JP2020088577A - Predictive image generation device, moving image decoding device, and moving image encoding device - Google Patents

Abstract

To reduce an interpolation process to generate an interpolated image.SOLUTION: An inter-prediction image generation unit (309) includes an OBMC interpolated image generation unit (30912) that generates a prediction image by using OBMC processing, and generates an interpolated image used for generation of a prediction image by motion compensation using a motion vector, the OBMC interpolation image generation unit (30912) performs motion compensation by converting a motion vector with decimal pixel precision into a motion vector with integer pixel precision for a region overlapping with an adjacent block.SELECTED DRAWING: Figure 9

Description

Embodiments of the present invention relate to a predictive image generation device, a moving image decoding device, and a moving image encoding device.

In order to efficiently transmit or record a moving image, a moving image encoding device that generates encoded data by encoding the moving image, and a moving image that generates a decoded image by decoding the encoded data. An image decoding device is used.

As a specific moving image coding method, for example, a method proposed by H.264/AVC or HEVC (High-Efficiency Video Coding) can be cited.

In such a moving image coding method, an image (picture) that constitutes a moving image is a slice obtained by dividing the image, and a coding tree unit (CTU: Coding Tree Unit) obtained by dividing the slice. ), a coding unit obtained by dividing the coding tree unit (sometimes called a coding unit (CU)), and a transform unit (TU: obtained by dividing the coding unit). CU is encoded/decoded for each CU.

In addition, in such a moving image coding method, a predicted image is usually generated based on a locally decoded image obtained by coding/decoding an input image, and the predicted image is generated from the input image (original image). The prediction error obtained by the subtraction (also referred to as “difference image” or “residual image”) is encoded. As a method of generating a predicted image, inter-screen prediction (inter prediction) and intra-screen prediction (intra prediction) can be mentioned. Non-Patent Document 1 is mentioned as a technique of recent video encoding and decoding.

In addition, in recent video encoding and decoding techniques, in a motion compensation process for generating a predicted image, an interpolated image generated using an inter prediction parameter added to the target PU and a neighboring PU of the target PU. A process (OBMC process) for generating an interpolated image of a target PU is performed by using an interpolated image generated by using the motion parameter of (non-patent document 2).

"Algorithm Description of Joint Exploration Test Model 7", JVET-G1001, Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO/IEC JTC 1/SC 29/WG 11, 2018-10-19 "A simplified design of overlapped block motion compensation based on the combination of CE10.2.1 and CE10.2.2", JVET-L0255, Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO/IEC JTC 1/SC 29/WG 11, 2018-10-03 "CE10-related: OBMC bandwidth reduction and line buffer reduction", JVET-K0259, Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO/IEC JTC 1/SC 29/WG 11, 2018-07- Ten

The OBMC process has a problem that a memory band for accessing image data becomes large. Further, not only the interpolated image generated using the inter prediction parameter added to the target PU but also the interpolated image generated using the motion parameter of the adjacent PU is used, so that the motion image of the adjacent PU is generated. However, there is a problem in that interpolation processing is required to generate an interpolated image.

In order to solve the above problems, a prediction image generation device according to an aspect of the present invention is a prediction image generation device that generates a prediction image using OBMC (Overlapped block motion compensation) processing, and the prediction image generation device An interpolating image used for the above is provided with a motion compensating unit that generates by motion compensation using a motion vector, and the motion compensating unit converts a motion vector of decimal pixel precision into a motion vector of integer pixel precision in a region overlapping with an adjacent block. Then, the motion compensation is performed.

In order to solve the above problems, a prediction image generation device according to an aspect of the present invention is a prediction image generation device that generates a prediction image using OBMC (Overlapped block motion compensation) processing, and for the target block, AMVP ( In the Advanced Motion Vector Prediction mode, when the motion vector is derived with decimal pixel accuracy, the OBMC process is not executed for the target block.

In order to solve the above problems, a prediction image generation apparatus according to an aspect of the present invention generates a prediction image using an OBMC (Overlapped block motion compensation) process and a BIO (Bi-directional potical flow) process. A device, comprising a motion compensating unit that generates an interpolated image used for generating the predicted image by motion compensation using a motion vector, and the motion compensating unit performs the BIO processing on a region overlapping with an adjacent block. It is characterized by not doing.

According to one aspect of the present invention, it is possible to suppress a decrease in encoding efficiency.

It is a schematic diagram showing the composition of the image transmission system concerning this embodiment. It is the figure which showed the structure of the transmission apparatus which mounts the moving image encoding apparatus which concerns on this embodiment, and the receiving apparatus which mounts the moving image decoding apparatus. (a) shows a transmitter equipped with a moving picture coding device, and (b) shows a receiver equipped with a moving picture decoding device. It is the figure which showed the structure of the recording device which mounts the moving image encoding apparatus which concerns on this embodiment, and the reproducing|regenerating apparatus which mounts a moving image decoding apparatus. (a) shows a recording device equipped with a moving image encoding device, and (b) shows a reproducing device equipped with a moving image decoding device. It is a figure which shows the hierarchical structure of the data of an encoding stream. It is a figure which shows the example of division of CTU. It is a conceptual diagram which shows an example of a reference picture and a reference picture list. It is a schematic diagram showing the composition of a moving picture decoding device. It is a schematic diagram showing the composition of the inter prediction parameter decoding part. It is a schematic diagram showing the composition of the inter prediction picture generation part. It is a block diagram showing the composition of a moving picture coding device. It is a schematic diagram showing the composition of the inter prediction parameter coding part. It is a figure which shows an example of the area|region which performs prediction image generation using the motion parameter of the adjacent PU which concerns on this embodiment. It is a block diagram which shows the principal part structure of the motion compensation part which performs the OBMC process which concerns on this embodiment. 6 is a flowchart showing an example of a processing flow of a motion compensation unit related to OBMC processing according to the present embodiment. It is a figure which shows an example of the pseudo code showing the OBMC process which concerns on this embodiment. (A)-(c) is a figure for demonstrating the reason why additional bandwidth is required in OBMC processing. (A), (b) is a figure for demonstrating the example 1 of a process, and is a figure which shows the example which rounds the motion vector of decimal pixel precision to integer pixel precision. FIG. 11 is a diagram for explaining processing steps of the flowchart in processing example 2; It is a flow chart which shows a flow of processing when carrying out OBMC processing and BIO processing.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing the configuration of an image transmission system 1 according to this embodiment.

The image transmission system 1 is a system that transmits an encoded stream obtained by encoding an encoding target image, decodes the transmitted encoded stream, and displays an image. The image transmission system 1 is configured to include a moving image encoding device (image encoding device) 11, a network 21, a moving image decoding device (image decoding device) 31, and a moving image display device (image display device) 41. ..

The image T is input to the moving image encoding device 11.

The network 21 transmits the encoded stream Te generated by the moving image encoding device 11 to the moving image decoding device 31. The network 21 is the Internet, a wide area network (WAN: Wide Area Network), a small network (LAN: Local Area Network), or a combination thereof. The network 21 is not necessarily a bidirectional communication network, but may be a unidirectional communication network that transmits broadcast waves such as terrestrial digital broadcasting and satellite broadcasting. Further, the network 21 may be replaced with a storage medium such as a DVD (Digital Versatile Disc: registered trademark) or a BD (Blue-ray Disc: registered trademark) that records the encoded stream Te.

The moving image decoding device 31 decodes each of the encoded streams Te transmitted by the network 21 and generates one or a plurality of decoded images Td.

The moving image display device 41 displays all or part of one or a plurality of decoded images Td generated by the moving image decoding device 31. The moving image display device 41 includes a display device such as a liquid crystal display or an organic EL (Electro-luminescence) display. The form of the display includes stationary, mobile, HMD and the like. Further, when the video decoding device 31 has high processing capability, it displays an image with high image quality, and when it has only lower processing capability, it displays an image that does not require high processing capability or display capability. ..

<Operator>
The operators used in this specification are described below.

>> is right bit shift, << is left bit shift, & is bitwise AND, | is bitwise OR, |= is an OR assignment operator, and || is a logical sum.

x?y:z is a ternary operator that takes y when x is true (other than 0) and z when x is false (0).

Clip3(a,b,c) is a function that clips c to a value greater than or equal to a and less than or equal to b. Returns a if c<a, returns b if c>b, and otherwise. Is a function that returns c (however, a<=b).

abs(a) is a function that returns the absolute value of a.

Int(a) is a function that returns the integer value of a.

floor(a) is a function that returns the largest integer less than or equal to a.

ceil(a) is a function that returns the smallest integer greater than or equal to a.

a/d represents division of a by d (rounding down after the decimal point).

<Structure of encoded stream Te>
Prior to a detailed description of the moving picture coding apparatus 11 and the moving picture decoding apparatus 31 according to the present embodiment, the data of the coded stream Te generated by the moving picture coding apparatus 11 and decoded by the moving picture decoding apparatus 31. The structure will be described.

FIG. 4 is a diagram showing a hierarchical structure of data in the encoded stream Te. The coded stream Te illustratively includes a sequence and a plurality of pictures forming the sequence. 4A to 4F respectively show an encoded video sequence defining the sequence SEQ, an encoded picture defining the picture PICT, an encoding slice defining the slice S, and an encoding slice defining the slice data. It is a figure which shows the data, the coding tree unit contained in coding slice data, and the coding unit contained in a coding tree unit.

(Encoded video sequence)
In the encoded video sequence, a set of data referred to by the moving picture decoding apparatus 31 in order to decode the sequence SEQ to be processed is defined. As shown in FIG. 4(a), the sequence SEQ includes a video parameter set (Video Parameter Set), a sequence parameter set SPS (Sequence Parameter Set), a picture parameter set PPS (Picture Parameter Set), a picture PICT, and additional extension. Information SEI (Supplemental Enhancement Information) is included.

The video parameter set VPS is a set of coding parameters common to a plurality of moving pictures in a moving picture composed of a plurality of layers and a plurality of layers included in the moving picture and coding parameters related to individual layers. Sets are defined.

The sequence parameter set SPS defines a set of coding parameters that the moving image decoding apparatus 31 refers to in order to decode the target sequence. For example, the width and height of the picture are specified. There may be a plurality of SPSs. In that case, one of the plurality of SPSs is selected from the PPS.

The picture parameter set PPS defines a set of coding parameters that the moving picture decoding apparatus 31 refers to in order to decode each picture in the target sequence. For example, a quantization width reference value (pic_init_qp_minus26) used for decoding a picture and a flag (weighted_pred_flag) indicating application of weighted prediction are included. There may be a plurality of PPSs. In that case, one of the plurality of PPSs is selected from each picture in the target sequence.

(Encoded picture)
The coded picture defines a set of data that the moving picture decoding apparatus 31 refers to in order to decode the picture PICT to be processed. As shown in FIG. 4B, the picture PICT includes slice 0 to slice NS-1 (NS is the total number of slices included in the picture PICT).

In addition, hereinafter, when it is not necessary to distinguish each of the slice 0 to the slice NS-1, the suffix of the code may be omitted. The same applies to other data that is included in the coded stream Te described below and that has a subscript.

(Encoding slice)
In the encoded slice, a set of data referred to by the video decoding device 31 in order to decode the slice S to be processed is defined. The slice contains a slice header and slice data, as shown in FIG. 4(c).

The slice header includes a coding parameter group referred to by the video decoding device 31 in order to determine the decoding method of the target slice. The slice type designation information (slice_type) that designates the slice type is an example of an encoding parameter included in the slice header.

The slice types that can be designated by the slice type designation information include (1) an I slice that uses only intra prediction during encoding, (2) a unidirectional prediction that uses encoding during prediction, or a P slice that uses intra prediction. (3) B slices using unidirectional prediction, bidirectional prediction, or intra prediction at the time of encoding are included. Note that inter prediction is not limited to uni-prediction and bi-prediction, and a larger number of reference pictures may be used to generate a prediction image. Hereinafter, when the slices are referred to as P and B slices, they refer to slices including blocks that can use inter prediction.

The slice header may include a reference (pic_parameter_set_id) to the picture parameter set PPS.

(Encoded slice data)
The encoded slice data defines a set of data that the moving image decoding apparatus 31 refers to in order to decode the slice data to be processed. The slice data includes a CTU as shown in FIG. 4(d). The CTU is a fixed-size (eg, 64x64) block that constitutes a slice, and is sometimes referred to as the maximum coding unit (LCU).

(Encoding tree unit)
In FIG. 4(e), a set of data referred to by the video decoding device 31 in order to decode the CTU to be processed is defined. CTU is the basic coding process by recursive quadtree partition (QT (Quad Tree) partition), binary tree partition (BT (Binary Tree) partition) or ternary tree partition (TT (Ternary Tree) partition). It is divided into coding units CU, which are the basic units. The BT partition and the TT partition are collectively called a multi-tree partition (MT (Multi Tree) partition). A tree-structured node obtained by recursive quadtree partitioning is called a coding node. Intermediate nodes of the quadtree, the binary tree, and the ternary tree are coding nodes, and the CTU itself is also defined as the uppermost coding node.

CT, as CT information, QT split flag (cu_split_flag) indicating whether to perform QT split, MT split flag (split_mt_flag) indicating the presence or absence of MT split, MT split direction (split_mt_dir) indicating the split direction of MT split, The MT split type (split_mt_type) indicating the split type of MT split is included. cu_split_flag, split_mt_flag, split_mt_dir, split_mt_type are transmitted for each coding node.

When cu_split_flag is 1, the coding node is divided into four coding nodes (Fig. 5(b)).

When cu_split_flag is 0 and the split_mt_flag is 0, the coding node is not split and has one CU as a node (FIG. 5(a)). The CU is the end node of the coding node and is not further divided. The CU is a basic unit of encoding processing.

When split_mt_flag is 1, the coding node is MT-split as follows. When split_mt_type is 0 and split_mt_dir is 1, the coding node is horizontally split into two coding nodes (Fig. 5(d)), and when split_mt_dir is 0, the coding node is perpendicular to the two coding nodes. It is divided (Fig. 5(c)). In addition, when split_mt_type is 1, when split_mt_dir is 1, the coding node is horizontally divided into three coding nodes (Fig. 5(f)), and when split_mt_dir is 0, the coding node is three coding nodes. Is vertically divided into two parts (Fig. 5(e)). These are shown in FIG. 5(g).

When the CTU size is 64x64 pixels, the CU size is 64x64 pixels, 64x32 pixels, 32x64 pixels, 32x32 pixels, 64x16 pixels, 16x64 pixels, 32x16 pixels, 16x32 pixels, 16x16 pixels, 64x8 pixels, 8x64 pixels. , 32x8 pixels, 8x32 pixels, 16x8 pixels, 8x16 pixels, 8x8 pixels, 64x4 pixels, 4x64 pixels, 32x4 pixels, 4x32 pixels, 16x4 pixels, 4x16 pixels, 8x4 pixels, 4x8 pixels, and 4x4 pixels ..

(Encoding unit)
As shown in FIG. 4(f), a set of data referred to by the video decoding device 31 for decoding the encoding unit to be processed is defined. Specifically, the CU includes a CU header CUH, a prediction parameter, a conversion parameter, a quantized conversion coefficient, and the like. The prediction mode etc. are specified in the CU header.

The prediction process may be performed in CU units or may be performed in sub CU units obtained by further dividing the CU. When the CU and the sub CU have the same size, there is one sub CU in the CU. If the CU is larger than the size of the sub CU, the CU is divided into sub CUs. For example, if the CU is 8x8 and the sub-CU is 4x4, the CU is divided into four sub-CUs, which are divided into two horizontally and vertically.

There are two types of prediction (prediction mode): intra prediction and inter prediction. Intra prediction refers to prediction within the same picture, and inter prediction refers to prediction processing performed between different pictures (for example, between display times).

The transform/quantization process is performed in CU units, but the quantized transform coefficients may be entropy coded in subblock units such as 4x4.

(Prediction parameter)
The predicted image is derived from the prediction parameters associated with the block. The prediction parameters include intra prediction and inter prediction parameters.

The prediction parameters of inter prediction will be described below. The inter prediction parameter is composed of prediction list use flags predFlagL0 and predFlagL1, reference picture indexes refIdxL0 and refIdxL1, and motion vectors mvL0 and mvL1. The prediction list use flags predFlagL0 and predFlagL1 are flags indicating whether or not reference picture lists called L0 list and L1 list are used, and the reference picture list corresponding to a value of 1 is used. In addition, in the present specification, when it is referred to as “a flag indicating whether it is XX”, a flag other than 0 (for example, 1) is XX, 0 is not XX, and logical negation, logical product, etc. Treat 1 as true and 0 as false (same below). However, in an actual device or method, other values can be used as the true value and the false value.

Syntax elements for deriving inter prediction parameters include, for example, affine flag affine_flag, matching flag fruc_flag, merge flag merge_flag, merge index merge_idx, inter prediction identifier inter_pred_idc, reference picture index refIdxLX, prediction vector index mvp_LX_idx, difference vector mvdLX. , There is a motion vector accuracy mode amvr_mode.

(Reference picture list)
The reference picture list is a list of reference pictures stored in the reference picture memory 306. FIG. 6 is a conceptual diagram showing an example of a reference picture and a reference picture list. In FIG. 6(a), a rectangle is a picture, an arrow is a picture reference relationship, a horizontal axis is time, I, P, and B in the rectangle are intra pictures, uni-predictive pictures, bi-predictive pictures, and numbers in the rectangle are decoded Show the order. As shown in the figure, the decoding order of pictures is I0, P1, B2, B3, B4, and the display order is I0, B3, B2, B4, P1. FIG. 6B shows an example of the reference picture list of the picture B3 (target picture). The reference picture list is a list showing candidates for reference pictures, and one picture (slice) may have one or more reference picture lists. In the illustrated example, the target picture B3 has two reference picture lists, an L0 list RefPicList0 and an L1 list RefPicList1. In each CU, the reference picture index refIdxLX specifies which picture in the reference picture list RefPicListX (X=0 or 1) is actually referred to. The figure shows an example of refIdxL0=2 and refIdxL1=0. It should be noted that LX is a description method used when the L0 prediction and the L1 prediction are not distinguished, and hereinafter, the parameters for the L0 list and the parameters for the L1 list are distinguished by replacing LX with L0 and L1.

(Motion vector)
The motion vector mvLX indicates the shift amount between blocks on two different pictures. The prediction vector and the difference vector regarding the motion vector mvLX are called the prediction vector mvpLX and the difference vector mvdLX, respectively.

(Inter prediction identifier inter_pred_idc and prediction list usage flag predFlagLX)
The inter-prediction identifier inter_pred_idc is a value indicating the type and number of reference pictures, and takes any value of PRED_L0, PRED_L1, and PRED_BI. PRED_L0 and PRED_L1 indicate uni-prediction using one reference picture managed in the L0 list and the L1 list, respectively. PRED_BI indicates bi-prediction BiPred using two reference pictures managed by the L0 list and the L1 list.

The relationship between the inter prediction identifier inter_pred_idc and the prediction list use flags predFlagL0 and predFlagL1 is as follows, and they can be converted mutually.

inter_pred_idc = (predFlagL1<<1)+predFlagL0
predFlagL0 = inter_pred_idc & 1
predFlagL1 = inter_pred_idc >> 1
(Judgment of bi-predictive biPred)
The flag biPred indicating whether it is bi-prediction BiPred can be derived depending on whether the two prediction list use flags are both 1. For example, it can be derived by the following formula.

biPred = (predFlagL0==1 && predFlagL1==1)
Alternatively, the flag biPred can be derived depending on whether the inter prediction identifier is a value indicating that two prediction lists (reference pictures) are used. For example, it can be derived by the following formula.

biPred = (inter_pred_idc==PRED_BI) ?1: 0
(Structure of video decoding device)
The configuration of the moving picture decoding device 31 (FIG. 7) according to the present embodiment will be described.

The moving image decoding device 31 includes an entropy decoding unit 301, a parameter decoding unit (prediction image decoding device) 302, a loop filter 305, a reference picture memory 306, a prediction parameter memory 307, a prediction image generation unit (prediction image generation device) 308, and an inverse. The quantization/inverse conversion unit 311 and the addition unit 312 are included. It should be noted that there is a configuration in which the moving image decoding device 31 does not include the loop filter 305 in accordance with the moving image encoding device 11 described later.

The parameter decoding unit 302 further includes a header decoding unit 3020, a CT information decoding unit 3021, and a CU decoding unit 3022 (prediction mode decoding unit), and the CU decoding unit 3022 further includes a TU decoding unit 3024. These may be collectively referred to as a decoding module. The header decoding unit 3020 decodes the parameter set information such as VPS, SPS, PPS and the slice header (slice information) from the encoded data. The CT information decoding unit 3021 decodes the CT from the encoded data. The CU decoding unit 3022 decodes the CU from the encoded data. The TU decoding unit 3024 decodes the QP update information (quantization correction value) and the quantized prediction error (residual_coding) from the encoded data when the TU includes a prediction error.

Further, the parameter decoding unit 302 is configured to include an inter prediction parameter decoding unit 303 and an intra prediction parameter decoding unit 304 (not shown). The predicted image generation unit 308 includes an inter predicted image generation unit (predicted image generation device) 309 and an intra predicted image generation unit 310.

Further, although an example in which CTU and CU are used as a processing unit is described below, the processing is not limited to this example, and processing may be performed in sub CU units. Alternatively, the CTU and CU may be read as a block and the sub CU may be read as a sub block, and processing may be performed in block or sub block units.

The entropy decoding unit 301 performs entropy decoding on the coded stream Te input from the outside to separate and decode individual codes (syntax elements). The separated codes include prediction information for generating a prediction image and prediction error for generating a difference image. The entropy decoding unit 301 outputs the separated code to the parameter decoding unit 302.

(Configuration of inter prediction parameter decoding unit)
The inter prediction parameter decoding unit 303 decodes the inter prediction parameter based on the code input from the entropy decoding unit 301 with reference to the prediction parameter stored in the prediction parameter memory 307. Further, the inter prediction parameter decoding unit 303 outputs the decoded inter prediction parameter to the prediction image generation unit 308 and stores it in the prediction parameter memory 307.

FIG. 8 is a schematic diagram showing the configuration of the inter prediction parameter decoding unit 303 according to the present embodiment. The inter prediction parameter decoding unit 303 includes a merge prediction unit 30374, a DMVR unit 30375, a sub-block prediction unit (affine prediction unit) 30372, an MMVD prediction unit 30376, a Triangle prediction unit 30377, an AMVP prediction parameter derivation unit 3032, and an addition unit 3038. Composed of. The merge prediction unit 30374 includes a merge prediction parameter derivation unit 3036. Since the AMVP prediction parameter derivation unit 3032, the merge prediction parameter derivation unit 3036, and the affine prediction unit 30372 are means common to the moving image coding device and the moving image decoding device, they are collectively referred to as the motion vector derivation unit (motion vector May be referred to as a derivation device).

The inter prediction parameter decoding unit 303 instructs the entropy decoding unit 301 to decode syntax elements related to inter prediction, and syntax elements included in the encoded data, for example, affine flag affine_flag, matching flag fruc_flag, merge flag merge_flag. , Merge index merge_idx, inter prediction identifier inter_pred_idc, reference picture index refIdxLX, prediction vector index mvp_LX_idx, difference vector mvdLX, motion vector precision mode amvr_mode.

(Affine prediction unit)
The affine prediction unit 30372 derives the affine prediction parameter of the target block. In this embodiment, the motion vectors (mv0_x, mv0_y) (mv1_x, mv1_y) of the two control points (V0, V1) of the target block are derived as affine prediction parameters. Specifically, the motion vector of each control point may be derived by predicting from the motion vector of the block adjacent to the target block, or derived from the prediction vector derived as the motion vector of the control point and the encoded data. The motion vector of each control point may be derived from the sum of the difference vectors.

The affine prediction unit 30372 calculates a motion vector spMvLX[xi][yi] (xi=xPb+sbW*i, yj=yPb+sbH*j, i of each sub-block in the target block based on the affine prediction parameter of the target block. =0,1,2,...,bW/sbW-1, j=0,1,2,...,bH/sbH-1) is derived using the following formula.

spMvLX[xi][yi][0] = mv0_x+(mv1_x-mv0_x)/bW*(xi+sbW/2)-(mv1_y-mv0_y)/bH*(yi+sbH/2)
spMvLX[xi][yi][1] = mv0_y+(mv1_y-mv0_y)/bW*(xi+sbW/2)+(mv1_x-mv0_x)/bH*(yi+sbH/2)
(Merge prediction)
The merge candidate is configured to include the prediction list use flag predFlagLX, the motion vector mvLX, and the reference picture index refIdxLX, and is stored in the merge candidate list. An index is assigned to the merge candidates stored in the merge candidate list according to a predetermined rule.

The merge candidate derivation unit 30361 derives a merge candidate by using the motion vector of the decoded adjacent block and the reference picture index refIdxLX as they are.

(AMVP prediction)
The AMVP prediction parameter derivation unit 3032 derives a prediction vector candidate from the motion vector mvLX of the decoded adjacent block stored in the prediction parameter memory 307 based on the reference picture index refIdxLX, and stores it in the prediction vector candidate list mvpListLX[].

Then, among the prediction vector candidates of the prediction vector candidate list mvpListLX[], the motion vector mvpListLX[mvp_LX_idx] indicated by the prediction vector index mvp_LX_idx is selected as the prediction vector mvpLX, and mvpLX is output to the addition unit 3038.

The adjacent block includes a block spatially adjacent to the target block, for example, a left block, an upper block, and an area temporally adjacent to the target block, for example, a block including the same position as the target block and having different display times. It includes the region obtained from the prediction parameters.

The addition unit 3038 adds the prediction vector mvpLX input from the AMVP prediction parameter derivation unit 3032 and the decoded difference vector mvdLX to calculate the motion vector mvLX. The addition unit 3038 outputs the calculated motion vector mvLX to the prediction image generation unit 308 and the prediction parameter memory 307.

mvLX[0] = mvpLX[0]+mvdLX[0]
mvLX[1] = mvpLX[1]+mvdLX[1]
The motion vector accuracy mode amvr_mode is a syntax for switching the accuracy of the motion vector derived in the AMVP mode. For example, in amvr_mode=0, 1, 2, 1/4 pixel, 1 pixel, or 4 pixel accuracy is switched.

When the motion vector precision is 1/16 precision, it is derived from amvr_mode as follows to change the motion vector difference of 1/4, 1, 4 pixel precision to the motion vector difference of 1/16 pixel precision. Dequantization may be performed using MvShift (=1<<amvr_mode).

mvdLX[0] = mvdLX[0] << (MvShift + 2)
mvdLX[1] = mvdLX[1] << (MvShift + 2)
The parameter decoding unit 302 may further derive mvdLX[2] by decoding the following syntax.
・Abs_mvd_greater0_flag
・Abs_mvd_minus2
・Mvd_sign_flag
Decrypt. Then, the parameter decoding unit 302 decodes the difference vector 1Mvd[] from the syntax by using the following formula.

lMvd[ compIdx ]= abs_mvd_greater0_flag[ compIdx ]* (abs_mvd_minus2[ compIdx ]+ 2 )* (1-2 * mvd_sign_flag[ compIdx ])
Further, the decoded difference vector lMvd[] is set to MvdLX in the case of translation MVD (MotionModelIdc[ x ][ y ]== 0) and is set in the case of control point MVD (MotionModelIdc[ x ][ y ]!= 0) Set to MvdCpLX.

if (MotionModelIdc[ x ][ y ]== 0)
mvdLX[ x0 ][ y0 ][ compIdx ]= lMvd[ compIdx ]<<(MvShift + 2)
else
mvdCpLX[ x0 ][ y0 ][ compIdx ]= lMvd[ compIdx ]<<2
(DMVR)
Next, the DMVR (Decoder side Motion Vector Refinement) processing performed by the DMVR unit 30375 will be described. The DMVR unit 30375 applies the merge prediction mode, the skip mode, the MMVD prediction mode, and the Triangle prediction mode to the target CU, that is, the AMVP mode for transmitting the motion vector and the mode for dividing into sub-blocks (affine , ATMVP), the motion vector mvLX relating to the target CU is corrected using the reference-decoded image. Specifically, in the case of bi-prediction, the motion vector is corrected using the prediction image derived from the motion vector corresponding to the two reference pictures. The corrected motion vector mvLX is supplied to the inter prediction image generation unit 309.

(Triangle prediction)
Next, the Triangle prediction will be described. In the Triangle prediction, the target CU is divided into two triangular prediction units with the target CU as a boundary in the diagonal or opposite diagonal direction. The inter prediction image in each triangle prediction unit is derived by performing weighting mask processing on each pixel of the prediction image of the target CU (rectangular block including the triangle prediction unit) according to the position of the pixel. For example, a triangular image can be derived from a rectangular image by multiplying by a mask in which the pixels in the triangular area in the rectangular area are 1 and the areas other than the triangle are 0. It is generated using inter prediction parameters of unidirectional prediction. In addition, after the inter prediction image is generated, the adaptive weighting process is applied to both regions with diagonal corners, and the target CU (rectangular block) is subjected to the adaptive weighting process using the two prediction images. One predicted image of is derived. This processing is called Triangle composition processing. Then, the transformation (inverse transformation) and the quantization (inverse quantization) processing are applied to the entire target CU. The Triangle prediction is applied only in the merge prediction mode or the skip mode.

The Triangle prediction unit 30377 derives and decodes prediction parameters corresponding to the two triangular regions used for Triangle prediction, and supplies the prediction parameters to the inter prediction image generation unit 309. The Triangle prediction may be configured without bi-prediction for simplification of processing. In this case, inter prediction parameters for unidirectional prediction are derived in one triangular area. Note that the derivation of the two predicted images and the synthesis using the predicted images are performed by the motion compensation unit 3091 and the Triangle synthesis unit 30952.

The loop filter 305 is a filter provided in the coding loop and removes block distortion and ringing distortion and improves image quality. The loop filter 305 applies filters such as a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) to the CU decoded image generated by the addition unit 312.

The reference picture memory 306 stores the decoded image of the CU generated by the addition unit 312 at a predetermined position for each target picture and target CU.

The prediction parameter memory 307 stores the prediction parameter in a predetermined position for each CTU or CU to be decoded. Specifically, the prediction parameter memory 307 stores the parameters decoded by the parameter decoding unit 302, the prediction mode predMode separated by the entropy decoding unit 301, and the like.

A prediction mode predMode, a prediction parameter, and the like are input to the prediction image generation unit 308. Further, the predicted image generation unit 308 reads the reference picture from the reference picture memory 306. The predicted image generation unit 308 generates a predicted image of a block or sub-block using the prediction parameter and the read reference picture (reference picture block) in the prediction mode indicated by the prediction mode predMode. Here, the reference picture block is a set of pixels on the reference picture (usually called a block because it is a rectangle), and is an area referred to for generating a predicted image.

(Inter prediction image generation unit 309)
When the prediction mode predMode indicates the inter prediction mode, the inter prediction image generation unit 309 uses the inter prediction parameter input from the inter prediction parameter decoding unit 303 and the read reference picture to predict the image of the block or sub-block by inter prediction. To generate.

FIG. 9 is a schematic diagram showing the configuration of the inter-prediction image generation unit 309 included in the prediction image generation unit 308 according to this embodiment. The inter prediction image generation unit 309 includes a motion compensation unit (prediction image generation device) 3091 and a synthesis unit 3095.

(Motion compensation)
The motion compensation unit 3091 (interpolation image generation unit 3091) uses the reference picture memory based on the inter prediction parameters (prediction list use flag predFlagLX, reference picture index refIdxLX, motion vector mvLX) input from the inter prediction parameter decoding unit 303. From 306, an interpolation image (motion compensation image) is generated by reading a block at a position shifted by the motion vector mvLX from the position of the target block in the reference picture RefPicLX specified by the reference picture index refIdxLX. Here, when the precision of the motion vector mvLX is not an integer precision, a filter called a motion compensation filter for generating pixels at decimal positions is applied to generate a motion compensated image.

The motion compensation unit 3091 first derives the integer position (xInt, yInt) and the phase (xFrac, yFrac) corresponding to the coordinate (x, y) in the prediction block by the following formula.

xInt = xPb+(mvLX[0]>>(log2(MVPREC)))+x
xFrac = mvLX[0]&(MVPREC-1)
yInt = yPb+(mvLX[1]>>(log2(MVPREC)))+y
yFrac = mvLX[1]&(MVPREC-1)
Here, (xPb,yPb) is the upper left coordinates of the block of bW*bH size, x=0...bW-1, y=0...bH-1, and MVPREC is the accuracy of motion vector mvLX (1/MVPREC Pixel accuracy). For example MVPREC=16. MVBIT=log2(MVPREC).

The motion compensation unit 3091 derives a temporary image temp[][] by performing horizontal interpolation processing on the reference picture refImg using an interpolation filter. Σ below is the sum of k=0..N for k in NTAP-1, shift1 is a normalization parameter for adjusting the range of values, offset1=1<<(shift1-1).

temp[x][y] = (ΣmcFilter[xFrac][k]*refImg[xInt+k-NTAP/2+1][yInt]+offset1)>>shift1
Subsequently, the motion compensation unit 3091 derives an interpolated image Pred[][] by performing vertical interpolation processing on the temporary image temp[][]. Σ below is the sum of k=0..N for k in NTAP-1, shift2 is a normalization parameter for adjusting the range of values, and offset2=1<<(shift2-1).

Pred[x][y] = (ΣmcFilter[yFrac][k]*temp[x][y+k-NTAP/2+1]+offset2)>>shift2
The above interpolation image generation processing may be represented by Interpolation (refImg, xPb, yPb, bW, bH, mvLX).

(Synthesis section)
The combining unit 3095 refers to the interpolated image supplied from the motion compensation unit 3091, the inter prediction parameter supplied from the inter prediction parameter decoding unit 303, and the intra image supplied from the intra prediction image generation unit 310 to perform prediction. An image is generated, and the generated predicted image is supplied to the addition unit 312.

The combining unit 3095 includes a combined intra/inter combining unit 30951, a Triangle combining unit 30952, an OBMC unit 30953, and a BIO unit 30954.

(Combined intra/inter synthesis processing)
The Combined intra/inter combining unit 30951 generates a predicted image by using a unidirectional predicted image in AMVP, a predicted image in the skip mode or the merge predicted mode, and an intra predicted image in combination.

(Triangle composition processing)
The Triangle synthesis unit 30952 generates a prediction image using the above-mentioned Triangle prediction.

(OBMC processing)
The OBMC unit 30953 generates a predicted image using OBMC (Overlapped block motion compensation) processing. Details of the OBMC process will be described later.

(BIO processing)
The BIO unit 30954 generates a predicted image by performing BIO (Bi-directional optical flow; bi-prediction gradient change) processing. In the BIO processing, a prediction image is generated by referring to the motion compensation images PredL0 and PredL1 and the gradient correction term. The BIO unit 30954 may be configured to generate a predicted image by performing weight prediction described below.

(Weight prediction)
In the weight prediction, the motion compensation image PredLX is multiplied by a weight coefficient to generate a prediction image of a block. When one of the prediction list use flags (predFlagL0 or predFlagL1) is 1 (single prediction) and weight prediction is not used, the motion compensation image PredLX (LX is L0 or L1) is adjusted to the pixel bit number bitDepth. I do.

Pred[x][y] = Clip3(0,(1<<bitDepth)-1,(PredLX[x][y]+offset1)>>shift1)
Here, shift1=14-bitDepth and offset1=1<<(shift1-1).
Further, when both of the reference list use flags (predFlagL0 and predFlagL1) are 1 (bi-prediction BiPred) and weight prediction is not used, the motion compensation images PredL0 and PredL1 are averaged and the processing of the following formula is performed to match the pixel bit number. To do.

Pred[x][y] = Clip3(0,(1<<bitDepth)-1,(PredL0[x][y]+PredL1[x][y]+offset2)>>shift2)
Here, shift2=15-bitDepth and offset2=1<<(shift2-1).

Further, when performing uni-prediction and weight prediction, the weight prediction coefficient w0 and the offset o0 are derived from the encoded data, and the processing of the following formula is performed.

Pred[x][y] = Clip3(0,(1<<bitDepth)-1,((PredLX[x][y]*w0+2^(log2WD-1))>>log2WD)+o0)
Here, log2WD is a variable indicating a predetermined shift amount.

Furthermore, when bi-prediction BiPred and weight prediction are performed, weight prediction coefficients w0, w1, o0, and o1 are derived from the encoded data, and the processing of the following formula is performed.

Pred[x][y] = Clip3(0,(1<<bitDepth)-1,(PredL0[x][y]*w0+PredL1[x][y]*w1+((o0+o1+1)<<log2WD))>>(log2WD+1))
Then, the predicted image of the generated block is output to the addition unit 312.

The inverse quantization/inverse transform unit 311 dequantizes the quantized transform coefficient input from the entropy decoding unit 301 to obtain a transform coefficient. These quantized transform coefficients are DCT (Discrete Cosine Transform, Discrete Cosine Transform), DST (Discrete Sine Transform, Discrete Sine Transform), KLT (Karyhnen Loeve Transform, Karhunen-Loeve Transform) for the prediction error in the encoding process. Is a coefficient obtained by performing frequency conversion and quantizing. The inverse quantization/inverse transform unit 311 performs inverse frequency transform such as inverse DCT, inverse DST, and inverse KLT on the obtained transform coefficient to calculate a prediction error. The inverse quantization/inverse transformation unit 311 outputs the prediction error to the addition unit 312.

The addition unit 312 adds the prediction image of the block input from the prediction image generation unit 308 and the prediction error input from the dequantization/inverse conversion unit 311 for each pixel to generate a decoded image of the block. The addition unit 312 stores the decoded image of the block in the reference picture memory 306, and also outputs it to the loop filter 305.

(Structure of video encoding device)
Next, the configuration of the moving picture coding device 11 according to the present embodiment will be described. FIG. 10 is a block diagram showing the configuration of the moving picture coding device 11 according to the present embodiment. The moving image coding device 11 includes a predicted image generation unit 101, a subtraction unit 102, a conversion/quantization unit 103, an inverse quantization/inverse conversion unit 105, an addition unit 106, a loop filter 107, a prediction parameter memory (prediction parameter storage unit). , A frame memory) 108, a reference picture memory (reference image storage unit, frame memory) 109, a coding parameter determination unit 110, a parameter coding unit 111, and an entropy coding unit 104.

The predicted image generation unit 101 generates a predicted image for each CU that is an area obtained by dividing each picture of the image T. The predicted image generation unit 101 has the same operation as the predicted image generation unit 308 described above, and thus the description thereof will be omitted.

The subtraction unit 102 subtracts the pixel value of the predicted image of the block input from the predicted image generation unit 101 from the pixel value of the image T to generate a prediction error. The subtraction unit 102 outputs the prediction error to the conversion/quantization unit 103.

The transform/quantization unit 103 calculates a transform coefficient by frequency transform for the prediction error input from the subtraction unit 102, and derives a quantized transform coefficient by quantization. The transform/quantization unit 103 outputs the quantized transform coefficient to the entropy coding unit 104 and the inverse quantization/inverse transform unit 105.

The inverse quantizing/inverse transforming unit 105 is the same as the inverse quantizing/inverse transforming unit 311 (FIG. 7) in the moving picture decoding device 31, and the description thereof is omitted. The calculated prediction error is output to the addition unit 106.

The entropy coding unit 104 receives the quantized transform coefficient from the transform/quantization unit 103 and the coding parameter from the parameter coding unit 111. The encoding parameters include, for example, reference picture index refIdxLX, prediction vector index mvp_LX_idx, difference vector mvdLX, motion vector accuracy mode amvr_mode, prediction mode predMode, and merge index merge_idx.

The entropy coding unit 104 entropy-codes the division information, the prediction parameter, the quantized transform coefficient, and the like to generate and output a coded stream Te.

The parameter coding unit 111 includes a header coding unit 1110, a CT information coding unit 1111, a CU coding unit 1112 (prediction mode coding unit), an inter prediction parameter coding unit 112, and an intra prediction parameter coding unit (not shown). It has 113. The CU coding unit 1112 further includes a TU coding unit 1114.

(Structure of inter prediction parameter coding unit)
The inter prediction parameter coding unit 112 derives an inter prediction parameter based on the prediction parameter input from the coding parameter determination unit 110. The inter prediction parameter encoding unit 112 includes a part of the same structure as the structure in which the inter prediction parameter decoding unit 303 derives the inter prediction parameter.

The configuration of the inter prediction parameter encoding unit 112 will be described. As shown in FIG. 11, the parameter coding control unit 1121, the merge prediction unit 30374, the sub-block prediction unit (affine prediction unit) 30372, the DMVR unit 30375, the MMVD prediction unit 30376, the Triangle prediction unit 30377, and the AMVP prediction parameter derivation unit 3032. , And a subtracting unit 1123. The merge prediction unit 30374 includes a merge prediction parameter derivation unit 3036. The merge prediction parameter derivation unit 3036, AMVP prediction parameter derivation unit 3032, affine prediction unit 30372, MMVD prediction unit 30376, and Triangle prediction unit 30377 may be collectively referred to as a motion vector derivation unit (motion vector derivation device). The inter prediction parameter coding unit 112 outputs mvLX (subMvLX), refIdxLX, inter_pred_idc, or information indicating these to the predicted image generation unit 101. Further, the inter prediction parameter encoding unit 112 outputs merge_flag, skip_flag, merge_idx, inter_pred_idc, refIdxLX, mvp_lX_idx, mvdLX, amvr_mode, and affine_flag to the entropy encoding unit 104.

The merge prediction parameter derivation unit 3036 derives an inter prediction parameter based on merge_idx.

The AMVP prediction parameter derivation unit 3032 derives the prediction vector mvpLX based on the motion vector mvLX. The AMVP prediction parameter derivation unit 3032 outputs the prediction vector mvpLX to the subtraction unit 1123. Note that refIdxLX and mvp_lX_idx are output to the entropy coding unit 104.

The subtraction unit 1123 subtracts the prediction vector mvpLX output from the AMVP prediction parameter derivation unit 3032 from the motion vector mvLX input from the coding parameter determination unit 110 to generate a difference vector mvdLX. The difference vector mvdLX is output to the entropy coding unit 104.

The addition unit 106 adds the pixel value of the prediction image of the block input from the prediction image generation unit 101 and the prediction error input from the inverse quantization/inverse conversion unit 105 for each pixel to generate a decoded image. The addition unit 106 stores the generated decoded image in the reference picture memory 109.

The loop filter 107 applies a deblocking filter, SAO, and ALF to the decoded image generated by the addition unit 106. Note that the loop filter 107 does not necessarily have to include the above three types of filters, and may have a configuration of only a deblocking filter, for example.

The prediction parameter memory 108 stores the prediction parameter generated by the coding parameter determination unit 110 in a predetermined position for each target picture and CU.

The reference picture memory 109 stores the decoded image generated by the loop filter 107 at a predetermined position for each target picture and CU.

The coding parameter determination unit 110 selects one set from among a plurality of sets of coding parameters. The coding parameter is the above-mentioned QT, BT or TT partition information, a prediction parameter, or a parameter to be coded generated in association with these. The predicted image generation unit 101 generates a predicted image using these coding parameters.

The coding parameter determination unit 110 calculates the RD cost value indicating the size of the information amount and the coding error for each of the plurality of sets. The RD cost value is, for example, the sum of the code amount and the squared error multiplied by the coefficient λ. The coding parameter determination unit 110 selects a set of coding parameters that minimizes the calculated cost value. As a result, the entropy coding unit 104 outputs the selected set of coding parameters as the coded stream Te. The coding parameter determination unit 110 stores the determined coding parameter in the prediction parameter memory 108.

Note that the moving picture coding device 11 and part of the moving picture decoding device 31 in the above-described embodiment, for example, the entropy decoding unit 301, the parameter decoding unit 302, the loop filter 305, the predicted image generation unit 308, the inverse quantization/inverse. Transforming unit 311, adding unit 312, prediction image generating unit 101, subtracting unit 102, transforming/quantizing unit 103, entropy coding unit 104, dequantizing/inverse transforming unit 105, loop filter 107, coding parameter determining unit 110. The parameter encoding unit 111 may be realized by a computer. In that case, the program for realizing the control function may be recorded in a computer-readable recording medium, and the program recorded in the recording medium may be read by a computer system and executed. The “computer system” referred to here is a computer system built in either the moving image encoding device 11 or the moving image decoding device 31, and includes an OS and hardware such as peripheral devices. Further, the “computer-readable recording medium” refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a storage device such as a hard disk built in a computer system. Further, "computer-readable recording medium" means a program that dynamically holds a program for a short time, such as a communication line when transmitting the program through a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory that holds a program for a certain period of time, such as a volatile memory inside a computer system that serves as a server or a client, may be included. Further, the program may be for realizing a part of the above-described functions, and may be a program for realizing the above-mentioned functions in combination with a program already recorded in the computer system.

Further, part or all of the moving picture coding device 11 and the moving picture decoding device 31 in the above-described embodiments may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each functional block of the moving picture coding device 11 and the moving picture decoding device 31 may be individually made into a processor, or a part or all of them may be integrated and made into a processor. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. In addition, when a technique for forming an integrated circuit that replaces LSI appears with the progress of semiconductor technology, an integrated circuit according to the technique may be used.

Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design changes and the like without departing from the gist of the present invention. It is possible to

[Application example]
The moving image encoding device 11 and the moving image decoding device 31 described above can be used by being mounted in various devices that perform transmission, reception, recording, and reproduction of moving images. The moving image may be a natural moving image captured by a camera or the like, or an artificial moving image (including CG and GUI) generated by a computer or the like.

First, it will be described with reference to FIG. 2 that the moving image encoding device 11 and the moving image decoding device 31 described above can be used for transmitting and receiving a moving image.

FIG. 2(a) is a block diagram showing the configuration of the transmission device PROD_A equipped with the moving image encoding device 11. As shown in the figure, the transmission device PROD_A is a coding unit PROD_A1 that obtains encoded data by encoding a moving image, and a modulated signal by modulating a carrier wave with the encoded data obtained by the encoding unit PROD_A1. It includes a modulator PROD_A2 for obtaining and a transmitter PROD_A3 for transmitting the modulated signal obtained by the modulator PROD_A2. The moving picture coding device 11 described above is used as this coding unit PROD_A1.

The transmission device PROD_A, as a source of the moving image input to the encoding unit PROD_A1, a camera PROD_A4 that captures the moving image, a recording medium PROD_A5 that records the moving image, an input terminal PROD_A6 for inputting the moving image from the outside, and An image processing unit A7 for generating or processing an image may be further provided. In the figure, a configuration in which the transmission device PROD_A includes all of these is illustrated, but a part thereof may be omitted.

The recording medium PROD_A5 may be a non-encoded moving image recorded, or a moving image encoded by a recording encoding method different from the transmission encoding method may be recorded. It may be one. In the latter case, a decoding unit (not shown) that decodes the coded data read from the recording medium PROD_A5 according to the recording coding method may be interposed between the recording medium PROD_A5 and the coding unit PROD_A1.

FIG. 2B is a block diagram showing the configuration of the receiving device PROD_B equipped with the moving image decoding device 31. As shown in the figure, the receiving device PROD_B is a receiving unit PROD_B1 that receives a modulated signal, a demodulating unit PROD_B2 that obtains encoded data by demodulating the modulated signal that the receiving unit PROD_B1 received, and a demodulating unit PROD_B2 And a decoding unit PROD_B3 that obtains a moving image by decoding encoded data. The moving picture decoding device 31 described above is used as this decoding unit PROD_B3.

The receiving device PROD_B has a display PROD_B4 for displaying a moving image, a recording medium PROD_B5 for recording the moving image, and an output terminal for outputting the moving image to the outside as a supply destination of the moving image output by the decoding unit PROD_B3. PROD_B6 may be further provided. In the drawing, the configuration in which the receiving device PROD_B is provided with all of them is illustrated, but a part thereof may be omitted.

The recording medium PROD_B5 may be one for recording a non-encoded moving image, or may be one encoded by a recording encoding method different from the transmission encoding method. May be. In the latter case, an encoding unit (not shown) that encodes the moving image acquired from the decoding unit PROD_B3 according to the recording encoding method may be interposed between the decoding unit PROD_B3 and the recording medium PROD_B5.

The transmission medium that transmits the modulated signal may be wireless or wired. Further, the transmission mode of transmitting the modulated signal may be broadcast (here, it means a transmission mode in which the transmission destination is not specified in advance) or communication (transmission in which the transmission destination is specified in advance here). Embodiment). That is, the transmission of the modulated signal may be realized by any of wireless broadcasting, wired broadcasting, wireless communication, and wired communication.

For example, a terrestrial digital broadcasting broadcasting station (broadcasting equipment or the like)/receiving station (television receiver or the like) is an example of a transmitting device PROD_A/receiving device PROD_B that transmits and receives modulated signals by wireless broadcasting. Also, a broadcasting station (broadcasting equipment, etc.)/receiving station (television receiver, etc.) of cable television broadcasting is an example of a transmitting device PROD_A/receiving device PROD_B that transmits and receives modulated signals by wired broadcasting.

In addition, a server (workstation, etc.)/client (TV receiver, personal computer, smartphone, etc.) for VOD (Video On Demand) services and video sharing services using the Internet is a transmission device that transmits and receives modulated signals by communication. This is an example of PROD_A/reception device PROD_B (generally, either wireless or wired is used as a transmission medium in LAN, and wired is used as a transmission medium in WAN). Here, the personal computer includes a desktop PC, a laptop PC, and a tablet PC. The smartphone also includes a multifunctional mobile phone terminal.

Note that the client of the video sharing service has a function of decoding the encoded data downloaded from the server and displaying it on the display, as well as a function of encoding the moving image captured by the camera and uploading it to the server. That is, the client of the video sharing service functions as both the transmission device PROD_A and the reception device PROD_B.

Next, it will be described with reference to FIG. 3 that the moving image encoding device 11 and the moving image decoding device 31 described above can be used for recording and reproducing a moving image.

FIG. 3(a) is a block diagram showing a configuration of a recording device PROD_C equipped with the above-described moving image encoding device 11. As shown in the figure, the recording device PROD_C includes a coding unit PROD_C1 that obtains coded data by coding a moving image, and a writing unit PROD_C2 that writes the coded data obtained by the coding unit PROD_C1 to a recording medium PROD_M. And are equipped with. The moving picture coding device 11 described above is used as the coding unit PROD_C1.

The recording medium PROD_M may be (1) a type such as an HDD (Hard Disk Drive) or SSD (Solid State Drive) built in the recording device PROD_C, or (2) SD memory. It may be of a type that is connected to the recording device PROD_C, such as a card or a USB (Universal Serial Bus) flash memory, or (3) DVD (Digital Versatile Disc: registered trademark) or BD (Blu-ray). For example, a disc (registered trademark) or the like may be loaded in a drive device (not shown) incorporated in the recording device PROD_C.

Further, the recording device PROD_C has a camera PROD_C3 for capturing a moving image, an input terminal PROD_C4 for inputting the moving image from the outside, and a receiving unit for receiving the moving image as a supply source of the moving image input to the encoding unit PROD_C1. The unit PROD_C5 and the image processing unit PROD_C6 for generating or processing an image may be further provided. In the drawing, the configuration in which the recording device PROD_C is provided with all of them is illustrated, but a part thereof may be omitted.

The receiving unit PROD_C5 may be one that receives an unencoded moving image, or receives encoded data that has been encoded by a transmission encoding method different from the recording encoding method. It may be one that does. In the latter case, a transmission decoding unit (not shown) that decodes the encoded data encoded by the transmission encoding method may be interposed between the reception unit PROD_C5 and the encoding unit PROD_C1.

Examples of such a recording device PROD_C include a DVD recorder, a BD recorder, an HDD (Hard Disk Drive) recorder, and the like (in this case, the input terminal PROD_C4 or the receiving unit PROD_C5 is the main supply source of the moving image). .. In addition, a camcorder (in this case, the camera PROD_C3 is the main source of moving images), a personal computer (in this case, the receiving unit PROD_C5 or the image processing unit C6 is the main source of moving images), a smartphone (this In this case, the camera PROD_C3 or the receiving unit PROD_C5 is a main supply source of the moving image) and the like are also examples of such a recording device PROD_C.

FIG. 3B is a block showing the configuration of the playback device PROD_D equipped with the moving image decoding device 31 described above. As shown in the figure, the playback device PROD_D includes a reading unit PROD_D1 that reads the encoded data written in the recording medium PROD_M, and a decoding unit PROD_D2 that obtains a moving image by decoding the encoded data read by the reading unit PROD_D1. , Are provided. The moving picture decoding device 31 described above is used as this decoding unit PROD_D2.

The recording medium PROD_M may be (1) of a type built into the playback device PROD_D, such as a HDD or SSD, or (2) such as an SD memory card or a USB flash memory. It may be of a type that is connected to the playback device PROD_D, or (3) loaded into a drive device (not shown) built in the playback device PROD_D, such as a DVD or BD. Good.

Also, the playback device PROD_D is a display PROD_D3 that displays a moving image, an output terminal PROD_D4 for outputting the moving image to the outside as a supply destination of the moving image output by the decoding unit PROD_D2, and a transmitting unit that transmits the moving image. PROD_D5 may be further provided. In the drawing, a configuration in which the playback device PROD_D is provided with all of them is illustrated, but a part thereof may be omitted.

The transmission unit PROD_D5 may be one that transmits an unencoded moving image, or transmits encoded data that has been encoded by a transmission encoding method different from the recording encoding method. It may be one that does. In the latter case, an encoding unit (not shown) that encodes a moving image with an encoding method for transmission may be interposed between the decoding unit PROD_D2 and the transmission unit PROD_D5.

Examples of such a playback device PROD_D include a DVD player, a BD player, an HDD player, etc. (in this case, the output terminal PROD_D4 to which a television receiver or the like is connected is a main supply destination of the moving image). .. Also, a television receiver (in this case, the display PROD_D3 is the main supply destination of the moving image), digital signage (also called an electronic signboard or electronic bulletin board, etc.), the display PROD_D3 or the transmission unit PROD_D5 is the main supply of the moving image. Desktop PC (in this case, the output terminal PROD_D4 or transmitter PROD_D5 is the main destination of the moving image), laptop or tablet PC (in this case, the display PROD_D3 or transmitter PROD_D5 An example of such a playback device PROD_D is also a smartphone (in which case, the display PROD_D3 or the transmission unit PROD_D5 is the main destination of a moving image), and the like.

(OBMC processing)
General OBMC processing will be described with reference to FIGS. 12 to 15.

(Outline of OBMC processing)
In the OBMC (Overlapped block motion compensation) processing according to the present embodiment, a motion compensation unit 3091 and an OBMC unit 30953 may be used to generate a predicted image. Here, the OBMC process will be described. The OBMC unit 30953 includes an OBMC interpolation image creation unit 30912 and an OBMC correction unit 3093. The OBMC process is performed by using an interpolated image (CU interpolated image) generated by using an inter prediction parameter (hereinafter, motion parameter) of the target sub-block (target CU) and a motion parameter of an adjacent sub-block of the target sub-block. This is a process of generating an interpolation image (motion compensation image) of the target sub-block by using the generated interpolation image (OBMC interpolation image). In the following description, when the prediction is in sub-block units, CU is read as sub-block.

In particular, in a pixel (boundary pixel) in the target CU that is close to the CU boundary, a process of correcting the interpolated image of the target CU may be performed by the OBMC interpolation image based on the motion parameter of the adjacent CU.

FIG. 12 is a diagram showing an example of a region in which predicted image generation is performed by using motion parameters of adjacent CUs according to this embodiment. As shown in FIG. 12, when the OBMC process is applied to the predicted image generation, the pixels within a predetermined distance from the CU boundary filled with black are the application targets of the OBMC process.

(Interpolation image generation)
FIG. 13 is a block diagram showing the main configuration of the motion compensation unit 3091 and the OBMC unit 30953 included in the inter prediction image generation unit 309 that performs the OBMC process according to this embodiment. The motion compensation unit 3091 uses the upper left coordinates (xb,yb), size (nW,nH), motion vector mvLX, reference image refImg (reference picture pointed to by the reference picture index refIdxLX) of the prediction block (CU or sub-block), and interpolation. The filter coefficient mcFilter[] and the number of taps NTAP of the interpolation filter are input, and the interpolation image is output.

As shown in the figure, when the CU interpolated image Pred_C[x][y] is generated, (xb,yb)=(xPb,yPb), (nW,nH)=(nPbW,nPbH) in the motion compensation unit 3091. , MvLX=motion vector mvLX[xb][yb] of the target CU (target sub-block), reference image refImg=refIdxLX[xb][yb], motion vector accuracy MVPREC, and tap number NTAP are input. When dividing the CU into sub-blocks for processing, (xb,yb)=(xPb+nSbW*i,yPb+nSbH*j) (where i=0,1,2,...nPbW/nSbW-1, j=0,1,2,...nPbH/nSbH-1), (nW,nH)=(nSbW,nSbH) are input. Alternatively, instead of using the motion compensation unit 3091, a CU interpolation image generation unit 30911 specialized for CU interpolation image generation may be provided.

In other words, the interpolation image is generated by applying the motion information of the target CU to the corresponding block on the reference image.

When generating the OBMC interpolation image Pred_N[x][y], the OBMC interpolation image generation unit 30912 in the OBMC unit 30953 is used. The main processing of the OBMC interpolation image generation unit 30912 is the same as that of the motion compensation unit 3091, but the motion information of one or more adjacent CUs is input and one or more interpolation images are generated. The OBMC interpolation image generation unit 30912 has (xb,yb)=(xPb+nSbW*i,yPb+nSbH*j), (nW,nH)=(nSbW,nSbH), mvLX=mvLXN[xNb][yNb], refImg=refIdxLXN[xb][yb] is input.

In other words, the motion information of the CU adjacent to the target CU is applied to the block on the reference image corresponding to the target CU to generate an additional interpolated image.

In the configuration for performing OBMC processing, the OBMC correction unit 3093 described above performs the weighted average processing on the received Pred_N[x][y] and Pred_C[x][y] to obtain the predicted image Pred[x][ generate or update y]. More specifically, when the input OBMC flag obmc_flag is not 0 (OBMC processing is valid), the OBMC correction unit 3093 performs the weighted average processing shown by the following equation.

Pred[x][y]＝((w1*Pred_C[x][y]＋w2*Pred_N[x][y])+o)>>shift
Here, the weights w1 and w2 in the weighted average processing will be described. The weights w1 and w2 in the weighted averaging process are determined according to the distance (the number of pixels) of the target pixel from the CU boundary. The shift value shift may be changed or fixed depending on the distance.

The OBMC processing sizes nOBMCW and nOBMCH use 4 pixels, but if the CU size is less than a predetermined threshold value, nOBMCW and nOBMCH may be reduced from 4 to 2. For example, the predetermined threshold may be 64. For example, in the case of 4 pixels, {w1,w2} = {24,8}, {28,4}, {30,2}, {31,1}, o = 16, shift = 5 may be set. In this case, Pred[x][y] is generated by the following formula.

Pred[x][y]=(24*Pred_C[x][y]+8*Pred_N[x][y]+16)>>5 Distance=0 pixels
Pred[x][y]=(28*Pred_C[x][y]+4*Pred_N[x][y]+16)>>5 Distance = 1 pixel
Pred[x][y]=(30*Pred_C[x][y]+2*Pred_N[x][y]+16)>>5 Distance = 2 pixels
Pred[x][y]=(31*Pred_C[x][y]+1*Pred_N[x][y]+16)>>5 Distance=3 pixels Also {w1, w2} = {24,8 }, {28,4}, {32,0}, {32,0}, o = 16, shift = 5. Alternatively, the weight is changed by the luminance component and the color difference component, and the color difference component is {w1,w2} = {24,8}, {28,4}, {30,2}, {31,1}, o = 16, shift = 5, or {w1,w2} = {24,8}, {232,0}, {32,0}, {32,0}, o = 16, shift = 5 may be set. Note that w1 and w2 may be derived by table lookup as in the following formula.

w1[i] = weightOBMC[i]
w2[i] = (1<<shift)-weightOBMC[i]
shift = 5, o = 16
Where weightOBMC[] = {24,28,32,32}.
The color difference component may be weightOBMC[]={24,28,30,31}.

When nOBMCW and nOBMCH have two pixels, for example, {w1,w2,o,shift}={3,1,2,2}, {7,1,4,3} may be set. In this case, Pred[x][y] is generated by the following formula.

Pred[x][y]=(3*Pred_C[x][y]+1*Pred_N[x][y]+2)>>2 Distance=0 pixels
Pred[x][y]=(7*Pred_C[x][y]+1*Pred_N[x][y]+4)>>3 Distance = 1 pixel As in the case of 4 pixels, set w1 and w2 You may derive like the following formula.

w1[i] = weightOBMC[i], weightOBMC[] = {3,2}
w2[i] = (1<<shift)-weightOBMC[i]
shift = 2, o = 2
Alternatively, the following weights may be used.

w1[i] = weightOBMC[i], weightOBMC[] = {7,1}
w2[i] = (1<<shift)-weightOBMC[i]
shift = 3, o = 4
In the OBMC process, a predicted image is generated using the motion parameters of a plurality of adjacent CUs (CUs that are adjacent to the upper left of the target CU). Here, a method of generating Pred[x][y] from motion parameters of a plurality of adjacent CUs will be described.

First, the OBMC correction unit 3093 applies Pred_C[x][y] and Pred_N[x][y] created using the motion parameters of the upper adjacent CU of the target CU to the above formula to apply Pred[x][y ] Is generated.

Pred[x][y]＝((w1*Pred_C[x][y]＋w2*Pred_N[x][y])+o)>>shift
Next, the OBMC correction unit 3093 uses Pred_N[x][y] created using the motion parameters of the left adjacent CU of the target CU, and Pred[x] using Pred[x][y] created previously. ] [y] is updated.

Pred[x][y]＝((w1*Pred[x][y]＋w2*Pred_N[x][y])+o)>>shift
According to the above configuration, the inter-prediction image generation unit 309 generates the interpolation image of the target CU and the additional interpolation image using the motion parameter of the target CU and the motion parameter of the CU adjacent to the target CU. Then, the OBMC correction unit 3093 can generate a predicted image using the interpolation image generated by the motion compensation unit 3091 and the OBMC interpolation image generation unit 30912. Therefore, it is possible to generate a predicted image with high prediction accuracy.

(Flow of OBMC processing)
Next, the flow of OBMC processing according to this embodiment will be described.

FIG. 14 is a flowchart showing the flow of processing of the inter prediction image generation unit 309 according to this embodiment. FIG. 15 is a diagram showing an example of pseudo code representing the OBMC process. FIG. 15A shows an example of performing OBMC processing in sub-block units, and (xSb, ySb) shows the upper left coordinates of the target sub-block in pixel units. (nCtbW,nCtbH) indicates the CTU size, (nPbW,nPbH) indicates the block size (CU size), and (nSbW,nSbH) indicates the sub-block size. (subX, subY) indicates the position (subblock unit) of the target subblock in the target block (target CU). Also, dir indicates the direction of the adjacent block in the OBMC process. The OBMC process is performed for each sub-block whose upper left coordinates are (xSb, ySb). The size of the sub-block may be equal to the block. In this case, the OBMC process is performed for each block having the upper left coordinates of (xSb, ySb) (FIG. 14; in this case, the sub-blocks of the following process may be read as blocks and processed).

The motion compensation unit 3091 derives Pred_C[x][y] (S1).

The OBMC unit 30953 determines whether the flag obmc_flag indicating whether to apply OBMC is not 0 (S11). If obmc_flag is not 0, that is, if OBMC is on (YES in S11), the OBMC unit 30953 performs the following sub-block loop processing and directional loop processing (S2). In the drawing, the judgment of obmc_flag !=0 is described as obmcDir !=0.

In detail, the OBMC unit 30953 performs a loop process for each sub block forming the CU. The loop variable of the sub-block loop has coordinates (subX, subY), and the loop processing is performed by sequentially setting the coordinates of the sub-blocks in the CU (the end of the loop is S7).

Further, the OBMC unit 30953 performs a loop process for each upward dir and left left dir. Loop processing is performed by sequentially setting the values of the directions included in the direction set dirSet(dirSet={above, left}) for the loop variable dir of the direction loop (the end of the loop is S7). It should be noted that 0,1 may be assigned to above,left and processing may be performed for dirSet={0,1}.

Hereinafter, in the loop, when the conditions of S3 and S4 are satisfied for the direction dir of the adjacent sub-block defined in S2 and the sub-block of the coordinates defined in S2, the OBMC interpolation image generation unit 30912 determines that Pred_N[x ] [y] is generated (S5), and the OBMC correction unit 3093 corrects the predicted image (S6).

Details of the sub-block loop processing will be described. The OBMC unit 30953 determines whether the prediction parameter of the adjacent sub block located in the direction dir of the target sub block is valid (S3). Note that the positions (xNb, yNb) of adjacent sub-blocks that refer to the motion parameters when the direction dir is up and left are (xSb, ySb-1) and (xSb-1, ySb), respectively.

When the adjacent sub block is valid (YES in S3), the OBMC unit 30953 determines whether or not the motion parameter of the adjacent sub block (xNb,yNb) is equal to the motion parameter of the target sub block (S4). Here, DiffMotionAvail is set to 1 when the motion parameters are different, and DiffMotionAvail is set to 0 when the motion parameters are equal. On the contrary, when the adjacent sub-block is not valid (NO in S3), the identity determination process (S4), the OBMC interpolation image generation (S5), and the prediction image correction (S6) are omitted, and the next The process transits to the sub-block processing (S7).

The identity determination is 1) the prediction lists of the adjacent block and the target block are the same, 2) the reference pictures of the adjacent block and the target block are the same, and 3) the difference between the motion vector of the adjacent block and the target block is predetermined. It is determined whether or not it is larger than the threshold value of. When all of 1) to 3) are satisfied, it is determined that the motion parameters are the same, and DiffMotionAvail is set to 0 (YES in S4). Otherwise, set DiffMotionAvail=1 (NO in S4). The threshold may be 24 with 16 pixel precision. Alternatively, it may be 24 for bi-prediction and 16 for uni-prediction.

When the motion parameter of the adjacent sub block is not equal to the motion parameter of the target sub block (NO in S4), the OBMC interpolation image generation unit 30912 generates (derives) Pred_N[x][y] (S5), and OBMC correction The unit 3093 generates or updates Pred[x][y] using Pred_N[x][y] and Pred_C[x][y] of the target sub block (S6).

Next, the OBMC correction unit 3093 refers to Pred_N[x][y] and Pred_C[x][y] to perform weighted averaging to generate or update Pred[x][y] (S6).

The weight is set according to the distance (the number of pixels) from the boundary, and the weight table weightOBMC may use the table weightOBMC in the weighted average processing described above, or may directly use the weights {w1, w2 without using the table. } May be used.

Next, the OBMC unit 30953 performs the OBMC processing of S3 to S6 by using whether or not there is an unprocessed subblock among the subblocks to be processed by OBMC and the motion parameters of the adjacent subblocks in all directions. It is determined whether or not (S7).

If there is no unprocessed subblock and the OBMC process is performed using the motion parameters of the adjacent subblocks in all directions (NO in S7), the process ends.

If there is an unprocessed sub-block or if the OBMC process is not performed using the motion parameters of the adjacent sub-blocks in all directions (YES in S7), the process proceeds to S2 and the process in the next direction is performed. I do.

When obmc_flag=0, the OBMC interpolation image generation unit 30912 and the OBMC correction unit 3093 do not perform processing, and Pred_C[x][y] is output as Pred_C[x][y] (Pred[][] =Pred_C[][]).

Although FIG. 14 shows an example in which CU is divided into sub-blocks and OBMC is performed in sub-block units, OBMC may be performed in CU units (block units). In this case, only the direction loop is determined in S7. FIG. 15B is an example of performing OBMC processing in CU units, and (xPb, yPb) shows the upper left coordinates of the target CU in pixel units. (cuX, cuY) indicates the position (CU unit) of the target CU within the target CTU. The OBMC process is performed for each block having (xPb, yPb) as the upper left coordinates.

(Details of OBMC processing)
As the OBMC processing, 1) the configuration of generating the OBMC additional area image (interpolation image) using the motion vector of the block adjacent to the target block has been described, but 2) the processing of the target block for the subsequent block of the target block It is also possible to generate an OBMC additional area image for the next block at the time point of. A method for simplifying the derivation of the OBMC additional area image will be described below by taking the configuration of 2) as an example. However, since the processing required for the simplification is the integer pixelization of the motion vector, it may be applied to the configuration 1). ..

When generating a prediction image of a target block (nW*nH) by motion compensation using an interpolation filter with the number of taps NTAP, in addition to the size of the target block, (NTAP/2-1) pixels on the left and above the target block , And (NTAP-1+nW)*(NTAP-1+nH) size obtained by adding the right and bottom (NTAP/2) pixels, it is necessary to acquire pixel values. An example of NTAP=8 is shown in Fig. 16(a).

In addition to this, when performing OBMC processing, if the size with the additional area for OBMC added, for example, the width and height of the OBMC area are nOBMCW and nOBMCH, (NTAP-1+nW+nOBMCW)*(NTAP -1+nH+nOBMCH) size pixels need to be acquired. An example of NTAP=8 is shown in Fig. 16(b).

Furthermore, if the target block is a sub-block, the pixel value required by the OBMC process increases to (NTAP-1+nSbW+2*nOBMCW)*(NTAP-1+nSbH+2*nOBMCH). An example of NTAP=8 is shown in Fig. 16(c). Here, nSbW and nSbH are the width and height of the sub-block.

Pixel values that need to be acquired for the additional area for OBMC are generated by padding. Specifically, when NTAP=8, as shown in the shaded area in FIG. 17A for the target block, the padding is the pixel value of the rightmost column of the target block or the target subblock, or the pixel value of the lower row. Generated by copying. In configuration 1, the rightmost column of the target block or target subblock corresponds to the left column of the target block, and the row below the target block is the rightmost column of the target subblock is the target block. Corresponds to the line above.

This eliminates the need to acquire additional pixel values to generate an interpolated image in the OBMC region, but still requires the sub-pel interpolation operations and additional memory access required for OBMC processing. In the present application, when deriving the overlap region, the motion vector is rounded to the integer pixel precision to perform the motion compensation, whereby the additional memory access and the sub-pel interpolation calculation can be omitted.

Note that, when dir==above, the OBMC interpolation image generation unit 30912 determines that the subblock (xNb,yNb)=(xSb,ySb) adjacent to the target block (OBMC processing unit, CU or subblock obtained by dividing CU). -1) referring to the motion parameter, the interpolated image of the area of size (nSbW, nOBMCH) with the upper left coordinates of (xSb, ySb) is derived.

Further, the OBMC interpolation image generation unit 30912, when dir==left, refers to the motion parameter of the block (xNb,yNb)=(xSb-1,ySb) adjacent to the left of the target block, (xSb,ySb) The interpolated image of the area of size (nOBMCW, nSbH) with the upper left coordinate as is derived.

The above process can be shown in pseudo code as follows: In the pseudo code, the reference image refPic, the upper left coordinates (xb,yb) of the target block, the width nW of the target block, the height nH, the interpolation image generation process of the motion vector mvRef Interpolation (refPic,xb,yb,nW,nH, mvRef). Here, the motion parameter of coordinates (x, y) is represented by mvLX[x][y] and refIdxLX[x][y].
nOBMCW = nOBMCH = (target block is not a subblock) ?4: 2
if (dir == above)
mvRef = mvLXN[xSb][ySb-1], refPic=refIdxLXN[xSb][ySb-1]
predN = Interpolation(refPic,xSb,ySb,nSbW,nOBMCH,mvRef)
else if (dir == left)
mvRef = mvLXN[xSb-1][ySb], refPic=refIdxLXN[xSb-1][ySb]
predN = Interpolation(refPic,xSb,ySb,nOBMCW,nSbH,mvRef)
The details of the process in step S6 of FIG. 14 are as follows. The OBMC correction unit 3093 performs weighted average processing by referring to Pred_N[x][y] and Pred_C[x][y] according to the distance from the boundary with the adjacent block. The weighted average processing is as follows.

Pred[x][y] = Pred_C[x][y]
When dir==above, the OBMC correction unit 3093 derives Pred[x][y] from the following equation, with i=0..nSbW-1 and j=0..nOBMCH-1.

x = xSb+i, y = ySb+j
Pred[x][y] = (w1*Pred[x][y]+w2*Pred_N[i][j]+o)>>shift
w1 = weightOBMC[j], w2 = (1<<shift)-w1, o = (1<<(shift-1))
Further, when dir==left, the OBMC correction unit 3093 derives Pred[x][y] from the following equation, with i=0..nOBMCW-1, j=0..nSbH-1.

x = xSb+i, y = ySb+j
Pred[x][y] = (w1*Pred[x][y]+w2*Pred_N[i][j]+o)>>shift
w1 = weightOBMC[i], w2 = (1<<shift)-w1, o = (1<<(shift-1))
[Processing example 1]
In this processing example, the OBMC interpolation image generation unit 30912 cuts off the decimal part of the motion vector with decimal pixel precision (eg, 1/4 pixel precision) when generating the interpolation image in the OBMC additional area, that is, the OBMC interpolation image. As a result, motion compensation is performed as a motion vector with integer pixel accuracy, and an interpolated image is generated.

For example, in the OBMC additional area, if the motion vector has a 1/4 pixel precision (5/4,5/4), the fractional part is cut off and the motion vector with an integer pixel precision (4/4, 4/4) is set. Motion compensation is performed to generate an interpolated image.

When an interpolation image is generated by using a motion vector with decimal pixel accuracy as it is, a process for interpolating decimal pixels is required even in the additional area for OBMC. For that purpose, for example, when the number of taps is 8, pixels in an area expanded by 4 pixels from the additional area for OBMC are required (area 2702 and area 2703 in FIG. 17A). Even if the pixels of the area 2702 and the area 2703 are not acquired from the memory but are derived by padding, the processing for interpolating the decimal pixel remains the same.

According to this processing example, for the additional area for OBMC, even if the motion vector of the adjacent block has decimal pixel precision, motion compensation is performed by converting it into an integer pixel precision motion vector, so that decimal pixel interpolation is performed. The processing of is unnecessary. When the motion vector of the target block is decimal precision, the pixels for generating the CU interpolation image of decimal precision of the target block can use the pixels of the additional area for OBMC, so the decimal pixels in the target block are interpolated. No additional memory access is required to do so. Therefore, it is possible to suppress a decrease in coding efficiency.

For example, when the precision of the motion vector mvLXN of the adjacent block is (1/MVPrec pixel precision), the motion vector is converted to integer precision by the following formula.

mvLXN[0] = (mvLXN[0] >> MVBIT) << MVBIT
mvLXN[1] = (mvLXN[1] >> MVBIT) << MVBIT
However, MVBIT=log2(MVPREC). For example, MVBIT=4
After that, the processing described in (motion compensation) is performed using mvLXN with integer precision. Since mvLXN has integer precision, the interpolation image generation process Interpolation(refPic,xb,yb,nW,nH,mvLXN) is simplified as follows.

The OBMC interpolation image generation unit 30912 derives the position (xInt, yInt) of the reference image corresponding to the coordinates (x, y) in the target block by the following formula.

xInt = xb+mvLXN[0]+x
yInt = yb+mvLXN[1]+y
The OBMC interpolation image generation unit 30912 reads the pixel value from the reference picture refPic and derives the predicted image Pred_N[][].

Pred_N[x][y] = refImg[xInt][yInt]
For example, in the 4:2:0 format mode, the luminance (luma) is 1/16 pixel precision and the color difference (chroma) is 1/32 pixel precision. It is necessary to round down to integer pixel precision by dropping the bit precision and then discarding the fractional part. If the color difference motion vector is mvLXN_C,
mvLXN_C[0] = (mvLXN[0] >> (MVBIT+1)) << MVBIT
mvLXN_C[1] = (mvLXN[1] >> (MVBIT+1)) << MVBIT
Furthermore, in this processing example, the inter-prediction image generation unit 309 may apply the OBMC processing to the target block when the motion vector in the target block is an integer vector. An example of applying the OBMC process to the target block in the AMVP mode and the integer vector will be described in the process example 2.

As described above, the inter-prediction image generation unit 309 according to the present processing example is for generating a prediction image using the OBMC process, and the interpolated image used for generating the prediction image is a motion using a motion vector. An OBMC interpolation image generation unit 30912 is generated by compensation, and the OBMC interpolation image generation unit 30912 converts a motion vector with decimal pixel precision into a motion vector with integer pixel precision for a region overlapping with an adjacent block, and performs motion compensation. It is something to do.

Further, the inter-prediction image generation unit 309 may apply the OBMC process to the target block in the IMV mode in which the motion vector in the target block is derived only with integer pixels.

[Processing example 2]
If the target block is in the AMVP (Advanced Motion Vector Prediction) mode (mode in which the motion vector is notified by encoded data) and the motion vector has decimal pixel precision, the inter prediction image generation unit 309 determines the target block. The OBMC process may not be applied to, but the OBMC process may be applied in other cases.

Further, in this processing example, the inter-prediction image generation unit 309 applies the OBMC processing to the target block in the IMV (Integer Motion Vector) mode in which the motion vector in the target block is derived with only integer pixels. Good. That is, the OBMC applicable flag (obmc_flag) may be derived using the flag imv_flag for notifying ON/OFF of the IMV mode.

obmc_flag = imv_flag
The following processing is performed in the configuration in which the accuracy of the motion vector derived in the AMVP mode is switched to 1/4, 1, 4 pixel accuracy by amvr_mode. The inter-prediction image generation unit 309 applies OBMC (derives obmc_flag=1) when amvr_mode is 1 or 2, that is, motion vector accuracy is 1 pixel accuracy and 4 pixel accuracy, and amvr_mode is 0, that is, 1/4 pixel. OBMC is turned off (obmc_flag is 0) in case of precision. This determination process may be derived by the following formula.

obmc_flag = (amvr_mode> 0) ?1 :0
Or
obmc_flag = (amvr_mode == 0) ?0 :1
Further, the inter prediction image generation unit 309 may determine whether the motion vector is an integer vector by using whether or not the lower bit of the motion vector is other than 0, and may decide to apply OBMC. For example, obmc_flag may be derived by the following formula.

obmc_flag = (mvLX[0] & maskFloatMV) || ((mvLX[1] & maskFloatMV )) ?0: 1
Where maskFloatMV = (1<<MVBIT)-1. For example, for 1/16 precision maskFloatMV = (1<<4)-1 = 15.

More specifically, step S11a shown in FIG. 18 is used instead of step S11 in the flowchart shown in FIG. That is, the determination of obmc_flag!=0 is made based on whether or not “the target block is in AMVP mode and the motion vector has decimal pixel precision”. If the determination is NO, the process proceeds to step S2, and if the determination is YES, the OBMC process is not executed and ends.

As a result, the OBMC process is executed when the motion vector has an integer pixel precision, and it is possible to exclude the case where the motion picture encoding device side determines that a motion vector with a decimal pixel precision is necessary. It is possible to reduce the amount of processing and the amount of memory access while suppressing a decrease in efficiency of conversion.

As described above, the inter-prediction image generation unit 309 according to the present processing example is for generating a prediction image using the OBMC process, the target block is in the AMVP mode, and the motion vector with decimal pixel precision is If it is derived, the OBMC process is not executed on the target block.

[Processing example 3]
In this processing example, the OBMC interpolation image generation unit 30912 does not perform BIO (Bi-directional optical flow) processing when generating an interpolation image in the OBMC additional area, that is, an OBMC interpolation image. FIG. 19 is a flow chart showing the flow of processing when OBMC processing and BIO processing are executed. The difference between FIG. 19 and FIG. 14 is that in FIG. 19, the BIO unit 30954 applies BIO to the CU interpolation image derived in S1. However, the BIO unit 30954 does not apply BIO to the OBMC interpolated image derived in S5.

As described above, the processing amount can be reduced by not executing the BIO processing for the additional area for OBMC.

As described above, the inter-prediction image generation unit 309 according to the present processing example is for generating a prediction image using the OBMC process and the BIO process, and the interpolation image used for generating the prediction image is a motion vector. The motion compensating unit 309 is generated by motion compensation using, and the motion compensating unit 309 does not perform the BIO processing on the area overlapping the adjacent block.

Note that the inter-predicted image generation unit 309 applies the process by MC (motion compensation), the BIO process, and the OBMC process in this order when generating the predicted image of the target block.

(Hardware realization and software realization)
Further, each block of the moving image decoding device 31 and the moving image encoding device 11 described above may be realized by hardware by a logic circuit formed on an integrated circuit (IC chip), or by a CPU (Central Processing Unit), and may be realized by software.

In the latter case, each of the above devices is a CPU that executes instructions of a program that realizes each function, a ROM (Read Only Memory) that stores the program, a RAM (Random Access Memory) that expands the program, the program, and various types of devices. A storage device (recording medium) such as a memory for storing data is provided. The object of the embodiment of the present invention is to record the program code (execution format program, intermediate code program, source program) of the control program of each device, which is software for realizing the above-described functions, in a computer-readable manner. This can also be achieved by supplying a medium to each of the above devices and causing the computer (or CPU or MPU) to read and execute the program code recorded in the recording medium.

Examples of the recording medium include tapes such as magnetic tapes and cassette tapes, magnetic disks such as floppy (registered trademark) disks/hard disks, and CD-ROMs (Compact Disc Read-Only Memory)/MO disks (Magneto-Optical discs). )/MD (Mini Disc)/DVD (Digital Versatile Disc: registered trademark)/CD-R (CD Recordable)/Blu-ray Disc (registered trademark) and other optical discs, IC cards (memory cards) Card) such as optical card, mask ROM/EPROM (Erasable Programmable Read-Only Memory)/EEPROM (Electrically Erasable and Programmable Read-Only Memory: registered trademark)/semiconductor memory such as flash ROM, or PLD ( Logic circuits such as Programmable logic device) and FPGA (Field Programmable Gate Array) can be used.

Further, each of the above devices may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited as long as it can transmit the program code. For example, Internet, intranet, extranet, LAN (Local Area Network), ISDN (Integrated Services Digital Network), VAN (Value-Added Network), CATV (Community Antenna television/Cable Television) communication network, virtual private network (Virtual Private Network) Network), telephone network, mobile communication network, satellite communication network, etc. can be used. Further, the transmission medium that constitutes this communication network may be any medium that can transmit the program code, and is not limited to a specific configuration or type. For example, even if wired such as IEEE (Institute of Electrical and Electronic Engineers) 1394, USB, power line carrier, cable TV line, telephone line, ADSL (Asymmetric Digital Subscriber Line) line, infrared rays such as IrDA (Infrared Data Association) and remote control , BlueTooth (registered trademark), IEEE802.11 wireless, HDR (High Data Rate), NFC (Near Field Communication), DLNA (Digital Living Network Alliance: registered trademark), mobile phone network, satellite line, terrestrial digital broadcasting network, etc. It is also available wirelessly. It should be noted that the embodiment of the present invention can also be realized in the form of a computer data signal embedded in a carrier wave, in which the program code is embodied by electronic transmission.

The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims. That is, an embodiment obtained by combining technical means appropriately modified within the scope of the claims is also included in the technical scope of the present invention.

31 Image decoding device
301 Entropy decoding unit
302 Parameter decoding unit
303 Inter prediction parameter decoding unit
304 Intra prediction parameter decoding unit
308 Predicted image generator
309 Inter prediction image generation unit (prediction image generation device)
3091 Motion compensation unit
30912 OBMC interpolation image generator
3093 OBMC correction unit
30953 OBMC department
310 Intra prediction image generator
311 Inverse quantization/inverse transform unit
312 Adder
11 Image coding device
101 Prediction image generator
102 Subtractor
103 Transform/Quantization unit
104 Entropy encoder
105 Inverse quantization/inverse transform section
107 loop filter
110 Coding parameter determination unit
111 Parameter coding unit
112 Inter prediction parameter coding unit
113 Intra prediction parameter coding unit

Claims (6)

A predictive image generation device for generating a predictive image using OBMC (Overlapped block motion compensation) processing,
An interpolation image used for generating the predicted image is provided with a motion compensation unit that generates by motion compensation using a motion vector,
The predicted image generation device, wherein the motion compensation unit performs motion compensation by converting a motion vector having a decimal pixel accuracy into a motion vector having an integer pixel accuracy in a region overlapping with an adjacent block. The predicted image generation apparatus according to claim 1, wherein the OBMC process is applied to the target block in the IMV mode in which the motion vector in the target block is derived only with integer pixels. A predictive image generation device for generating a predictive image using OBMC (Overlapped block motion compensation) processing,
A predictive image generation device characterized by not performing OBMC processing on a target block when the target block is in an AMVP (Advanced Motion Vector Prediction) mode and a motion vector is derived with decimal pixel accuracy. A predictive image generation device for generating a predictive image using OBMC (Overlapped block motion compensation) processing and BIO (Bi-directional potical flow) processing,
An interpolation image used for generating the predicted image is provided with a motion compensation unit that generates by motion compensation using a motion vector,
The predicted image generation device, wherein the motion compensation unit does not perform the BIO processing on a region overlapping with an adjacent block. A prediction image generation device according to any one of claims 1 to 4,
A moving image decoding device, wherein an encoding target image is restored by adding or subtracting a residual image to or from the predicted image. A prediction image generation device according to any one of claims 1 to 4,
A moving picture coding apparatus characterized by coding a residual between the predicted picture and a picture to be coded.

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