2303 in FIG. 23, YES in S2304), the prediction block to be processed in the picture colPic at a different time The prediction block located at the upper left center of the same position is reset to the prediction block colPU at a different time (S2305 in FIG. 23). This prediction block corresponds to the prediction block T1 in FIG.

  Next, returning to the flowchart of FIG. 21, the LX prediction motion vector mvLXCol calculated from the prediction block of another picture at the same position as the prediction block to be encoded / decoded and the encoding information of the reference list LX of the prediction block group Col The flag availableFlagLXCol indicating whether or not is valid is calculated (S2103 in FIG. 21).

  FIG. 24 is a flowchart illustrating the inter prediction information derivation process in step S2103 of FIG.

  When PredMode of the prediction block colPU at different time is MODE_INTRA or cannot be used (NO in S2401 in FIG. 24, NO in S2402), availableFlagLXCol is set to 0 and mvLXCol is set to (0, 0) (S2403 and S2404 in FIG. 24). Exit.

  When the prediction block colPU is available and PredMode is not MODE_INTRA (YES in S2401 and YES in S2402 in FIG. 24), mvCol and refIdxCol are calculated in the following procedure.

  When the flag PredFlagL0 [xPCol] [yPCol] indicating whether or not the L0 prediction of the prediction block colPU is used (YES in S2405 in FIG. 24), the prediction mode of the prediction block colPU is Pred_L1, and thus the motion vector mvCol Is set to the same value as MvL1 [xPCol] [yPCol] which is the L1 motion vector of the prediction block colPU (S2406 in FIG. 24), and the reference index refIdxCol is set to the same value as the reference index RefIdxL1 [xPCol] [yPCol] of L1 It is set (S2407 in FIG. 24), and the list ListCol is set to L1 (S2408 in FIG. 24).

  On the other hand, when the L0 prediction flag PredFlagL0 [xPCol] [yPCol] of the prediction block colPU is not 0 (NO in S2405 in FIG. 24), it is determined whether the L1 prediction flag PredFlagL1 [xPCol] [yPCol] of the prediction block colPU is 0. . When the L1 prediction flag PredFlagL1 [xPCol] [yPCol] of the prediction block colPU is 0 (YES in S2409 in FIG. 24), the motion vector mvCol is the same as MvL0 [xPCol] [yPCol] that is the L0 motion vector of the prediction block colPU. (S2410 in FIG. 24), the reference index refIdxCol is set to the same value as the reference index RefIdxL0 [xPCol] [yPCol] of L0 (S2411 in FIG. 24), and the list ListCol is set to L0 (FIG. 24). S2412).

  When both the L0 prediction flag PredFlagL0 [xPCol] [yPCol] of the prediction block colPU and the L1 prediction flag PredFlagL1 [xPCol] [yPCol] of the prediction block colPU are not 0 (NO in S2405 in FIG. 24, NO in S2409), the prediction block colPU Since the inter prediction mode is bi-prediction (Pred_BI), one of the two motion vectors L0 and L1 is selected (S2413 in FIG. 24).

  FIG. 25 is a flowchart illustrating a procedure for deriving inter prediction information of a prediction block when the inter prediction mode of the prediction block colPU is bi-prediction (Pred_BI).

  First, it is determined whether the POCs of all the pictures registered in all the reference lists are smaller than the POC of the current encoding / decoding target picture (S2501), and L0 and all the reference lists of the prediction block colPU are determined. When the POC of all the pictures registered in L1 is smaller than the POC of the current encoding / decoding target picture (YES in S2501), X is 0, that is, the L0 motion vector of the prediction block to be encoded / decoding When the prediction vector candidate is calculated (YES in S2502), the inter prediction information of L0 of the prediction block colPU is selected, and X is 1, that is, the motion vector of L1 of the prediction block to be encoded / decoded. When the prediction vector candidate is calculated (NO in S2502), the inter prediction information on the L1 side of the prediction block colPU is selected. . On the other hand, when at least one of the POCs of the pictures registered in all the reference lists L0 and L1 of the prediction block colPU is larger than the POC of the current encoding / decoding target picture (NO in S2501), the flag collocated_from_l0_flag is 0 In the case (YES in S2503), the L0 inter prediction information of the prediction block colPU is selected. When the flag collocated_from_l0_flag is 1 (NO in S2503), the L1 inter prediction information of the prediction block colPU is selected.

When the inter prediction information of L0 of the prediction block colPU is selected (YES in S2502, YES in S2503), the motion vector mvCol is set to the same value as MvL0 [xPCol] [yPCol] (S2504), and the reference index refIdxCol is set. The same value as RefIdxL0 [xPCol] [yPCol] is set (S2505), and the list ListCol is set to L0 (S2506).
When the inter prediction information of L1 of the prediction block colPU is selected (NO in S2502 and NO in S2503), the motion vector mvCol is set to the same value as MvL1 [xPCol] [yPCol] (S2507), and the reference index refIdxCol is set. The same value as RefIdxL1 [xPCol] [yPCol] is set (S2508), and the list ListCol is set to L1 (S2509).

  Returning to FIG. 24, if inter prediction information can be acquired from the prediction block colPU, the availableFlagLXCol is set to 1 (S2414 in FIG. 24).

Next, returning to the flowchart of FIG. 21, when availableFlagLXCol is 1 (YES in S2104 of FIG. 21), the POC of the reference picture referenced in the list ListCol of the prediction block colPU is subtracted from the POC of the picture colPic at a different time. The inter-picture distance distCol is calculated (S2105), and the prediction vector candidate selection process ends. If the reference picture referenced in the list ListCol of the prediction block colPU is earlier in the display order than the picture colPic at a different time, the inter-picture distance distCol is a positive value, and the prediction block colPU is higher than the picture colPic at a different time When the reference picture referred to in the list ListCol is later in the display order, the inter-picture distance distCol is a negative value.
distCol = POC of picture colPic at different time-POC of reference picture referred to by list ListCol of prediction block colPU

  The procedure for adding the motion vector predictor candidate in S304 of FIG. 17 to the motion vector predictor list will be described in detail.

  The predicted motion vector candidates mvLXA, mvLXB, and mvLXCol of LX calculated in S301, S302, and S303 in FIG. 17 are added to the LX predicted motion vector list mvpListLX (S304). In the embodiment of the present invention, by assigning priorities and registering predicted motion vector candidates mvLXA, mvLXB, and mvLXCol in the LX predicted motion vector list mvpListLX in order of priority, elements having higher priorities are registered. It is arranged in front of the predicted motion vector list. When the number of elements in the motion vector predictor list is limited in step S306 in FIG. 17, the elements arranged at the rear of the motion vector predictor list are removed from the motion vector predictor list, thereby leaving the elements with higher priority.

  The motion vector predictor list mvpListLX has a list structure, is managed by an index i indicating the location inside the motion vector predictor list, and has a storage area for storing a motion vector predictor candidate corresponding to the index i as an element. The number of the index i starts from 0, and motion vector predictor candidates are stored in the storage area of the motion vector predictor list mvpListLX. In the subsequent processing, a motion vector predictor candidate that is an element of the index i registered in the motion vector predictor list mvpListLX is represented by mvpListLX [i].

  Next, the registration processing method of the LX predicted motion vector candidates mvLXA, mvLXB, and mvLXCol to the LX predicted motion vector list mvpListLX in S304 of FIG. 17 will be described in detail. FIG. 26 is a flowchart showing the predicted motion vector candidate registration processing procedure in step S304 of FIG.

  First, the index i of the motion vector predictor list mvpListLX is set to 0 (S3101). When availableFlagLXA is 1 (YES in S3102), the LX predicted motion vector candidate mvLXA and the inter-picture distance distA corresponding to the predicted motion vector candidate are registered at the position corresponding to the index i in the predicted motion vector list mvpListLX (S3103). ), And updating by adding 1 to the index i (S3104).

  Subsequently, when availableFlagLXB is 1 (YES in S3105), the LX predicted motion vector candidate mvLXB and the inter-picture distance distB corresponding to the predicted motion vector candidate are registered at the position corresponding to the index i of the predicted motion vector list mvpListLXmvpListLX. Then, the index i is updated by adding 1 (S3107).

  Subsequently, when availableFlagLXCol is 1 (YES in S3108), the LX predicted motion vector candidate mvLXCol and the inter-picture distance distCol corresponding to the predicted motion vector candidate are registered at the position corresponding to the index i of the predicted motion vector list mvpListLX. In step S3109, the process of registering in the motion vector predictor list ends.

  Next, a method for deleting redundant motion vector predictor candidates in the motion vector predictor list in S305 in FIG. 17 will be described in detail. FIG. 27 is a flowchart showing the predicted motion vector redundant candidate deletion processing procedure in S305 of FIG.

  First, the motion vector redundancy candidate deletion units 123 and 223 compare candidates registered in the motion vector predictor list mvpListLX (S4101). At this time, the candidate motion vectors are compared with each other, and the inter-picture distances corresponding to the motion vectors are also compared. When the inter-picture distances of a plurality of motion vector candidates are the same value and the motion vectors have the same value or close values (YES in S4102), it is determined as a redundant motion vector candidate, and the smallest order, that is, the most Redundant motion vector candidates are removed except for motion vector candidates with a small index i (S4103). After the redundant motion vector candidates are removed, the predicted motion vector list mvpListLX has an empty storage area for the deleted predicted motion vector candidates. Are packed in the order of the predicted motion vector candidates with the smallest (S4104). For example, if the motion vector candidate mvListLX [0] with index i 0 is deleted and the motion vector candidates mvListLX [1] and mvListLX [2] with index i 1 and 2 remain, the index i is 1 The predicted motion vector candidate mvListLX [1] is newly changed to a predicted motion vector candidate mvListLX [0] having an index i of 0. Furthermore, the motion vector candidate mvListLX [2] with index i of 2 is newly changed to the motion vector candidate mvListLX [1] with index i of 1. Further, it is set that the motion vector candidate mvListLX [2] having the index i of 2 does not exist.

  In step S4101, in order to reduce the amount of comparison processing, the comparison of the inter-picture distance can be omitted and only the motion vector can be set as the comparison target. In this case, candidates with different inter-picture distances may be deleted, but this is effective when priority is given to reducing the processing amount.

  Next, the method for limiting the number of motion vector candidates in the predicted motion vector list in S306 of FIG. 17 will be described in detail. FIG. 28 is a flowchart for explaining the predicted motion vector candidate number limit processing procedure in S306 of FIG.

  The predicted motion vector candidate number limit unit 124 and the predicted motion vector candidate number limit unit 224 limit the LX predicted motion vector candidate number numMVPCandLX registered in the LX predicted motion vector list mvpListLX to the defined final candidate number finalNumMVPCand.

  First, the number of elements registered in the LX prediction motion vector list mvpListLX is counted and set to the number of LX prediction motion vector candidates numMVPCandLX (S5101).

  Subsequently, when the number of predicted motion vectors numMVPCandLX of LX is smaller than the number of final candidates finalNumMVPCand (YES in S5103), the index i of the predicted motion vector list mvpListLX of LX has a value of (0, 0) at the position corresponding to numMVPCandLX. And the inter-picture distance having a value of 1 corresponding thereto is registered (S5104), and 1 is added to numMVPCandLX (S5105). If numMVPCandLX and finalNumMVPCand have the same value (YES in S5105), this restriction process is terminated. If numMVPCandLX and finalNumMVPCand are not the same value (NO in S5105), the processes in steps S5104 and S5105 are repeated until they have the same value. That is, MVs having a value of (0, 0) are registered until the LX predicted motion vector candidate number numMVPCandLX reaches the final candidate number finalNumMVPCand. In this way, by registering MVs having a value of (0, 0) overlappingly, the predicted motion vector is determined regardless of the value of the predicted motion vector index within the range of 0 or more and less than the final candidate number finalNumMVPCand. be able to.

  On the other hand, when the number of predicted motion vectors numMVPCandLX for LX is larger than the number of final candidates finalNumMVPCand (NO in S5103, YES in S5107), all predicted motion vectors for which the index i of the predicted motion vector list mvpListLX for LX is greater than finalNumMVPCand-1 The candidate is deleted (S5108), the same value as finalNumMVPCand is set in numMVPCandLX (S5105), and this restriction process is terminated.

  When the number of predicted motion vectors numMVPCandLX of LX is equal to the number of final candidates finalNumMVPCand (NO in S5103, NO in S5107), the limiting process is terminated without performing the limiting process.

  In the present embodiment, the final candidate number finalNumMVPCand is defined. This is because if the number of motion vector predictor candidates registered in the motion vector predictor list fluctuates according to the state of construction of the motion vector predictor list, the motion vector predictor list must be constructed before entropy decoding of the motion vector predictor index. Because you can't. Furthermore, if entropy decoding depends on the construction state of the motion vector predictor list including the motion vector candidate mvLXCol derived from the prediction block of the picture at different time, when an error occurs when decoding the encoded bit string of another picture The encoded bit string of the current picture is also affected by this, and there is a problem that entropy decoding cannot be continued normally. If the final candidate number finalNumMVPCand is defined as a fixed number, the prediction motion vector index can be entropy-decoded independently of the construction of the prediction motion vector list, and an error occurs when decoding the encoded bit string of another picture. However, it is possible to continue the entropy decoding of the coded bit string of the current picture without being affected by this.

  Next, the motion vector scaling calculation method in S105 of FIG. 15 and S205 of FIG. 16 will be described in detail.

  FIG. 29 is a flowchart showing the motion vector scaling calculation processing procedure of S105 of FIG. 15 and S205 of FIG.

  First, the predicted motion vector scaling calculators 127 and 226 set the inter-picture distance distLX as the inter-picture distance td (S1601).

The inter-picture distance tb is calculated by subtracting the POC of the reference picture referenced by the reference list LX of the current encoding / decoding target picture from the POC of the current encoding / decoding target picture (S1602). When the reference picture referenced by the current encoding / decoding target picture list LX is earlier in the display order than the current encoding / decoding target picture, the inter-picture distance tb is a positive value, When the reference picture referred to by the encoding / decoding target picture list LX is later in the display order, the inter-picture distance tb is a negative value.
tb = POC of current encoding / decoding target picture-POC of reference picture referenced by reference list LX of current encoding / decoding target picture

Subsequently, the inter-picture distances td and tb are compared (S1603). If the inter-picture distances td and tb are equal (YES in S1603), the scaling calculation process is terminated. When the inter-picture distances td and tb are not equal (NO in S1603), scaling operation is performed by multiplying mvLXN by the scaling coefficient tb / td according to the following equation (S1604) to obtain a scaled motion vector mvLXN.
mvLXN = tb / td * mvLXN

  FIG. 30 shows an example in which the calculation in step S1604 is performed with integer precision. The processing in steps S1605 to S1607 in FIG. 30 corresponds to the processing in step S1604 in FIG.

First, as in the flowchart of FIG. 29, the inter-picture distance distLX is set as the inter-picture distance td (S2601), and the inter-picture distance tb is calculated (S2602).
Subsequently, the inter-picture distances td and tb are compared (S2603). If the inter-picture distances td and tb are equal (YES in S2603), the scaling calculation process ends. If the inter-picture distances td and tb are not equal (NO in S2603), a variable tx is calculated by the following equation (S1605).
tx = (16384 + Abs (td / 2)) / td

Subsequently, the scaling coefficient DistScaleFactor is calculated by the following equation (S1606).
DistScaleFactor = (tb * tx + 32) >> 6

Subsequently, a scaled motion vector mvLXN is obtained by the following equation (S1607).
mvLXN = ClipMv (Sign (DistScaleFactor * mvLXN) * ((Abs (DistScaleFactor * mvLXN) + 127) >> 8))

  In the above embodiment, the method of deriving motion vector predictor candidates from the prediction block group N adjacent on the left and upper sides by the above-described scanning method 1 in S301 and S302 of FIG. 17 has been described. Here, in S301 and S302 of FIG. 17, a method of deriving motion vector predictor candidates from the prediction block group N adjacent on the left and upper sides by the above-described scanning method 2 will be described. FIG. 31 is a flowchart showing the prediction motion vector candidate derivation processing procedure in steps S301 and S302 in FIG. Subscript X contains 0 or 1 representing the reference list, and N represents A (left side) or B (upper side) representing the area of the adjacent prediction block group. The flowchart showing the prediction motion vector candidate derivation processing procedure in steps S301 and S302 in FIG. 17 by the scanning method 1 in FIG. 18 is that step S1108 in FIG. 18 becomes step S1111 in FIG. 31, and step S1110 in FIG. However, step S1112 in FIG. 31 is different, and otherwise the operation is the same. Here, steps S1111 and S1112 of FIG. 31 that are different from FIG. 17 will be described.

  First, a method for selecting a motion vector predictor candidate that matches the condition determination 5 in step S1111 of FIG. 31 will be described. FIG. 32 is a flowchart showing the processing procedure of step S1111 of FIG. For adjacent prediction blocks Nk (k = 0, 1, 2, where 2 is only the upper adjacent prediction block group), the following processing is performed in the order of k, 0, 1, 2 (S1401 to S1405). ). When N is A, the following processing is performed in the order of A0 and A1 from bottom to top, and when N is B, the following processing is performed in the order of B0, B1, and B2 from right to left.

  When the adjacent prediction block Nk can be used and the prediction mode PredMode of the prediction block Nk is not intra (MODE_INTRA) (YES in S1402), a condition determination is performed as to whether or not the above condition determination 5 is satisfied (S1403). When the flag predFlagLX [xNk] [yNk] indicating whether or not to use the LX of the adjacent prediction block Nk is 1, that is, when the adjacent prediction block Nk is inter-predicted using the same LX motion vector as the calculation target (S1403) YES), the process proceeds to step S1404. Otherwise (NO in S1403), the process proceeds to the loop end of step S1405.

  When step S1403 is YES, the flag availableFlagLXN is set to 1, the prediction motion vector mvLXN of the prediction block group N is set to the same value as the LX motion vector mvLX [xNk] [yNk] of the adjacent prediction block Nk, and prediction is performed. The reference index refIdxN of the block group N is set to the same value as the LX reference index refIdxLX [xNk] [yNk] of the adjacent prediction block Nk, and the reference list ListN of the prediction block group N is set to LX (S1404). The process proceeds to S1406.

Subsequently, when availableFlagLXN is 1 (YES in S1406), the inter-picture distance distN is calculated by subtracting the POC of the reference picture referenced by the reference list ListN of the adjacent prediction block from the POC of the current encoding / decoding target picture. (S1407), and the prediction vector candidate selection process ends. When the reference picture referred to in the adjacent prediction block list ListN is earlier in the display order than the current encoding / decoding target picture, the inter-picture distance distN is a positive value, and the current encoding / decoding target When the reference picture referenced in the reference list ListN of the adjacent prediction block is later in the display order than the picture, the inter-picture distance distN is a negative value.
distN = POC of current encoding / decoding target picture—POC of reference picture referenced in reference list ListN of adjacent prediction block

  When these conditions are not met, that is, when NO in S1402 or NO in S1403, k is incremented by 1 and the next adjacent prediction block processing (S1401 to S1405) is performed, and availableFlagLXN becomes 1 or adjacent block Repeat until A1 or B2 is finished.

  First, a method for selecting a motion vector predictor candidate that matches the condition determination 6 in step S1112 of FIG. 31 will be described. FIG. 33 is a flowchart showing the processing procedure of step S1112 of FIG. For adjacent prediction blocks Nk (k = 0, 1, 2, where 2 is only the upper adjacent prediction block group), the following processing is performed in the order of k, 0, 1, 2 (S1401 to S1405). ). When N is A, the following processing is performed in the order of A0 and A1 from bottom to top, and when N is B, the following processing is performed in the order of B0, B1, and B2 from right to left.

  When the adjacent prediction block Nk can be used and the prediction mode PredMode of the prediction block Nk is not intra (MODE_INTRA) (YES in S1502), a condition determination is performed as to whether or not the above condition determination 6 is satisfied (S1503). When the flag predFlagLY [xNk] [yNk] indicating whether or not to use the LY of the adjacent prediction block Nk is 1, that is, when the adjacent prediction block Nk is inter-predicted using a motion vector of LY different from the calculation target (S1503) YES), the process proceeds to step S1504. Otherwise (NO in S1503), the process proceeds to the loop end of step S1505.

  When step S1503 is YES, the flag availableFlagLXN is set to 1, the prediction motion vector mvLXN of the prediction block group N is set to the same value as the LY motion vector mvLY [xNk] [yNk] of the adjacent prediction block Nk, and prediction is performed. The reference index refIdxN of the block group N is set to the same value as the LY reference index refIdxLY [xNk] [yNk] of the adjacent prediction block Nk, the reference list ListN of the prediction block group N is set to LY (S1504), step The process proceeds to S1506.

Subsequently, when availableFlagLXN is 1 (YES in S1506), the inter-picture distance distN is calculated by subtracting the POC of the reference picture referenced in the reference list ListN of the adjacent prediction block from the POC of the current encoding / decoding target picture. In step S1507, the prediction vector candidate selection process is terminated. When the reference picture referred to in the adjacent prediction block list ListN is earlier in the display order than the current encoding / decoding target picture, the inter-picture distance distN is a positive value, and the current encoding / decoding target When the reference picture referenced in the reference list ListN of the adjacent prediction block is later in the display order than the picture, the inter-picture distance distN is a negative value.
distN = POC of current encoding / decoding target picture—POC of reference picture referenced in reference list ListN of adjacent prediction block

  When these conditions are not met, that is, when NO in S1402 or NO in S1403, k is incremented by 1 and the next adjacent prediction block processing (S1401 to S1405) is performed, and availableFlagLXN becomes 1 or adjacent block Repeat until A1 or B2 is finished.

  In the embodiment described above, when a plurality of motion vector predictor candidates are registered in the motion vector predictor list, the scaling operation is performed after selecting the motion vector predictor without performing the scaling operation. According to the present embodiment, since the scaling operation only needs to be performed once per list, the number of scaling operations including division is less than the method of performing the scaling operation and registering it in the predicted motion vector list. The amount of processing can be reduced.

  Also, when registering motion vector predictor candidates in the motion vector predictor candidate list, predict motion vector predictor candidates by associating information about the inter-picture distance required for the scaling operation process with the predicted motion vector value before the scaling operation process. Register in the motion vector candidate list. Of the motion vector predictor candidates registered in the motion vector predictor candidate list, redundant candidates are deleted in advance. Candidates in which both the predicted motion vector value before the scaling calculation process and the inter-picture distance match each other are redundant. Without checking the inter-picture distance, the predicted motion vector values before scaling calculation processing are compared, and candidates with the same predicted motion vector values before scaling calculation processing are regarded as redundant, leaving one candidate remaining. Can also be deleted. This is because there is not much difference between inter-picture distances with the same vector value.Therefore, there is almost no problem even if a candidate with the same predicted motion vector value before scaling operation processing is considered redundant. The advantage of reducing the amount of processing is greater because the comparison is unnecessary.

  In the embodiment described above, when a motion vector predictor candidate is registered in the motion vector predictor candidate list, the information about the inter-picture distance necessary for the scaling operation processing is associated with the motion vector value before the scaling operation processing. Thus, although the motion vector candidates are registered in the motion vector predictor candidate list, it is only necessary to be able to specify information about the inter-picture distance corresponding to the motion vector predictor candidates, and any means for associating may be used in the present invention. For example, the information about the inter-picture distance may be registered in the prediction motion vector candidate list together with the prediction motion vector candidate, or an inter-picture distance information list managed in synchronization with the prediction motion vector candidate list is prepared, Information regarding the inter-distance may be registered in the inter-picture distance information list.

  Further, since the reference index of the prediction block to be encoded / decoded is not required when the prediction motion vector list is constructed, the encoding side starts the process of constructing the prediction motion vector list before determining the reference index. be able to. Also, the decoding side can start the process of constructing the motion vector predictor list before entropy decoding the reference index.

  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 101 Image memory, 102 Motion vector detection part, 103 Difference motion vector calculation part, 104 Inter prediction information estimation part, 105 Motion compensation prediction part, 106 Prediction method determination part, 107 Residual signal generation part, 108 Orthogonal transformation and quantization part 109 first encoded bit string generation unit, 110 second encoded bit string generation unit, 111 multiplexing unit, 112 inverse quantization / inverse orthogonal transform unit, 113 decoded image signal superimposing unit, 114 encoded information storage memory, 115 decoded image memory, 121 prediction motion vector candidate generation unit, 122 prediction motion vector candidate registration unit, 123 prediction motion vector redundant candidate deletion unit, 124 prediction motion vector candidate number limit unit, 125 prediction motion vector candidate code amount calculation unit, 126 Predicted motion vector selection unit, 127 prediction Vector scaling operation unit, 128 motion vector subtraction unit, 201 separation unit, 202 first encoded bit sequence decoding unit, 203 second encoded bit sequence decoding unit, 204 motion vector calculation unit, 205 inter prediction information estimation unit, 206 motion compensation Prediction unit, 207 inverse quantization / inverse orthogonal transform unit, 208 decoded image signal superimposing unit, 209 encoded information storage memory, 210 decoded image memory, 221 prediction motion vector candidate generation unit, 222 prediction motion vector candidate registration unit, 223 prediction A motion vector redundant candidate deletion unit, a 224 predicted motion vector candidate number limiting unit, a 225 predicted motion vector selection unit, a 226 predicted motion vector scaling operation unit, and a 227 motion vector addition unit.

Claims (5)

A moving picture decoding apparatus for decoding a coded bit string obtained by coding the moving picture using motion compensation in units of blocks obtained by dividing each picture of the moving picture,
A decoding unit that decodes information indicating an index of a predicted motion vector to be selected in the predicted motion vector candidate list together with a difference motion vector;
A motion vector predictor candidate generating unit that generates a plurality of motion vector predictor candidates by predicting from any motion vector of a decoded block adjacent to the current block in the same picture as the current block to be decoded;
Predicted motion vector candidates registered in the predicted motion vector candidate list by associating information about the inter-picture distance necessary for the scaling operation processing with the predicted motion vector value before the scaling operation processing, and generating the predicted motion vector candidates And
A prediction motion vector selection unit that selects a prediction motion vector from the prediction motion vector candidate list based on information indicating an index of the prediction motion vector to be selected in the decoded prediction motion vector candidate list;
A predicted motion vector scaling calculator that performs a scaling calculation on the predicted vector value before the scaling calculation processing of the selected predicted motion vector according to the inter-picture distance;
A moving picture decoding apparatus comprising: an addition unit that calculates the motion vector of the decoding target block by adding the predicted motion vector after the scaling calculation process and the difference motion vector.   Among the motion vector predictor candidates registered in the motion vector predictor candidate list, the motion vector redundancy candidates that have the same motion vector predictor value before the scaling calculation process are left out and the rest are deleted. The moving picture decoding apparatus according to claim 1, further comprising a candidate deletion unit.   Among the motion vector predictor candidates registered in the motion vector predictor candidate list, candidates for which the motion vector predictor values before the scaling calculation process and the inter-picture distances match each other remain, and the rest are deleted. The moving picture decoding apparatus according to claim 1, further comprising: a predicted motion vector redundant candidate deletion unit that performs. A moving picture decoding method for decoding a coded bit string obtained by coding the moving picture using motion compensation in units of blocks obtained by dividing each picture of the moving picture,
A decoding step of decoding information indicating an index of a predicted motion vector to be selected in the predicted motion vector candidate list together with a difference motion vector;
A prediction motion vector candidate generation step for generating a plurality of motion vector predictor candidates by predicting from any one of the decoded blocks adjacent to the decoding target block in the same picture as the decoding target block;
Predicted motion vector candidates registered in the predicted motion vector candidate list by associating information about the inter-picture distance necessary for the scaling operation processing with the predicted motion vector value before the scaling operation processing, and generating the predicted motion vector candidates Steps,
A prediction motion vector selection step of selecting a prediction motion vector from the prediction motion vector candidate list based on information indicating an index of the prediction motion vector to be selected in the decoded prediction motion vector candidate list;
A predicted motion vector scaling operation step for performing a scaling operation on a predicted vector value before the scaling operation processing of the selected predicted motion vector according to the inter-picture distance;
A moving picture decoding method comprising: an adding step of calculating a motion vector of the decoding target block by adding the predicted motion vector after the scaling calculation process and the difference motion vector. A moving picture decoding program for decoding a coded bit string obtained by coding the moving picture using motion compensation in units of blocks obtained by dividing each picture of the moving picture,
A decoding step of decoding information indicating an index of a predicted motion vector to be selected in the predicted motion vector candidate list together with a difference motion vector;
A prediction motion vector candidate generation step for generating a plurality of motion vector predictor candidates by predicting from any one of the decoded blocks adjacent to the decoding target block in the same picture as the decoding target block;
Predicted motion vector candidates registered in the predicted motion vector candidate list by associating information about the inter-picture distance necessary for the scaling operation processing with the predicted motion vector value before the scaling operation processing, and generating the predicted motion vector candidates Steps,
A prediction motion vector selection step of selecting a prediction motion vector from the prediction motion vector candidate list based on information indicating an index of the prediction motion vector to be selected in the decoded prediction motion vector candidate list;
A predicted motion vector scaling operation step for performing a scaling operation on a predicted vector value before the scaling operation processing of the selected predicted motion vector according to the inter-picture distance;
A moving picture decoding program that causes a computer to execute an adding step of calculating a motion vector of the decoding target block by adding the predicted motion vector after the scaling operation processing and the difference motion vector.

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