JP2013132046A - Video decoder, video decoding method, video decoding program, receiver, receiving method, and receiving program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the entire code amount by compressing the encoded information in an image encoding system using motion compensation prediction.SOLUTION: A decoding section 202 decodes a reference index for specifying a reference picture to be referred in the inter-prediction of a prediction block to be decoded among a plurality of reference images, and decodes a differential motion vector of a prediction motion vector to be selected and a motion vector of a prediction block to be decoded thus obtaining the inter-prediction information. A motion vector deriving section 204 derives a plurality of candidates of prediction motion vector with reference to the encoded information of a plurality of decoded blocks. The decoding section 202 has such a mode of not decoding at least one of the differential motion vector and reference index, for the inter-prediction information of first prediction or the inter-prediction information of second prediction, in units of slice, when the inter-prediction mode is bi-prediction.

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) and L1 prediction (list 1 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. That is, L0 prediction and L1 prediction have one reference index and one motion vector as inter prediction information, and bi-prediction has two reference indexes and two motion vectors as inter prediction 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 of the encoding target has a strong correlation with the motion vector of the neighboring neighboring block, the prediction motion vector is calculated by performing prediction from the neighboring neighboring block, and the encoding 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. L0 prediction and L1 prediction encode or decode one reference index and one differential motion vector as inter prediction information, and bi-prediction encodes or decodes two reference indexes and two differential motion vectors as inter prediction information. .

  Specifically, as shown in FIG. 41 (a), the median is calculated from the motion vectors of the neighboring blocks A, B, and C and is used as a predicted motion vector, and the difference between the motion vector and the predicted motion vector is calculated. 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 neighboring block are different as shown in FIG. 41 (b), if there are multiple neighboring blocks on the left, When there is a neighboring block, the leftmost block is used as a prediction block, and prediction is performed from the motion vector of the determined prediction block.

JP 2011-147172 A

  However, in the conventional method, since bi-prediction encodes or decodes two reference indexes and two differential motion vectors as inter prediction information, 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 circumstances, and an object of the present invention is to provide a moving picture decoding technique that improves the coding efficiency by reducing the code amount of a reference index or a differential motion vector.

  In order to solve the above-described problem, a moving picture decoding apparatus according to an aspect of the present invention decodes a coded bit string in which a moving picture is encoded using inter prediction in units of prediction blocks obtained by dividing each picture. An apparatus for decoding a reference index for specifying a reference picture to be referred to in inter prediction of a prediction block to be decoded from among a plurality of reference images, a prediction motion vector to be selected, and prediction of the decoding target A decoding unit (202) that obtains inter prediction information by decoding a difference motion vector with respect to a block motion vector, and deriving a plurality of motion vector predictor candidates with reference to encoding information of a plurality of decoded blocks Adding the predicted motion vector selected from the plurality of predicted motion vector candidates and the decoded difference motion vector And a motion vector derivation unit (204) for deriving a motion vector of the prediction block to be decoded. When the inter prediction mode is bi-prediction having the first prediction and the second prediction, the decoding unit performs the difference motion vector for the inter prediction information of the first prediction or the inter prediction information of the second prediction in units of slices. And a mode in which at least one decoding of the reference index is not performed.

  Another aspect of the present invention is a video decoding method. This method is a moving picture decoding method for decoding a coded bit string in which a moving picture is encoded using inter prediction in units of prediction blocks obtained by dividing each picture, and is referred to in inter prediction of a prediction block to be decoded. Inter-prediction is performed by decoding a reference index for specifying a reference picture to be selected from a plurality of reference images, and decoding a difference motion vector between a prediction motion vector to be selected and a motion vector of the prediction block to be decoded. A decoding step of obtaining information, deriving a plurality of prediction motion vector candidates with reference to encoding information of a plurality of decoded blocks, and a prediction motion vector selected from the plurality of prediction motion vector candidates; A motion vector for deriving a motion vector of the prediction block to be decoded by adding the decoded differential motion vector. And a torque derivation step. When the inter prediction mode is bi-prediction having the first prediction and the second prediction, the decoding step performs the difference motion vector for the inter prediction information of the first prediction or the inter prediction information of the second prediction in units of slices. And a mode in which at least one decoding of the reference index is not performed.

  Yet another embodiment of the present invention is a receiving device. This apparatus is a receiving apparatus that receives and decodes an encoded bit string in which a moving image is encoded, and an encoded bit sequence in which the moving image is encoded using inter prediction in units of blocks obtained by dividing each picture. A receiving unit that receives packetized encoded data, a restoration unit that performs packet processing on the received encoded data to restore the original encoded bit sequence, and predicts a decoding target from the restored encoded bit sequence A reference index for specifying a reference picture to be referred to in inter prediction of a block from among a plurality of reference images is decoded, and a difference motion vector between a prediction motion vector to be selected and a motion vector of the prediction block to be decoded And a decoding unit (202) that obtains inter prediction information and a plurality of decoded blocks with reference to the encoded information. A motion vector predictor candidate is derived, and a motion vector of the prediction block to be decoded is derived by adding a motion vector predictor selected from the plurality of motion vector predictor candidates and the decoded differential motion vector. A motion vector deriving unit (204). When the inter prediction mode is bi-prediction having the first prediction and the second prediction, the decoding unit performs the difference motion vector for the inter prediction information of the first prediction or the inter prediction information of the second prediction in units of slices. And a mode in which at least one decoding of the reference index is not performed.

  Yet another embodiment of the present invention is a reception method. This method is a reception method for receiving and decoding a coded bit sequence in which a moving image is encoded, and an encoded bit sequence in which a moving image is encoded using inter prediction in units of blocks obtained by dividing each picture. A reception step for receiving packetized encoded data, a restoration step for packetizing the received encoded data to restore the original encoded bit sequence, and prediction of a decoding target from the restored encoded bit sequence A reference index for specifying a reference picture to be referred to in inter prediction of a block from among a plurality of reference images is decoded, and a difference motion vector between a prediction motion vector to be selected and a motion vector of the prediction block to be decoded Decoding step to obtain inter prediction information and encoding information of a plurality of decoded blocks. Deriving a plurality of motion vector predictor candidates, adding a motion vector predictor selected from the motion vector predictor candidates and the decoded motion vector difference, and a motion vector of the prediction block to be decoded A motion vector deriving step for deriving. When the inter prediction mode is bi-prediction having the first prediction and the second prediction, the decoding step performs the difference motion vector for the inter prediction information of the first prediction or the inter prediction information of the second prediction in units of slices. And a mode in which at least one decoding of the reference index is not performed.

  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 the prediction block adjacent to the prediction block of an encoding or decoding object. It is a figure explaining the prediction block adjacent to the prediction block of an encoding or decoding object. It is a figure explaining the prediction block adjacent to the prediction block of an encoding or decoding object. It is a figure explaining the prediction block adjacent to the prediction block of an encoding or decoding object. It is a figure explaining the prediction block adjacent to the prediction block of an encoding or decoding object. It is a figure explaining an example of the syntax structure of a slice header. It is a figure explaining an example of the syntax structure of a slice header. It is a flowchart which shows the setting process procedure of the flag which shows whether the inter prediction information of L1 is encoded or decoded by bi-prediction in the case of switching according to the size of the prediction block to be encoded or decoded. It is a flowchart explaining the entropy encoding process sequence of the inter prediction information per prediction block. It is a flowchart explaining the entropy decoding process procedure of the inter prediction information per prediction block. It is a flowchart explaining the derivation | leading-out process of the reference index of LX in bi-prediction. It is a flowchart explaining the derivation | leading-out process of the reference index of LX in bi-prediction. It is a flowchart explaining the derivation | leading-out process of the reference index of LX in bi-prediction. It is a flowchart explaining the derivation | leading-out process of the reference index of LX in bi-prediction. It is a flowchart explaining the derivation | leading-out process of the reference index of LX in bi-prediction. It is a flowchart explaining the derivation | leading-out process of the reference index of LX in bi-prediction. It is a block diagram which shows the detailed structure of the difference motion vector derivation | leading-out part of FIG. FIG. 3 is a block diagram illustrating a detailed configuration of a motion vector deriving unit in FIG. 2. It is a flowchart which shows the difference motion vector calculation process procedure of the difference motion vector derivation part of FIG. It is a flowchart which shows the motion vector calculation process procedure of the motion vector derivation | leading-out 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 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 derivation | leading-out process of the picture of a different time. It is a flowchart which shows the prediction block candidate derivation | leading-out process 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 scaling calculation process procedure of a motion vector. It is a flowchart which shows the scaling process procedure of the motion vector by integer calculation. 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 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 a block to be encoded or decoded in a picture (a block to be encoded in the encoding process and a block to be decoded in the decoding process. Hereinafter, unless otherwise noted, 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 or decoded in units of encoded 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.) The following is used in this sense unless otherwise noted, and is used in this sense unless otherwise noted.) Intra prediction (MODE_INTRA) in which prediction is performed from the surrounding image signal, and a picture that has been encoded or decoded Inter prediction (MODE_INTER) for predicting from the image signal is switched. 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.

(Inter prediction mode, reference list, reference index)
In the embodiment of the present invention, in inter prediction in which prediction is performed from an image signal of a coded or decoded picture, a plurality of decoded pictures can be used as reference pictures. In order to specify a reference picture used for inter prediction from a plurality of reference pictures, each prediction block is designated by a reference index. In the B slice, any two reference pictures can be selected for each prediction block and inter prediction (motion compensation prediction) can be performed. As inter prediction modes, 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. The L0 prediction (Pred_L0) is inter prediction that generates a predicted image signal with reference to a reference picture managed in L0, and the L1 prediction (Pred_L1) is a predicted image signal with reference to a reference picture managed in L1. The bi-prediction (Pred_BI) is an L0 prediction image signal obtained by referring to one reference picture managed by each of L0 and L1. And L1 prediction image signals are averaged or weighted and added to generate a prediction image signal. Only L0 prediction (Pred_L0) can be used for inter prediction of P slice, and L0 prediction (Pred_L0), L1 prediction (Pred_L1), and bi-prediction (Pred_BI) can be used for inter prediction of B slice. The L0 prediction and the L1 prediction have one reference index and one motion vector as inter prediction information, and the bi-prediction has two reference indexes and two motion vectors as inter prediction information. 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 predicted motion vectors, differential motion vectors, and predicted motion vector indexes)
In the embodiment of the present invention, in order to reduce the code amount of the motion vector generated in each prediction block, a prediction process is performed on the motion vector. A plurality of motion vector predictor candidates are derived, one motion vector predictor is selected from the motion vector predictor candidates, and a difference that is a difference between the motion vector to be encoded or decoded and the selected motion vector predictor A motion vector is calculated. In order to specify a prediction motion vector used for inter prediction from a plurality of prediction motion vectors, each prediction block is designated by a prediction motion vector index.

(Merge mode, merge candidate)
In the merge mode, the prediction mode of the prediction block to be encoded or decoded, the inter prediction information such as the reference index and the motion vector is not encoded or decoded, but within the same picture as the prediction block to be encoded or decoded. The prediction block adjacent to the prediction block to be encoded or decoded, or the same position as the prediction block to be encoded or decoded of the encoded or decoded picture that is temporally different from the prediction block to be encoded or decoded. In this mode, inter prediction is performed by deriving inter prediction information of a prediction block to be encoded or decoded from inter prediction information of a prediction block existing in the vicinity (neighboring position). A prediction block close to the prediction block to be encoded or decoded in the same picture as the prediction block to be encoded or decoded and inter prediction information of the prediction block are spatial merge candidates, a prediction block to be encoded or decoded, and time Prediction information derived from a prediction block existing at the same position as or near (previously near) a prediction block to be encoded or decoded of a differently encoded or decoded picture and inter prediction information of the prediction block Are time merge candidates. Each merge candidate is registered in the merge candidate list, and the merge candidate used in the inter prediction is specified by the merge index. The derived inter prediction information includes an inter prediction mode, a reference index of each reference list, and a motion vector.

(About adjacent prediction blocks)
5, FIG. 6, FIG. 7 and FIG. 8 are diagrams for explaining a prediction block close to the prediction block to be encoded or decoded in the same picture as the prediction block to be encoded or decoded. FIG. 9 shows an already encoded or decoded prediction existing in the same position as or near the prediction block to be encoded or decoded in a picture that has been encoded or decoded that differs in time from the prediction block to be encoded or decoded. It is a figure explaining a block. A prediction block that is close in the spatial direction of a prediction block to be encoded or decoded and a prediction block at the same position at different times will be described with reference to FIGS. 5, 6, 7, 8, and 9.

  As shown in FIG. 5, in the same picture as the prediction block to be encoded or decoded, a prediction block A1 close to the left side of the prediction block to be encoded or decoded, prediction block B1 close to the upper side, The prediction block B0 close to the top right vertex, the prediction block A0 close to the bottom left vertex, and the prediction block B2 close to the top left vertex are defined as prediction blocks close to the spatial direction.

  As shown in FIG. 6, when the size of the prediction block adjacent to the left side of the prediction block to be encoded or decoded is smaller than the prediction block to be encoded or 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.

  Similarly, when the size of the prediction block adjacent to the upper side of the prediction block to be encoded or decoded is smaller than the prediction block to be encoded or decoded and there are a plurality of prediction blocks, the left side in the present embodiment Only the rightmost prediction block B10 in the prediction blocks close to is set as the prediction block B1 close to the upper side.

  In addition, as shown in FIG. 7, even when the size of the prediction block A adjacent to the left side of the prediction block to be encoded or decoded is larger than the prediction block to be encoded or decoded, it is close to the left side according to the above condition. If the prediction block A is close to the left side of the prediction block to be encoded or decoded, the prediction block A1 is used. If the prediction block A is close to the lower left vertex of the prediction block to be encoded or decoded, the prediction block A0 is set. If it is close to the upper left vertex of the prediction block to be encoded or decoded, the prediction block is B2. In the example of FIG. 6, the prediction block A0, the prediction block A1, and the prediction block B2 are the same prediction block.

  As shown in FIG. 8, even when the size of the prediction block B adjacent to the upper side of the prediction block to be encoded or decoded is larger than the prediction block to be encoded or decoded, the size is close to the upper side according to the above condition. If the prediction block B is close to the upper side of the prediction block to be encoded or decoded, the prediction block B1 is set. If the prediction block B is close to the upper right vertex of the prediction block to be encoded or decoded, the prediction block B0 is set. If it is close to the upper left vertex of the prediction block to be encoded or 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. 9, in a picture that has been encoded or decoded that is temporally different from the prediction block to be encoded or decoded, already encoded or existing at the same position as or near the prediction block to be encoded or decoded. The decoded prediction blocks T0 and T1 are defined as prediction blocks at the same position at different times.

(About prediction block groups)
A group composed of a plurality of prediction blocks is defined as a prediction block group. The prediction block A1 close to the left side of the prediction block to be encoded or decoded in the same picture as the prediction block to be encoded or decoded shown in FIG. 5, and the lower left vertex of the prediction block to be encoded or decoded Is defined as a prediction block group adjacent to the left side.

  In the same picture as the prediction block to be encoded or decoded shown in FIG. 5, the prediction block B1 close to the upper side of the prediction block to be encoded or decoded, and the upper right vertex of the prediction block to be encoded or decoded A second prediction block group including a prediction block B0 that is close and a prediction block B2 that is close to the top left vertex of the prediction block to be encoded or decoded is defined as a prediction block group that is close to the upper side.

  In a picture that has been encoded or decoded that is temporally different from the prediction block to be encoded or decoded shown in FIG. 9, already encoded or decoded at the same position as or near the prediction block to be encoded or decoded A third prediction block group composed of already-predicted prediction block groups T0 and T1 is defined as a prediction block group at different times.

(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.

  In the moving image encoding device, the moving image encoding method, the moving image encoding program, the moving image decoding device, the moving image decoding method, and the moving image decoding program according to the embodiment of the present invention, the size of the slice unit or the prediction block Accordingly, when the inter prediction mode is bi-prediction (Pred_BI), whether to encode or decode either L0 or L1 inter prediction information is switched. The inter prediction information to be switched is a difference motion vector, a reference index, a part or all of a prediction motion vector index.

  When the inter prediction mode is bi-prediction (Pred_BI), since inter prediction is performed using two motion vectors of L0 and L1, a motion vector is encoded as compared with L0 prediction and L1 prediction using only one motion vector. Requires a large amount of code. When encoding a motion vector, a differential motion vector is derived in order to reduce the amount of code, and the derived differential motion vector is encoded. In the case of bi-prediction, coding of one of the differential motion vectors corresponding to the L0 or L1 motion vector is not performed, and the value of the differential motion vector is set to (0, 0). Reduce. However, in bi-prediction, by setting the value of one of the difference motion vectors of L0 or L1 to (0, 0), the value of the predicted motion vector becomes the motion vector as it is, and an arbitrary motion vector cannot be used. Therefore, the code amount of the residual signal may increase. Therefore, in this embodiment, even if one of the motion vectors corresponding to the L0 or L1 motion vector is set to the same value as the predicted motion vector in bi-prediction, the code amount of the residual signal is unlikely to increase. In a situation where the amount of code of L is likely to decrease, one of the differential motion vectors corresponding to the L0 or L1 motion vector is not encoded, and one of the motion vectors corresponding to the L0 or L1 motion vector is predicted in bi-prediction If it is set to the same value as the motion vector, the code amount of the residual signal is likely to increase, and in a situation where the overall code amount is likely to increase, the differential motion vectors corresponding to the L0 and L1 motion vectors are encoded.

  In the present embodiment, as a first method, depending on the size of the prediction block, when the inter prediction mode is bi-prediction (Pred_BI), encoding or decoding of either L0 or L1 differential motion vector Switch whether to do. When the predicted block size is small, either the L0 or L1 differential motion vector is not encoded or decoded, and when the predicted block size is large, both the L0 and L1 differential motion vectors are encoded or decoded. I do. When the size of the prediction block is small, the number of pixels is small, so the code amount of the residual signal per prediction block is also small. Therefore, even if one of the differential motion vectors is not encoded in bi-prediction, the code amount of the residual signal is difficult to increase, and the code amount as a whole decreases. On the other hand, when the size of the prediction block is large, since the number of pixels is large, the code amount of the residual signal per prediction block is also large. Therefore, if one of the differential motion vectors is not encoded in bi-prediction, the code amount of the residual signal is likely to increase, and the code amount as a whole increases.

  In the present embodiment, as the second method, for each slice, when the inter prediction mode is bi-prediction (Pred_BI), either differential motion vector of L0 or L1 is encoded or decoded. To switch.

  For example, a slice including the same reference image in L0 and L1, or both L0 and L1 are encoded in the temporal direction, or used as forward prediction to refer to a reference picture before the decoding target picture, and encoded in the temporal direction. Alternatively, in a slice that does not include backward prediction that refers to a reference picture after the picture to be decoded, even if one of L0 and L1 is used instead of the motion vector detected by the motion vector, the prediction accuracy is used. Since the amount of increase in the code amount of the residual component is small, the difference motion vector of either L0 or L1 is not encoded or decoded in order to reduce the code amount of the difference motion vector.

  For slices that do not include the same reference image in L0 and L1, or slices that use L0 as forward prediction and L1 as backward prediction, predict either L0 or L1 instead of the motion vector detected by the motion vector. If a motion vector is used, the prediction accuracy decreases and the amount of increase in the residual component code amount is large. Therefore, in order to increase the prediction accuracy and reduce the residual component code amount, the difference motion vectors of both L0 and L1 are used. Is encoded or decoded.

  Also, for the same reason as the difference motion vector, it is possible to switch whether or not the reference index of either L0 or L1 is also encoded or decoded in bi-prediction according to the slice unit or the size of the prediction block. . In the case of bi-prediction in which the code amount of inter prediction information is large, one of the reference indexes corresponding to the L0 and L1 motion vectors is not encoded, and whether or not the reference index value is derived is set as a default value. Thus, the code amount of the inter prediction information is reduced. However, by setting whether to derive the reference index value of either L0 or L1 in the bi-prediction as a default value, an arbitrary reference picture cannot be used, so the code amount of the residual signal increases. There are things to do. Therefore, in this embodiment, even if the value of one of the reference indexes of L0 or L1 is derived or set to the default value in bi-prediction, the code amount of the residual signal hardly increases, and the code as a whole In a situation where the amount is likely to decrease, one of the L0 or L1 reference indexes is not encoded, and if bi-prediction derives the value of either the L0 or L1 reference index or sets the default value, the residual In a situation where the code amount of the signal is likely to increase and the code amount as a whole is likely to increase, both the L0 and L1 reference indexes are encoded.

  Also, for the same reason as the difference motion vector and the reference index, whether or not to encode or decode either the L0 or L1 difference prediction vector index in bi-prediction according to the slice unit or the size of the prediction block Can be switched. In the case of bi-prediction in which the code amount of inter prediction information is large, one of the prediction vector indexes corresponding to the motion vector of L0 or L1 is not encoded, and the value of the prediction vector index is the same value as the other prediction vector index By setting to, the code amount of inter prediction information is reduced. However, since the prediction vector index value of either L0 or L1 is set to the same value as the other prediction vector index in bi-prediction, an arbitrary prediction vector index cannot be used. May increase. Therefore, in the present embodiment, even if the value of one of the prediction vector indexes of L0 or L1 is set to the same value as the other prediction vector index in bi-prediction, the code amount of the residual signal is unlikely to increase. In a situation where the overall code amount is likely to decrease, one of the L0 or L1 prediction vector indexes is not encoded, and in bi-prediction, the value of one of the L0 or L1 prediction vector indexes is used as the other prediction vector. When the same value as the index is set, the code amount of the residual signal is likely to increase, and in a situation where the code amount as a whole is likely to increase, both the L0 and L1 prediction vector indexes are encoded.

  In the following description, whether to perform inter prediction encoding or decoding of either L0 or L1 when the inter prediction mode is bi-prediction (Pred_BI) according to the slice unit or the size of the prediction block. However, the present invention is not limited to switching all of the inter-prediction information, that is, the differential motion vector, the reference index, and the prediction motion vector index. It is also possible to switch only part of the index, ie only one or two. For example, it is possible to encode or decode both the L0 and L1 reference indexes and the prediction motion vector index by switching whether to encode or decode only one of the L0 and L1 prediction motion vectors. The prediction motion vector and the reference index of either L0 or L1 may be switched to encode or decode, and the prediction motion vector index of both L0 and L1 may be encoded or decoded.

  Also, in the following description, it is assumed that whether to perform encoding or decoding of L1 inter prediction when the inter prediction mode is bi-prediction (Pred_BI) according to the slice unit or the size of the prediction block. As will be described, the present invention is not limited to L1, and it is also possible to switch whether to perform encoding or decoding of L0 inter prediction.

  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 100 according to an embodiment of the present invention. The moving image encoding apparatus according to the embodiment includes an image memory 101, a reference index deriving unit 116, a motion vector detecting unit 102, a differential motion vector deriving unit 103, an inter prediction information estimating unit 104, a motion compensation predicting unit 105, and a prediction method determination. Unit 106, 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 superimposing unit 113, encoded information storage memory 114, and decoded image memory 115.

  In the present embodiment, when the inter prediction mode is bi-prediction, whether to encode inter prediction information for L1 prediction is switched for each slice or according to the size of a prediction block to be encoded. The inter prediction information to be switched is a reference index, a prediction motion vector index, a part of or all of a difference motion vector. Therefore, in the video encoding device 100 according to the embodiment, a flag interInfoCodingL1Flag indicating whether or not L1 inter prediction information is encoded in bi-prediction is set to 0 or 1. A flag interInfoCodingL1Flag of 1 indicates that L1 inter prediction information is encoded in bi-prediction, and a flag interInfoCodingL1Flag of 0 indicates that L1 inter prediction information is not encoded in bi-prediction. A flag interInfoCodingL1Flag indicating whether or not L1 inter prediction information is encoded in bi-prediction includes a reference index deriving unit 116, a motion vector detecting unit 102, a differential motion vector deriving unit 103, a motion compensation predicting unit 105, and a prediction method determining unit 106. Reference is made by the first encoded bit string generation unit 109.

  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.

  In the present embodiment, when the inter prediction mode is bi-prediction, whether to encode inter prediction information for L1 prediction is switched for each slice or according to the size of a prediction block to be encoded. When the L1 reference index in bi-prediction is included as the inter prediction information to be switched, and the L1 reference index in bi-prediction is not encoded, the reference index deriving unit 116 refers to L1 in bi-prediction. An index is derived and supplied to the motion vector detection unit 102 and the prediction method determination unit 106. The L1 reference index of the prediction block to be encoded may be derived using the encoding information including the L1 reference index of the adjacent prediction block stored in the encoding information storage memory. When the reference picture of L0 corresponding to the reference index is also included in L1, the same reference picture may be used in L1, and the reference index of L1 corresponding to the reference picture may be derived.

  The motion vector detection unit 102 uses the L0 and L1 in each prediction block size and each inter prediction mode by block matching or the like between the image signal supplied from the image memory 101 and the reference picture supplied from the decoded image memory 115. Each motion vector for each reference index is detected for each prediction block, and the detected motion vector is supplied to the motion compensation prediction unit 105, the difference motion vector derivation unit 103, and the prediction method determination unit 106.

  When the inter prediction is bi-prediction, the motion vectors detected for L0 prediction and L1 prediction may be combined into a motion vector for bi-prediction, or a separate motion vector may be detected for bi-prediction.

  In the present embodiment, when the inter prediction mode is bi-prediction, whether to encode L1 inter prediction information is switched for each slice or according to the size of the prediction block to be encoded. When the L1 differential motion vector in bi-prediction is included as the inter prediction information to be switched, and the L1 differential motion vector is not encoded, the L1 predicted motion vector is derived by the method described later, and the predicted motion Let the vector be the L1 motion vector in bi-prediction.

  Further, when the L1 reference index in bi-prediction is included as the inter prediction information to be switched and the L1 reference index is not encoded, the value of the L1 reference index is derived or set as a default value.

  The differential motion vector deriving 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. In the present embodiment, when the inter prediction mode is bi-prediction, whether to encode L1 inter prediction information is switched for each slice or according to the size of the prediction block to be encoded. When the L1 differential motion vector in bi-prediction is included as inter prediction information to be switched, and the L1 differential motion vector in bi-prediction is not encoded, the differential motion vector is set to (0, 0). 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 differential motion vector deriving 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 encoded inter-predicted adjacent prediction block 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 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. A code amount of encoded information such as inter prediction information and intra prediction 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. The generated code amount calculated here is preferably a simulation of the encoding process, but can be approximated or approximated easily.

  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 prediction method, a prediction method with the least generated code amount and the coding distortion is determined.

PredMode that determines whether inter prediction (PRED_INTER) or intra prediction (PRED_INTRA) is optimized for each coding block among multiple prediction methods, determines the partition mode PartMode, and predictive block units for inter prediction (PRED_INTER) In the merge mode, a merge index is determined. In the merge mode, an inter prediction flag, a prediction motion vector index, a reference index of L0 and L1, a difference motion vector, and the like are determined. Thus, the encoded information corresponding to the determination is supplied to the 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 intra prediction (MODE_INTRA), a flag predFlagL0 indicating whether to use L0 prediction and a 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, when the prediction mode PredMode for each coding block is inter prediction (PRED_INTER), a flag for determining whether or not the mode is a merge mode, a merge index when the mode is merge mode, an inter prediction mode when the mode is not merge mode, and a reference index Then, inter prediction information such as a prediction motion vector index and a difference motion vector is encoded according to a prescribed syntax rule to generate a first encoded bit string, which is supplied to the multiplexing unit 111. In the present embodiment, when the inter prediction mode is bi-prediction, whether to encode L1 inter prediction information is switched for each slice or according to the size of the prediction block to be encoded. The inter prediction information to be switched is a part or all of the L1 reference index, predicted motion vector index, and differential motion vector in bi-prediction.

  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 a configuration of a moving picture decoding apparatus 200 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 reference index derivation unit 211, a motion vector derivation unit 204, and an inter prediction information estimation unit 205. 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, for prediction mode PredMode, split mode PartMode, and inter prediction (PRED_INTER) that determine whether inter prediction (PRED_INTER) or intra prediction (PRED_INTRA) is performed in units of coding blocks, whether or not merge mode is used in units of prediction blocks. The merge flag to be determined, the merge index when the merge flag is in the merge mode, and the encoded information regarding the inter prediction mode, the predicted motion vector index, the difference motion vector, etc. when the merge flag is not the merge mode The reference index deriving unit 211 and the encoded information are supplied to the motion vector deriving unit 204 and the inter prediction information estimating unit 205.

  In the present embodiment, when the inter prediction mode is bi-prediction, whether to decode L1 prediction inter prediction information is switched for each slice or according to the size of a prediction block to be decoded. The inter prediction information to be switched is a reference index, a prediction motion vector index, a part of or all of a difference motion vector. Therefore, in the first encoded bit string decoding unit 202, a flag interInfoCodingL1Flag indicating whether or not L1 inter prediction information is encoded in bi-prediction is set to 0 or 1. A flag interInfoCodingL1Flag of 1 indicates that L1 inter prediction information is encoded in bi-prediction, and a flag interInfoCodingL1Flag of 0 indicates that L1 inter prediction information is not encoded in bi-prediction. Information of a flag interInfoCodingL1Flag indicating whether or not L1 inter prediction information is encoded in the set bi-prediction is supplied to the reference index deriving unit 211 and the motion vector deriving unit 212.

  When the flag interInfoCodingL1Flag indicating whether or not the L1 inter prediction information is encoded by bi-prediction is 1, when the L1 differential motion vector in bi-prediction is included as the inter prediction information to be switched, the bi-prediction When the differential motion vector of L1 is not decoded, the differential motion vector of L1 in bi-prediction is set to (0, 0), and the predicted motion vector index of L1 in bi-prediction is set as inter prediction information to be switched. If the prediction motion vector index of L1 in bi-prediction is not decoded, the prediction motion vector index of L1 in bi-prediction is set to the value of the prediction motion vector index of L0, and the encoding information is derived as a reference index. To the unit 211 and the motion vector deriving unit 204. Note that in this embodiment, when the L1 reference index in bi-prediction is included as inter prediction information to be switched in the motion vector deriving unit 204, and the L1 reference index in bi-prediction is not decoded, bi-prediction is performed. Although the reference index of L1 in prediction is set to a derived value, the reference index of L1 in bi-prediction can be set to a default value. In that case, the first encoded bit string decoding unit 202 sets the reference index of L1 in bi-prediction to a default value, and supplies the encoded information to the reference index deriving unit 211.

  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.

  The reference index deriving unit 211 determines that the prediction mode PredMode is inter prediction (MODE_INTER) from the supplied encoded information, the merge flag is not merge mode, the inter prediction mode is bi prediction (Pred_BI), and L1 in bi prediction When the flag interInfoCodingL1Flag indicating whether or not the inter prediction information is encoded is 0, the L1 reference index is derived and supplied to the motion compensation prediction unit 206. The L1 reference index of the prediction block to be decoded may be derived using the encoding information including the L1 reference index of the adjacent prediction block stored in the encoding information storage memory, or the L0 reference When the reference picture of L0 corresponding to the index is also included in L1, the same reference picture may be used in L1, and the reference index of L1 corresponding to the reference picture may be derived.

  When the merge flag is not in the merge mode, the motion vector deriving unit 204 calculates a plurality of motion vector predictor candidates using the encoded information of the already decoded image signal stored in the encoded information storage memory 209. In accordance with a prediction motion vector index that is registered in a prediction motion vector list (to be described later) and decoded and supplied by the first encoded bit string decoding unit 202 from among a plurality of prediction motion vector candidates registered in the prediction motion vector list. A predicted motion vector is selected, a motion vector is calculated from the difference vector decoded by the first encoded bit string decoding unit 202 and the selected predicted motion vector, and is supplied to the motion compensated prediction unit 206 together with other encoded information. At the same time, it 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 intra prediction (MODE_INTRA), a flag predFlagL0 indicating whether to use L0 prediction and a 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 detailed configuration and operation of the motion vector deriving unit 204 will be described later.

  The inter prediction information estimation unit 205 estimates the inter prediction information in the merge mode when the merge flag of 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 compensated prediction unit 206 generates a predicted image signal by motion compensated prediction from the reference picture using the motion vector calculated by the motion vector derivation unit 204, and supplies the predicted image signal to the decoded image signal superimposing unit 208. In the case of bi-prediction (Pred_BI), a weighted coefficient is adaptively multiplied to two prediction image signals of L0 prediction and L1 prediction, and an offset value is added and superimposed to generate a final prediction 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.

  In the moving picture coding apparatus 100 and the moving picture decoding apparatus 200 according to the present embodiment, when the inter prediction mode is bi-prediction, L1 is performed by bi-prediction according to slice units or the size of a prediction block to be encoded or decoded. Whether to encode or decode the inter prediction information.

  When switching whether to encode or decode L1 inter prediction information in units of slices, as shown in the example of the syntax structure of the slice header in FIG. 10, the L1 inter prediction information is encoded by bi-prediction in the slice header. Alternatively, a syntax element inter_info_coding_l1_flag for encoding or decoding a flag interInfoCodingL1Flag indicating whether or not to decode is prepared, and this syntax element is the first encoding of the video encoding device 100 when the slice type is B slice. Whether the L1 inter prediction information is to be encoded or decoded in bi-prediction is determined by encoding in the bit string generation unit 109 and decoding in the first encoded bit string decoding unit 202 of the video decoding device 200. Further, whether to encode or decode the L0 inter prediction information in units of slices may be switched. When switching the L0 inter prediction information, a syntax element inter_info_coding_l0_flag for encoding or decoding a flag interInfoCodingL0Flag indicating whether to encode or decode the L0 inter prediction information is prepared and encoded or decoded. Determine. In the present embodiment, the amount of code is reduced by switching whether at least one of the differential motion vector, the reference index, and the predicted motion vector index is encoded or decoded. For example, in bi-prediction, only the L1 differential motion vector is used as switching target inter prediction information, and whether to encode or decode only the bi-predictive L1 differential motion vector is switched in units of slices. When the encoding side reduces the amount of computation by reducing the L1 motion vector detection process in bi-prediction, or when it is determined that the encoding efficiency is improved by omitting the L1 differential prediction motion vector , Encoding or decoding the syntax element inter_info_coding_l1_flag with the value of the flag interInfoCodingL1Flag indicating whether to encode or decode the L1 inter prediction information in bi-prediction as 0, and depending on the value, the differential motion vector of the L1 in bi-prediction By omitting the encoding and decoding, the code amount of the inter prediction information is reduced. When encoding and decoding of the L1 differential motion vector in bi-prediction are omitted, the value of the L1 differential motion vector is set to (0, 0) on both the encoding side and the decoding side. That is, when the encoding and decoding of the L1 differential motion vector are omitted in bi-prediction, the L1 motion vector is used as it is on both the encoding side and the decoding side.

  Note that only the reference index may be the inter prediction information to be switched, only the predicted motion vector index may be the inter prediction information to be switched, or all may be the inter prediction information to be switched. Also, whether to encode or decode only the bi-predicted L1 inter prediction information in units of slices may be switched, and whether to encode or decode only the bi-predicted L0 inter prediction information in units of slices. You may switch. Here, the mode is switched to a mode in which at least one of the differential motion vector, the reference index, and the predicted motion vector index is not encoded or decoded in the inter prediction information of one of L0 and L1 of bi-prediction in units of slices. Like that.

  Also, instead of the flag interInfoCodingL1Flag indicating whether or not L1 inter prediction information is encoded or decoded in bi-prediction, the flag refIdxCodingL1Flag indicating whether or not the L1 reference index is encoded or decoded in bi-prediction, and L1 in bi-prediction It is also possible to prepare a flag mvpIdxCodingL1Flag indicating whether or not to encode or predict the predicted motion vector index, or a flag mvdCodingL1Flag indicating whether or not to encode or decode the L1 differential prediction motion vector in bi-prediction, it can. Also, a flag refIdxCodingL0Flag indicating whether or not the L0 reference index is encoded or decoded in bi-prediction, a flag mvpIdxCodingL0Flag indicating whether or not the L0 motion vector index is encoded or decoded in bi-prediction, and the difference of L0 in bi-prediction It is also possible to prepare a flag mvdCodingL0Flag indicating whether or not to encode or decode a predicted motion vector and switch them individually. As shown in the example of the syntax structure of the slice header in FIG. 11, a syntax element ref_idx_coding_l1_flag for encoding or decoding a flag refIdxCodingL1Flag indicating whether or not the L1 reference index is encoded or decoded by bi-prediction in the slice header , A syntax element mvp_idx_coding_l1_flag for encoding or decoding a flag mvpIdxCodingL1Flag indicating whether to encode or decode the L1 motion vector predictor index in bi-prediction, and L1 differential prediction motion vector in bi-prediction A syntax element mvd_coding_l1_flag for encoding or decoding a flag mvdCodingL1Flag indicating whether or not the first encoding bit sequence of the video encoding device 100 is generated when the slice type is a B slice Encoded by the unit 109 and moving image By decoding with the first encoded bit string decoding unit 202 of the decoding device 200, it is also possible to determine whether or not each L1 inter prediction information is encoded or decoded in bi-prediction. Also, when switching each L0 inter prediction information, a syntax element ref_idx_coding_l0_flag for encoding or decoding a flag refIdxCodingL0Flag indicating whether to encode or decode a reference index of L0 in bi-prediction, L0 in bi-prediction A flag indicating whether to encode or decode the predicted motion vector index of mvpIdxCodingL0Flag, a syntax element mvp_idx_coding_l0_flag for encoding or decoding, and a flag indicating whether to encode or decode the differential prediction motion vector of L0 in bi-prediction It discriminate | determines by preparing the syntax element mvd_coding_l0_flag for encoding or decoding mvdCodingL0Flag, and encoding or decoding. In the present embodiment, the code amount is reduced by switching whether at least one of these inter prediction information is encoded or decoded. For example, in bi-prediction, only the L1 differential motion vector is used as switching target inter prediction information, and whether to encode or decode only the bi-predictive L1 differential motion vector is switched in units of slices. When the encoding side reduces the amount of computation by reducing the L1 motion vector detection process in bi-prediction, or when it is determined that the encoding efficiency is improved by omitting the L1 differential prediction motion vector , Encoding or decoding the syntax element mvp_idx_coding_l1_flag with the value of the flag mvdCodingL1Flag indicating whether to encode or decode the L1 differential prediction motion vector in bi-prediction as 0, and bi-prediction L1 differential motion according to the value By omitting vector encoding and decoding, the code amount of inter prediction information is reduced. When omitting encoding and decoding of the L1 differential motion vector in bi-prediction, the L1 differential motion vector is set to (0, 0) on both the encoding side and the decoding side. That is, when the encoding and decoding of the L1 differential motion vector are omitted in bi-prediction, the L1 motion vector is used as it is on both the encoding side and the decoding side.

  Note that whether or not to encode or decode only the bi-predicted L0 differential prediction motion vector may be switched in units of slices. Further, whether to encode or decode only the bi-predictive L1 reference index in units of slices may be switched or whether to encode or decode only the bi-predictive L0 reference index in units of slices. Also good. Further, whether to encode or decode only the bi-predictive L1 reference index in units of slices may be switched or whether to encode or decode only the bi-predictive L0 reference index in units of slices. Also good. Further, whether to encode or decode only the prediction motion vector index of bi-predicted L1 in units of slices may be switched, or whether to encode or decode only the prediction motion vector index of bi-prediction L0 in units of slices. It may be switched. Whether to encode or decode bi-predictive L0 and L1 differential prediction motion vectors, respectively, or to encode or decode bi-predictive L0 and L1 reference indexes, respectively, in units of slices. Switching may be performed, and whether to predict or decode bi-predicted L0 and L1 motion vector predictor indexes may be switched. Also, whether to encode or decode the bi-predicted L1 differential motion vector, reference index, and predicted motion vector index may be switched in units of slices, or bi-predicted L0 differential motion vector and reference in units of slices. Whether to encode or decode the index and the motion vector predictor index may be switched. Here, the mode is switched to a mode in which at least one of the differential motion vector, the reference index, and the predicted motion vector index is not encoded or decoded in the inter prediction information of one of L0 and L1 of bi-prediction in units of slices. Like that.

  Next, a case of switching whether to encode or decode L1 inter prediction information according to the size of a prediction block to be encoded or decoded will be described with reference to FIG. These processes are performed as necessary in each block of the video encoding device 100 and the video decoding device 200 of the present embodiment.

  FIG. 12 is a flowchart illustrating a setting process procedure of a flag interInfoCodingL1Flag indicating whether to encode or decode L1 inter prediction information in bi-prediction when switching according to the size of a prediction block to be encoded or decoded.

  First, the size of the prediction block to be encoded or decoded is obtained (step S401). When the size of the prediction block to be encoded or decoded is equal to or smaller than the size sizePUInterPredInfoCodingL1 (YES in step S402), the flag interInfoCodingL1Flag is set to 0 (step S403). On the other hand, when the size of the prediction block to be encoded or decoded is larger than the specified size sizePUInterPredInfoCodingL1 (NO in step S402), interInfoCodingL1Flag is set to 1 (step S404). In the present embodiment, the prescribed size sizePUInterPredInfoCodingL1 is 8 × 8. The prescribed size sizePUInterPredInfoCodingL1 may be a fixed value, or may be set to an arbitrary value by preparing a syntax element for each sequence, picture, or slice. In addition, if the size is the same size, such as 8x4 and 4x8, multiplied by the width and height, it is considered the same size. That is, when the specified size sizePUInterPredInfoCodingL1 is set to 8x4, it is considered that 4x8 is also set. In step S402, if the size of the prediction block to be encoded or decoded is smaller than the specified size sizePUInterPredInfoCodingL1, interInfoCodingL1Flag may be set to 0. Otherwise, interInfoCodingL1Flag may be set to 1.

  An entropy encoding process procedure for inter prediction information in units of prediction blocks, which is performed by the first encoded bit string generation unit 109 of the moving image encoding apparatus in FIG. 1, will be described with reference to the flowchart in FIG. 13. First, a merge flag mergeFlag for determining whether or not the merge mode is set in units of prediction blocks is encoded (step S501). When the merge flag is 1 (YES in step S502), the merge index mergeIdx that identifies the merge candidate selected by the inter prediction information estimation unit 104 is encoded (step S503), and this encoding processing procedure is terminated.

  On the other hand, when the merge flag is 0 (NO in step S502), the condition determination in steps S504 and S505 is performed. When the inter prediction mode is L0 prediction (YES in step S504), the L0 reference index refIdxL0 is encoded (step S506), the L0 prediction motion vector index mvpIdxL0 is encoded (step S507), and the L0 differential motion vector is encoded. (Step S508), and the present encoding process procedure ends.

  On the other hand, when the inter prediction mode is L1 prediction (NO in step S504, YES in step S505), the L1 reference index refIdxL1 is encoded (step S509), and the L1 prediction motion vector index mvpIdxL1 is encoded (step S510). The differential motion vector of L1 is encoded (step S511), and this encoding processing procedure is terminated.

  On the other hand, if the inter prediction mode is bi-prediction (NO in step S504, NO in step S505), the L0 reference index refIdxL0 is encoded (step S512), and the L0 prediction motion vector index mvpIdxL0 is encoded (step S513). The differential motion vector of L0 is encoded (step S514).

  Subsequently, when the flag interPredInfoCodingL1Flag is 1, that is, when the L1 inter prediction information is encoded (YES in step S516), the L1 reference index refIdxL1 is encoded (step S517), and the L1 motion vector predictor index mvpIdxL1 is encoded. (Step S518), the differential motion vector of L1 is encoded (Step S519), and this encoding processing procedure is terminated.

  On the other hand, when the flag interPredInfoCodingL1Flag is 0, that is, when the inter prediction information of L1 is not encoded (NO in step S516), the encoding processing procedure is terminated.

  Next, an entropy decoding process procedure for inter prediction information in units of prediction blocks, which is performed by the first encoded bit string decoding unit 202 of the moving picture decoding apparatus in FIG. 2, will be described with reference to the flowchart in FIG. First, the merge flag mergeFlag for determining whether or not the merge mode is set for each prediction block is decoded (step S601). When the merge flag is 1 (YES in step S602), the merge index mergeIdx that identifies the merge candidate selected by the inter prediction information estimation unit 104 is decoded (step S603), and this decoding processing procedure ends.

  On the other hand, if the merge flag is 0 (NO in step S602), the condition determination in steps S604 and S605 is performed. When the inter prediction mode is L0 prediction (YES in step S604), the reference index refIdxL0 of L0 is decoded (step S606), the prediction motion vector index mvpIdxL0 of L0 is decoded (step S607), and the differential motion vector of L0 is decoded. (Step S608), and this decoding processing procedure is terminated.

  On the other hand, when the inter prediction mode is L1 prediction (NO in step S604, YES in step S605), the L1 reference index refIdxL1 is decoded (step S609), and the L1 prediction motion vector index mvpIdxL1 is decoded (step S610). The difference motion vector of L1 is decoded (step S611), and this decoding processing procedure is ended.

  On the other hand, when the inter prediction mode is bi-prediction (NO in step S604, NO in step S605), the L0 reference index refIdxL0 is decoded (step S612), and the L0 prediction motion vector index mvpIdxL0 is decoded (step S613). The differential motion vector of L0 is decoded (step S614).

  Subsequently, a flag interPredInfoCodingL1Flag is set (step S615). When switching according to the size of the prediction block to be decoded, the flag interPredInfoCodingL1Flag is set by the method described with reference to FIG. When switching whether to decode L1 inter prediction information in units of slices, the flag interPredInfoCodingL1Flag is set at the time of slice header decoding.

  Subsequently, when the flag interPredInfoCodingL1Flag is 1, that is, when the L1 inter prediction information is decoded (YES in step S616), the L1 reference index refIdxL1 is decoded (step S617), and the L1 motion vector predictor index mvpIdxL1 is decoded ( Step S618), the differential motion vector of L1 is decoded (Step S619), and this decoding processing procedure is terminated.

  On the other hand, when the flag interPredInfoCodingL1Flag is 0, that is, when the inter prediction information of L1 is not decoded (NO in step S616), the reference index deriving unit 211 derives the reference index refIdxL1 of L1 (step S620). Subsequently, the predicted motion vector index mvpIdxL1 of L1 is set to the value of the predicted motion vector index mvpIdxL0 of L0 (step S621). Subsequently, the differential motion vector of L1 is set to (0, 0) (step S622), and this decoding processing procedure is terminated.

  Next, a method for deriving the L1 reference index in bi-prediction performed by the reference index deriving unit 116 in FIG. 1 and the reference index deriving unit 211 in FIG. 2 will be described in detail.

  In the present embodiment, the reference index refIdxLX of L1 in the bi-prediction of the prediction block to be encoded or decoded is derived using the reference index used in the surrounding prediction block. This is because it is considered that the reference index of the prediction block to be encoded or decoded has a high correlation with the reference indexes of neighboring prediction blocks. In particular, only the reference indexes of the prediction block A1 close to the left side of the prediction block to be encoded or decoded and the prediction block B1 close to the upper side are used. This is because, among the adjacent prediction blocks A0, A1, B0, B1, and B2 shown in FIG. 5, the prediction blocks A1 and B1 that are in contact with the sides of the prediction block to be encoded or decoded are the prediction blocks to be encoded or decoded. This is because the correlation is considered to be higher than that of the prediction blocks A0, B0, and B2 that are in contact with the vertices. The prediction block to be used is limited to the prediction blocks A1 and B1 without using the prediction blocks A0, B0, and B2, thereby obtaining the improvement effect of the encoding efficiency by the derivation of the reference index, and the reference index derivation process Reduce the amount of computation and memory access.

Example 1
Hereinafter, this embodiment will be described by dividing it into several examples. First, Example 1 of the present embodiment will be described. In Example 1 of the present embodiment, both the prediction block A1 and the prediction block B1 are LX predictions (a list from which a reference index is derived is LX, and prediction using LX is LX prediction. That is, a reference index of L0) LX is set to L0 when L is derived, and LX is set to L1 when the reference index of L1 is derived.Hereafter, this is used in this sense unless otherwise noted). The smaller LX reference index value of A1 and prediction block B1 is adopted as the LX reference index value in bi-prediction of the prediction block to be encoded or decoded. Here, bi-prediction performs both L0 prediction and L1 prediction. However, when only one of the prediction block A1 and the prediction block B1 performs LX prediction, the value of the LX reference index of the prediction block that performs LX prediction is encoded or decoded by bi-prediction of the prediction block to be decoded. When the prediction block A1 and the prediction block B1 do not perform LX prediction, the LX reference index value in bi-prediction of the prediction block to be encoded or decoded is the default value 0. And

  The reason why the default value of the LX reference index in bi-prediction of the prediction block to be encoded or decoded when both the prediction block A1 and the prediction block B1 do not perform LX prediction is that the value of the reference index in inter prediction This is because there is a high probability that the reference picture corresponding to 0 is most selected. However, the present invention is not limited to this, and the default value of the reference index may be a value other than 0 (1, 2, etc.), and the default value of the reference index may be set in the encoded stream at the sequence level, picture level, or slice level. The syntax element shown may be installed and transmitted so that it can be selected on the encoding side.

  FIG. 15 is a flowchart for explaining a derivation process procedure of an LX reference index refIdxLX in bi-prediction of a prediction block to be encoded or decoded by the method of Example 1 of the present embodiment. First, the encoding information of the prediction block A1 adjacent to the left and the encoding information of the prediction block B1 are acquired from the encoding information storage memory 114 or 209 (steps S6101 and S6102).

  When both the flag predFlagLX [xA] [yA] indicating whether to perform LX prediction of the prediction block A and the flag predFlagLX [xB] [yB] indicating whether to perform LX prediction of the prediction block B1 are not 0 (in step S6103) YES), the LX reference index refIdxLX is set to the same value as the smaller of the LX reference index refIdxLX [xA] [yA] of the prediction block A1 and the LX reference index refIdxLX [xB] [yB] of the prediction block B1 In step S6104, the reference index deriving process is terminated. Here, xA and yA are indexes indicating the position of the upper left pixel of the prediction block A1 in the picture. Here, xB and yB are indexes indicating the position of the upper left pixel of the prediction block B1 in the picture.

  In the present embodiment, in the prediction block N (N = A, B), when the prediction block N cannot be used outside the slice to be encoded or decoded, the prediction block N is encoded or encoded in the decoding order. Alternatively, a flag indicating whether or not to use L0 prediction when the encoding block is not encoded or decoded after the decoding target prediction block and cannot be used, or when the prediction mode PredMode of the prediction block N is intra prediction (MODE_INTRA). Both predFlagL0 [xN] [yN] and the flag predFlagL1 [xN] [yN] indicating whether to use the L1 prediction of the prediction block N are 0. Here, xN and yN are indexes indicating the position of the upper left pixel of the prediction block N in the picture. When the prediction mode PredMode of the prediction block N is inter prediction (MODE_INTER) and the inter prediction mode is L0 prediction (Pred_L0), the flag predFlagL0 [xN] [yN] indicating whether to use the L0 prediction of the prediction block N is 1 , Flag predFlagL1 [xN] [yN] indicating whether to use L1 prediction is zero. When the inter prediction mode of the prediction block N is L1 prediction (Pred_L1), a flag predFlagL0 [xN] [yN] indicating whether or not to use the L0 prediction of the prediction block N is 0 and a flag indicating whether or not to use the L1 prediction predFlagL1 [xN] [yN] is 1. When the inter prediction mode of the prediction block N is bi-prediction (Pred_BI), a flag predFlagL0 [xN] [yN] indicating whether to use the L0 prediction of the prediction block N, and a flag predFlagL1 [indicating whether to use the L1 prediction xN] [yN] are both 1.

  When the flag predFlagLX [xA] [yA] indicating whether to perform LX prediction of the prediction block A1 is not 0 and the flag predFlagLX [xB] [yB] indicating whether to perform LX prediction of the prediction block B1 is 0 (NO in step S6103, YES in step S6105), the LX reference index refIdxLX is set to the same value as the LX reference index refIdxLX [xA] [yA] of the prediction block A1 (step S6106), and this reference index derivation process Exit. Here, xA and yA are indices indicating the position of the upper left pixel of the prediction block A1 in the picture, and xB and yB are indices indicating the position of the upper left pixel of the prediction block B1 in the picture.

  When the flag predFlagLX [xA] [yA] indicating whether to perform LX prediction of the prediction block A1 is 0 and the flag predFlagLX [xB] [yB] indicating whether to perform LX prediction of the prediction block B1 is not 0 ( NO in step S6103, NO in step S6105, YES in step S2107), the LX reference index refIdxLX is set to the same value as the LX reference index refIdxLX [xB] [yB] in the prediction block B1 (step S6108), The reference index derivation process is terminated.

  When the flag predFlagLX [xA] [yA] indicating whether to perform LX prediction of the prediction block A1 and the flag predFlagLX [xB] [yB] indicating whether to perform LX prediction of the prediction block B1 are both 0 (step S6103) In step S6105, step S6105 is NO, step S6107 is NO), the LX reference index refIdxLX is set to a default value of 0 (step S6109), and the reference index derivation process ends.

(Example 2)
Next, Example 2 of the present embodiment will be described. Also in Example 2 of the present embodiment, similar to Example 1, the reference index of the prediction block A1 that is close to the left side and the prediction block B1 that is close to the upper side is used for encoding or decoding. A reference index of LX in bi-prediction of the prediction block is derived. Compared to the first embodiment, the processing in step S6103 and step S6104 in FIG. 15 is omitted, and it is determined whether or not LX prediction is performed in the order of the prediction block A1 and the prediction block B1, and the LX prediction first found is determined. The difference is that the processing amount is further reduced by adopting the reference index of the prediction block to be performed. When the prediction block A1 performs LX prediction, the LX reference index of the prediction block A1 is adopted as the value of the LX reference index in the bi-prediction of the prediction block to be encoded or decoded, and the prediction block A1 performs LX prediction Instead, when the prediction block B1 performs LX prediction, the LX reference index of the prediction block B1 is adopted as the value of the LX reference index in the bi-prediction of the prediction block to be encoded or decoded. When neither the prediction block A1 nor the prediction block B1 performs LX prediction, the value of the LX reference index is set to 0, which is the default value.

  FIG. 16 is a flowchart for explaining a derivation process procedure of the LX reference index refIdxLX in the bi-prediction of the prediction block to be encoded or decoded by the method of Example 2 of the present embodiment. First, the encoding information of the prediction block A1 adjacent to the left and the encoding information of the prediction block B1 are acquired from the encoding information storage memory 114 or 209 (steps S6201 and S6202). Note that LX is set to L0 when the L0 reference index is derived, and LX is set to L1 when the L1 reference index is derived.

  If the flag predFlagLX [xA] [yA] indicating whether to perform LX prediction of the prediction block A1 is not 0 (YES in step S6203), the LX reference index refIdxLX is used as the LX reference index refIdxLX [xA] [xA] [ yA] is set to the same value (step S6204), and the reference index derivation process is terminated.

  When the flag predFlagLX [xA] [yA] indicating whether to perform LX prediction of the prediction block A1 is 0 and the flag predFlagLX [xB] [yB] indicating whether to perform LX prediction of the prediction block B1 is not 0 ( In step S6203 NO, step S6205 YES), the LX reference index refIdxLX is set to the same value as the LX reference index refIdxLX [xB] [yB] of the prediction block B1 (step S6206), and this reference index derivation process is performed. finish.

  When the flag predFlagLX [xA] [yA] indicating whether to perform LX prediction of the prediction block A1 and the flag predFlagLX [xB] [yB] indicating whether to perform LX prediction of the prediction block B1 are both 0 (step S6203). (NO in step S6205), the reference index refIdxLX of LX is set to the default value 0 (step S6207), and this reference index derivation process is terminated.

  In Example 2 of the present embodiment, whether or not LX prediction is performed in the order of the prediction block A1 close to the left side and the prediction block B1 close to the upper side is first found. Although it has been described that the reference index of the prediction block for performing the LX prediction is adopted, it may be determined whether or not the LX prediction is performed in the order of the prediction block B1 and the prediction block A1, and the prediction index found first may be adopted. it can.

(Example 3)
Next, Example 3 of the present embodiment will be described. Also in Example 3 of the present embodiment, encoding is performed using the reference indexes of the prediction block A1 that is close to the left side and the prediction block B1 that is close to the upper side in the same manner as in Example 1 and Example 2. Alternatively, an LX reference index in bi-prediction of a prediction block to be decoded is derived. Compared to Example 2, it is determined whether or not to perform inter prediction in the order of the prediction block A1 and the prediction block B1, and the processing amount is further increased by adopting the prediction index of the prediction block that performs the inter prediction first found. The difference is that it reduces. When the prediction mode (PredMode) of the prediction block A1 is inter prediction (MODE_INTER), the LX reference index of the prediction block A1 is adopted as the value of the LX reference index in the bi-prediction of the prediction block to be encoded or decoded. At this time, if the prediction block A1 does not perform LX prediction, the LX reference index in bi-prediction of the prediction block to be encoded or decoded is set to 0. When the prediction mode (PredMode) of the prediction block A1 is not inter prediction (MODE_INTER) and the prediction mode (PredMode) of the prediction block B1 is inter prediction (MODE_INTER), the LX reference index of the prediction block B1 is to be encoded or decoded. This is adopted as the value of the LX reference index in bi-prediction of the prediction block. At this time, if the prediction block B1 does not perform LX prediction, the LX reference index in bi-prediction of the prediction block to be encoded or decoded is set to 0. When the prediction modes (PredMode) of the prediction block A1 and the prediction block B1 are not inter prediction (MODE_INTER), the value of the LX reference index in bi-prediction of the prediction block to be encoded or decoded is set to 0.

  FIG. 17 is a flowchart for describing the derivation process procedure of the LX reference index refIdxLX in the bi-prediction of the prediction block to be encoded or decoded by the method of Example 3 of the present embodiment. First, the encoding information of the prediction block A1 adjacent to the left and the encoding information of the prediction block B1 are acquired from the encoding information storage memory 114 or 209 (steps S6301 and S6302).

  Subsequently, when the prediction block A1 can be used and the prediction mode (PredMode) of the prediction block A1 is intra prediction (MODE_INTRA) (YES in step S6303), that is, the prediction mode (PredMode) of the prediction block A1 is inter prediction (MODE_INTER). ), The process proceeds to step S6305. If the prediction mode (PredMode) of the prediction block A1 is not inter prediction (MODE_INTER), the process proceeds to step S6307.

  When the flag predFlagLX [xA] [yA] indicating whether to perform LX prediction of the prediction block A1 is not 0 (YES in step S6304), the LX reference index refIdxLX is used as the LX reference index refIdxLX [xA] [xA] [ If the flag predFlagLX [xA] [yA] is 0 (NO in step S6304), the LX reference index refIdxLX is set to 0 (step S6306). The index derivation process ends.

  On the other hand, in step S6307, when the prediction block B1 can be used and the prediction mode (PredMode) of the prediction block B1 is intra prediction (MODE_INTRA) (YES in step S6307), that is, the prediction mode (PredMode) of the prediction block B1 is inter. In the case of prediction (MODE_INTER), the process proceeds to step S6308. When the prediction mode (PredMode) of the prediction block A1 is not inter prediction (MODE_INTER), the process proceeds to step S6311.

  When the flag predFlagLX [xB] [yB] indicating whether to perform LX prediction of the prediction block B1 is not 0 (YES in step S6309), the LX reference index refIdxLX is used as the LX reference index refIdxLX [xB] [xB] [ yB] is set to the same value (step S6309), and when the flag predFlagLX [xB] [yB] is 0 (NO in step S6308), the LX reference index refIdxLX is set to 0 (step S6310). The index derivation process ends.

  On the other hand, in the case of NO in step S6307, the reference index refIdxLX of LX is set to 0 (step S6311), and this reference index derivation process ends.

  In Example 3 of the present embodiment, whether or not to perform inter prediction in the order of the prediction block A1 close to the left side and the prediction block B1 close to the upper side is found first. Although it was described as adopting the reference index of the prediction block that performs inter prediction, it is determined whether or not inter prediction is performed in the order of the prediction block B1 and the prediction block A1, and the prediction block that performs the inter prediction first found is determined. A predictive index can also be employed.

Example 4
Next, Example 4 of the present embodiment will be described. In Example 4 of the present embodiment, a reference index of LX in bi-prediction of a prediction block to be encoded or decoded is derived using a reference index of a prediction block A1 close to the left side. The second embodiment is different from the second embodiment in that the processing amount is further reduced by omitting the processes of steps S6202, S6205, and S6206 of FIG. When the prediction block A1 performs LX prediction (LX is a list from which a reference index is derived), the LX reference index of the prediction block A1 is encoded or decoded as the value of the LX reference index in bi-prediction of the prediction block to be decoded When the prediction block A1 does not perform LX prediction, the value of the LX reference index in bi-prediction of the prediction block to be encoded or decoded is set to 0 as the default value.

  FIG. 18 is a flowchart for explaining the derivation process procedure of the LX reference index refIdxLX in the bi-prediction of the prediction block to be encoded or decoded by the method of Example 4 of the present embodiment. First, the encoding information of the prediction block A1 adjacent to the left is acquired from the encoding information storage memory 114 or 209 (step S6401).

  When the flag predFlagLX [xA] [yA] indicating whether to perform LX prediction of the prediction block A1 is not 0 (YES in step S6402), the LX reference index refIdxLX is used as the LX reference index refIdxLX [xA] [xA] [ yA] is set to the same value (step S6403).

  When the flag predFlagLX [xA] [yA] indicating whether to perform LX prediction of the prediction block A1 is 0 (NO in step S6402), the LX reference index refIdxLX is set to 0 (step S6404).

  In Example 4 of the present embodiment, the LX reference index refIdxLX is described as being derived using the reference index refIdxLX [xA] [yA] of the prediction block A1 close to the left side. Instead of the prediction block A1 close to the left side, the reference index of LX can be derived using the reference index refIdxLX [xB] [yB] of the prediction block B1 close to the upper side.

(Example 5)
Next, Example 5 of the present embodiment will be described. In Example 5 of the present embodiment, when the reference picture of L0 is also included in L1, the reference index of L1 corresponds to the reference index of L0 in order to use the reference picture of L0 as the reference picture of L1. When the reference picture is set to a value indicating that the reference picture of L0 is not included in L1, the reference picture of L1 is set to the default value of 0. By using the L0 reference picture as the L1 reference picture, inter prediction with the same reference is performed.

  FIG. 19 is a flowchart for explaining a derivation process procedure of the reference index refIdxLX of LX (LX is a reference list to be derived) in bi-prediction of a prediction block to be encoded or decoded by the method of Example 5 of the present embodiment. is there.

  Subsequently, the POC of the reference picture RefPicListY [refIdxLY] registered in the LY reference list RefPicListY corresponding to the reference index refIdxLY of LY (LY is a reference list opposite to the derivation target) is acquired (step S6501).

  Subsequently, the LX reference index i is set to 0 (step S6502). Subsequently, the condition determination in step S6504 and the update of the reference index i in step S6506 are repeated until the reference index i reaches the number of LX reference indexes (steps S6503 to S6507). Reference of LY corresponding to reference index refIdxLY where POC of LX reference picture RefPicListX [i] registered in reference list RefPicListX of LX corresponding to reference index i is LY (LY is a reference list opposite to the derivation target) It is determined whether or not the reference picture RefPicListY [refIdxLY] registered in the list RefPicListY has the same value as the POC. (Step S6505), this derivation process is terminated. If the values are different (NO in step S6504), the LX reference index refIdxLX is updated by adding 1 to the reference index i (step S6506).

  When the iterative processing from step S6503 to S6507 is ended and the reference index of LX is not set, refIdxLX is set to a default value of 0, and this derivation processing ends.

(Example 6)
Next, Example 6 of the present embodiment will be described. In Example 6 of the present embodiment, whether to perform bi-prediction with the same reference using the L0 reference picture as the L1 reference picture is switched. In this switching, when both L0 and L1 perform forward prediction, in order to perform bi-prediction using the same reference picture, a reference picture derivation process similar to that in the fifth embodiment is performed. In the case of a slice for which backward prediction is performed, the reference index is set to 0 in order to perform bi-prediction using the preceding and following reference pictures.

  FIG. 20 is a flowchart for describing a derivation process procedure of the reference index refIdxLX of LX (LX is a reference list to be derived) in bi-prediction of a prediction block to be encoded or decoded by the method of Example 6 of the present embodiment. is there. The reference index derivation process in FIG. 20 is different from the reference picture derivation process in FIG. 19 in that the condition determination in step S6500 is added, and the processes in other steps are the same. Therefore, only step S6500 different from the reference picture derivation process of FIG. 19 will be described.

  When bi-prediction using the same reference picture is not performed (NO in step S6500), the reference index is set to 0 (step 6508), and this derivation process is terminated. When bi-prediction is performed using the same reference picture (YES in step S6500), processing similar to that in FIG. 19 after step S6501 is performed.

  Whether to perform bi-prediction with the same reference picture is prepared by providing a flag sameRefPicFlag indicating whether bi-prediction with the same reference picture is performed. For example, when both L0 and L1 perform forward prediction, the same reference picture is used. In order to perform bi-prediction, the flag sameRefPicFlag is set to 1, and in the case of a slice in which forward prediction is performed in L0 and backward prediction is performed in L1, the flag sameRefPicFlag is set to 0 in order to perform bi-prediction using the preceding and following reference pictures. Set. Furthermore, the encoding side and the decoding side are discriminated by preparing and encoding or decoding the syntax element same_ref_pic_flag for encoding or decoding the flag sameRefPicFlag indicating whether bi-prediction using the same reference picture is performed or not. can do.

  Next, a motion vector prediction method performed in the differential motion vector deriving unit 103 of the moving image encoding device in FIG. 1 and the motion vector deriving unit 204 in the moving image decoding device in FIG. 2 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 differential motion vector derivation method according to the embodiment in the video encoding device 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 a differential motion vector that is not a merge mode.

  FIG. 21 is a diagram illustrating a detailed configuration of the differential motion vector derivation unit 103 of the video encoding device in FIG. A portion surrounded by a thick frame line in FIG. 21 indicates the differential motion vector deriving 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 derivation 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, and a motion vector subtraction unit 127.

  In the difference motion vector calculation process in the difference motion vector deriving unit 103, the difference 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 block to be encoded is bi-prediction (Pred_BI), both L0 prediction and L1 prediction are performed, a prediction motion vector list mvpListL0 of L0 is constructed, a prediction motion vector mvpL0 of L0 is selected, and L0 Prediction motion vector index mvpIdxL0 of L1 is calculated, differential motion vector mvdL0 of motion vector mvL0 of L0 is calculated, prediction motion vector list mvpListL1 of L1 is constructed, prediction motion vector mvpL1 of L1 is selected, and prediction of L1 is performed A motion vector index mvpIdxL1 is determined, and a differential motion vector mvdL1 of the L1 motion vector mvL1 is calculated. In the present embodiment, when the inter prediction mode is bi-prediction, whether to encode inter prediction information for L1 prediction is switched for each slice or according to the size of the prediction block to be encoded. When the L1 differential motion vector mvdL1 in bi-prediction is included as the inter prediction information to be switched, and the L1 differential motion vector mvdL1 in bi-prediction is not encoded, the L1 differential motion vector mvdL1 in bi-prediction Is set to (0,0). When the prediction motion vector index mvpIdxL1 in bi-prediction is included as inter prediction information to be switched, and the prediction motion vector index mvpIdxL1 in bi-prediction is not encoded, the prediction motion of L1 in bi-prediction The vector index mvpIdxL1 is set to the same value as the L0 predicted motion vector index mvpIdxL0.

  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 generating unit 121 predicts 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, and supplies the predicted motion vector candidate registration unit 122. Hereinafter, mvLXA and mvLXB are referred to as spatial prediction motion vectors, and mvLXCol is referred to as a temporal prediction motion vector. When calculating the prediction motion vector candidates, 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.

  These predicted motion vector candidates mvLXA, mvLXB, and mvLXCol may be derived by scaling according to the relationship between the POC of the current picture and the POC of the reference picture.

  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 motion vector predictor from a prediction block group adjacent to the left side, the prediction approaching the upper side in the order from the bottom to the top of the prediction block group adjacent to the left side (order A0 to A0, 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 the right to the left of the prediction block group adjacent to the upper side (order from 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 proximity 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 proximity prediction block group, the right prediction 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 proximity prediction blocks of the proximity prediction block group on the left side and the proximity prediction block group on the upper side, in the scanning methods 1, 2, 3, and 4 to be described later, the following condition determinations 1, 2, 3, and 4 are prioritized. Each condition decision is applied in order. However, with the exception of only scan method 5 described later, the respective condition determinations are applied in the priority order of condition determinations 1, 3, 2, and 4.
Condition determination 1: Prediction using the same reference index, that is, the same reference picture, is performed in the proximity 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 or 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 or decoded, prediction using the same reference picture is performed in the proximity prediction block.
Condition determination 3: Prediction using a different reference picture is performed in the proximity prediction block with the same reference list LX as the motion vector of the LX that is the differential motion vector calculation target of the prediction block to be encoded or decoded.
Condition determination 4: Prediction using a different reference picture in the reference list LY different from the motion vector of the LX that is the difference motion vector calculation target of the prediction block to be encoded or decoded is performed in the proximity prediction block.

  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. Note that when the condition of condition determination 1 or condition determination 2 is met, the motion vector of the corresponding adjacent prediction block corresponds to the same reference picture, and thus is used as a candidate for the motion vector predictor. If the condition of condition determination 4 is met, the motion vector of the corresponding adjacent prediction block corresponds to a different reference picture, and therefore, the motion vector is calculated by scaling and used as a predicted motion vector candidate.

  The following five methods can be set as a 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 will be described later in detail with reference to the flowcharts of FIGS. 26 to 30, but for other scanning methods 2 to 5, a person skilled in the art also knows how to perform the scanning methods 2 to 5 by using the scanning method 1. Since this is an item that can be appropriately designed in accordance with the procedure for carrying out the above, detailed description is 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 motion vector predictor that does not require a scaling operation using the same reference picture. 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. Condition determination 1 of the prediction block N2 (the same reference list LX, the same reference picture), only the prediction block group adjacent to the upper side 6. 6. Condition determination 2 of the prediction block N2 (different reference list LY, the same reference picture), only the prediction block group adjacent to 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 to the upper side Prediction block 4 for condition block 4 (different reference list LY, different reference picture), only the prediction block group adjacent to the upper side

  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 number of rounds of condition determination is a maximum of 2, the number of memory accesses to the encoded information of the prediction block is less than that in the scanning method 2 described later when considering implementation in hardware, and complexity is increased. Is reduced.

Scanning method 2:
Among 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 (the same reference list LX, the same reference picture), only the prediction block group adjacent to 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 to 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 to 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 Prediction block 4 for condition block 4 (different reference list LY, different reference picture), only the prediction block group adjacent to the upper side

  According to the scan method 2, since a predicted motion vector that does not require a scaling operation using the same reference picture is easily selected, there is an effect of increasing the possibility that the code amount of the difference motion vector is reduced. 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.

Scan method 3:
In the first round, the condition determination of condition determination 1 is performed for each prediction block, and if the condition is not satisfied, the process proceeds to the condition determination of the adjacent prediction block. In the next lap, the condition determination is performed in the order of condition determination 2, condition determination 3, condition determination 4 for each prediction block, and then the process moves 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 (the same reference list LX, the same reference picture), only the prediction block group adjacent to 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, the same reference picture), only the prediction block group adjacent to 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 to the upper side Prediction block 4 for condition block 4 (different reference list LY, different reference picture), only the prediction block group adjacent to the upper side

  According to the scan method 3, 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 rounds for condition determination is two, the number of memory accesses to the encoded information of the prediction block is smaller than that in the scanning method 2 when considering implementation in hardware, and complexity is reduced. Is done.

Scanning method 4:
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 to the upper side 10. Condition determination 2 of the prediction block N2 (different reference list LY, the same reference picture), only the prediction block group adjacent to 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 to the upper side Prediction block 4 for condition block 4 (different reference list LY, different reference picture), only the prediction block group adjacent to the upper side

  According to the scan method 4, 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 when the implementation in hardware is taken into consideration is the scan method 1 and the scan method 2. Compared with the scanning method 3, the complexity is reduced.

Scanning method 5:
Similar to the scanning method 4, priority is given to the condition determination of the same prediction block, and four condition determinations are performed within one prediction block. If all the conditions are not met, the motion vector matching the condition is not included in the prediction block. It is determined that it does not exist, and the condition of the next prediction block is determined. However, in the condition determination in the prediction block, the scan method 4 gives priority to the same reference picture, but the scan method 5 gives priority to the same reference list.

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 3 of the prediction block N0 (same reference list LX, different reference pictures)
3. Prediction block N0 condition determination 2 (different reference list LY, same reference picture)
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 3 of the prediction block N1 (same reference list LX, different reference pictures)
7). Condition determination 2 of the prediction block N1 (different reference list LY, same reference picture)
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 to the upper side 10. Condition determination 3 of the prediction block N2 (same reference list LX, different reference pictures), only the prediction block group adjacent to the upper side 11. Condition determination 2 of the prediction block N2 (different reference list LY, the same reference picture), only the prediction block group adjacent to the upper side Prediction block 4 for condition block 4 (different reference list LY, different reference picture), only the prediction block group adjacent to the upper side

  According to the scan method 5, the number of times of reference block reference lists can be reduced compared to the scan method 4, and the complexity is reduced by reducing the number of times of access to the memory and the amount of processing such as condition determination. can do. Similarly to scan method 4, since the number of rounds for condition determination is at most one, the number of memory accesses to the encoded information of the prediction block is the scan method 1, scan when considering implementation in hardware. Compared with Method 2 and Scan Method 3, the complexity is reduced.

  Next, the predicted motion vector candidate registration unit 122 stores the calculated predicted motion vector candidates mvLXA, mvLXB, and mvLXCol in the predicted motion vector list 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. However, when the defined final candidate number finalNumMVPCand is 1, this redundancy determination process can be omitted.

  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 the error, and there is a problem that entropy decoding cannot be continued normally. If the final candidate number finalNumMVPCand is defined as a fixed number according to the size of the prediction block, the prediction motion vector index can be entropy-decoded independently of the construction of the prediction motion vector list, and an encoded bit string of another picture Even if an error occurs during decoding, it is possible to continue entropy decoding of the encoded bit string of the current picture without being affected by the error.

  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 (specified number of 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 elements registered at an index larger than finalNumMVPCand-1 are deleted from the predicted motion vector list mvpListLX, and the predicted motion vector for LX 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.

  In the present embodiment, when the inter prediction mode is bi-prediction, whether to encode inter prediction information for L1 prediction is switched for each slice or according to the size of the prediction block to be encoded. When the L1 differential motion vector mvdL1 in bi-prediction is included as the inter prediction information to be switched, and the L1 differential motion vector mvdL1 in bi-prediction is not encoded, the L1 differential motion vector mvdL1 in bi-prediction Is set to 0. When the prediction motion vector index mvpIdxL1 in bi-prediction is included as inter prediction information to be switched, and the prediction motion vector index mvpIdxL1 in bi-prediction is not encoded, the prediction motion of L1 in bi-prediction The code amount of the vector index mvpIdxL1 is set to 0.

  The motion vector predictor selection unit 126 selects a motion vector candidate mvpListLX [i] that has the smallest code amount for each motion vector predictor candidate from among the elements registered in the motion vector list mvpListLX of LX. Select as the predicted motion vector mvpLX. 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 is supplied to the motion vector subtraction unit 127. Further, the index i in the predicted motion vector list mvpListLX corresponding to the selected predicted motion vector mvpLX is output as a predicted motion vector index mvpIdxLX of LX.

  In the present embodiment, when the inter prediction mode is bi-prediction, whether to encode inter prediction information for L1 prediction is switched for each slice or according to the size of the prediction block to be encoded. When the prediction motion vector index mvpIdxL1 in bi-prediction is included as inter prediction information to be switched, and the prediction motion vector index mvpIdxL1 in bi-prediction is not encoded, the prediction motion of L1 in bi-prediction The vector index mvpIdxL1 is set to the same value as the L0 predicted motion vector index mvpIdxL0 and is output.

Finally, the motion vector subtraction unit 127 calculates the LX differential motion vector mvdLX by subtracting the selected LX predicted motion vector mvpLX from the LX motion vector mvLX, and outputs the differential motion vector mvdLX.
mvdLX = mvLX-mvpLX

  In the present embodiment, when the inter prediction mode is bi-prediction, whether to encode inter prediction information for L1 prediction is switched for each slice or according to the size of the prediction block to be encoded. When the L1 differential motion vector mvdL1 in bi-prediction is included as the inter prediction information to be switched, and the L1 differential motion vector mvdL1 in bi-prediction is not encoded, the L1 differential motion vector mvdL1 in bi-prediction Is set to (0,0) and output.

(Prediction of motion vector in decoding)
The operation of the motion vector deriving method according to the present invention in the moving image decoding apparatus for decoding the encoded moving image bit stream based on the above-described syntax will be described.

  When the motion vector deriving method according to the embodiment is performed, processing is performed by the motion vector deriving unit 204 of the video decoding device in FIG. FIG. 22 is a diagram illustrating a detailed configuration of the motion vector deriving 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. 22 indicates the motion vector deriving 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.

  In the present embodiment, for the reason explained on the encoding side, the final motion vector finalNumMVPCand is set on the decoding side as well as the encoding side according to the size of the prediction block to be decoded. The motion vector derivation unit 204 sets finalNumMVPCand to a number smaller than the latter if the size of the prediction block of the luminance signal to be decoded is equal to or smaller than the sizePUInterPredInfoCodingL1, and otherwise sets the finalNumMVPCand to a number larger than the former To do. In the present embodiment, the specified size sizePUInterPredInfoCodingL1 is set to 8x8, and the finalNumMVPCand is set to 1 if the size of the prediction block of the luminance signal to be decoded is smaller than the specified sizesizePUInterPredInfoCodingL1, otherwise the finalNumMVPCand is set to 1. Set to 2.

  The motion vector deriving unit 204 includes a predicted motion vector candidate generating unit 221, a predicted motion vector candidate registering unit 222, a predicted motion vector redundant candidate deleting unit 223, a predicted motion vector candidate number limiting unit 224, a predicted motion vector selecting unit 225, and a motion vector. An adder 226 is included.

  In the motion vector deriving process in the motion vector deriving unit 204, motion vectors used in inter prediction are 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), a prediction motion vector list mvpListL0 of L0 is constructed, and L0 The motion vector mvpL0 of L0 is calculated by selecting the motion vector predictor mvpL0 indicated by the motion vector index mvpIdxL0 and adding the motion vector mvdL0 of L0. When the inter prediction mode of the encoding target block is L1 prediction (Pred_L1), a prediction motion vector list mvpListL1 of L1 is constructed, a prediction motion vector mvpL1 indicated by the prediction motion vector index mvpIdxL1 of L1 is selected, and differential motion of L1 The vector mvdL1 is added to calculate the L1 motion vector mvL1. When the inter prediction mode of the encoding target block is bi-prediction (Pred_BI), both L0 prediction and L1 prediction are performed, and a prediction motion vector list mvpListL0 of L0 is constructed, and the prediction motion vector index mvpIdxL0 of L0 indicates L0. The predicted motion vector mvpL0 is selected and the difference motion vector mvdL0 of L0 is added to calculate the motion vector mvL0 of L0, and the predicted motion vector list mvpListL1 of L1 is constructed, and the predicted motion vector index mvpIdxL1 of L1 indicates The L1 predicted motion vector mvpL1 is calculated, and the L1 differential motion vector mvdL1 is added to calculate the L1 motion vector mvL1. In the present embodiment, when the inter prediction mode is bi-prediction, whether to decode inter prediction information for L1 prediction is switched for each slice or according to the size of a prediction block to be encoded. In the case where the L1 differential motion vector mvdL1 in bi-prediction is included as inter prediction information to be switched, and the L1 differential motion vector mvdL1 in bi-prediction is not decoded, the first encoded bit string decoding unit 202 performs bi-prediction. The difference motion vector mvdL1 of L1 at is set to (0, 0) and supplied to the motion vector deriving unit 204. When the L1 motion vector index mvpIdxL1 in bi-prediction is included as inter prediction information to be switched, and the L1 motion vector predictor index mvpIdxL1 in bi-prediction is not decoded, the first encoded bit string decoding unit 202 The predicted motion vector index mvpIdxL1 of L1 in bi-prediction is set to the same value as the predicted motion vector index mvpIdxL0 of L0 and is supplied to the motion vector deriving unit 204.

  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 deriving unit 204 includes a motion vector predictor candidate generating unit 221, a motion vector predictor candidate registering unit 222, a motion vector predictor redundant candidate deleting unit 223, and a motion vector predictor candidate number restricting unit 224, which are encoded difference motion vectors It is specified that the motion vector predictor candidate generating unit 121, the motion vector predictor candidate registering unit 122, the motion vector predictor redundant candidate deleting unit 123, and the motion vector predictor candidate number limiting unit 124 in the derivation unit 103 perform the same operation. Thus, the same motion vector predictor candidates that are consistent between encoding and decoding can be obtained on the encoding side and the 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. Decoded and recorded in the encoded information storage memory 209, the decoded predicted block close to the decoding target block in the same picture as the decoding target block, and the same position as or near the decoding target block in a different picture Are read out from the encoded information storage memory 209. Predicted motion vector candidates mvLXA, mvLXB, and mvLXCol are generated for each predicted block group from the motion vectors of other decoded blocks read from the encoded information storage memory 209 and supplied to the predicted motion vector candidate registration unit 222. .

  These predicted motion vector candidates mvLXA, mvLXB, and mvLXCol may be calculated by scaling according to the reference index. 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. 21, 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, and 5 for calculating the motion vector predictor can also be applied to the motion vector predictor candidate generation unit 221 and detailed description thereof is omitted here.

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

  Next, the motion vector redundancy candidate deletion unit 223 performs the same process as that performed by the motion vector redundancy candidate deletion unit 123 on the encoding side in FIG. Among the predicted motion vector candidates stored in the LX predicted motion vector list mvpListLX, those having the same motion vector value are determined, and one predicted motion vector candidate determined to have the same motion vector value. The remaining motion vectors are deleted from the predicted motion vector list mvpListLX, the predicted motion vector candidates are not duplicated, and the predicted motion vector list mvpListLX is updated.

  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 elements registered at an index larger than finalNumMVPCand-1 are deleted from the predicted motion vector list mvpListLX, and the predicted motion vector for LX 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 226. 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 prediction motion vector selection unit 225 is supplied with the prediction motion vector index mvpIdxLX of the LX decoded by the first encoded bit string decoding unit 202, and selects a prediction motion vector candidate mvpListLX [mvpIdxLX] corresponding to the supplied index mvpIdxLX. It extracts from the motion vector list mvpListLX as the motion vector motion vector mvpLX of LX. The supplied motion vector predictor candidate is supplied to the motion vector adding unit 226 as a motion vector predictor mvpLX.

Finally, the motion vector addition unit 226 calculates the LX motion vector mvLX by adding the LX differential motion vector mvdLX and the LX prediction motion vector mvpLX that are supplied after being decoded by the first encoded bit string decoding unit 202. And outputs a motion vector mvLX.
mvLX = mvpLX + mvdLX

  In the present embodiment, when the inter prediction mode is bi-prediction, whether to decode inter prediction information for L1 prediction is switched for each slice or according to the size of a prediction block to be encoded. In the case where the L1 differential motion vector mvdL1 in bi-prediction is included as inter prediction information to be switched, and the L1 differential motion vector mvdL1 in bi-prediction is not decoded, the first encoded bit string decoding unit 202 performs bi-prediction. Since the difference motion vector mvdL1 of L1 is set to (0, 0) and is supplied to the motion vector deriving unit 204, the motion vector mvL1 of L1 becomes the same as the value of the predicted motion vector mvpL1 of L1.

  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.

  Next, processing procedures of the differential motion vector deriving unit 103 of the moving image encoding device and the motion vector deriving unit 204 of the moving image decoding device will be described using the flowcharts of FIGS. 23 and 24, respectively. FIG. 23 is a flowchart showing a difference motion vector calculation processing procedure by the moving image encoding device, and FIG. 24 is a flowchart showing a motion vector calculation processing procedure by the moving image decoding device.

  With reference to FIG. 23, the differential motion vector calculation processing procedure on the encoding side will be described. On the encoding side, first, the differential motion vector deriving 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 S106). 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 deriving 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 motion vector predictor candidate code amount calculation unit 125 calculates each motion vector difference which is a difference between the motion vector mvLX and each motion vector candidate mvpListLX [i] stored in the motion vector predictor list mvpListLX. Then, the coding amount when the difference motion vector is encoded is calculated for each element of the prediction motion vector list mvpListLX, and the prediction motion vector selection unit 126 among the elements registered in the prediction motion vector list mvpListLX, A predicted motion vector candidate mvpListLX [i] that minimizes the code amount for each predicted motion vector candidate is selected as a predicted motion vector mvpLX. 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 subtraction unit 127 calculates an LX differential motion vector mvdLX by subtracting the selected LX motion vector mvpLX from the LX motion vector mvLX (S105).
mvdLX = mvLX-mvpLX

  In the present embodiment, when the inter prediction mode is bi-prediction, whether to encode inter prediction information for L1 prediction is switched for each slice or according to the size of the prediction block to be encoded. When the L1 differential motion vector mvdL1 in bi-prediction is included as the inter prediction information to be switched, and the L1 differential motion vector mvdL1 in bi-prediction is not encoded, the L1 differential motion vector mvdL1 in bi-prediction Is set to (0,0).

  Next, the decoding-side motion vector calculation processing procedure will be described with reference to FIG. On the decoding side, the motion vector deriving unit 204 calculates motion vectors used for inter prediction for each of L0 and L1 (S201 to S206). 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). In the motion vector deriving unit 204, a motion vector predictor candidate generation unit 221 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 is selected from the predicted motion vector list mvpListLX by the predicted motion vector selection unit 225. The predicted motion vector mvpLX is extracted (S204). However, if the maximum candidate number finalNumCandLX is 1, the only predicted motion vector candidate mvpListLX [0] registered in the predicted motion vector list mvpListLX is extracted as the selected predicted motion vector mvpLX.

Subsequently, the motion vector addition unit 226 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. (S205 in FIG. 24).
mvLX = mvpLX + mvdLX

  In the present embodiment, when the inter prediction mode is bi-prediction, whether to decode inter prediction information for L1 prediction is switched for each slice or according to the size of a prediction block to be encoded. In the case where the L1 differential motion vector mvdL1 in bi-prediction is included as inter prediction information to be switched, and the L1 differential motion vector mvdL1 in bi-prediction is not decoded, the first encoded bit string decoding unit 202 performs bi-prediction. Since the difference motion vector mvdL1 of L1 is set to (0, 0) and is supplied to the motion vector deriving unit 204, the motion vector mvL1 of L1 becomes the same as the value of the predicted motion vector mvpL1 of L1.

  Next, a procedure for derivation of a prediction motion vector candidate common to S103 in FIG. 23 and S203 in FIG. 24 and a prediction motion vector list construction process will be described in detail with reference to the flowchart in FIG.

(Motion vector prediction method)
FIG. 25 shows motion vector predictor candidate generating units 121 and 221 having a function common to the motion vector deriving unit 103 of the video encoding device and the motion vector deriving unit 204 of the video decoding device, and a motion vector predictor 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 generating units 121 and 221 derive motion vector predictor candidates from a motion block adjacent to the left side, a flag availableFlagLXA indicating whether the motion vector predictor candidate of the motion block adjacent to the left side is available, and motion A vector mvLXA, a reference index refIdxA, and a list ListA are derived (S301 in FIG. 25). 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 a prediction block adjacent to the upper side, and a flag availableFlagLXB indicating whether the motion vector predictor candidate of the prediction block adjacent to the upper side can be used. , And a motion vector mvLXB, a reference index refIdxB, and a list ListB are derived (S302 in FIG. 25). The processes in steps S301 and S302 in FIG. 25 are the same except that the positions and numbers of adjacent blocks to be referenced are different, and a flag availableFlagLXN indicating whether or not a motion vector candidate of a predicted block can be used, and a motion vector mvLXN A common derivation processing procedure for deriving the indexes refIdxN and ListN (N is A or B, and so on) will be described in detail later using 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. A flag availableFlagLXCol, a motion vector mvLXCol, a reference index refIdxCol, and a list ListCol are derived (S303 in FIG. 25). The derivation process 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 a motion vector predictor list mvpListLX, and add the respective motion vector candidates mvLXA, mvLXB, and mvLXCol of LX (S304 in FIG. 25). The registration processing procedure in step S304 will be described in detail later using the flowchart in FIG.

  Subsequently, the motion vector redundancy candidate deletion units 123 and 223 determine that motion vector candidates are redundant motion vector candidates when the motion vector candidates have the same value or close values in the motion vector predictor list mvpListLX. The 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. 25). The deletion processing procedure in step S305 will be described in detail later using the flowchart in 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. 25). The restriction process procedure of step S306 will be described in detail later with reference to the flowchart of FIG.

  A procedure for deriving motion vector predictor candidates from the prediction blocks adjacent to the left side or upper side of S301 and S302 in FIG. 25 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 prediction motion vector 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 motion vector predictor candidates from the prediction block group N adjacent to the left and upper sides, which is the processing procedure of S301 and S302 in FIG. 25, will be described. FIG. 26 is a flowchart showing the predicted motion vector candidate derivation process procedure of S301 and S302 of FIG. The subscript X contains 0 or 1 representing the reference list, and N contains A (left side) or B (upper side) representing the adjacent prediction block group region.

  In order to derive motion vector predictor candidates from the left prediction block (S301 in FIG. 25), prediction is performed from prediction blocks A0 and A1 that are close to the left side of the prediction block to be encoded or decoded in FIG. In order to derive motion vector candidates from the upper prediction block (S302 in FIG. 25), predicted motion vectors from the B0, B1, and B2 prediction blocks that are close to the upper side with N as B in FIG. The candidates are calculated according to the following procedure.

  First, a prediction block close to a prediction block to be encoded or decoded is identified, 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 indices 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 or 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) close to the upper side of the prediction block to be encoded or decoded (NO in S1101), close to the prediction block B0 close to the upper right Encoding 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 or 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 Condition Determination 1 or Condition Determination 2 described above is derived (S1108). Reference list that is currently targeted by the prediction block to be encoded or decoded in the proximity prediction blocks N0, N1, and N2 (N2 is only the upper proximity 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 prediction block to be encoded or decoded (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. 27 is a flowchart showing the derivation process procedure of step S1108 of FIG. For the 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 (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 close When the LX reference index refIdxLX [xNk] [yNk] of the prediction block Nk is the same as the index refIdxLX of the prediction block to be processed, 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, and 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. 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 (S1204). The predicted motion vector candidate calculation process is terminated.

  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 being the same and the POC of the reference picture in the LX of the prediction block to be processed are the same If yes (YES in S1205), the process proceeds to step S1206, the flag availableFlagLXN is set to 1, and the motion vector mvLY [xNk] [yNk] of the prediction block Nk in which the prediction motion vector mvLXN of the prediction block group N is close. And the reference index refIdxN of the prediction block group N is The same value as the LY reference index refIdxLY [xNk] [yNk] of the adjacent prediction block Nk is set, the reference list ListN of the prediction block group N is set to LY (S1206), and the prediction motion vector candidate calculation process is terminated. To do.

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

  Subsequently, returning to the flowchart of FIG. 26, 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). Reference list LX that is currently the target of the prediction block to be encoded or 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 or 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. 28 is a flowchart showing the derivation process procedure of step S1110 of FIG. For the 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 The reference index refIdxN of the prediction block Nk is set to the same value as the LX reference index refIdxLX [xNk] [yNk], 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 proximity prediction block is processed (S1301 to S1307), and availableFlagLXN becomes 1, The processing 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), mvLXN is scaled (S1309). The procedure of the scaling operation of the spatial prediction motion vector candidate in step S1309 will be described with reference to FIGS.

  FIG. 29 is a flowchart showing the motion vector scaling processing procedure in step S1309 of FIG.

The inter-picture distance td is calculated by subtracting the POC of the reference picture referred to by the list of adjacent prediction blocks ListN from the POC of the current encoding or decoding target picture (S1601). If the reference picture referenced in the list of adjacent prediction blocks ListN is earlier in the display order than the current encoding or decoding target picture, the inter-picture distance td becomes a positive value, and the current encoding or decoding target When the reference picture referenced in the reference list ListN of the proximity prediction block is later in the display order than the picture, the inter-picture distance td is a negative value.
td = POC of the current coding or decoding target picture—POC of the reference picture referenced in the reference list ListN of the near prediction block

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

Subsequently, scaling operation processing is performed by multiplying mvLXN by the scaling coefficient tb / td according to the following equation (S1603) to obtain a scaled motion vector mvLXN.
mvLXN = tb / td * mvLXN

  FIG. 30 shows an example of the case where the scaling operation in step S1603 is performed with integer precision arithmetic. The processing in steps S1604 to S1606 in FIG. 30 corresponds to the processing in step S1603 in FIG.

  First, as in the flowchart of FIG. 29, the inter-picture distance td and the inter-picture distance tb are calculated (S1601, S1602).

Subsequently, the variable tx is calculated by the following equation (S1604).
tx = (16384 + Abs (td / 2)) / td

Subsequently, the scaling coefficient DistScaleFactor is calculated by the following equation (S1605).
DistScaleFactor = (tb * tx + 32) >> 6

Subsequently, a scaled motion vector mvLXN is obtained by the following equation (S1606).
mvLXN = ClipMv (Sign (DistScaleFactor * mvLXN) * ((Abs (DistScaleFactor * mvLXN) + 127) >> 8))

  Next, a method of deriving motion vector predictor candidates from the prediction blocks of pictures at different times in S303 in FIG. 25 will be described in detail. FIG. 31 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 calculated based on slice_type and collocated_from_l0_flag (S2101 in FIG. 31).

  FIG. 32 is a flowchart for explaining the procedure for deriving the picture colPic at different times in step S2101 of FIG. When slice_type is B and the above-described flag collocated_from_l0_flag is 0 (YES in S2201 in FIG. 32, YES in S2202), RefPicList1 [0], that is, pictures with a reference index 0 in the reference list L1 are pictures colPic at different times. (S2203 in FIG. 32). 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. 32), 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. 32).

  Next, returning to the flowchart of FIG. 31, a prediction block colPU at a different time is calculated, and encoded information is acquired (S2102 of FIG. 31).

  FIG. 33 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 the picture colPic at a different time is set as a prediction block colPU at a different time (S2301 in FIG. 33). 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. 33). When PredMode of the prediction block colPU at different time is MODE_INTRA or cannot be used (S2303 and S2304 in FIG. 33), the prediction block located at the center upper left of the same position as the processing target prediction block in the picture colPic at different time is different in time. The prediction block colPU is reset (S2305 in FIG. 33). This prediction block corresponds to the prediction block T1 in FIG.

  Next, returning to the flowchart of FIG. 31, the LX prediction motion vector mvLXCol calculated from the prediction block of the other picture at the same position as the prediction block to be encoded or 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. 31).

  FIG. 34 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. 34, NO in S2402), availableFlagLXCol is set to 0 and mvLXCol is set to (0, 0) (S2403 and S2404 in FIG. 34). Exit.

  When the prediction block colPU is available and PredMode is not MODE_INTRA (YES in S2401 in FIG. 34, YES in S2402), 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. 34), the prediction mode of the prediction block colPU is Pred_L1, and therefore 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. 34), and the reference index refIdxCol is set to the same value as the reference index RefIdxL1 [xPCol] [yPCol] of L1 The list ListCol is set to L1 (S2408 in FIG. 34).

  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. 34), 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. 34), the motion vector mvCol is the same as MvL0 [xPCol] [yPCol] that is the L0 motion vector of the prediction block colPU. Is set to a value (S2410 in FIG. 34), the reference index refIdxCol is set to the same value as the reference index RefIdxL0 [xPCol] [yPCol] of L0 (S2411 in FIG. 34), and the list ListCol is set to L0 (FIG. 34). 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. 34, 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. 34).

  FIG. 35 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 POC of all pictures registered in all reference lists is smaller than the POC of the current encoding or decoding target picture (S2501), and L0 and all 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 or decoding target picture (YES in S2501), X is 0, that is, the L0 motion vector of the prediction block to be encoded or 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 or decoded. When the prediction vector candidate is calculated (NO in S2502), the prediction block colPU in the L1 direction is calculated. To select the measurement information. On the other hand, when at least one of the POCs of pictures registered in all the reference lists L0 and L1 of the prediction block colPU is larger than the POC of the current encoding or decoding target picture (NO in S2501), and the flag collocated_from_l0_flag is 0 (YES in S2503), the L0 inter prediction information of the prediction block colPU is selected. If 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. 34, if inter prediction information can be acquired from the prediction block colPU, the availableFlagLXCol is set to 1 (S2414 in FIG. 34).

  Next, returning to the flowchart in FIG. 31, when availableFlagLXCol is 1 (YES in S2104 in FIG. 31), mvLXCol is scaled as necessary (S2105 in FIG. 31). A procedure for scaling operation of the motion vector mvLXCol will be described with reference to FIGS.

  FIG. 36 is a flowchart showing the motion vector scaling calculation processing procedure in step S2105 of FIG.

The inter-picture distance td is calculated by subtracting the POC of the reference picture referenced in the list ListCol of the prediction block colPU from the POC of the picture colPic at a different time (S2601). Note that when the POC of the reference picture referenced in the list Col of the prediction block colPU is earlier in the display order than the picture colPic at a different time, the inter-picture distance td is a positive value, and the prediction is more accurate than the picture colPic at a different time. When the POC of the reference picture referenced in the list ListCol of the block colPU is later in the display order, the inter-picture distance td is a negative value.
td = POC of picture colPic at different time-POC of reference picture referenced by list ListCol of prediction block colPU

The inter-picture distance tb is calculated by subtracting the POC of the reference picture referenced by the current encoding or decoding target picture list LX from the POC of the current encoding or decoding target picture (S2602). If the reference picture referenced in the list LX of the current encoding or decoding target picture is earlier than the current encoding or decoding target picture in the display order, the inter-picture distance tb is a positive value. When the reference picture referred to in the encoding or decoding target picture list LX is later in the display order, the inter-picture distance tb is a negative value.
tb = POC of the current encoding or decoding target picture-POC of the reference picture referenced in the reference list LX of the current encoding or decoding target picture

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. When the inter-picture distances td and tb are not equal (NO in S2603), scaling operation processing is performed by multiplying mvLXCol by the scaling coefficient tb / td according to the following equation (S2604) to obtain a scaled motion vector mvLXCol.
mvLXCol = tb / td * mvLXCol

  FIG. 37 shows an example of the case where the scaling calculation in step S2604 is performed with integer precision calculations. The processing in steps S2605 to S2607 in FIG. 37 corresponds to the processing in step S2604 in FIG.

  First, as in the flowchart of FIG. 36, the inter-picture distance td and the inter-picture distance tb are calculated (S2601, 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 (S2605).
tx = (16384 + Abs (td / 2)) / td

Subsequently, the scaling coefficient DistScaleFactor is calculated by the following equation (S2606).
DistScaleFactor = (tb * tx + 32) >> 6

Subsequently, a scaled motion vector mvLXN is obtained by the following equation (S2607).
mvLXN = ClipMv (Sign (DistScaleFactor * mvLXN) * ((Abs (DistScaleFactor * mvLXN) + 127) >> 8))

  The procedure for adding the predicted motion vector candidate in S304 of FIG. 25 to the predicted motion vector list will be described in detail.

  The candidate motion vector candidates mvLXA, mvLXB, and mvLXCol of LX calculated in S301, S302, and S303 of FIG. 25 are added to the LX motion vector predictor 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 S306 of FIG. 25, the elements placed behind the motion vector predictor list are removed from the motion vector predictor list, 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. 25 will be described in detail. FIG. 38 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 is registered at the position corresponding to the index i in the predicted motion vector list mvpListLX (S3103), and is updated by adding 1 to the index i (S3103). S3104).

  Subsequently, when availableFlagLXB is 1 (YES in S3105), an LX predicted motion vector candidate mvLXB is registered at a position corresponding to the index i of the predicted motion vector list mvpListLXmvpListLX (S3106), and 1 is added to the index i. Update (S3107).

  Subsequently, when availableFlagLXCol is 1 (YES in S3108), the LX predicted motion vector candidate mvLXCol is registered at the position corresponding to the index i of the predicted motion vector list mvpListLX (S3109), and the registration process to the predicted motion vector list is performed. finish.

  Next, a method for deleting redundant prediction motion vector candidates in the prediction motion vector list in S305 of FIG. 25 will be described in detail. FIG. 39 is a flowchart showing the predicted motion vector redundant candidate deletion processing procedure in S305 of FIG.

  When the final candidate number finalNumMVPCand is larger than 1 (YES in S4101), the motion vector redundancy candidate deletion units 123 and 223 compare motion vector candidates registered in the motion vector predictor list mvpListLX (S4102), If the motion vector candidates have the same value or close values (YES in S4103), the motion vector candidates are determined to be redundant motion vector candidates, and are redundant except for the motion vector candidate with the smallest order, that is, the smallest index i. A candidate for a motion vector is removed (S4104). 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 (S4105). 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.

  When the final candidate number finalNumMVPCand is 1 (NO in S4101), it is not necessary to perform the process of deleting redundant motion vector predictor candidates in S305, and thus the redundant candidate deletion process is terminated. This is because the number of candidates is limited to one in the process of limiting the number of elements in step S306.

  When the size of the prediction block is small, the number of prediction blocks per unit area increases, so that the number of processes for deleting redundant prediction motion vector candidates also increases.

  Next, the method for limiting the number of motion vector candidates in the predicted motion vector list in S306 of FIG. 25 will be described in detail. FIG. 40 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. 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 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.

  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. .

  101 image memory, 116 reference index derivation unit, 102 motion vector detection unit, 103 differential motion vector derivation unit, 104 inter prediction information estimation unit, 105 motion compensation prediction unit, 106 prediction method determination unit, 107 residual signal generation unit, 108 Orthogonal transform / quantization unit, 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 superimposition unit, 114 Coding 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 limiting unit, 125 prediction motion vector candidate Code amount calculation unit, 126 prediction Vector selection unit, 127 motion vector subtraction unit, 201 separation unit, 202 first encoded bit string decoding unit, 203 second encoded bit string decoding unit, 211 reference index deriving unit, 204 motion vector deriving unit, 205 inter prediction information estimation , 206 motion compensation prediction unit, 207 inverse quantization / inverse orthogonal transform unit, 208 decoded image signal superposition unit, 209 encoded information storage memory, 210 decoded image memory, 221 prediction motion vector candidate generation unit, 222 prediction motion vector candidate A registration unit, 223 predicted motion vector redundancy candidate deletion unit, 224 predicted motion vector candidate number limit unit, 225 predicted motion vector selection unit, and 226 motion vector addition unit.

Claims (17)

A video decoding device that decodes a coded bit sequence in which a video is encoded using inter prediction in units of prediction blocks obtained by dividing each picture,
Decoding a reference index for identifying a reference picture to be referred to in inter prediction of a prediction block to be decoded from among a plurality of reference images, a prediction motion vector to be selected, and a motion vector of the prediction block to be decoded; A decoding unit that decodes the difference motion vector of the signal to obtain inter prediction information;
A plurality of motion vector predictor candidates are derived by referring to encoding information of a plurality of decoded blocks, and the motion vector predictor selected from the plurality of motion vector predictor candidates and the decoded difference motion vector And a motion vector deriving unit for deriving a motion vector of the prediction block to be decoded by adding
When the inter prediction mode is bi-prediction having the first prediction and the second prediction, the decoding unit performs the difference motion vector for the inter prediction information of the first prediction or the inter prediction information of the second prediction in units of slices. And a mode in which at least one of the reference indexes is not decoded.   The decoding unit further decodes a prediction motion vector index that identifies a prediction motion vector to be selected from a plurality of prediction motion vector candidates, and when the inter prediction mode is bi-prediction, The inter-prediction information for one prediction or the inter-prediction information for second prediction has a mode in which at least one of the differential motion vector, the reference index, and the prediction motion vector index is not decoded. The moving picture decoding apparatus described.   3. The moving picture decoding apparatus according to claim 1, wherein when the difference motion vector is not decoded, the motion vector deriving unit sets the difference motion vector to (0, 0). 4.   4. The decoding unit according to claim 1, wherein when the inter prediction mode is bi-prediction, the decoding unit has a mode in which the differential motion vector is not decoded for inter prediction information of the second prediction in units of slices. Any one of the moving image decoding apparatuses. The decoding unit indicates whether or not to perform differential motion vector decoding of second prediction in bi-prediction for each slice, and sets the differential motion vector to (0, 0). And when the inter prediction mode is bi-prediction, the mode is switched to a mode in which the differential motion vector of the second prediction is not decoded according to the mode information in units of slices.
The motion vector deriving unit sets the differential motion vector of the second prediction to (0, 0) when the differential motion vector of the second prediction is not decoded according to the mode information, and the decoding target The moving picture decoding apparatus according to claim 1, wherein a motion vector of the prediction block is derived. A moving picture decoding method for decoding a coded bit string in which a moving picture is coded using inter prediction in units of prediction blocks obtained by dividing each picture,
Decoding a reference index for identifying a reference picture to be referred to in inter prediction of a prediction block to be decoded from among a plurality of reference images, a prediction motion vector to be selected, and a motion vector of the prediction block to be decoded; A decoding step of decoding the difference motion vector to obtain inter prediction information;
A plurality of motion vector predictor candidates are derived by referring to encoding information of a plurality of decoded blocks, and the motion vector predictor selected from the plurality of motion vector predictor candidates and the decoded difference motion vector And a motion vector deriving step of deriving a motion vector of the prediction block to be decoded by adding
When the inter prediction mode is bi-prediction having the first prediction and the second prediction, the decoding step performs the difference motion vector for the inter prediction information of the first prediction or the inter prediction information of the second prediction in units of slices. And a mode of not decoding at least one of the reference indexes.   The decoding step according to claim 6, wherein when the inter prediction mode is bi-prediction, the decoding step has a mode in which the differential motion vector is not decoded for inter prediction information of the second prediction in units of slices. Video decoding method. A moving picture decoding program for decoding a coded bit string in which a moving picture is coded using inter prediction in units of prediction blocks obtained by dividing each picture,
Decoding a reference index for identifying a reference picture to be referred to in inter prediction of a prediction block to be decoded from among a plurality of reference images, a prediction motion vector to be selected, and a motion vector of the prediction block to be decoded; A decoding step of decoding the difference motion vector to obtain inter prediction information;
A plurality of motion vector predictor candidates are derived by referring to encoding information of a plurality of decoded blocks, and the motion vector predictor selected from the plurality of motion vector predictor candidates and the decoded difference motion vector And a motion vector deriving step of deriving a motion vector of the prediction block to be decoded by adding
When the inter prediction mode is bi-prediction having the first prediction and the second prediction, the decoding step performs the difference motion vector for the inter prediction information of the first prediction or the inter prediction information of the second prediction in units of slices. And a moving picture decoding program having a mode in which at least one decoding of the reference index is not performed.   The decoding step according to claim 8, wherein when the inter prediction mode is bi-prediction, the decoding step includes a mode in which the differential motion vector is not decoded for inter prediction information of the second prediction in units of slices. A video decoding program. A receiving device that receives and decodes an encoded bit sequence in which a moving image is encoded,
A receiving unit that receives encoded data in which a coded bit sequence in which a moving image is coded using inter prediction in units of blocks obtained by dividing each picture is packetized;
A restoring unit that packet-processes the received encoded data and restores the original encoded bit string;
A reference index that identifies a reference picture to be referred to in inter prediction of a prediction block to be decoded from among a plurality of reference images is decoded from the restored encoded bit string, and a prediction motion vector to be selected and the decoding A decoding unit that obtains inter prediction information by decoding a difference motion vector from a motion vector of a target prediction block;
A plurality of motion vector predictor candidates are derived by referring to encoding information of a plurality of decoded blocks, and the motion vector predictor selected from the plurality of motion vector predictor candidates and the decoded difference motion vector And a motion vector deriving unit for deriving a motion vector of the prediction block to be decoded by adding
When the inter prediction mode is bi-prediction having the first prediction and the second prediction, the decoding unit performs the difference motion vector for the inter prediction information of the first prediction or the inter prediction information of the second prediction in units of slices. And a receiving apparatus having a mode in which at least one decoding of the reference index is not performed.   The decoding unit according to claim 10, wherein when the inter prediction mode is bi-prediction, the decoding unit has a mode in which the differential motion vector is not decoded for inter prediction information of the second prediction in units of slices. Receiver device.   The receiving apparatus according to claim 10 or 11, wherein when the differential motion vector is not decoded, the motion vector deriving unit sets the differential motion vector to (0, 0). The decoding unit indicates whether or not to perform differential motion vector decoding of second prediction in bi-prediction for each slice, and sets the differential motion vector to (0, 0). And when the inter prediction mode is bi-prediction, the mode is switched to a mode in which the differential motion vector of the second prediction is not decoded according to the mode information in units of slices.
The motion vector deriving unit sets the differential motion vector of the second prediction to (0, 0) when the differential motion vector of the second prediction is not decoded according to the mode information, and the decoding target The receiving apparatus according to claim 10, wherein a motion vector of a prediction block is derived. A receiving method for receiving and decoding an encoded bit string in which a moving image is encoded,
A reception step of receiving encoded data in which a coded bit sequence in which a moving image is encoded using inter prediction in units of blocks obtained by dividing each picture is packetized;
A restoration step of packetizing the received encoded data to restore the original encoded bit sequence;
A reference index that identifies a reference picture to be referred to in inter prediction of a prediction block to be decoded from among a plurality of reference images is decoded from the restored encoded bit string, and a prediction motion vector to be selected and the decoding A decoding step of decoding the motion vector difference from the motion vector of the target prediction block to obtain inter prediction information;
A plurality of motion vector predictor candidates are derived by referring to encoding information of a plurality of decoded blocks, and the motion vector predictor selected from the plurality of motion vector predictor candidates and the decoded difference motion vector And a motion vector deriving step of deriving a motion vector of the prediction block to be decoded by adding
When the inter prediction mode is bi-prediction having the first prediction and the second prediction, the decoding step performs the difference motion vector for the inter prediction information of the first prediction or the inter prediction information of the second prediction in units of slices. And a mode in which at least one decoding of the reference index is not performed.   15. The decoding step according to claim 14, wherein when the inter prediction mode is bi-prediction, the decoding step includes a mode in which the differential motion vector is not decoded for inter prediction information of the second prediction in units of slices. Reception method. A receiving program that receives and decodes a coded bit string in which a moving image is coded,
A reception step of receiving encoded data in which a coded bit sequence in which a moving image is encoded using inter prediction in units of blocks obtained by dividing each picture is packetized;
A restoration step of packetizing the received encoded data to restore the original encoded bit sequence;
A reference index that identifies a reference picture to be referred to in inter prediction of a prediction block to be decoded from among a plurality of reference images is decoded from the restored encoded bit string, and a prediction motion vector to be selected and the decoding A decoding step of decoding the motion vector difference from the motion vector of the target prediction block to obtain inter prediction information;
A plurality of motion vector predictor candidates are derived by referring to encoding information of a plurality of decoded blocks, and the motion vector predictor selected from the plurality of motion vector predictor candidates and the decoded difference motion vector And a motion vector deriving step of deriving a motion vector of the prediction block to be decoded by adding
When the inter prediction mode is bi-prediction having the first prediction and the second prediction, the decoding step performs the difference motion vector for the inter prediction information of the first prediction or the inter prediction information of the second prediction in units of slices. And a receiving program having a mode in which at least one decoding of the reference index is not performed.   The decoding step according to claim 16, wherein when the inter prediction mode is bi-prediction, the decoding step includes a mode in which the differential motion vector is not decoded for inter prediction information of the second prediction in units of slices. Receiving program.

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