JP2020108085A - Image encoding device, image encoding method, and image encoding program - Google Patents

Abstract

To provide a technique capable of improving encoding efficiency by performing block division suitable for image encoding and decoding.SOLUTION: An image encoding device comprises: a motion information history memory which stores a history of a plurality of motion information; a prediction motion vector candidate derivation unit which derives prediction motion vector candidates containing a history prediction motion vector candidate from a memory holding encoded block motion information; and a merge candidate derivation unit which derives merge candidates containing a history merge candidate from a memory holding the encoded block motion information. When the prediction motion vector candidates are derived, the image encoding device stores motion information in the motion information history memory. When the merge mode candidates are derived, the image encoding device does not store motion information in the motion information history memory.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image coding and decoding technique that divides an image into blocks and performs prediction.

In image encoding and decoding, an image to be processed is divided into blocks, which are a set of a predetermined number of pixels, and processing is performed in block units. By dividing into appropriate blocks and appropriately setting intra-frame prediction (intra prediction) and inter-frame prediction (inter prediction), coding efficiency is improved.

In coding/decoding of moving images, coding efficiency is improved by inter prediction that predicts from a coded/decoded picture. Patent Document 1 describes a technique of applying an affine transformation at the time of inter prediction. It is not uncommon for an object to be deformed in a moving image such as enlargement/reduction or rotation, and by applying the technique of Patent Document 1, efficient encoding is possible.

JP, 9-172644, A

However, since the technique of Patent Document 1 involves image conversion, there is a problem that the processing load is large. In view of the above problems, the present invention provides a low-load and efficient encoding technique.

In order to solve the above problems, a moving picture coding apparatus according to an aspect of the present invention uses a motion information history memory that stores a history of a plurality of motion information and a history prediction from a memory that holds motion information of encoded blocks. A motion vector predictor candidate derivation unit that derives a motion vector predictor candidate including a motion vector candidate, and a merge candidate derivation unit that derives a merge candidate including a history merge candidate from a memory holding motion information of an encoded block. When the motion vector history candidate is derived, the motion information is stored in the motion information history memory, and when the merge mode candidate is derived, the motion information is not stored in the motion information history memory.

According to the present invention, highly efficient image encoding/decoding processing can be realized with a low load.

It is a block diagram of the image coding apparatus which concerns on 1st Embodiment. It is a block diagram of the image decoding apparatus which concerns on 1st Embodiment. 9 is a flowchart illustrating an operation of dividing a tree block. It is a figure which shows a mode that the input image is divided into tree blocks. It is a figure explaining z-scan. It is a figure which shows the division|segmentation shape of a block. 7 is a flowchart illustrating an operation of dividing a block into four. 6 is a flowchart for explaining an operation of dividing a block into two or three. It is a syntax for expressing the shape of block division. It is a figure for explaining intra prediction. It is a figure for demonstrating the reference block of inter prediction. It is a syntax for expressing a coding block prediction mode. It is a figure which shows the correspondence of the syntax element and mode regarding inter prediction. It is a figure for demonstrating the affine transformation motion compensation of two control points. It is a figure for demonstrating the affine transformation motion compensation of three control points. FIG. 3 is a block diagram of a detailed configuration of an inter prediction unit 201 in FIG. 1. FIG. 17 is a block diagram of a detailed configuration of a normal motion vector predictor mode deriving unit 301 in FIG. 16. FIG. 17 is a block diagram of a detailed configuration of a normal merge mode derivation unit 302 in FIG. 16. 17 is a flowchart for explaining a normal motion vector predictor mode derivation process of the normal motion vector predictor mode deriving unit 301 in FIG. 16. 6 is a flowchart showing a processing procedure of a normal motion vector predictor mode derivation process having a common function between the normal motion vector predictor mode derivation unit 301 and the normal motion vector predictor mode derivation unit 401 according to the embodiment of the present invention. 7 is a flowchart illustrating a procedure of a merge mode derivation process having a common function between the normal merge mode derivation unit 302 and the normal merge mode derivation unit 402 according to the embodiment of the present invention. FIG. 3 is a block diagram of a detailed configuration of an inter prediction unit 203 in FIG. 2. 23 is a block diagram of a detailed configuration of a normal motion vector predictor mode deriving unit 301 in FIG. 22. FIG. FIG. 17 is a block diagram of a detailed configuration of a normal merge mode derivation unit 302 in FIG. 16. 23 is a flowchart for explaining a normal motion vector predictor mode derivation process of the normal motion vector predictor mode deriving unit 301 in FIG. 22. 6 is a block diagram of a sub-block motion vector predictor mode deriving unit 303 in the encoding device of the present application. FIG. 11 is a block diagram of a sub-block motion vector predictor mode deriving unit 403 in the decoding device of the present application. FIG. 4 is a block diagram of a sub-block merge mode derivation unit 304 in the encoding device of the present application. FIG. FIG. 11 is a block diagram of a sub-block merge mode derivation unit 404 in the decoding device of the present application. It is a figure explaining affine succession prediction motion vector candidate derivation. It is a figure explaining affine construction prediction motion vector candidate derivation. It is a figure explaining affine succession merge candidate derivation. It is a figure explaining affine construction merge candidate derivation. It is a flowchart of deriving an affine succession prediction motion vector candidate. It is a flowchart of deriving an affine construction prediction motion vector candidate. It is a flowchart of deriving an affine inheritance merge candidate. It is a flowchart of deriving an affine construction merge candidate. It is a flow chart explaining a history prediction motion vector candidate list initialization and update processing procedure. It is a flowchart of the same element confirmation processing procedure in the history prediction motion vector candidate derivation processing procedure. It is a flow chart of an element shift processing procedure in a history prediction motion vector candidate derivation processing procedure. It is a flow chart explaining a history prediction motion vector candidate derivation processing procedure. It is a flow chart explaining a history merge candidate derivation processing procedure. It is a figure for demonstrating the same candidate deletion process of a history motion vector predictor candidate list. 9 is a flowchart for explaining an operation of a sub block time merge candidate derivation unit 381. 9 is a flowchart for explaining a process of deriving block adjacent motion information. 9 is a flowchart for explaining a process of deriving a temporal motion vector. It is a flow chart for explaining derivation of inter prediction information. 7 is a flowchart illustrating a process of deriving sub-block motion information. It is a figure for demonstrating the temporal context of a picture. 7 is a flowchart for explaining a process of deriving a temporal motion vector predictor candidate in a normal motion vector predictor mode deriving unit 301. 9 is a flowchart for explaining a ColPic derivation process in a derivation process of temporal motion vector predictor candidates in the normal motion vector predictor mode deriving unit 301. 9 is a flowchart for explaining a process of deriving ColPic coding information in the process of deriving a temporal motion vector predictor candidate in the normal motion vector predictor mode deriving unit 301. It is a flow chart for explaining a derivation process of inter prediction information. 11 is a flowchart illustrating a procedure of deriving inter prediction information of a coding block when the inter prediction mode of the coding block colCb is bi-prediction (Pred_BI). 7 is a flowchart for explaining a scaling calculation processing procedure of a motion vector. It is a flow chart for explaining derivation processing of a time merge candidate. It is a figure for demonstrating the prediction direction of motion compensation prediction in the case of uni-prediction and the reference picture (RefL0Pic) of L0 exists in the time before the encoding target picture (CurPic). It is a figure for demonstrating the prediction direction of motion compensation prediction in the case of uni-prediction and the reference picture of L0 prediction is in the time after a picture to be coded. A prediction direction of motion-compensated prediction in the case of bi-prediction and a reference picture of L0 prediction at a time earlier than the current picture to be coded and a reference picture of L1 prediction at a later time than the current picture to be coded will be described. FIG. It is a figure for demonstrating the prediction direction of motion compensation prediction in the case where it is bi-prediction and the reference picture of L0 prediction and the reference picture of L1 prediction exist in the time before the encoding target picture. It is a figure for demonstrating the prediction direction of motion compensation prediction in the case of bi-prediction, and the reference picture of L0 prediction and the reference picture of L1 prediction are in the time after a picture to be coded. 11 is a table showing another example of the history motion vector predictor candidate added by the initialization of the history motion vector predictor candidate list. 11 is a table showing another example of the history motion vector predictor candidate added by the initialization of the history motion vector predictor candidate list. 11 is a table showing another example of the history motion vector predictor candidate added by the initialization of the history motion vector predictor candidate list. It is a flow chart explaining a history prediction motion vector candidate derivation processing procedure with additional restrictions. It is a flow chart explaining the history prediction motion vector candidate derivation processing procedure when the same candidate judgment is not performed.

The techniques and technical terms used in this embodiment are defined.

<Tree block>
In the embodiment, the encoding/decoding processing target image is equally divided into a predetermined size. This unit is defined as a tree block. As shown in FIG. 4, the size of the tree block is set to 128×128 pixels in the present embodiment, but the size of the tree block is not limited to this, and any size may be set. The tree blocks to be processed (corresponding to the encoding target in the encoding process and the decoding target in the decoding process) are switched in raster scan order, that is, from left to right and from top to bottom. The inside of each tree block can be further recursively divided. A block to be encoded/decoded after the tree block division is defined as an encoded block. Further, the tree block and the coding block are collectively defined as a block. Efficient encoding is possible by performing appropriate block division. The size of the tree block may be a fixed value pre-arranged by the encoding device and the decoding device, or the size of the tree block determined by the encoding device may be transmitted to the decoding device.

<Prediction mode>
Processing target image has been processed in units of processing target coding block (in the coding processing, a signal whose coding has been completed is used as a decoded image, an image signal, etc., and in the decoding processing, a decoding completed image and a preliminary image signal are used. , Etc.) are switched between intra prediction (MODE_INTRA) that performs prediction from image signals around () and inter prediction (MODE_INTER) that performs prediction from image signals of processed images. 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.

<Inter prediction>
In inter prediction in which prediction is performed from image signals of processed images, a plurality of processed images can be used as reference pictures. In order to manage a plurality of reference pictures, two types of lists, L0 (reference list 0) and L1 (reference list L1), are defined, and the reference pictures are specified using the respective reference indexes. L0 prediction (Pred_L0) is available for P slices. For the B slice, L0 prediction (Pred_L0), L1 prediction (Pred_L1), and bi-prediction (Pred_BI) can be used. L0 prediction (Pred_L0) is inter prediction that refers to the reference picture managed by L0, and L1 prediction (Pred_L1) is inter prediction that refers to the reference picture managed by L1. Bi-prediction (Pred_BI) is an inter prediction in which both L0 prediction and L1 prediction are performed and one reference picture managed by each of L0 and L1 is referred to. Information that specifies L0 prediction, L1 prediction, and bi-prediction is defined as a reference mode. In the subsequent processing, it is premised that the processing is performed for each of L0 and L1 for the constants and variables with the subscript LX attached to the output.

<Predictive motion vector mode>
The motion vector predictor mode is a mode in which an index for specifying a motion vector predictor, a differential motion vector, a reference mode, and a reference index are transmitted to determine inter prediction information of a current block. The motion vector predictor includes a motion vector predictor candidate derived from a processed block that is close to the process target block, or a block that belongs to the processed image and is located at the same position as the process target block or in the vicinity thereof (nearby), and the motion vector predictor. It is derived from the index for identifying the vector.

<Merge mode>
The merge mode is a processed block that is close to the processing target block without transmitting the differential motion vector or reference index, or a block that belongs to the processed image and is located at the same position as the processing target block or in the vicinity thereof (nearby). This is a mode for deriving the inter prediction information of the processing target block from the inter prediction information of.

A processed block close to the block to be processed and the inter prediction information of the processed block are defined as spatial merge candidates. A block that belongs to the processed image and is located at the same position as the processing target block or in the vicinity thereof (nearby) and the inter prediction information derived from the inter prediction information of the block are defined as temporal merge candidates. Each merge candidate is registered in the merge candidate list, and the merge candidate identifies the merge candidate to be used in the prediction of the block to be processed.

<Proximity block>
FIG. 11 is a diagram illustrating reference blocks referred to in order to derive inter prediction information in the motion vector predictor mode and the merge mode. A0, A1, A2, B0, B1, B2, B3 are processed blocks close to the processing target block. T0 is a block that belongs to an image that has been encoded/decoded and that is located at the same position as or near (near) the encoding/decoding process target block of the encoding/decoding process target image.

A1 and A2 are blocks located on the left side of the target coding block and adjacent to the target coding block. B1 and B3 are blocks located above the processing target coding block and adjacent to the processing target coding block. A0, B0, and B2 are blocks located at the lower left, upper right, and upper left of the process target coding block, respectively.

Details of how to handle adjacent blocks in the motion vector predictor mode and merge mode will be described later.

<Affine transformation motion compensation>
The affine transformation motion compensation is performed by dividing a sub-block into a predetermined unit, individually determining a motion vector for each sub-block, and performing motion compensation. The motion vector of each sub-block is derived from the inter prediction information of a processed block that is close to the processing target block, or a block that belongs to the processed image and is located at the same position as the processing target block or in the vicinity thereof (nearby) 1 Derivation based on one or more control points. In the present embodiment, the size of the sub block is 4×4 pixels, but the size of the sub block is not limited to this, and the motion vector may be derived in pixel units.

FIG. 14 shows an example of affine transformation motion compensation when there are two control points. In this case, since two control points have two parameters of a horizontal direction component and a vertical direction component, the affine transformation when there are two control points is called a four parameter affine transformation. CP1 and CP2 in FIG. 14 are control points. FIG. 15 shows an example of affine transformation motion compensation when there are three control points. In this case, since three control points have two parameters of a horizontal direction component and a vertical direction component, the affine transformation in the case of three control points is called a 6 parameter affine transformation. CP1, CP2, and CP3 in FIG. 15 are control points.

Affine transform motion compensation can be used in both the prediction motion vector mode and the merge mode. A mode in which affine transform motion compensation is applied in the motion vector predictor mode is defined as a sub-block motion vector predictor mode, and a mode in which affine transform motion compensation is applied in the merge mode is defined as a sub-block merge mode.

<Inter prediction syntax>
The syntax related to inter prediction will be described with reference to FIGS. 12 and 13. The merge_flag in FIG. 12 is a flag indicating whether the process target coding block is in the merge mode or the motion vector predictor mode. merge_affine_flag is a flag indicating whether or not the sub-block merge mode is applied to the processing target coding block in the merge mode. inter_affine_flag is a flag indicating whether or not to apply the sub-block motion vector predictor mode in the processing target coding block in the motion vector predictor mode. cu_affine_type_flag is a flag for determining the number of control points in the sub-block motion vector predictor mode. FIG. 13 shows the value of each syntax element and the corresponding prediction method. merge_flag=1 and merge_affine_flag=0 correspond to the normal merge mode, which is the merge mode that is not the sub-block merge. merge_flag=1 and merge_affine_flag=1 correspond to the sub-block merge mode. merge_flag=0 and inter_affine_flag=0 correspond to the normal motion vector predictor mode, which is a motion vector predictor merge that is not the sub-block motion vector predictor mode. merge_flag=0 and inter_affine_flag=1 correspond to the sub-block motion vector predictor mode. When merge_flag=0 and inter_affine_flag=1, cu_affine_type_flag is further transmitted to determine the number of control points.

<POC>
POC (Picture Order Count) is a variable associated with a picture to be encoded, and a value that is incremented by 1 in the output order of the picture is set. Depending on the value of POC, it is possible to determine whether they are the same picture, determine the context between pictures in the output order, and 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. If the POCs of the two pictures have different values, it can be determined that the picture with the smaller POC value is the picture that is output first, and the difference between the POCs of the two pictures determines the inter-picture distance in the time axis direction. Show.

(First embodiment)
The image encoding device 100 and the image decoding device 200 according to the first embodiment of the present invention will be described.

FIG. 1 is a block diagram of an image coding device 100 according to the first embodiment. The moving image coding apparatus according to the embodiment includes an image coding apparatus 100, a block division unit 101, an inter prediction unit 102, an intra prediction unit 103, a decoded image memory 104, a prediction method determination unit 105, a residual signal generation unit 106, An orthogonal transformation/quantization unit 107, a bit string encoding unit 108, an inverse quantization/inverse orthogonal transformation unit 109, a decoded image signal superimposing unit 110, and an encoding information storage memory 111 are provided.

The block division unit 101 recursively divides the input image to generate a coded block. The block dividing unit 101 includes a 4-dividing unit that divides a block to be divided into a horizontal direction and a vertical direction, and a 2-3 dividing unit that divides a block to be divided into either a horizontal direction or a vertical direction. .. The generated image signal of the process target coding block is supplied to the inter prediction unit 102, the intra prediction unit 103, and the residual signal generation unit 106. In addition, the information indicating the determined recursive division structure is supplied to the bit string encoding unit 108. The detailed operation of the block division unit 101 will be described later.

The inter prediction unit 102 performs inter prediction of the process target coding block. A plurality of inter prediction information candidates are derived from the prediction mode stored in the encoding information storage memory and the decoded image signal stored in the decoded image memory 104, and an inter prediction mode suitable from the plurality of candidates is derived. Is selected, and the selected inter prediction mode and the predicted image signal corresponding to the selected inter prediction mode are supplied to the prediction method determination unit 105. The detailed configuration and operation of the inter prediction unit 102 will be described later.

The intra prediction unit 103 performs intra prediction of the process target coding block. A predicted image signal is generated by intra prediction from the decoded image signal stored in the decoded image memory 104, a suitable intra prediction mode is selected from a plurality of intra prediction modes, and the selected intra prediction mode, and The prediction image signal according to the selected intra prediction mode is supplied to the prediction method determination unit 105. FIG. 10 shows an example of intra prediction. FIG. 10A shows the correspondence between the prediction direction of intra prediction and the prediction mode number. For example, the prediction mode 50 generates an intra prediction image by copying pixels in the vertical direction. Prediction mode 1 is a DC mode in which all the pixel values of the block to be processed are the average value of the reference pixels. Prediction mode 0 is the Planar mode, which is a mode in which a two-dimensional intra prediction image is created from reference pixels in the vertical and horizontal directions. FIG. 10B is an example of generating an intra prediction image in the prediction mode 40. The value of the reference pixel in the direction indicated by the prediction mode is copied to each pixel of the block to be processed. When the reference pixel in the prediction mode is not an integer position, the reference pixel value is determined by interpolation from the reference pixel values at the surrounding integer positions.

The decoded image memory 104 stores the decoded image generated by the decoded image signal superimposing unit 110. The decoded image stored in the decoded image memory is supplied to the inter prediction unit 102 and the inter prediction 103.

The prediction method determination unit 105 evaluates each prediction by using the coding information, the code amount of the residual signal, the distortion amount between the predicted image signal and the image signal, and the like, and thus the optimum prediction mode ( Inter prediction or intra prediction). In the case of the inter prediction merge mode, the coding information of the merge index and the information indicating the sub-block merge mode (sub-block merge flag) is supplied to the bit string coding unit 108, and the inter prediction motion vector mode In this case, the bit string encoding unit 108 provides the encoding information such as the inter prediction mode, the motion vector predictor index, the reference indexes of L0 and L1, the differential motion vector, and the information indicating the sub block mode (sub block motion vector predictor flag). Supply to. The determined encoded information is supplied to the encoded information storage memory 111.

The residual signal generation unit 106 generates a residual signal by subtracting the predicted image signal from the image signal to be processed, and supplies the residual signal to the orthogonal transformation/quantization unit 107.

The orthogonal transformation/quantization unit 107 performs orthogonal transformation and quantization on the residual signal according to the quantization parameter to generate an orthogonal transformation/quantized residual signal, and the bit string encoding unit 108 and the inverse quantization. The data is supplied to the conversion/inverse orthogonal transformation unit 109.

The bit string coding unit 108 codes coding information according to the prediction method determined by the prediction method determination unit 104 for each coding block, in addition to information on a sequence, picture, slice, and coding block basis. Specifically, the prediction mode PredMode for each coding block, the partition mode PartMode, the flag that determines whether it is the merge mode in the case of inter prediction (PRED_INTER), the sub-block merge flag, the merge index in the merge mode, the merge mode If not, the coding information such as the inter prediction mode, the motion vector predictor index, the information about the difference motion vector, and the sub-block motion vector predictor flag is coded according to a prescribed syntax rule described later to generate the first coded bit string. .. Further, the bit string encoding unit 108 entropy-encodes the orthogonally transformed and quantized residual signal according to a prescribed syntax rule to generate a second encoded bit string. The first coded bit string and the second coded bit string are multiplexed according to a prescribed syntax rule, and a bit stream is output.

The inverse quantization/inverse orthogonal transformation unit 109 performs inverse quantization and inverse orthogonal transformation on the orthogonal transformation/quantized residual signal supplied from the orthogonal transformation/quantization unit 107, calculates a residual signal, and decodes it. It is supplied to the image signal superimposing unit 110.

The decoded image signal superimposing unit 110 superimposes the prediction image signal according to the determination made by the prediction method determining unit 105 and the residual signal that has been inversely quantized and inversely orthogonally transformed by the inverse quantization/inverse orthogonal transformation unit 109 to obtain a decoded image. Is generated and stored in the decoded image memory 104. Note that the decoded image may be stored in the decoded image memory 104 after being subjected to filtering processing for reducing distortion such as block distortion due to encoding.

The coding information storage memory 111 stores coding information such as the prediction mode (inter prediction or intra prediction) determined by the prediction method determination unit 105. In the case of inter prediction, the coding information stored in the coding information storage memory 111 includes the determined motion vector, reference list, and reference index, and in the case of inter prediction merge mode, is the merge index or sub-block merge mode? Encoding information of information indicating whether or not (sub-block merge flag), inter-prediction mode in the case of inter-prediction motion vector mode, motion vector predictor index, reference index of L0 and L1, differential motion vector, sub-block mode Information indicating whether or not (sub-block motion vector predictor flag), in the case of intra prediction, the determined intra prediction mode and the like. The construction of the history candidate list managed by the encoded information storage memory 111 will be described later.

FIG. 2 is a block diagram showing a configuration of a moving picture decoding apparatus according to an embodiment of the present invention, which corresponds to the moving picture coding apparatus of FIG. The moving image decoding apparatus according to the embodiment includes a bit string decoding unit 201, a block dividing unit 202, an inter prediction unit 203, an intra prediction unit 204, an encoded information storage memory 205, an inverse quantization/inverse orthogonal transform unit 206, and a decoded image signal. The superimposing unit 207 and the decoded image memory 208 are provided.

The decoding process of the moving picture decoding apparatus of FIG. 2 corresponds to the decoding processing provided inside the moving picture coding apparatus of FIG. 1, and therefore, the coding information storage memory 205 of FIG. Each of the configurations of the inverse orthogonal transform unit 206, the decoded image signal superimposing unit 207, and the decoded image memory 208 includes an inverse quantizing/inverse orthogonal transforming unit 109, a decoded image signal superimposing unit 110, and a moving image encoding apparatus of FIG. It has a function corresponding to each configuration of the encoding information storage memory 111 and the decoded image memory 104.

The bit stream supplied to the bit string decoding unit 201 is separated according to the rules of the prescribed syntax. The separated first coded bit string is decoded to obtain a sequence, a picture, a slice, information in coding block units, and coding information in coding block units. Specifically, a prediction mode PredMode that determines inter prediction (PRED_INTER) or intra prediction (PRED_INTRA) for each coding block, a partition mode PartMode, and a flag that determines whether or not merge mode in the case of inter prediction (PRED_INTER), In the merge mode, the merge index, the sub-block merge flag, in the case of the motion vector predictor mode, the inter-prediction mode, the motion vector predictor index, the difference motion vector, the encoding information about the sub block motion vector predictor, etc. Decoding is performed according to the syntax rule, and the encoded information is supplied to the inter prediction unit 203 or the intra prediction unit 204, and the encoded information storage memory 205. The separated second encoded bit string is decoded to calculate an orthogonally transformed/quantized residual signal, and the orthogonally transformed/quantized residual signal is supplied to the inverse quantization/inverse orthogonal transformation unit 208.

The inter prediction unit 203, when the prediction mode PredMode of the coding block to be decoded is inter prediction (PRED_INTER) and is the motion vector predictor mode, codes the already decoded image signal stored in the coding information storage memory 205. The plurality of motion vector predictor candidates are derived using the encoding information and registered in a motion vector predictor list to be described later, and the first encoding is performed from among the plurality of motion vector predictor candidates registered in the motion vector predictor list. A motion vector predictor is selected according to the motion vector predictor index decoded and supplied by the bit string decoding unit 202, a motion vector is calculated from the difference vector decoded by the decoding unit 201 and the selected motion vector predictor, and another code is calculated. The encoded information is stored in the encoded information storage memory 205 together with the encoded information. The coding information of the coding block supplied/stored here is the flag predFlagL0[xP][yP], predFlagL1[xP][ which indicates whether to use the prediction mode PredMode, the division mode PartMode, the L0 prediction, and the L1 prediction. yP], L0, L1 reference indexes refIdxL0[xP][yP], refIdxL1[xP][yP], L0, L1 motion vectors mvL0[xP][yP], mvL1[xP][yP], etc. Here, xP and yP are indices indicating the position of the upper left pixel of the coded block in the picture. When the prediction mode PredMode is inter prediction (MODE_INTER) and the inter prediction mode is L0 prediction (Pred_L0), the flag predFlagL0 indicating whether to use L0 prediction is 1, and the flag predFlagL1 indicating whether to use L1 prediction is 0. Is. 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), the flag predFlagL0 indicating whether to use L0 prediction and the flag predFlagL1 indicating whether to use L1 prediction are both 1. Further, when the prediction mode PredMode of the coding block to be decoded is the inter prediction (PRED_INTER) and the merge mode, the merge candidate is derived. Using the coding information of the already decoded coding block stored in the coding information storage memory 205, a plurality of merge candidates are derived and registered in the merge candidate list described later, and registered in the merge candidate list. A flag predFlagL0 indicating whether or not the merge candidate corresponding to the merge index decoded and supplied by the bit string decoding unit 201 is selected from among the plurality of merge candidates and L0 prediction and L1 prediction of the selected merge candidate are used [xP][yP], predFlagL1[xP][yP], reference indices refIdxL0[xP][yP], L0, L1 motion vectors mvL0[xP][yP] of refIdxL1[xP][yP], L0, L1 Then, the inter prediction information such as mvL1[xP][yP] is supplied to the motion compensation prediction unit 206 and is also stored in the coding information storage memory 205. Here, xP and yP are indices indicating the position of the upper left pixel of the coded block in the picture. The detailed configuration and operation of the inter prediction unit will be described later.

The intra prediction unit 204 performs intra prediction when the prediction mode PredMode of the coding block to be decoded is intra prediction (PRED_INTRA). The coded information decoded by the bit string decoding unit 201 includes an intra prediction mode, and the decoded image signal stored in the decoded image memory 210 is used as the prediction image signal by the intra prediction according to the intra prediction mode. Is generated and the predicted image signal is supplied to the decoded image signal superimposing unit 209. The intra prediction unit 204 corresponds to the intra prediction unit 103 of the image encoding device 100, and therefore performs the same process as the intra prediction unit 103.

The inverse quantization/inverse orthogonal transformation unit 208 performs inverse orthogonal transformation and inverse quantization on the orthogonal transformation/quantized residual signal decoded by the first encoded bit string decoding unit 202, and performs the inverse orthogonal transformation/ Obtain the dequantized residual signal.

The decoded image signal superimposing unit 209 and the prediction image signal inter-predicted by the motion compensation prediction unit 206 or the prediction image signal intra-predicted by the intra prediction unit 204, and the inverse orthogonal transform by the inverse quantization/inverse orthogonal transform unit 208. The decoded image signal is decoded by superimposing it on the dequantized residual signal and stored in the decoded image memory 210. When the decoded image is stored in the decoded image memory 210, the decoded image may be stored in the decoded image memory 210 after being subjected to a filtering process for reducing block distortion due to encoding.

Next, the operation of the block division unit 101 in the image encoding device 100 will be described. FIG. 3 is a flowchart showing an operation of dividing an image into tree blocks and further dividing each tree block. First, the input image is divided into tree blocks of a predetermined size (step S1001). Each tree block is scanned in a predetermined order, that is, in raster scan order (step S1002), and the inside of the tree block to be processed is divided (step S1003).

FIG. 7 is a flowchart showing the detailed operation of the division processing in step S1003. First, it is determined whether or not the block to be processed is divided into four (step S1101).

When it is determined that the processing target block is divided into four, the processing target block is divided into four (step S1102). Each block obtained by dividing the block to be processed is scanned in the Z scan order, that is, in the order of upper left, upper right, lower left, and lower right (step S1103). FIG. 5 is an example of the Z scan order, and 601 of FIG. 6 is an example in which the processing target block is divided into four. The numbers 0 to 3 in 601 in FIG. 6 indicate the order of processing. Then, the flowchart of FIG. 7 is recursively called for each block divided in step S1101.

When it is determined that the block to be processed is not divided into four, 2-3 division is performed (step S1105).

FIG. 8 is a flowchart showing the detailed operation of the 2-3 division process of step S1105. First, it is determined whether or not the block to be processed is divided into 2-3, that is, whether to divide into 2 or 3 (step S1201).

When it is not determined that the processing target block is divided into 2-3, that is, when it is determined that the block is not divided, the division is ended (S1211), and the process returns to the block of the upper hierarchy.

When it is determined that the processing target block is divided into 2-3, it is further determined whether or not the processing target block is divided into two (step S1202).

When it is determined that the processing target block is divided into two, it is determined whether or not the processing target block is divided in the vertical direction (step S1203), and based on the result, the processing target block is divided in the vertical direction (step S1204). Alternatively, the block to be processed is divided in the horizontal direction (step S1205). As a result of step S1204, the processing target block is divided into two parts in the vertical direction as shown in FIG. 602, and as a result of step S1205, the processing target block is divided into two parts in the horizontal direction.

If it is not determined in step S1202 that the block to be processed is divided into two, that is, if it is determined that the block is to be divided into three, it is determined whether or not the block to be processed is divided in the vertical direction (step S1206). Based on this, the block to be processed is divided vertically (step S1207) or the block to be processed is divided horizontally (step S1208). As a result of step S1207, the processing target block is divided into three parts in the vertical direction as shown in FIG. 603, and as a result of step S1208, the processing target block is divided into three parts in the horizontal direction.

After executing any of steps S1204 to S1205, each block obtained by dividing the block to be processed is scanned from left to right and from top to bottom (step S1209). The numbers 0 to 3 of 602 to 605 in FIG. 6 indicate the order of processing. The flowchart of FIG. 8 is recursively called for each divided block.

In the recursive block division described here, the necessity of division may be limited depending on the number of divisions, the size of the block to be processed, or the like. The information that restricts the necessity of division may be realized in a configuration in which the information is not transmitted by making an agreement in advance between the encoding device and the decoding device, or the encoding device limits the necessity of division. It may be realized by a configuration in which the information to be determined is recorded and recorded in the encoded bit string and transmitted to the decoding device.

Next, the operation of the block division unit 202 in the image decoding device 200 will be described. The block division unit 202 divides a tree block by the same processing procedure as the block division unit 101 of the image encoding device 101. However, the block division unit 101 of the image encoding device 101 applies an optimization method such as estimation of an optimum shape by image recognition or optimization of a distortion rate to determine the optimum shape of the block division, whereas the image decoding device 101 The block division unit 202 in 200 is different in that the block division shape is determined by decoding the block division information recorded in the encoded bit string.

FIG. 9 shows the syntax (syntax rule of the encoded bit string) relating to the block division according to the first embodiment. coding_quadtree() represents the syntax for the block 4-division processing, and multi_type_tree() represents the syntax for the block 2-division or 3-division processing. qt_split is a flag indicating whether or not the block is divided into four. When the block is divided into four, qt_split=1 and when not divided into four, qt_split=0. When dividing into 4 (qt_split=1), each block divided into 4 is recursively divided into 4 (coding_quadtree(0), coding_quadtree(1), coding_quadtree(2), coding_quadtree(3)). When not divided into four (qt_split=0), the subsequent division is determined according to multi_type_tree(). mtt_split is a flag indicating whether or not to further divide. When further division is performed (mtt_split=1), mtt_split_vertical, which is a flag indicating whether to divide vertically or horizontally, and mtt_split_binary, which is a flag for determining whether to divide into two or three, are referred to. mtt_split_vertical=1 indicates vertical division, and mtt_split_vertical=0 indicates horizontal division. mtt_split_binary=1 indicates that the image is divided into two, and mtt_split_binary=0 indicates that the image is divided into three. Hierarchical block division is performed by recursively calling multi_type_tree until mtt_split=0.

<Inter prediction>
The inter prediction method according to the embodiment is implemented in the inter prediction unit 102 of the moving picture coding apparatus of FIG. 1 and the inter prediction unit 203 of the moving picture decoding apparatus of FIG.

An inter prediction method according to the embodiment will be described with reference to the drawings. The inter-prediction method is carried out in both coding and decoding processing in coding block units.

(Description of Inter Prediction Unit 102 on Coding Side)
FIG. 16 is a diagram showing a detailed configuration of the inter prediction unit 102 of the moving picture coding apparatus of FIG. The normal motion vector predictor deriving unit 301 derives a plurality of normal motion vector predictor candidates, selects a motion vector predictor, and calculates a difference vector from the detected motion vector. The detected inter prediction mode, reference index, motion vector, and calculated difference vector serve as inter prediction information in the normal motion vector predictor mode. This inter prediction information is supplied to the inter prediction mode determination unit 305. The detailed configuration and processing of the normal motion vector predictor deriving unit 301 will be described later.

The normal merge mode derivation unit 302 derives a plurality of normal merge candidates, selects a normal merge candidate, and obtains inter prediction information in the normal merge mode. This inter prediction information is supplied to the inter prediction mode determination unit 306. The detailed configuration and processing of the normal merge mode derivation unit 302 will be described later.

The sub-block motion vector predictor deriving unit 303 derives a plurality of sub-block motion vector predictor candidates, selects a sub-block motion vector predictor, and calculates a difference vector from the detected motion vector. The detected inter prediction mode, reference index, motion vector, and calculated difference vector serve as inter prediction information in the normal motion vector predictor mode. This inter prediction information is supplied to the inter prediction mode determination unit 306. The detailed configuration and processing of the sub-block motion vector predictor deriving unit 303 will be described later.

The sub-block merge mode deriving unit 304 derives a plurality of sub-block merge candidates, selects a sub-block merge candidate, and obtains inter prediction information in the sub-block merge mode. This inter prediction information is supplied to the inter prediction mode determination unit 306. The detailed configuration and processing of the sub block merge mode derivation unit 304 will be described later.

In the inter prediction mode determination unit 305, based on the inter prediction information supplied from the normal motion vector predictor derivation unit 301, the normal merge mode derivation unit 302, the sub block motion vector predictor derivation unit 303, and the sub block merge mode derivation unit 304. Determine the prediction mode. The inter prediction information according to the determination result is supplied from the inter prediction mode determination unit 305 to the motion compensation prediction unit 306.

The motion compensation prediction unit 306 performs inter prediction on the reference image signal stored in the decoded image memory 104 based on the determined inter prediction information. The detailed configuration and processing will be described later.

<Description of Inter Prediction Unit 203 on Decoding Side>
22 is a diagram showing a detailed configuration of the inter prediction unit 203 of the moving picture decoding apparatus of FIG.

The normal motion vector predictor deriving unit 401 derives a plurality of normal motion vector predictor candidates, selects a motion vector predictor, and calculates a difference vector from the detected motion vector. The detected inter prediction mode, reference index, motion vector, and difference vector serve as inter prediction information in the normal motion vector predictor mode. This inter prediction information is supplied to the motion compensation prediction unit 406 via the switch 408. The detailed configuration and processing of the normal motion vector predictor deriving unit 401 will be described later.

The normal merge mode derivation unit 402 derives a plurality of normal merge candidates, selects a normal merge candidate, and obtains inter prediction information in the normal merge mode. This inter prediction information is supplied to the motion compensation prediction unit 406 via the switch 408. The detailed configuration and processing of the normal merge mode derivation unit 402 will be described later.

The sub-block motion vector predictor deriving unit 403 derives a plurality of sub-block motion vector predictor candidates, selects a sub-block motion vector predictor, and calculates a difference vector from the detected motion vector. The detected inter prediction mode, reference index, motion vector, and calculated difference vector serve as inter prediction information in the normal motion vector predictor mode. This inter prediction information is supplied to the motion compensation prediction unit 406 via the switch 408. The detailed configuration and processing of the sub block motion vector predictor 403 will be described later.

The sub-block merge mode deriving unit 404 derives a plurality of sub-block merge candidates, selects a sub-block merge candidate, and obtains inter prediction information in the sub-block merge mode. This inter prediction information is supplied to the motion compensation prediction unit 406 via the switch 408. The detailed configuration and processing of the sub block merge mode derivation unit 404 will be described later.

The motion compensation prediction unit 406 performs inter prediction on the reference image signal stored in the decoded image memory 108 based on the determined inter prediction information. The detailed configuration and processing are the same as those on the encoding side.

<Normal motion vector vector deriving unit (normal AMVP)>
The normal motion vector predictor mode derivation unit 301 of FIG. 16 includes a spatial motion vector predictor candidate derivation unit 321, a temporal motion vector predictor candidate derivation unit 322, a history motion vector predictor candidate derivation unit 323, a motion vector predictor candidate supplementation unit 325, and a normal motion. A vector detection unit 326, a motion vector predictor candidate selection unit 327, and a motion vector subtraction unit 328 are included.

The normal motion vector predictor mode derivation unit 402 in FIG. 23 includes a spatial motion vector predictor candidate derivation unit 421, a temporal motion vector predictor candidate derivation unit 422, a history motion vector predictor candidate derivation unit 423, a motion vector predictor candidate supplementation unit 425, and a motion predictive motion. A vector candidate selection unit 426 and a motion vector addition unit 428 are included.

The processing procedures of the normal motion vector predictor mode deriving unit 301 on the encoding side and the normal motion vector predictor mode deriving unit 401 on the decoding side will be described with reference to the flowcharts of FIGS. 19 and 25, respectively. FIG. 19 is a flowchart showing the procedure of the normal motion vector predictor mode deriving processing by the normal motion vector mode deriving section 301 on the encoding side, and FIG. 25 is the normal motion vector predictor mode deriving processing by the normal motion vector mode deriving section 401 on the decoding side. It is a flowchart which shows a procedure.

<Normal motion vector predictor (normal AMVP): Description of coding side>
The normal motion vector predictor mode derivation process procedure on the encoding side will be described with reference to FIG.

First, the normal motion vector detection unit 326 detects a normal motion vector for each inter prediction mode and reference index (step S100 in FIG. 19).

Subsequently, the spatial motion vector predictor candidate derivation unit 321, the temporal motion vector predictor candidate derivation unit 322, the history motion vector predictor candidate derivation unit 323, the motion vector predictor candidate supplementation unit 325, the motion vector predictor candidate selection unit 327, the motion vector subtraction unit. In 328, the differential motion vector of the motion vector used in the inter prediction in the normal motion vector predictor mode is calculated for each of L0 and L1 (steps S101 to S106 in FIG. 19). Specifically, when the prediction mode PredMode of the current block is inter prediction (MODE_INTER) and the inter prediction mode is L0 prediction (Pred_L0), the motion vector predictor list mvpListL0 of L0 is calculated and the motion vector predictor 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 current block is L1 prediction (Pred_L1), the L1 motion vector predictor list mvpListL1 is calculated, the motion vector predictor mvpL1 is selected, and the differential motion vector mvdL1 of the L1 motion vector mvL1 is calculated. .. When the inter prediction mode of the current block is bi-prediction (Pred_BI), both L0 prediction and L1 prediction are performed, the motion vector predictor list mvpListL0 of L0 is calculated, and the motion vector predictor mvpL0 of L0 is selected, and L0 is calculated. Of the motion vector mvL0 of the motion vector mvL0, the motion vector mvpL1 of the motion vector mvpL1 of the motion vector mvpL1 of L1, and the motion vector mvdL1 of the motion vector mvL1 of L1 are calculated. ..

The differential motion vector calculation process is performed for each of L0 and L1, but both L0 and L1 are common processes. Therefore, in the following description, L0 and L1 are represented as common LX. X is 0 in the process of calculating the differential motion vector of L0, and X is 1 in the process of calculating the differential motion vector of L1. 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 differential motion vector mvdLX of LX is calculated (YES in step S102 of FIG. 19 ), the motion vector predictor candidate of LX is calculated to construct the motion vector predictor list mvpListLX of LX (step S103 of FIG. 19 ). In the normal motion vector predictor mode deriving unit 301, the spatial motion vector predictor candidate deriving unit 321, the temporal motion vector predictor candidate deriving unit 322, the history motion vector predictor candidate deriving unit 323, and the motion vector predictor candidate replenishing unit 325 include a plurality of motion predictive motions. The motion vector list mvpListLX is constructed by deriving vector candidates. The detailed processing procedure of step S103 of FIG. 19 will be described later with reference to the flowchart of FIG.

Then, the motion vector predictor candidate selection unit 327 selects the motion vector predictor mvpLX of LX from the motion vector predictor list of LX mvpListLX (step S104 in FIG. 19). A code when each differential motion vector that is the difference between the motion vector mvLX and each motion vector predictor candidate mvpListLX[i] stored in the motion vector predictor list mvpListLX is calculated, and these differential motion vectors are encoded. The amount is calculated for each element of the motion vector predictor list mvpListLX, and among the elements registered in the motion vector predictor list mvpListLX, the motion vector predictor candidate mvpListLX[i ] As the motion vector predictor mvpLX. When there are a plurality of motion vector predictor candidates having the smallest generated code amount in the motion vector predictor list mvpListLX, a motion vector predictor candidate with a smaller index i in the motion vector predictor list mvpListLX. Select mvpListLX[i] as the optimum motion vector predictor mvpLX.

Subsequently, the motion vector subtraction unit 328 calculates the LX differential motion vector mvdLX by subtracting the selected LX predicted motion vector mvpLX from the LX motion vector mvLX (step S105 in FIG. 19).

<Normal motion vector predictor (normal AMVP): Decoding side description>
Next, the normal motion vector predictor mode processing procedure on the decoding side will be described with reference to FIG. On the decoding side, the spatial motion vector predictor candidate derivation unit 421, the temporal motion vector predictor candidate derivation unit 422, the history motion vector predictor candidate derivation unit 423, and the motion vector predictor candidate supplementation unit 425 are used in inter prediction in the normal motion vector predictor mode. The motion vector is calculated for each of L0 and L1 (steps S201 to S206 in FIG. 25). Specifically, when the prediction mode PredMode of the decoding target block is inter prediction (MODE_INTER) and the inter prediction mode of the decoding target block is L0 prediction (Pred_L0), the prediction motion vector list mvpListL0 of L0 is calculated to calculate the prediction motion vector. Select mvpL0 and calculate the motion vector mvL0 of L0. When the inter prediction mode of the decoding target block is L1 prediction (Pred_L1), the motion vector predictor list mvpListL1 of L1 is calculated, the motion vector predictor mvpL1 is selected, and the motion vector mvL1 of L1 is calculated. When the inter prediction mode of the decoding target block is bi-prediction (Pred_BI), both L0 prediction and L1 prediction are performed, the motion vector predictor list mvpListL0 of L0 is calculated, and the motion vector predictor mvpL0 of L0 is selected, The motion vector mvL0 is calculated, the L1 predicted motion vector list mvpListL1 is calculated, the L1 predicted motion vector mvpL1 is calculated, and the L1 motion vector mvL1 is calculated.

Similar to the encoding side, the decoding side also performs the motion vector calculation processing 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 common LX. X is 0 in the process of calculating the motion vector of L0, and X is 1 in the process of calculating the motion vector of L1. Further, when referring to the information of the other list instead of the LX during the process of calculating the motion vector of the LX, the other list is represented as LY.

When calculating the LX motion vector mvLX (YES in step S202 of FIG. 25 ), the LX motion vector predictor candidates are calculated to construct the LX motion vector predictor list mvpListLX (step S203 of FIG. 25 ). In the normal motion vector predictor mode deriving unit 401, the spatial motion vector predictor candidate deriving unit 421, the temporal motion vector predictor candidate deriving unit 422, the history motion vector predictor candidate deriving unit 423, and the motion vector predictor candidate supplementing unit 425 include a plurality of motion predictive motions. Vector candidates are calculated and a motion vector predictor list mvpListLX is constructed. The detailed processing procedure of step S203 in FIG. 25 will be described later with reference to the flowchart in FIG.

Subsequently, the motion vector predictor candidate selection unit 426 selects a motion vector predictor candidate mvpListLX[mvpIdxLX] corresponding to the motion vector predictor index mvpIdxLX decoded and supplied from the motion vector predictor list mvpListLX by the bit string decoding unit 201. The predicted motion vector mvpLX is extracted (step S204 in FIG. 25).

Subsequently, in the motion vector addition unit 427, the LX motion vector mvLX is calculated by adding the LX differential motion vector mvdLX and the LX predicted motion vector mvpLX decoded and supplied by the bit string decoding unit 201 (FIG. 25). Step S205).

<Normal motion vector predictor (normal AMVP): Motion vector prediction method>
FIG. 20 shows a normal motion vector predictor having a common function with the normal motion vector predictor mode deriving unit 301 of the moving picture coding device and the normal motion vector predictor mode deriving unit 401 of the moving picture decoding device according to the embodiment of the present invention. It is a flow chart showing a processing procedure of mode derivation processing.

The normal motion vector predictor mode deriving unit 301 and the normal motion vector predictor mode deriving unit 401 include a motion vector predictor candidate list mvpListLXN (N is A or B, the same applies hereinafter). The motion vector predictor candidate list mvpListLXN has a list structure, and is provided with a motion vector predictor index indicating the location inside the motion vector predictor candidate list and a storage area for storing the motion vector predictor candidate corresponding to the index as an element. The number of the motion vector predictor index starts from 0, and the motion vector predictor candidates are stored in the storage area of the motion vector predictor candidate list mvpListLXN. In the following process, the coding block that is the motion vector predictor candidate of the motion vector predictor index i registered in the motion vector predictor candidate list mvpListLXN is represented by mvpListLXN [i], and the motion vector predictor candidate list mvpListLXN is arranged. It will be distinguished by notation. In the present embodiment, it is assumed that at least six motion vector predictor candidates (inter prediction information) can be registered in the motion vector predictor candidate list mvpListLXN. Further, 0 is set to a variable numMvpCand indicating the number of motion vector predictor candidates registered in the motion vector predictor candidate list mvpListLXN.

The spatial motion vector predictor candidate derivation units 321 and 421 derive a motion vector predictor candidate from the coding block adjacent to the left side, and a flag indicating whether the motion vector predictor candidate of the coded block adjacent to the left side is available or not availableFlagLXA , And the motion vector mvLXA, the reference index refIdxA, and the list ListA are derived, and mvLXA is added to the motion vector predictor list mvpListLXA (step S301 in FIG. 20). In addition, when L0, X is 0, and when L1, X is 1 (the same applies hereinafter). Subsequently, the motion vector predictor candidate generation units 121 and 221 derive a motion vector predictor candidate from the coding block adjacent to the upper side, and indicate whether the motion vector predictor candidate of the coded block adjacent to the upper side can be used. The flag availableFlagLXB, the motion vector mvLXB, the reference index refIdxB, and the list ListB are derived, and if mvLXA and mvLXB are not equal, mvLXB is added to the motion vector predictor list mvpListLXB (step S302 in FIG. 20). The processes of steps S301 and S302 of FIG. 20 are common except that the number of adjacent blocks to be referred to is different, and a flag availableFlagLXN indicating whether or not the motion vector predictor candidate of the coding block is available, and the motion vector mvLXN, The reference indexes refIdxN and ListN (N is A or B, and so on) are derived.

Subsequently, the temporal motion vector predictor candidate derivation units 322 and 422 derive the motion vector predictor candidates from the coded blocks of the pictures at different times, and can the motion vector predictor candidates of the coded blocks of the pictures at different times be used? A flag availableFlagLXCol indicating whether it is, a motion vector mvLXCol, a reference index refIdxCol, and a list ListCol are derived, and mvLXCol is added to the motion vector predictor list mvpListLX (step S303 in FIG. 20). The derivation processing procedure of step S303 will be described in detail later.

Here, it is assumed that the processing of the temporal motion vector predictor candidate derivation units 322 and 422 can be omitted for each sequence (SPS), picture (PPS), or slice.

Subsequently, the history motion vector predictor candidate derivation units 323 and 423 add the history motion vector predictor candidates registered in the history motion vector predictor list HmvpCandList to the motion vector predictor list mvpListLX. (Step S304 of FIG. 20). The registration processing procedure of step S304 will be described later in detail with reference to the flowchart of FIG.

Subsequently, the motion vector predictor candidate supplementing units 325 and 425 add motion vectors having a predetermined value such as (0, 0) until the motion vector predictor list mvpListLX is satisfied (S305 in FIG. 20).

<Normal merge mode derivation unit (normal merge)>
The normal merge mode derivation unit 302 in FIG. 18 includes a spatial merge candidate derivation unit 341, a temporal merge candidate derivation unit 342, an average merge candidate derivation unit 344, a history merge candidate derivation unit 345, a merge candidate replenishment unit 346, and a merge candidate selection unit 347. including.

The normal merge mode derivation unit 402 of FIG. 24 includes a spatial merge candidate derivation unit 441, a temporal merge candidate derivation unit 442, an average merge candidate derivation unit 444, a history merge candidate derivation unit 445, a merge candidate replenishment unit 446, and a merge candidate selection unit 447. including.

FIG. 21 illustrates a procedure of a merge mode derivation process having a common function with the normal merge mode derivation unit 302 of the moving picture coding device and the normal merge mode derivation unit 402 of the moving picture decoding device according to the embodiment of the present invention. It is a flowchart to do.

Hereinafter, various processes will be described step by step. In the following description, the case where the slice type slice_type is B slice will be described unless otherwise specified, but the present invention can also be applied to the case of P slice. However, when the slice type slice_type is P slice, there is only L0 prediction (Pred_L0) as an inter prediction mode, and there is no L1 prediction (Pred_L1) or bi-prediction (Pred_BI), so the processing related to L1 can be omitted.

The normal merge mode derivation unit 302 and the normal merge mode derivation unit 402 include a merge candidate list mergeCandList. The merge candidate list mergeCandList has a list structure, and is provided with a merge index indicating the location inside the merge candidate list and a storage area for storing the merge candidate corresponding to the index as an element. The number of the merge index starts from 0, and the merge candidate is stored in the storage area of the merge candidate list mergeCandList. In the following processing, the coding blocks that are the merge candidates of the merge index i registered in the merge candidate list mergeCandList are represented by mergeCandList[i], and the merge candidate list mergeCandList is distinguished by using array notation. And In the present embodiment, it is assumed that the merge candidate list mergeCandList can register at least six merge candidates (inter prediction information). Further, 0 is set to the variable numMergeCand indicating the number of merge candidates registered in the merge candidate list mergeCandList.

In the space merge candidate derivation unit 341 and the space merge candidate derivation unit 441, the code is extracted from the coding information stored in the coding information storage memory 115 of the moving picture coding apparatus or the coding information storage memory 210 of the moving picture decoding apparatus. The spatial merge candidates A, B, C, D, and E are derived from the respective coding blocks A, B, C, D, and E that are adjacent to the block to be encoded/decoded, and the derived spatial merge candidates are merged candidates. It is registered in the list mergeCandList (step S401 in FIG. 21). Here, N indicating any of A, B, C, D, E or the time merge candidate Col is defined. A flag availableFlagN indicating whether the inter prediction information of the coding block N can be used as the spatial merge candidate N, a reference index refIdxL0N of L0 and a reference index refIdxL1N of L1 of the spatial merge candidate N, and L0 indicating whether L0 prediction is performed. The prediction flag predFlagL0N and the motion vector mvL0N of the L1 prediction flag predFlagL1N and L0 indicating whether the L1 prediction is performed and the motion vector mvL1N of the L1 are derived. However, in the present embodiment, since the merge candidate is derived without referring to the coding block included in the same coding block as the coding block including the coding block to be processed, the coding block to be processed is A spatial merge candidate included in the same coding block as a coding block including is not derived.

Then, the temporal merge candidate derivation unit 342 and the temporal merge candidate derivation unit 442 derive temporal merge candidates from pictures at different times and register the derived temporal merge candidates in the merge candidate list mergeCandList (FIG. 21). Step S402). A flag availableFlagCol indicating whether the temporal merge candidate is available, an L0 prediction flag predFlagL0Col indicating whether L0 prediction of the temporal merge candidate is performed, and an L1 prediction flag predFlagL1Col indicating whether L1 prediction is performed, and a motion vector of L0. The motion vector mvL1Col of mvL0Col and L1 is derived. The detailed processing procedure of step S402 will be described later in detail.

Here, it is assumed that the processes of the temporal merge candidate derivation unit 342 and the temporal merge candidate derivation unit 442 can be omitted for each sequence (SPS), picture (PPS), or slice unit.

Subsequently, the average merge candidate derivation unit 344 and the average merge candidate derivation unit 444 derive the average merge candidate from the merge candidate list mergeCandList and register the derived average merge candidate in the merge candidate list mergeCandList (step in FIG. 21). S403).

Then, the history merge candidate derivation unit 345 and the history merge candidate derivation unit 445 add the history motion vector predictor candidates registered in the history motion vector predictor candidate list HmvpCandList to the merge candidate list mergeCandList (step S404 in FIG. 21). .. The detailed processing procedure of step S404 will be described later in detail with reference to the flowchart of FIG.

Subsequently, in the merge candidate supplementing unit 346 and the merge candidate supplementing unit 446, when the number of merge candidates numMergeCand registered in the merge candidate list mergeCandList is smaller than the maximum number of merge candidates maxNumMergeCand, the merge candidate list is registered in the merge candidate list mergeCandList. The number of existing merge candidates numMergeCand is used as an upper limit for the maximum number of merge candidates maxNumMergeCand, and additional merge candidates are derived and registered in the merge candidate list mergeCandList (step S405 in FIG. 21). With the maximum number of merge candidates maxNumMergeCand as the upper limit, in the P slice, merge candidates whose prediction mode having a value of (0, 0) at different reference indexes and whose prediction mode is L0 prediction (Pred_L0) are added. In the B slice, a merge candidate in which the prediction mode having a value of (0, 0) with a different reference index and the prediction mode of bi-prediction (Pred_BI) is added.

Subsequently, the merge candidate selecting unit 347 and the merge candidate supplementing unit 447 select merge candidates from the merge candidates registered in the merge candidate list mergeCandList. The merging candidate selecting unit 347 on the encoding side selects a merging candidate by calculating a code amount and a distortion amount, and a motion compensation prediction unit 406 selects a merging index indicating the selected merging candidate and inter prediction information of the merging candidate. Supply to. On the other hand, the merge candidate supplementing unit 447 on the decoding side selects a merge candidate based on the decoded merge index and supplies the selected merge candidate to the motion compensation prediction unit 406.

<Sub-block prediction motion vector mode derivation>
Sub-block motion vector predictor derivation will be described.

FIG. 26 is a block diagram of the sub-block motion vector predictor mode deriving unit 303 in the encoding device of the present application.

First, the affine succession motion vector predictor candidate derivation unit 361 derives affine succession motion vector predictor candidates. Details of deriving the affine succession motion vector predictor candidates will be described later.

Subsequently, the affine-constructed motion vector predictor candidate derivation unit 362 derives the affine-constructed motion vector predictor candidates. Details of derivation of affine-constructed motion vector predictor candidates will be described later.

Subsequently, the same affine motion vector predictor candidate derivation unit 363 derives the same affine motion vector predictor candidates. Details of deriving the same affine motion vector predictor candidate will be described later.

The sub-block motion vector detection unit 366 detects a sub-block motion vector suitable for the sub-block motion vector predictor mode, and supplies the detected vector to the sub-block motion vector predictor selection unit 367 and the difference calculation unit 368.

The sub-block motion vector predictor candidate selection unit 367 is a sub-block motion vector predictor candidate derived by the affine inherited motion vector predictor candidate derivation unit 361, the affine constructed motion vector predictor candidate derivation unit 362, and the affine same motion vector predictor candidate derivation unit 363. From among the above, based on the motion vector supplied from the sub-block motion vector detection unit 366, a sub-block motion vector predictor candidate is selected, and information regarding the selected sub-block motion vector predictor candidate is obtained by the inter prediction mode determination unit 305. It is supplied to the difference calculation unit 368.

The difference calculation unit 368 subtracts the sub-block motion vector predictor selected by the sub-block motion vector predictor candidate selection unit 367 from the motion vector vector supplied from the sub-block motion vector detection unit 366, and calculates the difference motion vector predictor. It is supplied to the prediction mode determination unit 305.

FIG. 27 is a block diagram of the sub-block motion vector predictor mode deriving unit 403 in the decoding device of the present application.

First, the affine succession motion vector predictor candidate derivation unit 461 derives affine succession motion vector predictor candidates. The process of the affine inherited motion vector predictor candidate derivation unit 461 is the same as the process of the affine inherited motion vector predictor candidate derivation unit 361 in the encoding device of the present application.

Subsequently, the affine-constructed motion vector predictor candidate derivation unit 462 derives the affine-constructed motion vector predictor candidates. The process of the affine constructed motion vector predictor candidate derivation unit 462 is the same as the process of the affine constructed motion vector predictor candidate derivation unit 362 in the encoding device of the present application.

Then, the same affine motion vector predictor candidate derivation unit 463 derives the same affine motion vector predictor candidates. The process of the affine identical motion vector predictor candidate derivation unit 463 is the same as the process of the affine identical motion vector predictor candidate derivation unit 363 in the encoding device of the present application.

The sub-block motion vector predictor candidate selection unit 467 includes a sub-block motion vector predictor candidate derived by the affine succession motion vector predictor candidate derivation unit 461, the affine constructed motion vector predictor candidate derivation unit 462, and the affine identical motion vector predictor candidate derivation unit 463. From among the above, a sub-block motion vector predictor candidate is selected based on the motion vector predictor index transmitted and decoded from the encoding device, and information regarding the selected sub-block motion vector predictor candidate is added to the motion compensation prediction unit 406 and added. It is supplied to the calculation unit 467.

The addition operation unit 467 adds motion vectors generated by adding the differential motion vector transmitted and decoded from the encoding device to the sub-block motion vector predictor motion vector selected by the sub-block motion vector predictor candidate selection unit 466 to perform motion compensation prediction. It is supplied to the unit 406.

<Derivation of affine succession prediction motion vector candidates>
The affine succession prediction motion vector candidate derivation unit 361 will be described. The affine succession motion vector predictor candidate derivation unit 461 is the same as the affine succession motion vector predictor candidate derivation unit 361.

The affine inheritance prediction motion vector candidate inherits the motion vector information of the affine control points.

FIG. 30 is a diagram for explaining derivation of affine succession motion vector predictor candidates.

Affine inherited motion vector predictor candidates are obtained by searching for motion vectors of affine control points that spatially adjacent encoded/decoded blocks have.

Specifically, a maximum of one affine is provided for each of the blocks (A0, A1) adjacent to the left side of the encoding/decoding target block and the blocks (B0, B1, B2) adjacent to the upper side of the encoding/decoding target block. A mode is searched for and used as an affine succession prediction motion vector.

FIG. 34 is a flowchart of deriving an affine succession motion vector predictor candidate.

First, the block (A0, A1) adjacent to the left side of the encoding/decoding target block is set as a left group (S3101), and it is determined whether the block including A0 is a block using affine security (affine mode). (S3102). When A0 is in the affine mode (S3102: YES), the affine model used by A0 is acquired (S3103), and the process of the block adjacent to the upper side is performed. When A0 is not the affine mode (S3102: NO), the target of deriving the affine succession motion vector predictor candidate is A0->A1, and the affine mode is tried to be acquired from the block including A1.

Subsequently, blocks (B0, B1, B2) adjacent to the upper side of the encoding/decoding target block are set as an upper group (S3104), and it is determined whether the block including B0 is in the affine mode (S3105). If B0 is in the affine mode (S3105: YES), the affine model used by B0 is acquired (S3106), and the process ends. When B0 is not the affine mode (S3105: NO), the target of deriving the affine succession prediction motion vector candidate is set to B0->B1, and the affine mode is tried to be acquired from the block including B1. Furthermore, when B1 is not the affine mode (S3105: NO), the target of deriving the affine succession motion vector predictor candidate is B1->B2, and the affine mode is tried to be acquired from the block including B2.

In this way, the left block and the upper block are divided into groups, and for the left block, the affine model is searched in the order from the lower left to the upper left block, and for the left block, the affine model is searched in the order from the upper right to the upper left block. As a result, two affine models that differ as much as possible can be acquired, and an affine motion vector predictor candidate in which one of the affine motion vector predictors has a smaller difference motion vector can be derived.

<Affine construction prediction motion vector candidate derivation>
The affine construction motion vector predictor candidate derivation unit 362 will be described. The affine construction motion vector predictor candidate derivation unit 462 is also the same as the affine construction motion vector predictor candidate derivation unit 362.

The affine-constructed motion vector predictor candidate constructs motion vector information of affine control points from motion information of spatially adjacent blocks.

FIG. 31 is a diagram for explaining derivation of affine-construction motion vector predictor candidates.

The affine construction prediction motion vector candidate is obtained by constructing a new affine model by combining the motion vectors of the spatially adjacent encoded/decoded blocks.

Specifically, the motion vector of the upper left affine control point CP0 is derived from the block (B2, B3, A2) adjacent to the upper left side of the encoding/decoding target block and is adjacent to the upper right side of the encoding/decoding target block. The motion vector of the upper right affine control point CP1 is derived from the block (B1, B0), and the motion vector of the lower left affine control point CP2 is derived from the block (A1, A0) adjacent to the lower left side of the encoding/decoding target block.

FIG. 35 is a flowchart for deriving an affine construction motion vector predictor candidate.

First, the upper left control point CP0, the upper right control point CP1, and the lower left affine control point CP2 are derived (S3201). The upper left affine control point CP0 is calculated by searching a reference block having the same reference image as the encoding/decoding target block in the priority order of the B2, B3, and A2 reference blocks. The upper right affine control point CP1 is calculated by searching a reference block having the same reference image as the encoding/decoding target block in the priority order of the B1 and B0 reference blocks. The lower left affine control point CP2 is calculated by searching a reference block having the same reference image as the encoding/decoding target block in the priority order of the A1 and A0 reference blocks.

When the three-affine control point mode is selected as the affine construction prediction motion vector (S3202: YES), it is determined whether all three affine control points (CP0, CP1, CP2) have been derived (S3203). When all three affine control points (CP0, CP1, CP2) are derived (S3203: YES), an affine model using the three affine control points (CP0, CP1, CP2) is used as an affine construction prediction motion vector ( S3204). When the two-affine control point mode is selected without selecting the three-affine control point mode (S3202: NO), it is determined whether or not all two affine control points (CP0, CP1) have been derived (S3205). .. When all the two affine control points (CP0, CP1) are derived (S3205: YES), the affine model using the two affine control points (CP0, CP1) is set as the affine constructed prediction motion vector (S3206).

<Affine same motion vector predictor derivation>
The affine same motion vector predictor candidate derivation unit 363 will be described. The affine identical motion vector predictor candidate derivation unit 463 is similar to the affine identical motion vector predictor candidate derivation unit 363.

Affine same motion vector predictor candidates are obtained by deriving the same motion vector at each affine control point.

Specifically, similar to the affine construction motion vector predictor candidate derivation units 362 and 462, it is obtained by deriving each affine control point information and setting all affine control points to be the same in any of CP0 to CP2. .. It can also be obtained by setting the derived temporal motion vector to all affine control points as in the normal motion vector predictor mode.

<Sub-block merge mode derivation>
Sub-block merge mode derivation will be described.

FIG. 28 is a block diagram of the sub-block merge mode deriving unit 304 in the encoding device of the present application. The sub-block merge mode deriving unit 304 includes a sub-block merge candidate list subblockMergeCandList. This is the same as the merge candidate list mergeCandList in the normal merge mode deriving unit 302, and is different only in that it becomes a different candidate list in sub-block units.

First, the sub-block time merge candidate derivation unit 381 derives a sub-block time merge candidate. Details of derivation of sub-block time merge candidates will be described later.

Then, the affine inheritance merge candidate derivation unit 382 derives the affine inheritance merge candidate. Details of the affine inheritance merge candidate derivation will be described later.

Then, the affine construction merge candidate derivation unit 383 derives the affine construction merge candidate. Details of deriving an affine construction merge candidate will be described later.

Then, the affine fixed merge candidate derivation unit 384 derives the affine fixed merge candidate. Details of deriving an affine fixed merge candidate will be described later.

The sub-block merge candidate selection unit 386 selects the sub-block merge candidates derived in the sub-block time merge candidate derivation unit 381, the affine inheritance merge candidate derivation unit 382, the affine construction merge candidate derivation unit 383, and the affine fixed merge candidate derivation unit 384. A sub-block merge candidate is selected from the inside, and information regarding the selected sub-block merge candidate is supplied to the inter prediction mode determination unit 305.

FIG. 29 is a block diagram of the sub-block merge mode derivation unit 404 in the decoding device of the present application. The sub-block merge mode deriving unit 404 includes a sub-block merge candidate list subblockMergeCandList. This is the same as the sub-block merge mode deriving unit 304.

First, the sub-block time merge candidate derivation unit 481 derives a sub-block time merge candidate. The process of the sub block time merge candidate derivation unit 481 is the same as the process of the sub block time merge candidate derivation unit 381.

Then, the affine inheritance merge candidate derivation unit 482 derives the affine inheritance merge candidate. The process of the affine inheritance merge candidate derivation unit 482 is the same as the process of the affine inheritance merge candidate derivation unit 382.

Then, the affine construction merge candidate derivation unit 483 derives the affine construction merge candidate. The processing of the affine construction merge candidate derivation unit 483 is the same as the processing of the affine construction merge candidate derivation unit 383.

Then, the affine fixed merge candidate derivation unit 485 derives the affine fixed merge candidate. The process of the affine fixed merge candidate derivation unit 485 is the same as the process of the affine fixed merge candidate derivation unit 485.

The sub-block merge candidate selection unit 486 selects the sub-block merge candidates derived in the sub-block time merge candidate derivation unit 481, the affine inheritance merge candidate derivation unit 482, the affine construction merge candidate derivation unit 483, and the affine fixed merge candidate derivation unit 484. A sub-block merge candidate is selected from among the sub-block merge candidates based on the index transmitted and decoded from the encoding device, and information regarding the selected sub-block merge candidate is supplied to the motion compensation prediction unit 406.

<Sub-block time merge candidate derivation>
The operation of the sub block time merge candidate derivation unit 381 will be described later.

<Derivation of affine inheritance merge candidates>
The affine inheritance merge candidate derivation unit 382 will be described. The affine inheritance merge candidate derivation unit 482 is similar to the affine inheritance merge candidate derivation unit 382.

The affine inheritance merge candidate inherits the affine model of the affine control points from the affine models of blocks spatially adjacent to each other.

FIG. 32 is a diagram for explaining derivation of affine inheritance merge candidates. The derivation of the affine merge inheritance merge mode candidate is obtained by searching the motion vector of the affine control point of the spatially adjacent encoded/decoded blocks, similarly to the derivation of the affine inheritance prediction motion vector.

Specifically, a maximum of one affine is provided for each of the blocks (A0, A1) adjacent to the left side of the encoding/decoding target block and the blocks (B0, B1, B2) adjacent to the upper side of the encoding/decoding target block. Search mode and use for affine merge mode.

FIG. 36 is a flowchart of deriving an affine inheritance merge candidate.

First, the block (A0, A1) adjacent to the left side of the encoding/decoding target block is set as the left group (S3301), and it is determined whether the block including A0 is in the affine mode (S3302). When A0 is in the affine mode (S3102: YES), the affine model used by A0 is acquired (S3303), and the process moves to the block adjacent to the upper side. When A0 is not in the affine mode (S3302: NO), the target of the affine inheritance merge candidate derivation is A0->A1 and the acquisition of the affine mode from the block including A1 is tried.

Subsequently, blocks (B0, B1, B2) adjacent to the upper side of the encoding/decoding target block are set as an upper group (S3304), and it is determined whether the block including B0 is in the affine mode (S3305). If B0 is in the affine mode (S3305: YES), the affine model used by B0 is acquired (S3306), and the process ends. When B0 is not the affine mode (S3305: NO), the target of the affine inheritance merge candidate derivation is B0->B1 and the acquisition of the affine mode is attempted from the block including B1. Furthermore, when B1 is not in the affine mode (S3305: NO), the target of the affine inheritance merge candidate derivation is B1->B2, and the acquisition of the affine mode from the block including B2 is tried.

<Derivation of affine construction merge candidates>
The affine construction merge candidate derivation unit 383 will be described. The affine construction merge candidate derivation unit 483 is similar to the affine construction merge candidate derivation unit 383.

FIG. 33 is a diagram for explaining derivation of affine construction merge candidates. The affine construction merge candidate constructs an affine model of an affine control point from motion information and temporally encoded blocks that spatially adjacent blocks have.

Specifically, the motion vector of the upper left affine control point CP0 is derived from the block (B2, B3, A2) adjacent to the upper left side of the encoding/decoding target block and is adjacent to the upper right side of the encoding/decoding target block. A motion vector of the upper right affine control point CP1 is derived from the block (B1, B0), and a motion vector of the lower left affine control point CP2 is derived from the block (A1, A0) adjacent to the lower left side of the encoding/decoding target block. The motion vector of the lower right affine control point CP3 is derived from the time encoding block (T0) adjacent to the lower right side of the encoding/decoding target block.

FIG. 37 is a flowchart of deriving an affine construction merge candidate.

First, the upper left affine control point CP0, the upper right affine control point CP1, the lower left affine control point CP2, and the lower right affine control point CP3 are derived (S3401). The upper left control point CP0 is calculated by searching a block having motion information in the priority order of the B2, B3, and A2 blocks. The upper right control point CP1 is calculated by searching a block having motion information in the priority order of the B1 and B0 blocks. The lower left control point CP2 is calculated by searching a block having motion information in the priority order of the A1 and A0 blocks. The lower right control point CP3 is calculated by searching the motion information of the time block.

Subsequently, it is determined whether or not an affine model with three affine control points can be constructed using the derived CP0, CP1, and CP2 (S3402). If it is possible (S3402: YES), CP0, CP1, The three-affine control point affine model by CP2 is set as an affine merge candidate (S3403).

Subsequently, it is determined whether or not an affine model with three affine control points can be constructed by the derived CP0, CP1, and CP3 (S3404), and if it is possible (S3404: YES), CP0, CP1, The three-affine control point affine model by CP3 is set as an affine merge candidate (S3405).

Subsequently, it is determined whether or not an affine model with three affine control points can be constructed by the derived CP0, CP2, CP3 (S3406), and if it is possible (S3406: YES), CP0, CP2, The three-affine control point affine model by CP3 is set as an affine merge candidate (S3407).

Subsequently, it is judged whether or not an affine model with three affine control points can be constructed by the derived CP1, CP2, CP3 (S3408), and if it is possible (S3408: YES), CP1, CP2, The three-affine control point affine model by CP3 is set as an affine merge candidate (S3409).

Subsequently, it is determined whether or not it is possible to construct an affine model with two affine control points by the derived CP0 and CP1 (S3410), and if it is possible (S3410: YES), two affine models by CP0 and CP1. The affine control point affine model is set as an affine merge candidate (S3411).

Subsequently, it is determined whether or not an affine model with two affine control points can be constructed by the derived CP0 and CP2 (S3412). If it is possible (S3412: YES), two affine models by CP0 and CP2 can be constructed. The affine control point affine model is set as an affine merge candidate (S3413).

Here, whether or not the affine model is constructed is determined under the following conditions.

1. The reference images of all affine control points are the same. (Affine conversion possible)
2. At least one affine control point has different motion vectors. (Cannot be expressed by translation)
Further, for affine models other than the three-affine control point affine model by CP0, CP1, CP2 and the two-affine control point affine model by CP0, CP1, for the three-control affine model, three-affine control points by CP0, CP1, CP2. The control point affine model is converted to the two-control affine model by the CP0 and CP1.

<Affine fixed merge candidate derivation>
The affine fixed merge candidate derivation unit 385 will be described. The affine fixed merge candidate derivation unit 485 is similar to the affine fixed merge candidate derivation unit 385.

The affine fixed merge candidate fixes the motion information of the affine control points with the fixed motion information.

Specifically, the motion vector of each affine control point is fixed to (0,0).

<Temporal prediction motion vector>
Prior to the description of the temporal motion vector predictor, the temporal context of the picture will be described. FIG. 49A shows the relationship between a coding block to be coded and a coded picture that is temporally different from the picture to be coded. In the picture to be coded, a specific coded picture that is referred to for coding is defined as ColPic. ColPic is specified by the syntax.

Also, FIG. 49(b) shows the coded coding blocks that are present at the same position as the coding target coding block and in the vicinity thereof in the ColPic. These coding blocks T0 and T1 are coding blocks at substantially the same positions in a picture temporally different from the picture to be coded.

The above description of the temporal context of the picture is for encoding, but the same applies for decoding. That is, at the time of decoding, the coding in the above description is replaced with the decoding, and the same description will be made.

The operation of the temporal motion vector predictor candidate derivation unit 322 in the normal motion vector predictor mode derivation unit 301 of FIG. 17 will be described with reference to FIG.

First, ColPic is derived (step S4201). Derivation of ColPic will be described with reference to FIG.

When the slice type slice_type is a B slice and the flag collocated_from_l0_flag is 0 (YES in step S4211 and YES in step S4212), RefPicList1[0], that is, a picture with a reference index 0 in the reference list L1 is a picture at a different time colPic. (Step S4213). Otherwise, that is, if the slice type slice_type is a B slice and the above-mentioned flag collocated_from_l0_flag is 1 (YES in step S4211, NO in step S4212), or if the slice type slice_type is a P slice (NO in step S4211, step S4214). YES), RefPicList0[0], that is, the picture whose reference index is 0 in the reference list L0 becomes a picture colPic at a different time (step S4215). If slice_type is not a P slice (step S4214: NO), the processing ends.

Referring again to FIG. After deriving ColPic, the coding block colCb is derived and coding information is acquired (step S4202). This process will be described with reference to FIG.

First, the coding block located at the lower right (outside) of the same position as the coding block to be processed in the pictures colPic at different times is set as the coding block colCb at different times (step S4221). This coding block corresponds to the coding block T0 in FIG.

Next, the coded information of the coded blocks colCb at different times is acquired (step S4222). If the PredMode of the coded block colCb at a different time is not available or the prediction mode PredMode of the coded block colCb of a different time is intra prediction (MODE_INTRA) (step S4223: NO, step S4224: YES), a picture at a different time The coding block located at the lower right center of the same position as the coding block to be processed in colPic is set as a coding block colCb at a different time (step S4225). This coding block corresponds to the coding block T1 in FIG.

Referring again to FIG. Next, inter prediction information is derived for each reference list (S4203, S4204). Here, for the coding block colCb, a motion vector mvLXCol for each reference list and a flag availableFlagLXCol indicating whether or not the coding information is valid are derived. LX indicates a reference list, and LX becomes L0 when deriving the reference list 0, and LX becomes L1 when deriving the reference list 1. Derivation of inter prediction information will be described with reference to FIG.

When the coded blocks colCb at different times cannot be used (S4231 S4231: NO) or the prediction mode PredMode is intra prediction (MODE_INTRA) (S4232: NO), both the flag availableFlagLXCol and the flag predFlagLXCol are set to 0 (step S4233), and the motion is performed. The vector mvLXCol is set to (0, 0) (S4234), and the process ends.

When the coding block colCb is available (S4231: Yes) and the prediction mode PredMode is not intra prediction (MODE_INTRA) (S4322: YES), mvCol, refIdxCol and availableFlagCol are calculated by the following procedure.

When the flag PredFlagL0[xPCol][yPCol] indicating whether the L0 prediction of the coding block colCb is used is 0 (YES in S4235), the prediction mode of the coding block colCb is Pred_L1, and thus the motion vector mvCol is It is set to the same value as MvL1[xPCol][yPCol] which is the motion vector of L1 of the coding block colCb (S4236), and the reference index refIdxCol is set to the same value as the reference index RefIdxL1[xPCol][yPCol] of L1 ( S4237), and the list ListCol is set to L1 (S4238). Here, xPCol and yPCol are indices indicating the position of the upper left pixel of the coded block colCb in the pictures colPic at different times.

On the other hand, when the L0 prediction flag PredFlagL0[xPCol][yPCol] of the coding block colCb is not 0 (NO in S4235), it is determined whether the L1 prediction flag PredFlagL1[xPCol][yPCol] of the coding block colCb is 0. When the L1 prediction flag PredFlagL1[xPCol][yPCol] of the coding block colCb is 0 (YES in S4239), the motion vector mvCol is the same value as MvL0[xPCol][yPCol] which is the motion vector of L0 of the coding block colCb. (S4240), the reference index refIdxCol is set to the same value as the reference index RefIdxL0[xPCol][yPCol] of L0 (S4241), and the list ListCol is set to L0 (S4242).

When both the L0 prediction flag PredFlagL0[xPCol][yPCol] of the coding block colCb and the L1 prediction flag PredFlagL1[xPCol][yPCol] of the coding block colCb are not 0 (NO in S4235, NO in S4239), the coding block colCb Since the inter prediction mode of is bi-prediction (Pred_BI), one is selected from the two motion vectors L0 and L1 (S4243).

FIG. 54 is a flowchart illustrating a procedure of deriving inter prediction information of a coded block when the inter prediction mode of the coded block colCb is bi-prediction (Pred_BI).

First, it is determined whether or not the POCs of all pictures registered in all reference lists are smaller than the POCs of the current encoding target picture (S4251), and all reference lists L0 and L1 of the encoded block colCb are determined. If the POCs of all the pictures registered in are smaller than the POCs of the current picture to be coded (YES in S4251), LX is L0, that is, the motion vector prediction vector candidate of L0 of the coded block to be coded. In the case where L is derived (YES in S4252), the L0 inter prediction information of the coding block colCb is selected, and LX is L1, that is, the prediction vector candidate of the L1 motion vector of the coding block to be coded is selected. If it has been derived (NO in S4252), the inter prediction information of L1 of the coding block colCb is selected. On the other hand, when at least one of the POCs of the pictures registered in all the reference lists L0 and L1 of the coding block colCb is larger than the POC of the current picture to be coded (NO in S4251), the flag collocated_from_l0_flag is 0 ( If YES in S4253), the L0 inter prediction information of the coding block colCb is selected, and if the flag collocated_from_l0_flag is 1 (NO in S4253), the L1 inter prediction information of the coding block colCb is selected.

When selecting the L0 inter prediction information of the coding block colCb (YES in S4252, YES in S4253), the motion vector mvCol is set to the same value as MvL0[xPCol][yPCol] (S4254), and the reference index refIdxCol is set. Is set to the same value as RefIdxL0[xPCol][yPCol] (S4255), and the list ListCol is set to L0 (S4256).

When the inter prediction information of L1 of the coding block colCb is selected (NO in S4252, NO in S4253), the motion vector mvCol is set to the same value as MvL1[xPCol][yPCol] (S4257), and the reference index refIdxCol is set. Is set to the same value as RefIdxL1[xPCol][yPCol] (S4258), and the list ListCol is set to L1 (S4259).

Returning to FIG. 53, when the inter prediction information can be acquired from the coding block colCb, both the flag availableFlagLXCol and the flag predFlagLXCol are set to 1 (S4244).

Then, the motion vector mvCol is scaled to be a motion vector mvLXCol (S4245S4245). The scaling calculation processing procedure of this motion vector mvLXCol will be described with reference to FIG.

The inter-picture distance td is calculated by subtracting the POC of the reference picture corresponding to the reference index refIdxCol referenced in the list ListCol of the coding block colCb from the POCs of the pictures colPic at different times (S4261). Note that when the POC of the reference picture referenced by the list ListCol of the coding block colCb is earlier than the picture colPic of different time in the display order, the inter-picture distance td becomes a positive value, and the picture colPic of different time is more than that of the picture colPic of different time. When the POC of the reference picture referenced in the list ListCol of the coding block colCb is later in the display order, the inter-picture distance td has a negative value.
td = POC of pictures colPic at different times-POC of reference pictures referenced by list ListCol of coding block colCb
The inter-picture distance tb is calculated by subtracting the POC of the reference picture referenced by the current encoding target picture list LX from the POC of the current encoding target picture (S4262). If the reference picture referenced in the current encoding target picture list LX is earlier than the current encoding target picture in the display order, the inter-picture distance tb becomes a positive value, and the current encoding target picture is displayed. When the reference picture referred to in the list LX of 1 is later in the display order, the inter-picture distance tb has a negative value.
tb = POC of the current encoding/decoding target picture-POC of the reference picture corresponding to the reference index of the LX of the temporal merge candidate
Subsequently, the inter-picture distances td and tb are compared (S4263), and when the inter-picture distances td and tb are equal (YES in S4263), the motion vector mvLXCol is calculated by the following equation (S4264), and the scaling calculation processing is performed. finish.
mvLXCol = mvCol
On the other hand, when the inter-picture distances td and tb are not equal (NO in S4263), the variable tx is calculated by the following equation (S4265).
tx = (16384 + Abs( td) >> 1) / td
Then, the scaling coefficient distScaleFactor is calculated by the following formula (S4266).
distScaleFactor = Clip3( -4096, 4095, (tb * tx + 32) >> 6)
Here, Clip3(x,y,z) is a function that limits the minimum value to x and the maximum value to y for the value z. Then, the motion vector mvLXCol is calculated by the following equation (S4267), and the scaling calculation process is ended.
mvLXCol = Clip3( -32768, 32767, Sign( distScaleFactor * mvLXCol)
* ((Abs( distScaleFactor * mvLXCol) + 127) >> 8 ))
Here, Sign(x) is a function that returns the sign of the value x, and Abs(x) is a function that returns the absolute value of the value x.

Referring again to FIG. Then, the motion vector mvL0Col of L0 is added as a candidate to the motion vector predictor candidate list mvpListLXN in the normal motion vector predictor mode deriving unit 301 (S4205). However, this addition is performed only when the flag availableFlagL0Col=1, which indicates whether the coding block colCb of the reference list 0 is valid. Also, the motion vector mvL1Col of L1 is added as a candidate to the motion vector predictor candidate list mvpListLXN in the normal motion vector predictor mode deriving unit 301 (S4205). However, this addition is performed only when the flag availableFlagL1Col=1 indicating whether or not the coding block colCb of the reference list 1 is valid. With the above, the processing of the temporal motion vector predictor candidate derivation unit 322 ends.

The above description of the normal motion vector predictor mode derivation unit 301 is for encoding, but the same applies for decoding. That is, the operation of the temporal motion vector predictor candidate derivation unit 422 in the normal motion vector predictor mode derivation unit 401 of FIG. 23 is similarly described by replacing the encoding in the above description with decoding.

<Time merge>
The operation of the temporal merge candidate derivation unit 342 in the normal merge mode derivation unit 302 of FIG. 18 will be described with reference to FIG.

First, ColPic is derived (step S4301). Next, the coding block colCb is derived and the coding information is acquired (step S4302). Furthermore, inter prediction information is derived for each reference list (S4303, S4304). The above processing is the same as S4201 to S4204 in the temporal motion vector predictor deriving unit 322, and therefore description thereof will be omitted.

Next, a flag availableFlagCol indicating whether or not the coding block colCb is valid is calculated (S4305). When the flag availableFlagL0Col or the flag availableFlagL1Col is 1, availableFlagCol becomes 1. Otherwise, availableFlagCol is 0.

Then, the motion vector mvL0Col of L0 and the motion vector mvL1Col of L1 are added as candidates to the merge candidate list mergeCandList in the normal merge mode derivation unit 302 (S4306). However, this addition is performed only when the flag availableFlagCol=1 indicating whether or not the coding block colCb is valid. With the above, the processing of the time merge candidate derivation unit 3 42 is completed.

The above description of the temporal merge candidate derivation unit 342 is for encoding, but the same applies for decoding. That is, the operation of the temporal merge candidate derivation unit 442 in the normal merge mode derivation unit 402 in FIG. 24 is similarly described by replacing the encoding in the above description with decoding.

<Update of history prediction motion vector candidate list>
Next, a method of initializing and updating the history motion vector predictor candidate list HmvpCandList provided in the encoding side information storage memory 111 and the decoding side encoding information storage memory 205 will be described in detail. FIG. 38 is a flowchart for explaining the procedure of the process of initializing and updating the history motion vector predictor candidate list.

In the present embodiment, it is assumed that the history motion vector predictor candidate list HmvpCandList is updated in the coding information storage memory 111 and the coding information storage memory 205. A history candidate list update unit may be installed in the inter prediction unit 102 and the inter prediction unit 203 to update the history motion vector predictor candidate list HmvpCandList.

The history prediction motion vector candidate list HmvpCandList is initialized at the beginning of the slice, and the history prediction motion vector candidate list HmvpCandList is updated on the encoding side when the prediction method determination unit 106 selects the normal prediction vector mode or the normal merge mode. Then, on the decoding side, when the inter prediction mode decoded by the bit string decoding unit 201 is the normal prediction vector mode or the normal merge mode, the history motion vector predictor candidate list HmvpCandList is updated. The inter prediction information used when performing the inter prediction in the normal prediction vector mode or the normal merge mode is set as the inter prediction information candidate hMvpCand to be registered, and the coding information storage memory 111 on the coding side and the coding information storage memory 205 on the decoding side are included. In the inter prediction information registered in the history prediction motion vector candidate list HmvpCandList, if there is an inter prediction of the same value as the inter prediction information candidate hMvpCand to be registered, the element from the history prediction motion vector candidate list HmvpCandList (Inter prediction information) is deleted, and the same value as the inter prediction information candidate hMvpCand to be registered does not exist. If there is no inter prediction, the first element (inter prediction information) of the history motion vector predictor candidate list HmvpCandList is deleted, and the history The inter prediction information candidate hMvpCand to be registered is added to the end of the motion vector predictor candidate list HmvpCandList.

The number of elements of the historical motion vector predictor candidate list HmvpCandList provided in the coding information storage memory 111 on the coding side and the coding information storage memory 205 on the decoding side of the present invention is six.

First, the history motion vector predictor candidate list HmvpCandList is initialized in slice units. The history motion vector predictor candidate is added to all the elements of the motion vector predictor motion vector candidate list HmvpCandList at the beginning of the slice, and the number of motion vector predictor motion vector candidates registered in the motion vector predictor motion vector candidate list HmvpCandList is set to 6 for the value NumHmvpCand. It is set (step S2101 in FIG. 38).

Here, the initialization of the history motion vector predictor candidate list HmvpCandList is performed in slice units (the first coding block of a slice), but it is also possible to perform it in picture units, tile units, or tree block row units.

FIG. 62 is a table showing an example of historical motion vector predictor candidates added by initialization of the historical motion vector predictor list HmvpCandList. An example in which the slice type is a B slice and the number of reference pictures is 4 is shown. From the history motion vector predictor index (number of history motion vector predictor candidates NumHmvpCand-1) to 0, the motion vector value is (0, 0) according to the slice type, and the inter motion prediction information is used as the motion vector predictor candidate. Add to the motion vector predictor candidate list HmvpCandList and fill the history motion vector predictor candidate list with history candidates. At this time, the history motion vector predictor index starts from (the number of history motion vector predictor candidates NumHmvpCand-1), and the reference index refIdxLX (X is 0 or 1) is 0 to (the number of reference pictures numRefIdx-1). Set the incremented value. After that, overlapping of the motion vector predictor motion vector candidates is permitted, and a value of 0 is set in refIdxLX. By setting all the values to the number NumHmvpCand of history motion vector predictor candidates and setting the value of the number NumHmvpCand of history motion vector predictor candidates to a fixed value, invalid history motion vector predictor candidates are eliminated. In this way, by assigning a small value of the reference index having a generally high selection rate from the candidate of the value of the history motion vector predictor vector index having a high probability of being added to the motion vector predictor candidate list or the merge candidate list, Efficiency can be improved.

Further, by filling the history motion vector predictor candidate list in slice units with the history motion vector predictor candidates, the number of the motion vector predictor motion vectors can be treated as a fixed value. The history merge candidate derivation process can be simplified.

Here, the value of the motion vector is generally (0, 0), which has a high selection probability, but it may be a predetermined value. For example, the coding efficiency of the differential motion vector may be improved by setting a value such as (4,4), (0,32), (-128,0), or a plurality of predetermined values may be set to set the differential motion vector. The coding efficiency of may be improved.

In addition, the history motion vector predictor index starts from (the number of history motion vector predictor candidates NumHmvpCand-1), and the reference index refIdxLX (X is 0 or 1) ranges from 0 to 1 (the number of reference pictures numRefIdx-1). Although the incremented value is set, the history motion vector predictor index may be started from 0.

FIG. 63 is a table showing another example of the historical motion vector predictor candidates added by the initialization of the historical motion vector predictor candidate list HmvpCandList. An example in which the slice type is a B slice and the number of reference pictures is 2 is shown. In this example, inter prediction information with different reference index or motion vector value is added as a historical motion vector predictor candidate so that each element of the historical motion vector predictor list HmvpCandList does not overlap with each other. Then, the history motion vector predictor candidate list is filled. At this time, the history motion vector predictor index starts from (the number of history motion vector predictor candidates NumHmvpCand-1), and the reference index refIdxLX (X is 0 or 1) is 0 to (the number of reference pictures numRefIdx-1). Set the incremented value. After that, motion vectors having different values of 0 are added to refIdxLX as history motion vector predictor candidates. By setting all the values in the number NumHmvpCand of history motion vector predictor candidates and setting the value of the number NumHmvpCand of history motion vector predictor candidates to a fixed value, invalid history motion vector predictor candidates are eliminated.

In this way, by filling the history motion vector predictor candidate list in slice units with history motion vector predictor candidates that do not overlap, further history merge candidate in a normal merge mode deriving unit 302, which will be described later, which is performed in coding block units. The processing of the merge candidate supplementation unit 346 after the derivation unit 345 can be omitted, and the processing amount can be reduced.

Here, the value of the motion vector is set to a small value such as (0, 0) or (1, 0), but the value of the motion vector may be increased if the history prediction motion vector candidates do not overlap with each other.

In addition, the history motion vector predictor index starts from (the number of history motion vector predictor candidates NumHmvpCand-1), and the reference index refIdxLX (X is 0 or 1) ranges from 0 to 1 (the number of reference pictures numRefIdx-1). Although the incremented value is set, the history motion vector predictor index may be started from 0.

FIG. 64 is a table showing another example of the historical motion vector predictor candidates added by the initialization of the historical motion vector predictor list HmvpCandList.

An example when the slice type is B slice is shown. In this example, inter-prediction information with a reference index of 0 and a different motion vector value is added as a historical motion vector predictor candidate so that the elements of the historical motion vector predictor list HmvpCandList do not overlap with each other. Then, the history motion vector predictor candidate list is filled. At this time, the history motion vector predictor index starts from (the number of history motion vector predictor candidates NumHmvpCand-1), and the reference index refIdxLX (X is 0 or 1) is set to 0. By setting all the values to the number NumHmvpCand of history motion vector predictor candidates and setting the value of the number NumHmvpCand of history motion vector predictor candidates to a fixed value, invalid history motion vector predictor candidates are eliminated.

In this way, by setting the reference index to 0, initialization can be further performed without considering the number of reference pictures, so that the processing can be simplified.

Here, the value of the motion vector is a multiple of 2, but any other value may be used as long as the reference index is 0 and no overlap between the historical motion vector predictor candidates occurs.

In addition, the history motion vector predictor index starts from (the number of history motion vector predictor candidates NumHmvpCand-1), and the reference index refIdxLX (X is 0 or 1) ranges from 0 to 1 (the number of reference pictures numRefIdx-1). Although the incremented value is set, the history motion vector predictor index may be started from 0.

Subsequently, the following update processing of the history motion vector predictor candidate list HmvpCandList is repeated for each coded block in the slice (steps S2102 to S2111 in FIG. 38).

First, initial setting is performed for each coding block. A flag FALSE (false) indicating whether the same candidate exists or not is set, and a deletion target index removeIdx is set to 0 (step S2103 in FIG. 38).

It is determined whether or not the inter prediction information candidate hMvpCand to be registered exists in the history motion vector predictor candidate list HmvpCandList (step S2104 in FIG. 38). When the prediction method determination unit 105 on the encoding side determines the normal motion vector predictor mode or the normal merge mode, or when the bit string decoding unit on the decoding side decodes the normal motion vector predictor mode or the normal merge mode, the The prediction mode is hMvpCand. When the prediction method determination unit 105 on the encoding side determines the intra prediction mode, the sub-block prediction motion vector mode, or the sub-block merge mode, or the decoding-side bit string decoding unit determines the intra prediction mode, the sub-block prediction motion vector mode, or When decoded in the sub-block merge mode, the history motion vector predictor candidate list HmvpCandList is not updated, and there is no inter prediction information candidate hMvpCand to be registered. If the inter prediction information candidate hMvpCand to be registered does not exist, steps S2105 to S2110 are skipped (NO in step S2104 in FIG. 38). If the inter prediction information candidate hMvpCand to be registered is present, the processing from step S2105 is performed (YES in step S2104 in FIG. 38).

Here, in the present embodiment, when the coding/decoding is performed as the normal motion vector predictor mode, the inter prediction mode is set to hMvpCand and the history motion vector predictor candidate list HmvpCandList is updated, and the normal merge mode is coded as the normal merge mode. When decoded, the history motion vector predictor candidate list HmvpCandList is not updated. In step S2104 of FIG. 38, the determination process may be separated as in steps S2404 and S2405 of the flowchart of FIG. In step S2404, if it is not the normal merge mode, the process proceeds to step S2405, and if it is the normal merge mode, the process proceeds to step S2408.

In step S2405 of FIG. 65, if the prediction method determination unit 105 on the encoding side determines the normal motion vector predictor mode, or if the bit string decoding unit on the decoding side decodes the normal motion vector predictor mode, the inter prediction Set the mode to hMvpCand. When the prediction method determination unit 105 on the encoding side determines the intra prediction mode, the sub-block prediction motion vector mode, or the sub-block merge mode, or the decoding-side bit string decoding unit determines the intra prediction mode, the sub-block prediction motion vector mode, or When decoded in the sub-block merge mode, the history motion vector predictor candidate list HmvpCandList is not updated, and there is no inter prediction information candidate hMvpCand to be registered. If the inter prediction information candidate hMvpCand to be registered does not exist, the process proceeds to step S2408. If the inter-prediction information candidate hMvpCand to be registered exists, the processing from step S2406 is performed. Since the same processing may be performed in steps S2101 to S2103 of FIG. 38 and steps S2401 to S2403 of FIG. 65, description thereof will be omitted. Description of the steps S2105 to S2107 in FIG. 38 and the steps S2406 to S2408 in FIG.

In this way, by comparing the motion information with the existing candidates in the historical motion vector predictor candidate list, the history motion vector predictor candidate list is updated only when encoded/decoded in the normal motion vector predictor mode. There is no need to do it, and the processing load is reduced. In the normal motion vector predictor mode, difference motion vectors are added to generate new motion information that does not exist in the surrounding blocks, so that existing history motion vector predictor candidates and motion information can be calculated without comparing motion information. Duplicates are unlikely.

Returning to the description of step S2104 and subsequent steps in FIG.

Subsequently, it is determined whether or not the same element as the inter prediction information candidate hMvpCand to be registered exists in each element of the history motion vector predictor candidate list HmvpCandList (step S2105 in FIG. 38). FIG. 39 is a flowchart of the same element confirmation processing procedure. When the value of the number of historical motion vector predictor NumHmvpCand is 0 (NO in step S2121 in FIG. 39), the historical motion vector predictor candidate list HmvpCandList is empty and the same candidate does not exist, so steps S2122 to S2125 in FIG. 39 are skipped. Then, the same element confirmation processing procedure ends. When the value of the number of historical motion vector predictor NumHmvpCand is larger than 0 (YES in step S2121 of FIG. 39), the process of steps S2122 to S2125 is repeated from the historical motion vector predictor index hMvpIdx of 0 to NumHmvpCand-1 (FIG. 39). Steps S2121 to S2125). First, it is compared whether or not the hMvpIdx-th element HmvpCandList[MvpIdx] counting from 0 in the history motion vector predictor candidate list is the same as the inter prediction information candidate hMvpCand (step S2123 in FIG. 39). If they are the same (YES in step S2123 of FIG. 39), a value of TRUE (true) is set in the flag identicalCandExist indicating whether or not the same candidate exists, a value of hMVpIndex is set in the index to be deleted removeIdx, and this is the same. The element confirmation process ends. If they are not the same (NO in step S2123 in FIG. 39), hMvpIdx is incremented by 1 (steps S2121 and S2125 in FIG. 39), and the processing from step S2123 is performed.

Here, by filling the history motion vector predictor candidate list with history motion vector predictor candidates, step S2121 in FIG. 39 can be omitted.

Returning to the flowchart of FIG. 38 again, the process of shifting and adding the elements of the history motion vector predictor candidate list HmvpCandList is performed (step S2106 of FIG. 38). FIG. 40 is a flowchart of the element shift/addition processing procedure of the history motion vector predictor candidate list HmvpCandList in step S2106 of FIG. First, it is determined whether an element stored in the history motion vector predictor list HmvpCandList is removed and then a new element is added, or whether a new element is added without removing the element. Specifically, the flag “identicalCandExist” indicating whether the same candidate exists is compared with TRUE (true) or NumHmvpCand is 6 (step S2141 in FIG. 40). When TRUE (true) or NumHmvpCand satisfies the condition of 6 in the flag indicating whether the same candidate exists (YES in step S2141 of FIG. 40), the flag is stored in the history motion vector predictor candidate list HmvpCandList. Remove the existing element and add a new element. Set the initial value of index i to the value of removeIdx + 1. The element shift process of step S2143 is repeated from this initial value to NumHmvpCand. (Steps S2142 to S2144 of FIG. 40). By copying the element of HMVPCandList[i-1] to HMVPCandList[i-1], the element is shifted forward (step S2143 in FIG. 40) and i is incremented by 1 (steps S2142 and S2145 in FIG. 40). Subsequently, the inter prediction information candidate hMvpCand is added to the (NumHmvpCand-1)th HMVPCandList[NumHmvpCand-1] counting from 0 corresponding to the end of the history prediction motion vector candidate list (step S2145 in FIG. 40), and the main history prediction is performed. The element shift/addition processing of the motion vector candidate list HMVPCandList ends. On the other hand, when neither the condition TRUE (true) nor NumHmvpCand 6 is satisfied in the flag “identicalCandExist” indicating whether the same candidate exists (NO in step S2141 of FIG. 40 ), the history prediction motion vector candidate list HmvpCandList is stored. Add a new element without removing the existing element. The inter prediction information candidate hMvpCand is added to (NumHmvpCand-1)th HMVPCandList[NumHmvpCand] counting from 0 corresponding to the end of the history motion vector predictor candidate list, and NumHmvpCand is incremented by 1 (step S2145 in FIG. 40 ). The element shift/addition processing of the history motion vector predictor list HMVPCandList ends.

Here, the history motion vector predictor candidate list is applied to both the motion vector predictor mode and the merge mode, but may be applied to only one of them.

<History prediction motion vector candidate derivation process>
Next, a process common to the history motion vector predictor candidate derivation unit 323 of the encoding side normal motion vector predictor mode derivation unit 301 and the history motion vector predictor candidate derivation unit 423 of the decoding side normal motion vector predictor mode derivation unit 401 is performed. A method of deriving a historical motion vector predictor candidate from the historical motion vector predictor candidate list HMVPCandList, which is the processing procedure of step S304 in FIG. 20, will be described in detail. FIG. 41 is a flow chart for explaining a history motion vector predictor candidate derivation process procedure.

If the number numCurrMvpCand of the current motion vector predictor is equal to or larger than the maximum number of elements (here, 2) of the motion vector predictor list mvpListLX, or if the number of history motion vector predictor candidates is 0 in the value of NumHmvpCand (see step S2201 in FIG. 41). NO), the processes of steps S2202 to S2209 of FIG. 41 are omitted, and the history motion vector predictor candidate derivation process procedure ends. When the current number of motion vector predictor candidates numCurrMvpCand is smaller than 2, which is the maximum number of elements of the motion vector predictor list mvpListLX (YES in step S2201 of FIG. 41), the processes of steps S2202 to S2209 of FIG. 41 are performed.

Then, the processes of steps S2203 to S2208 of FIG. 41 are repeated until the index i is 1 to 4 and the number of historical motion vector predictor candidates numCheckedHMVPCand, whichever is smaller (steps S2202 to S2209 of FIG. 41). When the current number of motion vector predictor candidates numCurrMvpCand is 2 or more, which is the maximum number of elements of the motion vector predictor list mvpListLX (NO in step S2203 of FIG. 41), the processes of steps S2204 to S2209 of FIG. The motion vector predictor candidate derivation process procedure ends. If the current number of motion vector predictor candidates numCurrMvpCand is smaller than 2, which is the maximum number of elements of the motion vector predictor list mvpListLX (YES in step S2203 of FIG. 41), the processes of step S2204 and subsequent steps of FIG. 41 are performed.

Then, the processes from steps S2205 to S2207 are performed for indexes Y of 0 and 1 (L0 and L1), respectively (steps S2204 to S2208 of FIG. 41). If the current number of motion vector predictor candidates numCurrMvpCand is 2 or more, which is the maximum number of elements of the motion vector predictor list mvpListLX (NO in step S2205 of FIG. 41), the processes of steps S2206 to S2209 of FIG. The motion vector predictor candidate derivation process procedure ends. When the current number numCurrMvpCand of motion vector predictor candidates is smaller than 2, which is the maximum number of elements of the motion vector predictor list mvpListLX (YES in step S2205 of FIG. 41 ), the processing of step S2206 and subsequent steps of FIG. 41 is performed.

Subsequently, in the case of the element having the same reference index as the reference index refIdxLX of the motion vector to be encoded/decoded in the history motion vector predictor candidate list HmvpCandList, which is different from any element of the motion vector predictor list mvpListLX (FIG. 41). Step S2206: YES), the LY motion vector of the historical motion vector predictor candidate HmvpCandList[NumHmvpCand-i] is added to the numCurrMvpCand th element mvpListLX[numCurrMvpCand] counted from 0 in the motion vector predictor list (step in FIG. 41). S2207), the number of current motion vector predictor candidates numCurrMvpCand is incremented by 1. If there is no element in the historical motion vector predictor list HmvpCandList that has the same reference index as the reference index refIdxLX of the motion vector to be encoded/decoded and is not different from any element of the motion vector predictor list mvpListLX (step in FIG. 41). (NO of S2206), the additional process of step S2207 is skipped.

Here, in the normal motion vector predictor mode, the history motion vector predictor candidate list HmvpCandList is updated, and in the normal merge mode, the history motion vector predictor candidate list HmvpCandList is not updated, as shown in FIG. 66. In addition, the same candidate determination process, which is the process of step S2206 of FIG. 41, may be omitted. This is because the history prediction motion vector candidate list HmvpCandList is not updated in the normal merge mode, so that candidates that are the same or highly correlated are unlikely to be included.

With such a configuration, it is not necessary to perform the determination process of the same candidate, and thus the processing amount can be suppressed.

Both the processes of steps S2205 to S2207 of FIG. 41 are performed in L0 and L1 (steps S2204 to S2208 of FIG. 41).

The index i is incremented by 1 (steps S2202, S2209 in FIG. 41), and when the index i is 4 or less than the number of historical motion vector predictor candidates numCheckedHMVPCand, whichever is smaller, the processing in step S2203 and thereafter is performed again (FIG. 41). Steps S2202 to S2209).

<History merge candidate derivation process>
Next, the process of step S404 in FIG. 21, which is a process common to the history merge candidate derivation unit 345 of the encoding-side normal merge mode derivation unit 302 and the history merge candidate derivation unit 423 of the decoding-side normal merge mode derivation unit 401. A method of deriving a history merge candidate from the history merge candidate list HmvpCandList, which is a procedure, will be described in detail. FIG. 42 is a flowchart for explaining the history merge candidate derivation processing procedure.

First, initialization processing is performed (step S2301 in FIG. 42). Set the value of FALSE to each element from 0 to (numCurrMergeCand -1) of isPruned[i], and set the variable numOrigMergeCand to numCurrMergeCand, which is the number of elements registered in the current merge candidate list.

Subsequently, among the elements of the history motion vector predictor list, the elements that are not included in the merge candidate list are added to the merge candidate list. At this time, the history prediction motion vector list is confirmed and added in descending order. The initial value of the index hMvpIdx is set to 1, and the additional processing from step S2303 to step S2328 of FIG. 42 is repeated from this initial value to NumHmvpCand-1 (steps S2302 to S2329 of FIG. 42). If the number of elements registered in the current merge candidate list numCurrMergeCand is not less than (the maximum number of merge candidates MaxNumMergeCand-1), the merge candidates have been added to all elements in the merge candidate list, so this history merge candidate derivation The process ends (NO in step S2303 in FIG. 42). When the number numCurrMergeCand of elements registered in the current merge candidate list is (maximum merge candidate number MaxNumMergeCand-1) or less, the processing from step S2304 is performed. A value of FALSE (false) is set in sameMotion (step S2304 in FIG. 42). Subsequently, the initial value of the index i is set to 0, and the processes of steps S2306 and S2307 of FIG. 42 are performed from this initial value to numOrigMergeCand-1 (S2305 to S2308 of FIG. 42). Compares whether the (NumHmvpCand-hMvpIdx)th element HmvpCandList[NumHmvpCand- hMvpIdx] counting from 0 in the history motion vector prediction candidate list has the same value as the ith element mergeCandList[i] counting from 0 in the merge candidate list (Step S2306 in FIG. 42). The same value of the merge candidate means that the merge candidate has the same value when all the constituent elements (inter prediction mode, reference index, motion vector) of the merge candidate have the same value. If the values are the same (YES in step S2306 in FIG. 39), both sameMotion and isPruned[i] are set to TRUE (step S2307 in FIG. 42). If the values are not the same (NO in step S2306 in FIG. 39), the process in step S2307 is skipped. When the repeated processing from step S2305 to step S2308 in FIG. 42 is completed, it is compared whether sameMotion is FALSE (false) (step S2309 in FIG. 42). When sameMotion is FALSE (false) (YES in step S2309 in FIG. 42) ), that is, the (NumHmvpCand-hMvpIdx)th element HmvpCandList[NumHmvpCand-hMvpIdx] counting from 0 in the history motion vector predictor list does not exist in mergeCandList, so the history motion prediction motion is numCurrMergeCandth mergeCandList[numCurrMergeCand] in the merge candidate list. The (NumHmvpCand-hMvpIdx)th element HmvpCandList[NumHmvpCand-hMvpIdx] counting from 0 in the vector candidate list is added, and numCurrMergeCand is incremented by 1 (step S2310 in FIG. 42). The index hMvpIdx is incremented by 1 (step S2302 in FIG. 42), and the iterative process of steps S2302 to S2311 in FIG. 42 is performed.

When the confirmation of all the elements of the history motion vector predictor candidate list is completed or the merge candidates are added to all the elements of the merge candidate list, the process of deriving the history merge candidate is completed.

<Sub-block time merge candidate derivation>
The operation of the sub block time merge candidate derivation unit 381 in the sub block merge mode derivation unit 304 of FIG. 16 will be described with reference to FIG.

First, it is determined whether the coded block is less than 8x8 pixels (S4002).

If the number of encoded blocks is less than 8x8 pixels (S4002: Yes), the flag availableFlagSbCol=0 indicating the existence of the sub-block time merge candidate is set (S4003), and the process of the sub-block time merge candidate derivation unit ends. Here, when temporal motion vector prediction is prohibited by the syntax or when sub-block temporal merging is prohibited, the same processing as when the coding block is less than 8x8 pixels (S4002: Yes) is performed. ..

On the other hand, when the coded block is 8×8 pixels or more (S4002: No), adjacent motion information of the coded block in the coded picture is derived (S4004).

The process of deriving the adjacent motion information of the coding block will be described with reference to FIG. The process of deriving the adjacent motion information is similar to the process of the spatial motion vector predictor candidate derivation unit 321 described above. However, the order of searching for adjacent blocks is A0, B0, B1, A1, and B2 is not searched. First, the coding information is acquired with the adjacent block n=A0 (S4052). The coding information indicates a flag availableFlagN indicating whether or not an adjacent block can be used, a reference index refIdxLXN for each reference list, and a motion vector mvLXN.

Next, it is determined whether the adjacent block n is valid or invalid (S4054). A flag indicating whether or not an adjacent block can be used is available if availableFlagN=1, otherwise it is invalid.

If the adjacent block n is valid (S4054: Yes), the reference index refIdxLXN is set as the reference index refIdxLXn of the adjacent block n (S4056). Further, the motion vector mvLXN is set as the motion vector mvLXn of the adjacent block n (S4056), and the process of deriving the adjacent motion information of the block ends.

On the other hand, if the adjacent block n is invalid (S4106: No), the adjacent block n=B0 is set and the coding information is acquired (S4104). Thereafter, similar processing is performed, and the loop is made in the order of B1 and A1. The process of deriving the adjacent motion information loops until the adjacent block becomes valid, and if all the adjacent blocks A0, B0, B1, and A1 are invalid, the process of deriving the adjacent motion information of the block ends.

Again referring to FIG. When the adjacent motion information is derived (S4004), the temporal motion vector is derived (S4006).

The process of deriving the temporal motion vector will be described with reference to FIG. First, the temporal motion vector tempMv=(0,0) is initialized (S4062).

Next, it is determined whether the adjacent motion information is valid or invalid (S4064). A flag indicating whether or not an adjacent block can be used is available if availableFlagN=1, otherwise it is invalid. When the adjacent motion information is invalid (S4064: No), the process of deriving the temporal motion vector ends.

On the other hand, when the adjacent motion information is valid (S4064: Yes), it is determined whether the flag predFlagL1N indicating whether or not L1 prediction is used in the adjacent block N is 1 (S4066). If predFlagL1N=0 (S4066: No), the process advances to the next process (S4078). When predFlagL1N=1 (S4066: Yes), it is determined whether or not the POCs of all the pictures registered in all the reference lists are less than or equal to the POC of the current picture to be encoded (S4068). When this determination is true (S4068: Yes), the process proceeds to the next process (S4070).

When the slice type slice_type is a B slice and the flag collocated_from_l0_flag is 0 (S4070: Yes and S4072: Yes), it is determined whether ColPic and the reference picture RefPicList1[refIdxL1N] (picture of the reference index refIdxL1N of the reference list L1) are the same. It is determined (S4074). If this determination is true (S4074: Yes), the temporal motion vector tempMv=mvL1N is set (S4076). If this determination is false (S4074: No), the process proceeds to the next process (S4078). If the slice type slice_type is not a B slice and the flag collocated_from_l0_flag is not 0 (S4070: No or S4072: No), the process proceeds to the next process (S4078).

Then, it is determined whether or not the flag predFlagL0N indicating whether or not L0 prediction is used in the adjacent block N is 1 (S4078). If predFlagL0N=1 (S4078: Yes), it is determined whether ColPic and the reference picture RefPicList0[refIdxL0N] (picture of reference index refIdxL0N of the reference list L0) are the same (S4080). If this determination is true (S4080: Yes), the temporal motion vector tempMv=mvL0N is set (S4082). If this determination is false (S4080: No), the process of deriving the temporal motion vector ends.

Again referring to FIG. Next, ColPic is derived (S4016). This processing is the same as S4201 in the temporal motion vector predictor candidate derivation unit 322, and thus description thereof will be omitted.

Then, the coded blocks colCb at different times are set (S4017). This is to set, as colCb, the coded block located at the center lower right of the same position as the coded block to be processed in the pictures ColPic at different times. This coding block corresponds to the coding block T1 in FIG.

Next, the position where the temporal motion vector tempMv is added to the encoded block colCb is set as a new colCb (S4018). If the upper left position of the coding block colCb is (xColCb, yColCb) and the temporal motion vector tempMv is 1/16 pixel precision (tempMv[0], tempMv[1]), the upper left position of the new colCb is become that way.
xColCb = Clip3( xCtb, xCtb + CtbSizeY + 3, xcolCb + (tempMv[0] >> 4 ))
yColCb = Clip3( yCtb, yCtb + CtbSizeY-1, ycolCb + (tempMv[1] >> 4 ))
Here, the upper left position of the tree block is (xCtb, yCtb), and the size of the tree block is CtbSizeY. As shown in the above equation, the position after the addition of tempMv is corrected within the range of the size of the tree block so as not to be significantly displaced compared to the position before the addition of tempMv. If this position is outside the screen, it is corrected within the screen.

Then, it is determined whether or not the prediction mode PredMode of this coding block colCb is inter prediction (MODE_INTER) (S4020). If the prediction mode of colCb is not inter prediction (S4020: No), the flag availableFlagSbCol=0 indicating the existence of a sub-block time merge candidate is set (S4003), and the process of the sub-block time merge candidate derivation unit ends.

On the other hand, when the prediction mode of colCb is inter prediction (S4020: Yes), inter prediction information is derived for each reference list (S4022, S4023). Here, for colCb, a central motion vector ctrMvLX for each reference list and a flag ctrPredFlagLX indicating whether or not LX prediction is used are derived. LX indicates a reference list, and LX becomes L0 when deriving the reference list 0, and LX becomes L1 when deriving the reference list 1. Derivation of inter prediction information will be described with reference to FIG. 47.

When the coded blocks colCb at different times cannot be used (S4112: NO) or the prediction mode PredMode is intra prediction (MODE_INTRA) (S4114: NO), both the flag availableFlagLXCol and the flag predFlagLXCol are set to 0 (step S4116), and the motion is performed. The vector mvCol is set to (0, 0) (S4118), and the inter prediction information derivation process ends.

When the coding block colCb is available (S4112: Yes) and the prediction mode PredMode is not intra prediction (MODE_INTRA) (S4114: YES), mvCol, refIdxCol and availableFlagCol are calculated by the following procedure.

When the flag PredFlagLX[xPCol][yPCol] indicating whether the LX prediction of the coding block colCb is used is 1 (YES in S4120), the motion vector mvCol is MvLX[ which is the LX motion vector of the coding block colCb. It is set to the same value as xPCol][yPCol] (S4122), the reference index refIdxCol is set to the same value as the reference index RefIdxLX[xPCol][yPCol] of LX (S4124), and the list listCol is set to LX (S4126). ). Here, xPCol and yPCol are indices indicating the position of the upper left pixel of the coded block colCb in the pictures colPic at different times.

On the other hand, if the flag PredFlagLX[xPCol][yPCol] indicating whether the LX prediction of the coding block colCb is used is 0 (NO in S4120), the following process is performed. First, it is determined whether or not the POCs of all the pictures registered in all the reference lists are less than or equal to the POCs of the current picture to be encoded (S4128). At the same time, it is determined whether the flag PredFlagLY[xPCol][yPCol] indicating whether the LY prediction of colCb is used is 1 (S4128). Here, LY prediction is defined as a reference list different from LX prediction. That is, when LX=L0, LY=L1, and when LX=L1, LY=L0.

When this determination is true (S4128: Yes), the motion vector mvCol is set to the same value as MvLY[xPCol][yPCol] which is the LY motion vector of the coding block colCb (S4130), and the reference index refIdxCol is LY. It is set to the same value as the reference index RefIdxLY[xPCol][yPCol] (S4132), and the list listCol is set to LX (S4134).

On the other hand, if this determination is false (S4128: No), both the flag availableFlagLXCol and the flag predFlagLXCol are set to 0 (step S4116), the motion vector mvCol is set to (0, 0) (S4118), and the inter prediction information derivation process ends. To do.

When the inter prediction information can be acquired from the coding block colCb, both the flag availableFlagLXCol and the flag predFlagLXCol are set to 1 (S4136).

Then, the motion vector mvCol is scaled to be a motion vector mvLXCol (S4138). This process is the same as S4245 in the temporal motion vector predictor candidate derivation unit 322, and thus the description is omitted.

Again referring to FIG. After deriving the inter prediction information for each reference list, the calculated motion vector mvLXCol is set as the central motion vector ctrMvLX, and the calculated flag predFlagLXCol is set as the flag ctrPredFlagLX (S4022, S4023).

Then, it is determined whether the center motion vector is valid or invalid (S4024). If ctrPredFlagL0=0 and ctrPredFlagL1=0, it is determined to be invalid, otherwise it is determined to be invalid. When the central motion vector is invalid (S4024: No), the flag availableFlagSbCol=0 indicating the existence of the sub-block time merge candidate is set (S4003), and the process of the sub-block time merge candidate derivation unit ends.

On the other hand, when the central motion vector is valid (S4024: Yes), the flag availableFlagSbCol=1 indicating the existence of the sub block time merge candidate is set (S4025), and the sub block motion information is derived (S4026). This process will be described with reference to FIG.

First, from the width cbWidth and height cBheight of the coded block colCb, the number of sub-blocks in the width direction numSbX and the number of sub-blocks in the height direction numSbY are calculated (S4152). Also, refIdxLXSbCol=0 is set (S4152). After this processing, iterative processing is performed in units of the prediction sub-block colSb. This repetition is performed while changing the index ySbIdx in the height direction from 0 to numSbY and the index xSbIdx in the width direction from 0 to numSbX.

If the upper left position of the coding block colCb is (xCb,yCb), the upper left position (xSb,ySb) of the prediction sub-block colSb is calculated as follows.
xSb = xCb + xSbIdx * sbWidth
ySb = yCb + ySbIdx * sbHeight
Next, the position obtained by adding the temporal motion vector tempMv to the prediction sub-block colSb is set as a new colSb (S4154). If the upper left position of the prediction sub-block colSb is (xColSb, yColSb) and the temporal motion vector tempMv is 1/16 pixel accuracy (tempMv[0], tempMv[1]), the upper left position of the new colSb is become that way.
xColSb = Clip3( xCtb, xCtb + CtbSizeY + 3, xSb + (tempMv[0] >> 4 ))
yColSb = Clip3( yCtb, yCtb + CtbSizeY-1, ySb + (tempMv[1] >> 4 ))
Here, the upper left position of the tree block is (xCtb, yCtb), and the size of the tree block is CtbSizeY. As shown in the above equation, the position after the addition of tempMv is corrected within the range of the size of the tree block so as not to be significantly displaced compared to the position before the addition of tempMv. If this position is outside the screen, it is corrected within the screen.

Then, the inter prediction information is derived for each reference list (S4156, S4158). Here, for the prediction sub-block colSb, a motion vector mvLXSbCol for each reference list and a flag availableFlagLXSbCol indicating whether the prediction sub-block is valid are derived in sub-block units. LX indicates a reference list, and LX becomes L0 when deriving the reference list 0, and LX becomes L1 when deriving the reference list 1. The derivation of the inter prediction information is the same as in S4022 and S4023 of FIG.

After deriving the inter prediction information (S4156, S4158), it is determined whether the prediction sub-block colSb is valid (S4160). If availableFlagL0SbCol=0 and availableFlagL1SbCol=0, it is determined that colSb is invalid, and otherwise it is valid. If colSb is invalid (S4160: No), the motion vector mvLXSbCol is set as the central motion vector ctrMvLX (S4162). Furthermore, a flag predFlagLXSbCol indicating whether or not LX prediction is used is set as a flag ctrPredFlagLX in the central motion vector (S4162). With the above, the derivation of the sub-block motion information is completed.

Again referring to FIG. Then, the motion vector mvL0SbCol of L0 and the motion vector mvL1SbCol of L1 are added as candidates to the subblock merge candidate list subblockMergeCandList in the above-mentioned subblock merge mode deriving unit 304 (S4028). However, this addition is performed only when the flag availableSbCol=1 indicating the existence of the sub-block time merge candidate. With the above, the process of the time merge candidate derivation unit 342 is completed.

The above description of the sub-block time merge candidate derivation unit 381 is for encoding, but the same applies for decoding. That is, the operation of the sub-block time merge candidate derivation unit 481 in the sub-block merge mode derivation unit 404 of FIG. 22 is similarly described by replacing the coding in the above description with decoding.

<Motion compensation prediction processing>
The motion compensation prediction unit 306 acquires the position and size of the block that is currently the target of prediction processing in encoding. In addition, the motion compensation prediction unit 306 acquires the inter prediction information from the inter prediction mode determination unit 305. An image at a position obtained by deriving a reference index and a motion vector from the acquired inter prediction information, and moving the reference picture specified by the reference index in the decoded image memory from the same position as the image signal of the prediction block by the amount of the motion vector. The predicted signal is generated after the signal is acquired.

When the reference mode in inter prediction is prediction from a single reference picture such as L0 prediction or L1 prediction, the prediction signal acquired from one reference picture is used as the motion compensation prediction signal, and the reference mode is BI prediction. When the prediction mode is prediction from two reference pictures, the weighted average of the prediction signals obtained from the two reference pictures is used as the motion compensation prediction signal, and the motion compensation prediction signal is used by the prediction method determination unit. Supply. Here, the ratio of the weighted average of bi-prediction is set to 1:1, but the weighted average may be performed using another ratio. For example, the closer the picture interval between the picture to be predicted and the reference picture is, the larger the weighting ratio may be. Further, the weighting ratio may be calculated using a correspondence table between the combination of picture intervals and the weighting ratio.

The motion compensation prediction unit 406 has the same function as the motion compensation prediction unit 306 on the encoding side. The motion compensation prediction unit 406 outputs the inter prediction information to the switch 408 from the normal motion vector predictor mode derivation unit 401, the normal merge mode derivation unit 402, the sub block motion vector predictor mode derivation unit 403, and the sub block merge mode derivation unit 404. To get through.

The motion compensation prediction unit 406 supplies the obtained motion compensation prediction signal to the decoded image signal superimposing unit 207.

<Forecast direction>
57 to 61 are diagrams for explaining the prediction direction of motion compensation prediction. The process of performing prediction from a single reference picture is defined as uni-prediction, and in the case of uni-prediction, prediction using either one of the two reference pictures registered in the reference list, which is L0 prediction or L1 prediction, is performed. ..

FIG. 57 shows a case in which the L0 reference picture (RefL0Pic) is in uni-prediction and is at a time before the encoding target picture (CurPic). FIG. 58 shows the case where the reference picture of uni-prediction and L0 prediction is at a time later than the picture to be coded. Similarly, the L0 prediction reference picture in FIGS. 57 and 58 may be replaced with the L1 prediction reference picture (RefL1Pic) to perform simple prediction.

The process of performing prediction from two reference pictures is defined as bi-prediction, and in the case of bi-prediction, it is expressed as BI prediction using both L0 prediction and L1 prediction. FIG. 59 shows a case where the reference picture for bi-prediction and L0 prediction is at a time before the current picture to be coded, and the reference picture for L1 prediction is at a later time than the current picture. FIG. 60 shows a case where bi-prediction reference pictures for L0 prediction and reference pictures for L1 prediction are at a time before the picture to be coded. FIG. 61 shows a case in which bi-prediction reference pictures for L0 prediction and reference pictures for L1 prediction are at times after the picture to be coded. As described above, the relationship between the prediction type of L0/L1 and the time can be used without being limited to L0 being the past direction and L1 being the future direction. In the case of bi-prediction, L0 prediction and L1 prediction may be performed using the same reference picture. Note that the determination as to whether the motion-compensated prediction is performed in uni-prediction or bi-prediction is made based on information (for example, a flag) indicating whether or not L0 prediction is used and whether or not L1 prediction is used. It

<About reference index>
In the embodiment of the present invention, in order to improve the accuracy of motion compensation prediction, it is possible to select the optimum reference picture from a plurality of reference pictures in motion compensation prediction. Therefore, the reference picture used in the motion compensation prediction is used as a reference index, and the reference index is encoded in the encoded stream together with the encoded vector.

<Motion Compensation Processing Based on Normal Prediction Motion Vector Mode>
When the inter prediction mode determination unit 305 selects the inter prediction information by the normal motion vector predictor mode derivation unit 301, as shown in the inter prediction unit 102 on the coding side of FIG. The inter prediction information is acquired from the inter prediction mode determination unit 305, the reference mode, the reference index, and the motion vector of the currently processed block are derived, and the motion compensation prediction signal is generated. The generated motion compensation prediction signal is supplied to the prediction method determination unit 105.

Similarly, as shown in the inter prediction unit 203 on the decoding side in FIG. 22, the motion compensation unit 406 also performs normal prediction when the switch 408 is connected to the normal motion vector predictor mode derivation unit 401 during the decoding process. The motion vector mode derivation unit 401 acquires inter prediction information, derives the reference mode, reference index, and motion vector of the block currently being processed, and generates a motion compensation prediction signal. The generated motion compensation prediction signal is supplied to the decoded image signal superimposing unit 207.

<Motion compensation processing based on normal merge mode>
In the motion compensation unit 306, when the inter prediction mode determination unit 305 selects the inter prediction information by the normal merge mode derivation unit 302, as shown in the inter prediction unit 102 on the coding side in FIG. The inter prediction information is acquired from the inter prediction mode determination unit 305, the reference mode, the reference index, and the motion vector of the currently processed block are derived, and the motion compensation prediction signal is generated. The generated motion compensation prediction signal is supplied to the prediction method determination unit 105.

Similarly, the motion compensation unit 406, as shown in the inter prediction unit 203 on the decoding side in FIG. 22, when the switch 408 is connected to the normal merge mode derivation unit 402 during the decoding process, the normal merge mode derivation is performed. The inter prediction information by the unit 402 is acquired, the reference mode, the reference index, and the motion vector of the block currently being processed are derived, and the motion compensation prediction signal is generated. The generated motion compensation prediction signal is supplied to the decoded image signal superimposing unit 207.

<Motion Compensation Processing Based on Sub-block Prediction Motion Vector Mode>
When the inter prediction mode determination unit 305 selects the inter prediction information by the sub-block motion vector predictor mode derivation unit 303, as shown in the inter prediction unit 102 on the encoding side in FIG. Acquires this inter prediction information from the inter prediction mode determination unit 305, derives the reference mode, reference index, and motion vector of the block currently being processed, and generates a motion compensation prediction signal. The generated motion compensation prediction signal is supplied to the prediction method determination unit 105.

Similarly, when the switch 408 is connected to the sub-block motion vector predictor mode deriving unit 403 in the decoding process, as shown in the inter prediction unit 203 on the decoding side in FIG. The block prediction motion vector mode deriving unit 403 acquires inter prediction information, derives the reference mode, reference index, and motion vector of the block currently being processed, and generates a motion compensation prediction signal. The generated motion compensation prediction signal is supplied to the decoded image signal superimposing unit 207.

<Motion compensation processing based on sub-block merge mode>
When the inter prediction mode determination unit 305 selects the inter prediction information by the sub block merge mode derivation unit 304, as shown in the inter prediction unit 102 on the encoding side in FIG. This inter prediction information is obtained from the inter prediction mode determination unit 305, the reference mode, reference index, and motion vector of the block currently being processed are derived, and a motion compensation prediction signal is generated. The generated motion compensation prediction signal is supplied to the prediction method determination unit 105.

Similarly, when the switch 408 is connected to the sub-block merge mode derivation unit 404 in the decoding process, the motion compensation unit 406, as shown in the inter prediction unit 203 on the decoding side in FIG. The mode derivation unit 404 acquires the inter prediction information, derives the reference mode, reference index, and motion vector of the block currently being processed, and generates a motion compensation prediction signal. The generated motion compensation prediction signal is supplied to the decoded image signal superimposing unit 207.

<Motion compensation processing based on affine transformation prediction>
In the normal motion vector predictor mode and the normal merge mode, motion compensation by the affine model can be used based on the following flags. The following flags are reflected in the following flags based on the inter prediction condition determined by the inter prediction mode determination unit 305 in the encoding process, and are encoded in the encoded stream. In the decoding process, whether or not motion compensation by the affine model is performed is specified based on the following flags in the encoded stream.

sps_affine_enabled_flag indicates whether or not motion compensation using an affine model can be used in inter prediction. If sps_affine_enabled_flag is 0, the motion compensation by the affine model is suppressed in sequence units. Also, inter_affine_flag and cu_affine_type_flag are not transmitted in the CU syntax of the coded video sequence. If sps_affine_enabled_flag is 1, motion compensation by an affine model can be used in the coded video sequence.

sps_affine_type_flag indicates whether or not motion compensation using a 6-parameter affine model can be used in inter prediction.

If sps_affine_type_flag is 0, the motion compensation is not performed by the 6-parameter affine model. Also, cu_affine_type_flag is not transmitted in the CU syntax of the coded video sequence. If sps_affine_type_flag is 1, motion compensation by a 6-parameter affine model can be used in a coded video sequence.

If sps_affine_type_flag does not exist, it shall be 0.

When P or B slices are decoded, if inter_affine_flag is 1 in the CU currently being processed, the affine model is used to generate the motion compensation prediction signal of the CU currently being processed. Motion compensation is used.

If inter_affine_flag is 0, the affine model is not used for the CU currently being processed.

If inter_affine_flag does not exist, it shall be 0.

When decoding P or B slices, if cu_affine_type_flag is 1 in the CU currently being processed, a 6-parameter affine is used to generate the motion compensation prediction signal of the CU currently being processed. Model-based motion compensation is used.

If cu_affine_type_flag is 0, motion compensation by a 4-parameter affine model is used to generate a motion compensation prediction signal of the CU currently being processed.

In the motion compensation using the affine model, since the reference index and the motion vector are derived in the sub-block unit, the motion-compensated prediction signal is generated using the reference index and the motion vector that are the processing target in the sub-block unit.

According to the first embodiment described above, in the history motion vector predictor candidate derivation process, the process is branched in the case of the normal motion vector mode and the case of the normal merge mode, and in the case of the normal merge mode mode. By not performing the update process of the history motion vector predictor candidate list HmvpCandList, the processing amount required for the update process can be reduced. Further, in the case of the normal merge mode mode, by not performing the update process of the history motion vector predictor candidate list HmvpCandList, it is possible to suppress the addition of the same or highly correlated candidates to the motion vector predictor motion vector candidate list HmvpCandList, and the motion vector predictor motion vector In the candidate derivation process, since it is not necessary to perform the same candidate determination process, the processing amount can be further suppressed.

All of the above-described embodiments may be combined with each other.

In all the embodiments described above, the encoded bit stream output by the image encoding device has a specific data format so that it can be decoded according to the encoding method used in the embodiments. doing. Also, an image decoding device corresponding to this image encoding device can decode the encoded bit stream of this specific data format.

When a wired or wireless network is used to exchange the encoded bitstream between the image encoding device and the image decoding device, the encoded bitstream is converted into a data format suitable for the transmission mode of the communication path. You may transmit. In that case, a transmission device that converts the encoded bit stream output by the image encoding device into encoded data in a data format suitable for the transmission mode of the communication path and transmits the encoded data to the network, and receives the encoded data from the network. A receiving device is provided that restores the encoded bitstream and supplies the encoded bitstream to the image decoding device.

The transmission device includes a memory for buffering the encoded bitstream output from the image encoding device, a packet processing unit for packetizing the encoded bitstream, and a transmission unit for transmitting packetized encoded data via a network. Including and A receiving device receives a packetized encoded data via a network, a memory for buffering the received encoded data, a packet processing of the encoded data to generate an encoded bitstream, And a packet processing unit provided to the image decoding apparatus.

Further, a display unit that displays an image decoded by the image decoding device may be added to the configuration to provide a display device. In that case, the display unit reads the decoded image signal generated by the decoded image signal superimposing unit 205 and stored in the decoded image memory 206, and displays it on the screen.

Further, an image pickup unit may be added to the configuration, and the picked-up image may be input to the image coding apparatus to form the image pickup apparatus. In that case, the imaging unit inputs the captured image signal to the block division unit 101.

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

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

100 image coding apparatus, 101 block division unit, 102 inter prediction unit, 103 intra prediction unit, 104 decoded image memory, 105 prediction method determination unit, 106 residual signal generation unit, 107 orthogonal transform/quantization unit, 108 bit string code Coding unit, 109 inverse quantization/inverse orthogonal transformation unit, 110 decoded image signal superimposing unit, 111 encoded information storage memory, 200 image decoding device, 201 bit string decoding unit, 202 block division unit, 203 inter prediction unit 204 intra prediction unit 205 Decoding image storage memory 205 Dequantization/inverse orthogonal transformation unit 207 Decoded image signal superposition unit 208 Decoded image memory

Claims (1)

A motion information history memory that stores a history of a plurality of motion information,
A motion vector predictor candidate derivation unit that derives a motion vector predictor candidate including a history motion vector predictor candidate from a memory that holds motion information of encoded blocks,
A merge candidate derivation unit that derives a merge candidate including a history merge candidate from a memory that holds motion information of encoded blocks,
Equipped with
Motion information is stored in the motion information history memory when the predicted motion vector candidate is derived, and motion information is not stored in the motion information history memory when the merge mode candidate is derived. Image coding device.

Images