JP2013042304A - Image decoding apparatus, image decoding method and image decoding program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve encoding efficiency of motion information including a motion vector while suppressing an increases in encoding time.SOLUTION: A code string analysis section 201 acquires, from an encoded stream, information for specifying a reference image for use in motion compensation of a block to be decoded. A prediction vector candidate generation section generates a prediction vector candidate for a motion vector of the block to be decoded. A reference vector decision section decides a reference motion vector from motion vectors of decoded blocks adjacent to the block to be decoded. A reference image information setting section sets information for specifying a reference image for scaling. A scaling section scales the reference motion vector on the basis of the information for specifying the reference image for scaling. The reference image information setting section decides the reference image for scaling independently of the reference image for use in motion compensation of the block to be decoded.

Description

  The present invention relates to a moving image encoding technique using motion compensated prediction, and more particularly to an image decoding apparatus, an image decoding method, and an image decoding program for encoding motion information used in motion compensated prediction.

  In general video compression coding, motion compensation prediction is used. The motion compensated prediction divides the target image into fine blocks, uses the decoded image as a reference image, and based on the amount of motion indicated by the motion vector, the position of the position moved from the target block of the target image to the reference block of the reference image This is a technique for generating a signal as a prediction signal. There are two types of motion compensated prediction, one for single prediction using one motion vector and the other for bi-prediction using two motion vectors.

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

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

  Therefore, in MPEG-2, the motion vector of the block adjacent to the left of the block to be processed is simply used as a prediction vector (see, for example, Non-Patent Document 1), but in MPEG-4 AVC, the median of the motion vectors of a plurality of adjacent blocks is used. By using the prediction vector, the accuracy of the prediction vector is improved, and an increase in the code amount of the encoded vector is suppressed (for example, see Non-Patent Document 2).

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

  In any of the methods described in Non-Patent Documents 1 and 2, since only one prediction vector is obtained, the prediction accuracy is not sufficient and the encoding efficiency may not be sufficiently improved. The present inventors considered taking a method of improving the coding efficiency by using a plurality of prediction vector candidates including a prediction vector candidate generated using a reference image. In that case, it is necessary to decode an index for identifying a reference image, and it has been recognized that there is a problem that the time for generating prediction vector candidates is delayed.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a video decoding technique capable of improving the accuracy of motion vector prediction while suppressing the delay time required to generate prediction vector candidates. There is to do.

  In order to solve the above-described problem, an image decoding apparatus according to an aspect of the present invention is an image decoding apparatus that performs motion compensation prediction, and encodes information for specifying a reference image used in motion compensation of a decoding target block. A code string analysis unit (201) that is obtained from the stream, and a prediction vector candidate generation unit (151 and 152) for generating a prediction vector candidate of the motion vector of the decoding target block. The prediction vector candidate generation unit (151 and 152) includes a reference vector determination unit (170 and 175) that determines a reference motion vector from among motion vectors of decoded blocks adjacent to the decoding target block, and a scaling Reference image information setting units (171 and 176) for setting information for specifying a reference image, and scaling units (172, 172) for scaling the reference motion vector based on information for specifying the scaling reference image 177). The reference image information setting unit (171, 176) determines the scaling reference image without depending on the reference image used for motion compensation of the decoding target block. The “encoded block adjacent to the decoding target block” may be a block spatially adjacent to the encoding target block or a temporally adjacent block.

  The reference image information setting unit (171 or 176) may determine the scaling reference image based on a reference image used for motion compensation of a decoded block adjacent to the decoding target block. .

  Another aspect of the present invention is also an image decoding device. This apparatus is an image decoding apparatus that performs motion compensation prediction, and selects a block including a motion vector from a plurality of blocks adjacent to a decoding target block to generate a prediction vector candidate list generation unit (220). And a combined motion information candidate list generation unit (230) that generates a combined motion information candidate list by selecting a block including motion information including at least reference image information and a motion vector from a plurality of blocks adjacent to the decoding target block. A prediction mode selection unit (210) that selects which one of the first prediction mode using the prediction vector candidate list and the second prediction mode using the combined motion information candidate list is used; Information for specifying the prediction mode from the stream, and the prediction mode is the first prediction mode In this case, information for specifying a prediction vector indicating a position of a prediction vector in the prediction vector candidate list, a difference vector, and information for specifying a reference image of the decoding target block are acquired from the encoded stream. When the prediction mode is the second prediction mode, a code string analysis unit that acquires information for specifying motion information indicating the position of motion information in the combined motion information candidate list from the encoded stream ( 201), and a prediction vector selection unit (221) that selects a prediction vector of the decoding target block from prediction vector candidates included in the prediction vector candidate list based on information for specifying the prediction vector; , Adding the prediction vector and the difference vector to reproduce the motion vector of the decoding target block Combined motion for selecting motion information of the decoding target block from motion information candidates included in the combined motion information candidate list based on information for specifying the motion information When the prediction mode is the first prediction mode, the information selection unit (231) generates a prediction signal using the reference image specified by the information for specifying the reference image and the reproduced motion vector. When the prediction mode is the second prediction mode, a prediction signal is generated using a reference image specified by reference image information included in the selected motion information and a motion vector included in the selected motion information. The generated motion compensation unit (205) and a decoded block adjacent to the decoding target block, which are included in images temporally different from the image including the decoding target block And a scaling unit (172) for scaling the motion vector of the block to be processed. The motion vector scaled by the scaling unit (172) is shared by the first prediction mode and the second prediction mode.

  Yet another embodiment of the present invention is also an image decoding device. This apparatus is an image decoding apparatus that performs motion compensation prediction, and includes a code string analysis unit (201) that acquires information for specifying a prediction vector from an encoded stream, and a plurality of blocks adjacent to a decoding target block. A spatial prediction vector candidate generation unit (150) that checks a motion vector of a block including a motion vector as a spatial prediction vector candidate by checking in the first order, and a plurality of blocks adjacent to the decoding target block in a second order A spatial scaling prediction vector candidate generation unit (152) that uses a scaling motion vector obtained by scaling the motion vector of the block including the motion vector as a spatial scaling prediction vector candidate, and at least the spatial prediction vector candidate and the spatial scaling prediction Candidate list generation to generate a candidate list containing vector candidates (220) and a prediction vector for selecting a prediction vector of the decoding target block from prediction vector candidates included in the candidate list based on information for specifying the prediction vector acquired from the encoded stream And a selection unit (221).

  Yet another embodiment of the present invention is also an image decoding device. This apparatus is an image decoding apparatus that performs motion compensation prediction, a candidate list generation unit (220) that generates a candidate list by selecting a block including a motion vector from a plurality of blocks adjacent to a decoding target block, A code string analysis unit (201) for acquiring information for specifying a prediction vector indicating a position of a prediction vector in the candidate list, a difference vector, and information for specifying a reference image of the decoding target block from a stream A prediction vector selection unit (221) that selects a prediction vector of the decoding target block from prediction vector candidates included in the candidate list based on information for specifying the prediction vector; and the prediction vector And the difference vector to calculate a motion vector of the decoding target block Includes a 222), the. When the information for specifying the prediction vector is a predetermined value, the information for specifying the reference image is omitted.

  Yet another aspect of the present invention is an image decoding method. This method is an image decoding method for performing motion compensation prediction, the step of obtaining information for specifying a reference image used for motion compensation of a decoding target block from an encoded stream, and a motion vector of the decoding target block Generating a predicted vector candidate. The step of generating the prediction vector candidate sets a step of determining a reference motion vector from motion vectors of decoded blocks adjacent to the decoding target block, and information for specifying a reference image for scaling And scaling the reference motion vector based on information for identifying the reference image for scaling. In the step of setting information for specifying the reference image for scaling, the reference image for scaling is determined without depending on the reference image used for motion compensation of the decoding target block.

  Yet another embodiment of the present invention is also an image decoding method. This method is an image decoding method for performing motion compensation prediction, wherein a block including a motion vector is selected from a plurality of blocks adjacent to a decoding target block to generate a prediction vector candidate list; and Selecting a block including motion information including at least reference image information and a motion vector from a plurality of adjacent blocks to generate a combined motion information candidate list; a first prediction mode using the prediction vector candidate list; and the combining A step of selecting which prediction mode of the second prediction mode using the motion information candidate list is to be used; and information for specifying the prediction mode from the encoded stream is acquired, and the prediction mode is the first prediction mode. In this case, the prediction vector in the prediction vector candidate list is encoded from the encoded stream. Information for specifying a prediction vector indicating the position of the toll, a difference vector, and information for specifying a reference image of the decoding target block, and when the prediction mode is the second prediction mode, the code The prediction vector candidate list based on information for specifying motion information indicating the position of motion information in the combined motion information candidate list from the stream, and information for specifying the prediction vector Selecting a prediction vector of the decoding target block from prediction vector candidates included in the block, adding the prediction vector and the difference vector to reproduce the motion vector of the decoding target block, and the motion information Based on the information for specifying, from the motion information candidates included in the combined motion information candidate list, A step of selecting motion information of a block to be decoded; and, when the prediction mode is the first prediction mode, prediction is performed using a reference image specified by information for specifying the reference image and the reproduced motion vector A signal is generated, and when the prediction mode is the second prediction mode, a reference image specified by reference image information included in the selected motion information and a motion vector included in the selected motion information are used. Generating a prediction signal, and scaling a motion vector of a block that is a decoded block adjacent to the decoding target block and is included in an image temporally different from the image including the decoding target block, and Prepare. The scaled motion vector is shared by the first prediction mode and the second prediction mode.

  Yet another embodiment of the present invention is an image encoding device. The apparatus is an image encoding apparatus that performs motion compensated prediction, and includes a motion vector detection unit (108) that detects a motion vector for obtaining a prediction signal of an encoding target block, and a reference image including the prediction signal A code string generation unit (104) that encodes information for specifying a motion vector and a prediction vector candidate generation unit (151 and 152) for generating a motion vector prediction vector candidate. The prediction vector candidate generation unit (151 and 152) includes a reference vector determination unit (170 and 175) that determines a reference motion vector from motion vectors of an encoded block adjacent to the encoding target block, and scaling. A reference image information setting unit (171 and 176) for setting information for specifying a reference image for scaling, and a scaling unit for scaling the reference motion vector based on the information for specifying the reference image for scaling ( 172, 177). The reference image information setting unit (171 and 176) determines the reference image for scaling without depending on the reference image including the prediction signal. The “encoded block adjacent to the encoding target block” may be a block spatially adjacent to the encoding target block or a temporally adjacent block.

  Yet another embodiment of the present invention is also an image encoding device. The apparatus is an image encoding apparatus that performs motion compensation prediction, generates a motion vector for obtaining a prediction signal of an encoding target block, and makes the prediction vector of the motion vector adjacent to the encoding target block A first prediction mode to be obtained based on a motion vector selected from motion vectors of encoded blocks to be encoded and a motion vector selected from motion vectors of encoded blocks adjacent to the encoding target block. A prediction mode determination unit (122) that obtains a motion vector to be used for motion compensation based on the motion vector and selects one of the second prediction modes for generating a prediction signal of the coding target block using the motion vector; An encoded block adjacent to the encoding target block that is temporally different from an image including the encoding target block. It comprises a scaling unit (172) for scaling the motion vectors of blocks included in the. The motion vector scaled by the scaling unit is shared by the first prediction mode and the second prediction mode.

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

  ADVANTAGE OF THE INVENTION According to this invention, the moving image decoding technique which can improve the prediction precision of a motion vector can be provided, suppressing the delay time required for the production | generation of the candidate of a prediction vector.

It is a figure for demonstrating the example which divides | segments an image into the largest encoding block. 2A and 2B are diagrams for explaining an encoded block. 3A to 3D are diagrams for explaining a prediction block. It is a figure for demonstrating a prediction block size. It is a figure for demonstrating prediction encoding mode. It is a figure for demonstrating an example of the syntax of a prediction block. FIGS. 7A and 7B are diagrams illustrating code strings of the merge index and the prediction vector index according to the embodiment of the present invention. It is a figure which shows the structure of the moving image encoder which concerns on Embodiment 1 of this invention. It is a flowchart for demonstrating operation | movement of a moving image encoder. It is a figure which shows a mode in case the prediction block size of a process target is 16 pixels x 16 pixels. It is a figure which shows the structure of a motion information generation part. It is a flowchart for demonstrating operation | movement of a motion information generation part. It is a figure which shows the structure of a prediction vector mode determination part. It is a flowchart for demonstrating operation | movement of a prediction vector mode determination part. It is a figure which shows the adjacent block of the prediction block of a process target in case the prediction block size of a process target is 16 pixels x 16 pixels. It is a figure which shows the block in the prediction block on ColPic in the same position as the prediction block of a process target in case the prediction block size of a process target is 16 pixels x 16 pixels, and its peripheral block. It is a figure for demonstrating the structure of a prediction vector candidate list production | generation part. It is a flowchart for demonstrating operation | movement of a prediction vector candidate list production | generation part. It is a flowchart for demonstrating operation | movement of a spatial prediction vector candidate production | generation part. It is a figure for demonstrating the structure of a time prediction vector candidate production | generation part. It is a flowchart for demonstrating operation | movement of a time prediction vector candidate production | generation part. It is a figure for demonstrating the calculation method of a time prediction vector candidate. It is a figure for demonstrating the structure of a spatial scaling prediction vector candidate production | generation part. It is a flowchart for demonstrating operation | movement of a spatial scaling prediction vector candidate production | generation part. It is a figure for demonstrating the calculation method of a spatial scaling prediction vector candidate. It is a flowchart for demonstrating the operation | movement of determination of a prediction vector candidate list. It is a figure for demonstrating the structure of a merge mode determination part. It is a flowchart for demonstrating operation | movement of a merge mode determination part. It is a figure for demonstrating the structure of a joint motion information candidate list production | generation part. It is a flowchart for demonstrating operation | movement of a joint motion information candidate list production | generation part. It is a flowchart for demonstrating operation | movement of a space joint motion information candidate production | generation part. It is a figure for demonstrating the structure of a time combination motion information candidate production | generation part. It is a flowchart for demonstrating operation | movement of a time combination motion information candidate production | generation part. It is a figure for demonstrating the structure of a spatial scaling joint motion information candidate production | generation part. It is a flowchart for demonstrating operation | movement of a spatial scaling joint motion information candidate production | generation part. It is a flowchart for demonstrating the operation | movement of the determination of a joint motion information candidate list. 1 is a diagram illustrating a moving image decoding apparatus according to Embodiment 1. FIG. It is a flowchart for demonstrating operation | movement of a moving image decoding apparatus. It is a figure which shows the structure of a motion information reproduction part. It is a figure which shows the structure of a motion vector reproduction | regeneration part. It is a flowchart for demonstrating operation | movement of a motion vector reproduction | regeneration part. It is a figure which shows the structure of a joint motion information reproduction part. It is a flowchart for demonstrating operation | movement of a joint motion information reproduction | regeneration part. 10 is a flowchart for explaining an operation of a prediction vector candidate list generation unit in Modification 1 of Embodiment 1. 10 is a diagram for describing an example of a syntax of a prediction block according to Embodiment 2. FIG. 12 is a flowchart for explaining an operation of a prediction vector mode determination unit according to the second embodiment. 10 is a flowchart for explaining an operation of a prediction vector candidate list determination unit according to the second embodiment.

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

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

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

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

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

  In the standardization of HEVC, a plurality of adjacent blocks and another decoded block of images are used as a candidate block group, and an optimal candidate block is selected as a prediction block from these candidate block groups, and information on the selected candidate block is encoded. Techniques for converting and decoding are being studied.

  In HEVC, introduction of a prediction vector mode (also referred to as a motion detection mode) and a merge mode are being studied. In the prediction vector mode, a prediction vector is generated from the motion vector of the selected candidate block, and the prediction vector and the difference vector of the processing target block are added to reproduce the motion vector of the processing target block. In the merge mode, motion information including the prediction direction of motion compensation prediction of the selected candidate block, reference image information, and motion vector information is used as motion information of the processing target block.

  In prediction vector mode and merge mode, when a candidate block of another decoded image is selected as a prediction block, an operation called scaling according to the inter-image distance between the processing target image and the reference image in motion vector reproduction Is done. However, since the reference images to be scaled are different in the prediction vector mode and the merge mode, it is necessary to reproduce different motion vectors in the prediction vector mode and the merge mode, which makes it difficult to share the scaling calculation unit. Yes.

  In the merge mode, scaling can be performed immediately after the prediction block size is determined, but in the prediction vector mode, scaling cannot be performed until the decoding of the reference image information is completed. Therefore, either the merge mode or the prediction vector mode is selected. There is a restriction that scaling cannot be performed until it is fixed.

  Further, in the prediction vector mode, when a motion vector in a certain prediction direction of an adjacent block is insufficient, a motion vector obtained by scaling a motion vector in the opposite direction from the same candidate block group is used as a new prediction vector candidate. be able to. However, since the scaled motion vector is used as an alternative candidate for the motion vector of the adjacent block, there is a problem that the scaled motion vector cannot be used effectively.

(Encoding block)
In the embodiment of the present invention, an input image signal is divided into maximum coding block units as shown in FIG. 1, and the divided coding blocks are processed in a raster scan order. FIG. 1 is a diagram for explaining an example in which an image is divided into maximum coding blocks. The encoded block has a hierarchical structure, and can be made smaller encoded blocks by sequentially equally dividing into 4 in consideration of the encoding efficiency. Note that the encoded blocks divided into four are encoded in the zigzag scan order. An encoded block that cannot be further reduced is called a minimum encoded block. An encoded block is a unit of encoding, and the maximum encoded block is also an encoded block when the number of divisions is zero. In this embodiment, the maximum coding block is 64 pixels × 64 pixels, and the minimum coding block is 8 pixels × 8 pixels.

  2A and 2B are diagrams for explaining an encoded block. In the example of FIG. 2A, the encoded block is divided into ten. CU0, CU1 and CU9 are 32 × 32 pixel coding blocks, CU2, CU3 and CU8 are 16 × 16 pixel coding blocks, and CU4, CU5, CU6 and CU7 are 8 × 8 pixel coding blocks. It has become. In the example of FIG. 2B, the encoded block is divided into one.

(Prediction block)
In the embodiment of the present invention, the encoded block is further divided into prediction blocks. 3A to 3D are diagrams for explaining a prediction block. 3A is 2N × 2N that does not divide the encoded block, FIG. 3B is 2N × N that is horizontally divided, FIG. 3C is N × 2N that is vertically divided, and FIG. 3D. Indicates N × N divided horizontally and vertically. FIG. 4 is a diagram for explaining the prediction block size. In other words, as shown in FIG. 4, the prediction block size includes a CU division number of 0 and a maximum prediction block size of 64 pixels × 64 pixels to a CU division number of 3 and a minimum prediction block size. There are 13 predicted block sizes up to 4 pixels x 4 pixels.

  In the embodiment of the present invention, the maximum coding block is 64 pixels × 64 pixels and the minimum coding block is 8 pixels × 8 pixels, but the present invention is not limited to this combination. Further, although the prediction block division patterns are shown in FIGS. 3A to 3D, the division is not limited to this as long as it is divided into one or more.

(Predictive coding mode)
In the embodiment of the present invention, motion-compensated prediction and the number of encoded vectors can be switched according to the block size of the prediction block. Here, an example of a predictive coding mode in which motion compensation prediction is associated with the number of coding vectors will be briefly described with reference to FIG. FIG. 5 is a diagram for explaining the predictive coding mode.

  In the predictive coding mode shown in FIG. 5, the prediction direction of motion compensation prediction is single prediction (L0 prediction) and the number of coding vectors is PredL0, and the prediction direction of motion compensation prediction is single prediction (L1 prediction). PredL1 in which the number of encoding vectors is 1, PredBI in which the prediction direction of motion compensation prediction is bi-prediction (BI prediction) and the number of encoding vectors is 2, and the prediction direction in motion compensation prediction is single prediction ( There is a merge mode (MERGE) which is L0 prediction / L1 prediction) or bi-prediction (BI prediction) and the number of encoding vectors is zero. There is also an intra mode (Intra) which is a predictive coding mode in which motion compensation prediction is not performed. Here, PredL0, PredL1, and PredBI are prediction vector modes.

(Reference index)
In the embodiment of the present invention, it is possible to select an optimal reference image from a plurality of reference images in motion compensation prediction in order to improve the accuracy of motion compensation prediction. Therefore, the reference image used in motion compensation prediction is encoded as a reference image index together with the encoded vector. The reference image index used in motion compensation prediction is a numerical value of 0 or more. If the motion compensation prediction is uni-prediction, one reference index is used, and if the motion compensation prediction is bi-prediction, two reference indexes are used (FIG. 5).

(Reference index list)
In the embodiment of the present invention, a plurality of reference images that can be used in motion compensation prediction are registered in the reference index list, and the reference image registered in the reference index list is indicated by the reference index to determine the reference image. And used in motion compensated prediction. The reference index list includes a reference index list L0 and a reference index list L1. When the motion compensation prediction is simple prediction, either L0 prediction using a reference image in the reference index list L0 or L1 prediction using a reference image in the reference index list L1 is used. In the case of bi-prediction, BI prediction using the reference index list L0 and the reference index list L1 is used.

(Merge index)
In the embodiment of the present invention, in order to improve the coding efficiency, the motion of a candidate block is determined by setting a plurality of adjacent blocks and blocks around the same position as the processing target block of another coded image as candidate blocks. A candidate block having optimal motion information is selected from the information, and a merge index for indicating the selected candidate block is encoded and decoded. This is a motion compensation prediction technique (merge technique) that uses motion information including a prediction direction, motion vector information, and reference image information of a block indicated by a selected merge index in a processing target block. One merge index is used when the predictive coding mode is the merge mode (FIG. 5). If the motion information is bi-predicted, the motion information includes two pieces of motion vector information and reference image information. The maximum number of candidate blocks that can be selected by the merge index (hereinafter referred to as the maximum number of merge candidates) is 5, and the merge index is an integer from 0 to 4. Here, although the maximum number of merge candidates is set to 5, it may be 2 or more, and is not limited to this.

  Hereinafter, the motion information of the candidate block that is the target of the merge index is referred to as a combined motion information candidate, and the aggregate of combined motion information candidates is referred to as a combined motion information candidate list.

(Predicted vector index)
In the embodiment of the present invention, in order to improve the accuracy of a prediction vector, a plurality of adjacent blocks and blocks around the same position as a processing target block of another encoded image are used as candidate blocks. A candidate block having an optimal motion vector as a prediction vector is selected from the motion vectors, and a prediction vector index for indicating the selected candidate block is encoded and decoded. If the motion compensation prediction is uni-prediction, one prediction vector index is used, and if the motion compensation prediction is bi-prediction, two prediction vector indexes are used (FIG. 5). The maximum number of candidate blocks that can be selected with each prediction vector index (hereinafter referred to as the maximum number of prediction vector candidates) is 2, and the prediction vector index is an integer of 0 or 1. Although the maximum number of prediction vector candidates is 2 here, it may be 2 or more, and is not limited to this.

  Hereinafter, a motion vector of a candidate block that is a target of a prediction vector index is referred to as a prediction vector candidate, and a set of prediction vector candidates is referred to as a prediction vector candidate list.

  In the embodiment of the present invention, the maximum number of merge candidates is set to 5 and the maximum number of prediction vector candidates is set to 2, but any one may be 2 or more and is not limited to this combination.

(Syntax)
An example of the syntax of the prediction block according to the embodiment of the present invention will be described with reference to FIG. Whether the prediction block is intra or inter is specified by the higher-order encoding block, and FIG. 6 shows the syntax of the prediction block when the prediction block is inter. The prediction block includes a merge flag (merge_flag), a merge index (merge_idx), an inter prediction mode (inter_pred_type), a reference index (ref_idx_l0 and ref_idx_l1), and a difference vector (mvd_l0 [0], mvd_l0 [1], mvd_l mvd_l1 [1]) and prediction vector indexes (mvp_idx_l0 and mvp_idx_l1) are installed. [0] of the difference vector indicates a horizontal component and [1] indicates a vertical component.

  Here, ref_idx_l0, mvd_l0 [0], mvd_l0 [1], and mvp_idx_l0 are information related to L0 prediction, and ref_idx_l1 and mvd_l1 [0], mvd_l1 [1], and mvp_idx_l1 are information related to L1 prediction. inter_pred_type indicates the prediction direction of motion compensation prediction, and there are three types: Pred_L0 (single prediction of L0 prediction), Pred_L1 (single prediction of L1 prediction) and Pred_BI (bi prediction of BI).

  Although the syntax of the prediction block according to the embodiment of the present invention is set as shown in FIG. 6, according to the embodiment of the present invention, it is sufficient that the reference index is included in the prediction vector mode. It is not limited to.

(Code sequence of merge index and prediction vector index)
Next, the code strings of the merge index and the prediction vector index will be described. FIGS. 7A and 7B are diagrams illustrating code strings of the merge index and the prediction vector index according to the embodiment of the present invention. A Truncated Unary code string is used as the code string. FIG. 7A shows the code sequence of the merge index, and FIG. 7B shows the code sequence of the prediction vector index.

  As can be seen from FIGS. 7 (a) and 7 (b), since the code sequence is shorter in the smaller merge index (the code amount is smaller), encoding is performed by assigning a smaller merge index to a candidate having a relatively high selection rate. Efficiency can be improved.

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

  Hereinafter, with reference to the drawings, details of a moving image encoding apparatus, a moving image encoding method, a moving image encoding program, a moving image decoding apparatus, a moving image decoding method, and a moving image decoding program according to a preferred embodiment of the present invention will be described. explain. In the description of the drawings, the same elements are denoted by the same reference numerals and redundant description is omitted.

[Embodiment 1]
(Configuration of moving picture coding apparatus 100)
FIG. 8 shows a configuration of moving picture coding apparatus 100 according to Embodiment 1 of the present invention. The moving image encoding apparatus 100 is an apparatus that encodes a moving image signal in units of prediction blocks for performing motion compensated prediction. It is assumed that the coding block is divided, the prediction block size is determined, and whether the prediction coding mode is intra is determined by an upper coding control unit (not shown). In the first embodiment, the prediction coding mode is A case where it is not an intra will be described. In the first embodiment, a B picture corresponding to bi-prediction will be described, but L1 prediction may be omitted for a P picture not corresponding to bi-prediction.

  The moving image encoding apparatus 100 is realized by hardware such as an information processing apparatus including a CPU (Central Processing Unit), a frame memory, and a hard disk. The moving image encoding apparatus 100 realizes functional components described below by operating the above components. Note that the position information of the prediction block to be processed, the prediction block size, and the prediction direction of motion compensated prediction are assumed to be shared in the video encoding device 100 and are not shown.

  The moving image encoding apparatus 100 according to Embodiment 1 includes a prediction block image acquisition unit 101, a subtraction unit 102, a prediction error encoding unit 103, a code string generation unit 104, a prediction error decoding unit 105, a motion compensation unit 106, and an addition unit. 107, a motion vector detection unit 108, a motion information generation unit 109, a frame memory 110, and a motion information memory 111.

(Operation of moving picture coding apparatus 100)
Hereinafter, the function and operation of each unit will be described. FIG. 9 is a flowchart for explaining the operation of the moving picture coding apparatus 100. The prediction block image acquisition unit 101 acquires the image signal of the prediction block to be processed from the image signal supplied from the terminal 10 based on the position information and the prediction block size of the prediction block (S100), and the image signal of the prediction block Is supplied to the subtraction unit 102, the motion vector detection unit 108, and the motion information generation unit 109.

  The motion vector detection unit 108 obtains motion vectors and reference images of the L0 prediction and the L1 prediction from the image signal supplied from the prediction block image acquisition unit 101 and image signals corresponding to a plurality of reference images stored therein. The indicated reference index is detected (S101). The motion vector of the L0 prediction and the L1 prediction and the reference index of the L0 prediction and the L1 prediction are supplied to the motion information generation unit 109. Here, the number of reference images for L0 prediction and L1 prediction is 3 respectively. In the first embodiment, the number of reference images for L0 prediction and L1 prediction is three, but the number of reference images for L0 prediction and L1 prediction only needs to be one or more, and is not limited thereto.

  A general motion vector detection method calculates an error evaluation value for an image signal of a target image and a prediction signal of a reference image moved by a predetermined movement amount from the same position, and a movement amount that minimizes the error evaluation value. Is a motion vector. When there are a plurality of reference images, a motion vector is detected for each reference image, and a reference image having a minimum error evaluation value is selected. As the error evaluation value, SAD (Sum of Absolute Difference) indicating the sum of absolute differences, MSE (Mean Square Error) indicating the mean square error, or the like can be used.

  The motion information generation unit 109 includes the motion vectors of the L0 prediction and the L1 prediction supplied from the motion vector detection unit 108, the reference index of the L0 prediction and the L1 prediction, the candidate block group supplied from the motion information memory 111, and the frame memory 110. The predictive coding mode is determined from the reference image indicated by the reference index and the image signal supplied from the prediction block image acquisition unit 101 (S102).

  Based on the determined predictive coding mode, the merge flag, the merge index, the prediction direction of motion compensation prediction, the reference index of L0 prediction and L1 prediction, the difference vector of L0 prediction and L1 prediction, and the prediction vector of L0 prediction and L1 prediction The index is supplied to the code string generation unit 104 as necessary. The motion compensation prediction direction, the reference index of L0 prediction and L1 prediction, and the motion vector of L0 prediction and L1 prediction are supplied to the motion compensation unit 106 and the motion information memory 111. Details of the motion information generation unit 109 will be described later.

  If the prediction direction of the motion compensation prediction supplied from the motion information generation unit 109 is LN prediction, the motion compensation unit 106 stores the frame compensation information in the frame memory 110 indicated by the LN prediction reference index supplied from the motion information generation unit 109. The reference image is motion-compensated based on the LN prediction motion vector supplied from the motion information generation unit 109 to generate a prediction signal for LN prediction (S103). N is 0 or 1. If the prediction direction of motion compensation prediction is bi-prediction, the average value of the prediction signals of L0 prediction and L1 prediction is the prediction signal. The motion compensation unit 106 supplies the prediction signal to the subtraction unit 102.

  The subtraction unit 102 calculates a prediction error signal by subtracting the image signal supplied from the prediction block image acquisition unit 101 and the prediction signal supplied from the motion compensation unit 106 (S104), and calculates the prediction error signal as a prediction error code. To the conversion unit 103.

  The prediction error encoding unit 103 performs processing such as quantization and orthogonal transformation on the prediction error signal supplied from the subtraction unit 102 to generate prediction error encoded data (S105), and the prediction error encoding Data is supplied to the code string generation unit 104 and the prediction error decoding unit 105.

  The code string generation unit 104 includes prediction error encoded data supplied from the prediction error encoding unit 103, a merge flag, a merge index, and a motion compensation prediction prediction direction (inter prediction mode) supplied from the motion information generation unit 109. , L0 prediction and L1 prediction reference index, L0 prediction and L1 prediction difference vector and L0 prediction and L1 prediction prediction vector index are entropy-coded according to the syntax to generate a code string (S106), and the code string is a terminal 11 is supplied. Entropy coding is performed by a method including variable length coding such as arithmetic coding or Huffman coding.

  The prediction error decoding unit 105 performs a process such as inverse quantization or inverse orthogonal transform on the prediction error encoded data supplied from the prediction error encoding unit 103 to generate a prediction error signal, and the prediction error signal Is supplied to the adder 107. The addition unit 107 adds the prediction error signal supplied from the prediction error decoding unit 105 and the prediction signal supplied from the motion compensation unit 106 to generate a decoded image signal (S107), and the decoded image signal is stored in the frame memory. 110.

  The frame memory 110 stores the decoded image signal supplied from the adding unit 107 (S108). In addition, for a decoded image in which decoding of the entire image is completed, a predetermined number of images of 1 or more is stored as a reference image. The frame memory 110 supplies the stored reference image signal to the motion compensation unit 106 and the motion information generation unit 109. A storage area for storing the reference image is controlled by a FIFO (First In First Out) method.

  The motion information memory 111 stores the motion information supplied from the motion information generation unit 109 for a predetermined number of images in units of the minimum predicted block size (S109). The motion information of the adjacent block of the prediction block to be processed is set as a space candidate block group.

  In addition, the motion information memory 111 sets the motion information of the block on the ColPic located in the same position as the prediction block to be processed and its neighboring blocks as a time candidate block group. The motion information memory 111 supplies the spatial candidate block group and the temporal candidate block group to the motion information generation unit 109 as candidate block groups. The motion information memory 111 is synchronized with the frame memory 110 and is controlled by a FIFO (First In First Out) method.

  Here, ColPic refers to a decoded image different from the prediction block to be processed and stored in the frame memory 110 as a reference image. In Embodiment 1, ColPic is a reference image decoded immediately before. In Embodiment 1, ColPic is a reference image decoded immediately before. However, it may be an encoded image, for example, a reference image immediately before in display order or a reference image immediately after in display order may be used. It can also be specified in the encoded stream.

  Here, a method of managing motion information in the motion information memory 111 will be described with reference to FIG. The motion information is stored in each memory area in units of the smallest prediction block. FIG. 10 shows a state where the predicted block size to be processed is 16 pixels × 16 pixels. In this case, the motion information of the prediction block is stored in 16 memory areas indicated by hatching in FIG.

  When the predictive coding mode is the intra mode, (0, 0) is stored as a motion vector for L0 prediction and L1 prediction, and “−1” is stored as a reference index for L0 prediction and L prediction. Hereinafter, in the motion vector (H, V), H represents a horizontal component and V represents a vertical component. The reference index “−1” may be any value as long as it can be determined that the mode in which motion compensation prediction is not performed. From this point onward, unless expressed otherwise, the term “block” refers to the smallest predicted block unit when expressed simply as a block. Also, in the case of a block outside the area, (0, 0) is stored as a motion vector for L0 prediction and L1 prediction, and “−1” is stored as a reference index for L0 prediction and L1 prediction, as in the intra mode. The When the LX direction (X is 0 or 1) is valid, the reference index in the LX direction is 0 or more, and when the LX direction is invalid (not valid), the reference index in the LX direction is “−1”. It is to be.

(Configuration of the motion information generation unit 109)
Next, a detailed configuration of the motion information generation unit 109 will be described. FIG. 11 shows the configuration of the motion information generation unit 109. The motion information generation unit 109 includes a prediction vector mode determination unit 120, a merge mode determination unit 121, and a prediction encoding mode determination unit 122. The terminal 12 is in the motion information memory 111, the terminal 13 is in the motion vector detection unit 108, the terminal 14 is in the frame memory 110, the terminal 15 is in the prediction block image acquisition unit 101, the terminal 16 is in the code string generation unit 104, and the terminal 50 Are connected to the motion compensation unit 106, and the terminal 51 is connected to the motion information memory 111, respectively.

(Operation of the motion information generation unit 109)
Hereinafter, the function and operation of each unit will be described. FIG. 12 is a flowchart for explaining the operation of the motion information generation unit 109. The prediction vector mode determination unit 120 includes a candidate block group supplied from the terminal 12, a motion vector for L0 prediction and L1 prediction supplied from the terminal 13, a reference index for L0 prediction and L1 prediction, and a reference index supplied from the terminal 14. One prediction encoding mode is determined from each prediction encoding mode (prediction vector modes PredL0, PredL1, and PredBi) from the reference image indicated by (2) and the image signal supplied from the terminal 15 (S110), and rate distortion evaluation is performed. Calculate the value. Then, motion information, a difference vector, a prediction vector index, and a rate distortion evaluation value based on the prediction coding mode are supplied to the prediction coding mode determination unit 122. Details of the prediction vector mode determination unit 120 will be described later.

  The merge mode determination unit 121 generates a combined motion information candidate list from the candidate block group supplied from the terminal 12, the reference image supplied from the terminal 14, and the image signal supplied from the terminal 15, and the combined motion information One merged motion information candidate is selected from the candidate list to determine a merge index (S111), and a rate distortion evaluation value is calculated. Then, the motion information of the combined motion information candidate, the merge index, and the rate distortion evaluation value are supplied to the predictive coding mode determination unit 122. Details of the merge mode determination unit 121 will be described later.

  The predictive coding mode determination unit 122 compares the rate distortion evaluation value supplied from the prediction vector mode determination unit 120 with the rate distortion evaluation value supplied from the merge mode determination unit 121 to determine a merge flag (S112). ).

  If the former is less than the latter, the merge flag is set to “0”. The prediction coding mode determination unit 122 inputs the merge flag, the prediction direction of motion compensation prediction based on each prediction coding mode, the reference index supplied from the prediction vector mode determination unit 120, the difference vector, and the prediction vector index to the terminal 16. The motion information supplied from the prediction vector mode determination unit 120 is supplied to the terminal 50 and the terminal 51.

  If the latter is less than or equal to the former, the merge flag is set to “1”. The predictive coding mode determination unit 122 supplies the merge flag and the merge index supplied from the merge mode determination unit 121 to the terminal 16, and supplies the motion information supplied from the merge mode determination unit 121 to the terminal 50 and the terminal 51. To do. Although a specific calculation method of the rate distortion evaluation value is not the main point of the present invention, the details thereof will be omitted. However, the evaluation value has a characteristic that the encoding efficiency increases as the rate distortion evaluation value decreases.

(Configuration of Predictive Vector Mode Determination Unit 120)
Subsequently, a detailed configuration of the prediction vector mode determination unit 120 will be described. FIG. 13 shows the configuration of the prediction vector mode determination unit 120. The prediction vector mode determination unit 120 includes a prediction vector candidate list generation unit 130, a prediction vector determination unit 131, and a subtraction unit 132. The terminal 17 is connected to the predictive coding mode determination unit 122.

  The prediction vector candidate list generation unit 130 is also installed in the video decoding apparatus 200 that decodes the code sequence generated by the video encoding apparatus 100 according to Embodiment 1 in the same manner as the video encoding apparatus 100. The motion picture decoding apparatus 200 generates a prediction vector candidate list having no contradiction.

(Operation of prediction vector mode determination unit 120)
Hereinafter, the function and operation of each unit will be described. FIG. 14 is a flowchart for explaining the operation of the prediction vector mode determination unit 120.

  The prediction vector candidate list generation unit 130 generates a prediction vector candidate list for L0 prediction including the maximum number of prediction vector candidates from the candidate block group supplied from the terminal 12 (S120). The prediction vector candidate list generation unit 130 supplies the prediction vector candidate list for the L0 prediction to the prediction vector determination unit 131.

  The prediction vector determination unit 131 selects one prediction vector candidate as a prediction vector for L0 prediction from the prediction vector candidate list for L0 prediction supplied from the prediction vector candidate list generation unit 130, and determines a prediction vector index for L0 prediction. Then, the prediction vector of the L0 prediction is supplied to the subtraction unit 132 (S121).

  The subtraction unit 132 subtracts the L0 prediction prediction vector supplied from the prediction vector determination unit 131 from the L0 prediction motion vector supplied from the terminal 13 to calculate an L0 prediction difference vector (S122). Are supplied to the prediction vector determination unit 131.

  The prediction vector determination unit 131 motion-predicted the image signal supplied from the terminal 15 and the reference image supplied from the terminal 14 based on the L0 prediction motion vector and the L0 prediction reference index supplied from the terminal 13. Pred_L0 rate distortion evaluation value is calculated from the prediction error amount from the prediction signal of the L0 prediction, and from the prediction error amount, the difference vector of the L0 prediction, the reference index of the L0 prediction, and the code amount of the prediction vector index of the L0 prediction Is calculated (S123).

  The prediction vector candidate list generation unit 130 generates a prediction vector candidate list for L1 prediction including the maximum number of prediction vector candidates from the candidate block group supplied from the terminal 12 (S124). The prediction vector candidate list generation unit 130 supplies the prediction vector candidate list for the L1 prediction to the prediction vector determination unit 131.

  The prediction vector determination unit 131 selects one prediction vector candidate from the prediction vector candidate list for L1 prediction supplied from the prediction vector candidate list generation unit 130 as a prediction vector for L1 prediction, and determines a prediction vector index for L1 prediction. (S125), the prediction vector of the L1 prediction is supplied to the subtraction unit 132.

  The subtraction unit 132 subtracts the L1 prediction prediction vector supplied from the prediction vector determination unit 131 from the L1 prediction motion vector supplied from the terminal 13 to calculate an L1 prediction difference vector (S126). Are supplied to the prediction vector determination unit 131.

  The prediction vector determination unit 131 motion-predicted the image signal supplied from the terminal 15 and the reference image supplied from the terminal 14 based on the L1 prediction motion vector and the L1 prediction reference index supplied from the terminal 13. Pred_L1 rate distortion evaluation value is calculated from the prediction error amount from the prediction signal of the L1 prediction, and the prediction error amount, the difference vector of the L1 prediction, the reference index of the L1 prediction, and the code amount of the prediction vector index of the L1 prediction Is calculated (S127).

  The prediction vector determination unit 131 calculates a prediction error amount from the image signal supplied from the terminal 15 and the prediction signal of BI prediction obtained by averaging the prediction signal of L0 prediction and the prediction signal of L1 prediction, and the prediction error amount The Pred_BI rate distortion evaluation value is calculated from the difference vector between the L0 prediction and the L1 prediction, the reference index of the L0 prediction and the L1 prediction, and the code amount of the prediction vector index of the L0 prediction and the L1 prediction (S128).

  The prediction vector determination unit 131 compares the rate distortion evaluation value of Pred_L0, the rate distortion evaluation value of Pred_L1, and the rate distortion evaluation value of Pred_BI, and selects one prediction coding mode that is the minimum rate distortion evaluation value. (S129). Then, motion information, a difference vector, a prediction vector index, and a rate distortion evaluation value based on the prediction coding mode are supplied to the prediction coding mode determination unit 122. If the predictive coding mode is Pred_L0, the motion vector for L1 prediction is (0, 0), the reference index for L1 prediction is “−1”, and if the predictive coding mode is Pred_L1, the motion for L0 prediction. The vector is (0,0), and the reference index for L0 prediction is “−1”.

(Candidate block group supplied to prediction vector candidate list generation unit 130)
Here, the candidate block group supplied to the prediction vector candidate list production | generation part 130 is demonstrated using FIG. 15 and FIG. The candidate block group includes a spatial candidate block group and a temporal candidate block group.

  FIG. 15 shows adjacent blocks of a prediction block to be processed when the prediction block size to be processed is 16 pixels × 16 pixels. In the first embodiment, the space candidate block group is assumed to be five blocks of block A1, block C, block D, block B1, and block E shown in FIG. Here, the spatial candidate block group is five blocks of block A1, block C, block D, block B1, and block E, but the spatial candidate block group is at least one or more processed adjacent to the prediction block to be processed. Any block may be used, and the present invention is not limited to these. For example, all of block A1, block A2, block A3, block A4, block B1, block B2, block B3, block B4, block C, block D, and block E may be spatial candidate blocks.

  Next, the time candidate block group will be described with reference to FIG. FIG. 16 shows a block in a prediction block on ColPic and its peripheral blocks at the same position as the prediction block to be processed when the prediction block size to be processed is 16 pixels × 16 pixels. In the first embodiment, the time candidate block group includes two blocks, block H and block I6 shown in FIG.

  Here, the time candidate block group is two blocks of block H and block I6 on ColPic, but the time candidate block group is at least one block on a decoded image different from the prediction block to be processed. There is no limitation to these. For example, all of block I1 to block I16, block A1 to block A4, block B1 to block B4, block C, block D, block E, block F1 to block F4, block G1 to block G4 and block H on ColPic It may be a candidate block. Further, only the block H may be used. Hereinafter, unless otherwise specified, block A4 is referred to as block A, and block B4 is referred to as block B. Hereinafter, unless otherwise specified, blocks H and I6 are referred to as time blocks.

(Configuration of Predictive Vector Candidate List Generation Unit 130)
Next, a detailed configuration of the prediction vector candidate list generation unit 130 will be described. FIG. 17 is a diagram for explaining the configuration of the prediction vector candidate list generation unit 130. The terminal 18 is connected to the prediction vector determination unit 131. The prediction vector candidate list generation unit 130 includes a spatial prediction vector candidate generation unit 150, a temporal prediction vector candidate generation unit 151, a spatial scaling prediction vector candidate generation unit 152, a prediction vector candidate supplement unit 153, and a prediction vector candidate list determination unit 154. Including.

  The temporal prediction vector candidate generation unit 151 and the spatial scaling prediction vector candidate generation unit 152 are also installed in the combined motion information candidate list generation unit 140 according to the first embodiment.

(Operation of prediction vector candidate list generation unit 130)
Hereinafter, the function and operation of each unit will be described. FIG. 18 is a flowchart for explaining the operation of the prediction vector candidate list generation unit 130. The spatial prediction vector candidate generation unit 150 generates 0 to 2 spatial prediction vector candidates from the candidate block group supplied from the terminal 12 (S140), and supplies the spatial prediction vector candidates to the prediction vector candidate list determination unit 154. To do. The detailed operation of the spatial prediction vector candidate generation unit 150 will be described later.

  The temporal prediction vector candidate generation unit 151 generates zero or one temporal prediction vector candidate from the candidate block group supplied from the terminal 12 (S141), and supplies the temporal prediction vector candidate to the prediction vector candidate list determination unit 154. To do. Detailed operation of the temporal prediction vector candidate generation unit 151 will be described later.

  The spatial scaling prediction vector candidate generation unit 152 generates zero or one spatial scaling prediction vector candidate from the candidate block group supplied from the terminal 12 (S142), and the spatial scaling prediction vector candidate is a prediction vector candidate list determination unit. 154. The detailed operation of the spatial scaling prediction vector candidate generation unit 152 will be described later.

  The prediction vector candidate list determination unit 154 calculates the number of prediction vector supplements by subtracting the number of prediction vector candidates obtained by adding the spatial prediction vector candidates, temporal prediction vector candidates, and spatial scaling prediction vector candidates from the maximum number of prediction vector candidates. (S143) The prediction vector supplement candidate number is supplied to the prediction vector candidate supplement unit 153. Note that if the calculated number of prediction vector supplement candidates is less than zero, the number of prediction vector supplement candidates is zero.

  The prediction vector candidate supplementation unit 153 generates prediction vector supplementation candidates by the number of prediction vector supplementation candidates supplied from the prediction vector candidate list determination unit 154 (S144), and the prediction vector supplementation candidates are supplied to the prediction vector candidate list determination unit 154. Supply. The prediction vector supplement candidate is a motion vector (0, 0). Here, although the motion vector (0, 0) is used as the prediction vector supplement candidate, it may be a motion vector different from the spatial prediction vector candidate, temporal prediction vector candidate, and spatial scaling prediction vector candidate, and is not limited to this. For example, a motion vector in which the horizontal component and the vertical component of the spatial prediction vector candidate are +1 or −1 may be used.

  The prediction vector candidate list determination unit 154 sequentially selects the spatial prediction vector candidate, the temporal prediction vector candidate, the spatial scaling prediction vector candidate, and the prediction vector supplement candidate until the number of prediction vector candidates in the prediction vector candidate list reaches the maximum number of prediction vector candidates. Then, the prediction vector candidate list is confirmed by adding to the prediction vector candidate list (S145). The detailed operation for determining the prediction vector candidate list will be described later.

(Detailed operation of spatial prediction vector candidate generation unit 150)
Subsequently, a detailed operation of the spatial prediction vector candidate generation unit 150 will be described. FIG. 19 is a flowchart for explaining the operation of the spatial prediction vector candidate generation unit 150. If the prediction direction of the motion compensation prediction is uni-prediction, the spatial prediction vector candidate generation unit 150 generates zero to two spatial prediction vector candidates for L0 prediction or L1 prediction, and the prediction direction of motion compensation prediction is bi-prediction. If so, 0 to 2 spatial prediction vector candidates are generated for each of the L0 prediction and the L1 prediction. Hereinafter, the prediction direction of motion compensated prediction of a target for generating a spatial prediction vector candidate will be described as LX (X is 0 or 1). The spatial prediction vector candidate generation unit 150 repeatedly performs the following processing in the order of block E, block A1, block C, block B1, and block D on candidate blocks included in the spatial candidate block group supplied from the terminal 12 (from S150). S155). Here, the processing order is block E, block A1, block C, block B1, and block D, but the candidate blocks included in the spatial candidate block group only need to be processed at most once, and the present invention is not limited to this.

  It is checked whether the LX prediction of the candidate block does not require scaling (S151). That the LX prediction of the candidate block does not require scaling means that the reference index of the LX prediction of the candidate block is 0 or more. If the LX prediction of the candidate block does not require scaling (Y in S151), it is checked that the LX prediction motion vector of the candidate block is not the same as the already determined spatial prediction vector candidate (S152). If the LX prediction of the candidate block does not require scaling (N in S151), step S152 to step S154 are skipped and the next candidate block is inspected (S155). If the motion vector of the LX prediction of the candidate block is not the same as the already determined spatial prediction vector candidate (Y in S152), the LX prediction motion vector of the candidate block is determined as a spatial prediction vector candidate (S153). If the motion vector of the LX prediction of the candidate block is the same as the determined spatial prediction vector candidate (N in S152), step S153 and step S154 are skipped and the next candidate block is examined (S155). Following step S153, it is checked whether the number of spatial prediction vector candidates is a predetermined number (S154). Here, the predetermined number is 2. In the first embodiment, the predetermined number is set to 2, which is the same as the maximum number of prediction vector candidates. However, the predetermined number may be 1 or more and the number of candidate blocks included in the spatial candidate block group, and is not limited thereto. Moreover, the predetermined number of L0 prediction and L1 prediction can also be set to a different value. If the determined number of spatial prediction vector candidates is not a predetermined number (N in S154), the next candidate block is examined (S155). If the determined number of spatial prediction vector candidates is a predetermined number (Y in S154), the process ends.

  Here, the condition that the LX prediction of the candidate block does not need to be scaled is that the reference index of the LX prediction of the candidate block is 0 or more. However, the scaling is not limited to this as long as the scaling is unnecessary. For example, in order to improve the accuracy of the spatial prediction vector candidate, the LX prediction reference index of the encoding target block supplied from the terminal 13 is also supplied to the prediction vector candidate list generation unit 130 to refer to the LX prediction of the candidate block. For example, the index may be 0 or more, and the reference index for LX prediction of the current block and the reference index for LX prediction of the candidate block may be the same. The generation of the spatial prediction vector candidate does not require a scaling process, and the process is simple compared to the spatial scaling prediction vector candidate and the temporal prediction vector candidate. Therefore, in the generation of spatial prediction vector candidates, the delay time can be suppressed even when the LX prediction reference index of the encoding target block is used. In addition, here, the spatial prediction vector candidate whose prediction direction of motion compensation prediction is LX prediction is the motion vector of LX prediction of the candidate block, but it is sufficient that scaling is not necessary, and the present invention is not limited to this. For example, when the reference index of LY prediction of a candidate block is 0 or more and the reference index of LX prediction of the current block is the same as the reference index of LY prediction of the candidate block, the LY prediction motion of the candidate block The vector may be a spatial prediction vector candidate.

(Configuration of Temporal Prediction Vector Candidate Generation Unit 151)
Subsequently, a detailed configuration of the temporal prediction vector candidate generation unit 151 will be described. FIG. 20 is a diagram for explaining the configuration of the temporal prediction vector candidate generation unit 151. The temporal prediction vector candidate generation unit 151 includes a reference vector determination unit 170, a reference index setting unit 171, and a scaling unit 172. The terminal 20 is connected to the prediction vector candidate list determination unit 154.

(Detailed operation of temporal prediction vector candidate generation unit 151)
Hereinafter, the function and operation of each unit will be described. FIG. 21 is a flowchart for explaining the operation of the temporal prediction vector candidate generation unit 151. If the prediction direction of the motion compensation prediction is a single prediction, the temporal prediction vector candidate generation unit 151 generates zero or one temporal prediction vector candidate for the L0 prediction or the L1 prediction, and the prediction direction of the motion compensation prediction is a bi-prediction. If so, zero or one temporal prediction vector candidate is generated for each of the L0 prediction and the L1 prediction. Hereinafter, the prediction direction of motion compensated prediction for generating a temporal prediction vector candidate is described as LX (X is 0 or 1). The temporal prediction vector candidate generation unit 151 repeatedly performs the following processing in the order of block H and block I6 on candidate blocks included in the temporal candidate block group supplied from the terminal 12 (S160 to S166). Here, the processing order is block H and block I6, but the candidate blocks included in the time candidate block group only need to be processed once, and the present invention is not limited to this.

  It is checked whether the candidate block is valid (S161). The candidate block is valid when at least one of the reference index of the L0 prediction and the L1 prediction of the candidate block is 0 or more. If the candidate block is valid (Y in S161), the reference vector determination unit 170 determines a reference motion vector (S162). If the candidate block is not valid (N in S161), step S162 to step S165 are skipped and the next candidate block is inspected (S166).

  Here, the determination of the reference motion vector will be described. When the prediction direction of the motion compensation prediction of the candidate block is L0 prediction or L1 prediction, the motion vector in the prediction direction of the motion compensation prediction is selected as the reference motion vector. When the prediction direction of the motion compensated prediction of the candidate block is bi-prediction, either the L0 prediction or the L1 prediction is selected as the reference motion vector. For example, the direction where the motion vector of either the L0 prediction or the L1 prediction of the candidate block intersects the processing target image may be selected as the reference motion vector, or the motion vector in the same time direction as ColPic is selected as the reference motion vector Alternatively, a motion vector that is closer to the processing target image than either the L0 prediction or the L1 prediction reference image of the candidate block may be selected as the reference motion vector.

  Subsequent to step S162, the reference index setting unit 171 sets a reference index indicating a reference image for calculating a temporal prediction vector candidate for LX prediction to a predetermined value Ref_idx_TSscale (S163). The predetermined value Ref_idx_TSscale is a reference index that is most frequently used in LX prediction of block C, block D, and block E, which are spatial candidate blocks. Here, Ref_idx_TSscale is a reference index that is most frequently used in LX prediction of block C, block D, and block E, which are spatial candidate blocks. However, it may be a reference index that is not encoded into an encoded stream. It is not limited to. For example, a fixed value such as 0 or 1 may be used, or a reference index used in any candidate block (for example, block E) in the space candidate block group.

  Subsequent to step S163, the scaling unit 172 determines a motion vector obtained by scaling the reference motion vector as a temporal prediction vector candidate (S164). Following step S164, it is checked whether the determined number of temporal prediction vector candidates is a predetermined number (S165). Here, the predetermined number is 1. In the first embodiment, the predetermined number is 1. However, the predetermined number may be 1 or more and not more than the number of candidate blocks included in the time candidate block group, and is not limited thereto. Moreover, the predetermined number of L0 prediction and L1 prediction can also be set to a different value. If the determined number of temporal prediction vector candidates is not a predetermined number (N in S165), the next candidate block is examined (S166). If the determined number of spatial prediction vector candidates is a predetermined number (Y in S165), the process ends.

  Here, a method for calculating a temporal prediction vector candidate by scaling the reference motion vector will be described. FIG. 22 is a diagram for explaining a method of calculating temporal prediction vector candidates. The inter-image distance between ColPic and the reference image ColRefPic of the standard motion vector is ColDist, and the inter-image distance between the reference image RefPicL0 and the processing target image CurPic for calculating the L0 prediction temporal prediction vector candidate is CurL0Dist and L1 prediction. The inter-image distance between the reference image RefPicL1 and the processing target image CurPic for calculating the temporal prediction vector candidate is assumed to be CurL1Dist.

A motion vector obtained by scaling mvCol with the distance ratio of ColDist, CurL0Dist, and CurL1Dist according to the following Equation 1 is set as a temporal prediction vector candidate. mvL0t is a temporal prediction vector candidate for L0 prediction, and mvL1t is a temporal prediction vector candidate for L1 prediction. Here, the calculation of the inter-image distance is performed using the POC, and has a positive and negative sign. Division is rounded off.
mvL0t = mvCol × CurL0Dist / ColDist
mvL1t = mvCol × CurL1Dist / ColDist (Formula 1)

  Note that the time relationships of ColPic, ColRefPic, RefPicL0, and RefPicL1 in FIG. 22 are merely examples, and other time relationships may be used.

  As described above, by setting a reference image that does not depend on the reference index to be encoded in the encoded stream as a reference image for calculating the temporal prediction vector candidate, before decoding the reference index on the decoding side, More specifically, a temporal prediction vector candidate can be generated immediately after the prediction block size is determined. On the other hand, in the related art, particularly for L1 prediction, all of the merge flag, merge index, inter prediction mode, L0 prediction reference index, L0 prediction difference vector, L0 prediction prediction vector index, and L1 prediction reference index are all decoded. Otherwise, the temporal prediction vector candidate could not be generated. Furthermore, when these syntax elements include variable-length coding, it is difficult to perform parallel decoding of the syntax elements, and thus it is difficult to reduce the generation delay of the prediction vector candidate for L1 prediction. It was. Note that the reference image used in motion compensation prediction is a reference image indicated by a reference index to be encoded in the encoded stream.

(Configuration of Spatial Scaling Prediction Vector Candidate Generation Unit 152)
Next, a detailed configuration of the spatial scaling prediction vector candidate generation unit 152 will be described. FIG. 23 is a diagram for explaining the configuration of the spatial scaling prediction vector candidate generation unit 152. The spatial scaling prediction vector candidate generation unit 152 includes a reference vector determination unit 175, a reference index setting unit 176, and a scaling unit 177.

(Detailed Operation of Spatial Scaling Prediction Vector Candidate Generation Unit 152)
Subsequently, a detailed operation of the spatial scaling prediction vector candidate generation unit 152 will be described. FIG. 24 is a flowchart for explaining the operation of the spatial scaling prediction vector candidate generation unit 152. If the prediction direction of motion compensation prediction is single prediction, the spatial scaling prediction vector candidate generation unit 152 generates one to zero spatial scaling prediction vector candidates for L0 prediction or L1 prediction, and the prediction direction of motion compensation prediction is In the case of bi-prediction, 0 to 1 spatial scaling prediction vector candidates are generated for each of the L0 prediction and the L1 prediction. Hereinafter, the prediction direction of motion compensated prediction for generating a spatial scaling prediction vector candidate will be described as LX (X is 0 or 1). The spatial scaling prediction vector candidate generation unit 152 repeatedly performs the following processing in the order of block A1, block B1, block C, block E, and block D on candidate blocks included in the spatial candidate block group supplied from the terminal 12 (S170). To S176). Here, the processing order is block A1, block B1, block C, block E, and block D, which are the same processing order as the spatially coupled motion information candidate generation unit 160 described later. The order of processing is not limited to this as long as it is different from the order of processing. For example, the order of processing of the spatial prediction vector candidate generation unit 150 may be reversed.

  It is checked whether the LY prediction of the candidate block needs to be scaled (S171). Y is 1-X. That the LY prediction of the candidate block needs to be scaled means that the reference index of the LY prediction of the candidate block is 0 or more. If the LY prediction of the candidate block requires scaling (Y in S171), the reference vector determination unit 175 determines a reference motion vector (S172). The reference motion vector is a motion vector for LY prediction of the candidate block. If the candidate block does not need scaling (N of S171), the process skips Steps S172 to S175 and inspects the next candidate block (S176).

  Subsequent to step S172, the reference index setting unit 176 sets a reference index indicating a reference image for calculating a spatial prediction vector candidate for LX prediction to a predetermined value Ref_idx_SSscale (S173). The predetermined value Ref_idx_SSscale is a reference index that is most frequently used in LX prediction of block C, block D, and block E, which are spatial candidate blocks. Here, as Ref_idx_SSscale, a reference index that is most frequently used in LX prediction of block C, block D, and block E, which are spatial candidate blocks, may be a reference index that is not encoded into an encoded stream. It is not limited to. For example, a fixed value such as 0 or 1 may be used, or a reference index used in any candidate block (for example, block E) in the space candidate block group.

  Subsequent to step S173, the scaling unit 177 determines a motion vector obtained by scaling the reference motion vector as a spatial scaling prediction vector candidate (S174). Following step S174, it is checked whether the determined number of spatial scaling prediction vector candidates is a predetermined number (S175). Here, the predetermined number is 1. In Embodiment 1, the predetermined number is 1. However, the predetermined number may be 1 or more and not more than the number of candidate blocks included in the spatial candidate block group, and is not limited thereto. Moreover, the predetermined number of L0 prediction and L1 prediction can also be set to a different value. If the determined number of spatial scaling prediction vector candidates is not a predetermined number (N in S175), the next candidate block is inspected (S176). If the determined number of spatial scaling prediction vector candidates is a predetermined number (Y in S175), the process ends.

  Here, the spatial scaling prediction vector candidate whose prediction direction of motion compensation prediction is LX prediction is such that the motion vector of LY prediction of the candidate block becomes the reference motion vector, but it is only necessary to be able to determine the reference vector. Not. For example, the LX prediction motion vector of the candidate block may be the reference motion vector.

  Here, a method for scaling the reference motion vector and calculating a spatial scaling prediction vector candidate will be described. FIG. 25 is a diagram for explaining a method of calculating a spatial scaling prediction vector candidate. The inter-image distance between the reference image RefPicL0b of the base motion vector mvL0b for L0 prediction and the processing target image CurPic is curL0bDist, and the inter-image distance between the reference image RefPicL0s and the processing target image CurPic for calculating a spatial scaling prediction vector candidate for L0 prediction Is CurL0sDist, the inter-image distance between the reference image RefPicL1b of the base motion vector mvL1b of L1 prediction and the processing target image CurPic is curL1bDist, the reference image RefPicL1s and the processing target image CurPic for calculating the spatial scaling prediction vector candidate of L1 prediction The inter-image distance is CurL1sDist.

A motion vector mvL0s obtained by scaling mvL0b with a distance ratio between curL0bDist and CurL0sDist is set as a spatial scaling prediction vector candidate for L0 prediction, and mvL1b is scaled with a distance ratio between curL1bDist and CurL1sDist according to Equation 2 below. Let it be a spatial scaling prediction vector candidate for prediction. Here, the calculation of the inter-image distance is performed using the POC, and has a positive and negative sign. Division is rounded off.
mvL0s = mvL0b × CurL0sDist / CurL0bDist
mvL1s = mvL1b × CurL1sDist / CurL1bDist (Expression 2)

  Note that the time relationship among CurPic, RefPicL0b, RefPicL0s, RefPicL1b, and RefPicL1s in FIG. 25 is an example, and other time relationships may be used.

  As described above, by setting a reference image that does not depend on a reference index to be encoded in the encoded stream as a reference image for calculating a spatial scaling prediction vector candidate, before decoding the reference index on the decoding side More specifically, it is possible to generate a spatial scaling prediction vector candidate immediately after the prediction block size is determined. On the other hand, in the related art, particularly for L1 prediction, all of the merge flag, merge index, inter prediction mode, L0 prediction reference index, L0 prediction difference vector, L0 prediction prediction vector index, and L1 prediction reference index are all decoded. Otherwise, the spatial prediction vector candidate could not be generated. Furthermore, when these syntax elements include variable-length coding, it is difficult to perform parallel decoding of the syntax elements, and thus it is difficult to reduce the generation delay of the prediction vector candidate for L1 prediction. It was. Note that the reference image used in motion compensation prediction is a reference image indicated by a reference index to be encoded in the encoded stream.

  As described above, the processing order of the candidate blocks of the spatial prediction vector candidate generation unit 150 and the processing order of the candidate blocks of the spatial scaling prediction vector candidate generation unit 152 are different from each other, so that it becomes a target of the spatial scaling prediction vector candidate. The probability that the candidate block becomes a candidate block different from the candidate block that is the target of the spatial prediction vector candidate can be increased. Therefore, for example, in the case of a moving image that is moving at a constant speed and the motion vectors of the L0 prediction and the L1 prediction of a candidate block whose prediction directions are bidirectional are symmetrical, the spatial scaling prediction vector candidate and It is possible to avoid the overlap of the spatial prediction vector candidates and to increase the effectiveness of the spatial scaling prediction vector candidates. On the other hand, in the conventional technique, the processing order of candidate blocks in the spatial prediction vector candidate generation unit 150 and the processing order of candidate blocks in the spatial scaling prediction vector candidate generation unit 152 are the same, and the spatial prediction vector candidate is substituted for the spatial prediction vector candidate. It is used as a candidate. Therefore, in the case of constant velocity motion as seen in a general moving image, the spatial scaling prediction vector candidate may overlap with the spatial prediction vector candidate. Therefore, by installing step S152 in FIG. It was necessary to avoid the overlap of the scaling prediction vector candidate and the spatial prediction vector candidate.

(Detailed operation for determining the prediction vector candidate list)
Subsequently, a detailed operation for determining the prediction vector candidate list will be described. FIG. 26 is a flowchart for explaining the operation of determining the prediction vector candidate list. The prediction vector candidate list determination unit 154 adds the spatial prediction vector candidate to the prediction vector candidate list (S180). It is checked whether the number of prediction vector candidates in the prediction vector candidate list is the maximum number of prediction vector candidates (S181). If the number of prediction vector candidates in the prediction vector candidate list is the maximum number of prediction vector candidates (Y in S181), the prediction vector candidate list is confirmed, and the process is terminated by skipping steps S182 to S188. If the number of prediction vector candidates in the prediction vector candidate list is not the maximum number of prediction vector candidates (N in S181), the temporal prediction vector candidate is added to the prediction vector candidate list (S182). Subsequent to step S182, it is checked whether or not there are a plurality of identical prediction vector candidates in the prediction vector candidate list. If there are a plurality of prediction vector candidates, the first prediction vector candidate is left and the rest is deleted (S183).

  Following step S183, it is checked whether the number of prediction vector candidates in the prediction vector candidate list is the maximum number of prediction vector candidates (S184). If the number of prediction vector candidates in the prediction vector candidate list is the maximum number of prediction vector candidates (Y in S184), the prediction vector candidate list is confirmed, and the process is terminated by skipping steps S185 to S188. If the number of prediction vector candidates in the prediction vector candidate list is not the maximum number of prediction vector candidates (N in S184), the spatial scaling prediction vector candidate is added to the prediction vector candidate list (S185). Following step S185, it is checked whether there are a plurality of identical prediction vector candidates in the prediction vector candidate list. If there are a plurality of prediction vector candidates, the first prediction vector candidate is left and the rest is deleted (S186).

  Following step S186, it is checked whether the number of prediction vector candidates in the prediction vector candidate list is the maximum number of prediction vector candidates (S187). If the number of prediction vector candidates in the prediction vector candidate list is the maximum number of prediction vector candidates (Y in S187), the prediction vector candidate list is confirmed, and step S188 is skipped and the process is terminated. If the number of prediction vector candidates in the prediction vector candidate list is not the maximum number of prediction vector candidates (N in S187), the prediction vector supplement candidate is added to the prediction vector candidate list (S188), and the prediction vector candidate list is confirmed and processed. Exit.

  In general, a spatial prediction vector candidate is valid when the processing target block and the spatial candidate block are moving in the same manner. The temporal prediction vector candidate is valid when the processing target block and the temporal candidate block are in a state close to a stationary state. The spatial scaling prediction vector candidate is effective only when the accuracy of the motion vector having the opposite prediction direction is high. Therefore, in a general moving image, the order of high reliability as a prediction vector candidate is the order of a spatial prediction vector candidate, a temporal prediction vector candidate, a spatial scaling prediction vector candidate, and a prediction vector supplement candidate. However, in the conventional technique, since the spatial prediction vector candidate and the spatial scaling prediction vector candidate have a dependency, the order of the spatial prediction vector candidate and the spatial scaling prediction vector candidate is out of order.

  As described above, the spatial prediction vector candidate and the spatial scaling prediction vector candidate are eliminated, and the spatial prediction vector candidate, temporal prediction vector candidate, and spatial scaling prediction vector candidate that are in the order of relatively high selectivity as the prediction vector candidate. By adding to the prediction vector candidate list in the order of prediction vector supplementation candidates, the code amount of the prediction vector index can be suppressed.

(Configuration of merge mode determination unit 121)
Next, a detailed configuration of the merge mode determination unit 121 will be described. FIG. 27 is a diagram for explaining the configuration of the merge mode determination unit 121. The merge mode determination unit 121 includes a combined motion information candidate list generation unit 140 and a combined motion information selection unit 141. The combined motion information candidate list generation unit 140 is also installed in the video decoding device 200 that decodes the code sequence generated by the video encoding device 100 according to Embodiment 1 in the same manner. The moving image decoding apparatus 200 generates a combined motion information list that is consistent.

(Operation of merge mode determination unit 121)
Hereinafter, the function and operation of each unit will be described. FIG. 28 is a flowchart for explaining the operation of the merge mode determination unit 121. The combined motion information candidate list generation unit 140 generates a combined motion information candidate list including the maximum number of merge candidate motion information candidates from the candidate block group supplied from the terminal 12 (S130), and generates the combined motion information candidate list. This is supplied to the combined motion information selection unit 141. A detailed configuration of the combined motion information candidate list generation unit 140 will be described later.

  The combined motion information selection unit 141 selects the optimum combined motion information candidate from the combined motion information candidate list supplied from the combined motion information candidate list generation unit 140, and is information indicating the selected combined motion information candidate. A certain merge index is determined (S131), and the merge index is supplied to the terminal 17.

  Here, a method for selecting an optimal combined motion information candidate will be described. A prediction error amount is calculated from the reference image supplied from the terminal 14 obtained based on the prediction direction, the motion vector, and the reference index of the combined motion information candidate, and the image signal supplied from the terminal 15. A rate distortion evaluation value is calculated from the code amount of the merge index and the prediction error amount, and a combined motion information candidate that minimizes the rate distortion evaluation value is selected as an optimal combined motion information candidate.

(Candidate block group supplied to combined motion information candidate list generation unit 140)
Here, the candidate block group supplied to the combined motion information candidate list generation unit 140 is the same as the candidate block group supplied to the prediction vector candidate list generation unit 130. Here, the candidate block group supplied to the combined motion information candidate list generation unit 140 is the same as the candidate block group supplied to the prediction vector candidate list generation unit 130, but is supplied to the combined motion information candidate list generation unit 140. The spatial candidate block group to be included only needs to include at least one or more of the same candidate blocks as the spatial candidate block group supplied to the prediction vector candidate list generation unit 130, and the number and position of the blocks are not limited thereto. The temporal candidate block group supplied to the combined motion information candidate list generation unit 140 only needs to include at least one or more same candidate blocks as the temporal candidate block group supplied to the prediction vector candidate list generation unit 130. The number and position of blocks are not limited to these.

(Configuration of combined motion information candidate list generation unit 140)
Next, a detailed configuration of the combined motion information candidate list generation unit 140 will be described. FIG. 29 is a diagram for explaining the configuration of the combined motion information candidate list generation unit 140. The terminal 19 is connected to the combined motion information selection unit 141. The combined motion information candidate list generating unit 140 includes a spatial combined motion information candidate generating unit 160, a temporal combined motion information candidate generating unit 161, a spatial scaling combined motion information candidate generating unit 162, a combined motion information candidate supplementing unit 163, and combined motion information. A candidate list confirmation unit 164 is included.

(Operation of Combined Motion Information Candidate List Generation Unit 140)
Hereinafter, the function and operation of each unit will be described. FIG. 30 is a flowchart for explaining the operation of the combined motion information candidate list generation unit 140. The spatially coupled motion information candidate generation unit 160 generates 0 to 2 spatially coupled motion information candidates from the candidate block group supplied from the terminal 12 (S190), and confirms the spatially coupled motion information candidate as a coupled motion information candidate list. To the unit 164. The detailed operation of the spatially coupled motion information candidate generation unit 160 will be described later.

  The temporally combined motion information candidate generation unit 161 generates zero or one temporally combined motion information candidate from the candidate block group supplied from the terminal 12 (S191), and determines the temporally combined motion information candidate as a combined motion information candidate list. To the unit 164. The detailed operation of the time combination motion information candidate generation unit 161 will be described later.

  The spatial scaling combined motion information candidate generating unit 162 generates 0 or 1 spatial scaling combined motion information candidate from the candidate block group supplied from the terminal 12 (S192), and the spatial scaling combined motion information candidate is combined motion information. The data is supplied to the candidate list confirmation unit 164. The detailed operation of the spatial scaling combined motion information candidate generation unit 162 will be described later.

  The combined motion information candidate list determination unit 164 calculates the combined motion information supplement candidate number by subtracting the combined motion information candidate number obtained by adding the spatial combined motion information candidate and the temporal combined motion information candidate from the maximum merge candidate number (S193). ), The combined motion information supplement candidate number, the spatially coupled motion information candidate, the temporally coupled motion information candidate, and the spatial scaling motion information candidate are supplied to the coupled motion information candidate supplementing unit 163. When the calculated combined motion information supplement candidate number is less than 0, the combined motion information supplement candidate number is set to zero.

  The combined motion information candidate supplementing unit 163 combines the combined motion information from the spatially coupled motion information candidates, the temporally coupled motion information candidates, and the spatial scaling motion information candidates supplied from the combined motion information candidate list determining unit 164 by the number of combined motion information supplement candidates. A supplement candidate is generated (S194), and the combined motion information supplement candidate is supplied to the combined motion information candidate list determination unit 164. The combined motion information supplement candidate is motion information in which the direction of motion compensation prediction is bidirectional, the motion vector of L0 prediction and L1 prediction is (0, 0), and the reference index of L0 prediction and L1 prediction is 0. Here, the combined motion information supplement candidate is motion information in which the direction of motion compensation prediction is bidirectional, the motion vector of L0 prediction and L1 prediction is (0, 0), and the reference index of L0 prediction and L1 prediction is 0. The motion information may be different from the spatially combined motion information candidate, the temporally combined motion information candidate, and the spatially scaled combined motion information candidate, and is not limited thereto. For example, a bi-join motion information candidate combining the motion information of L0 prediction and the motion information of L1 prediction of two different candidate blocks may be added.

  The combined motion information candidate list determination unit 164 performs spatial combined motion information candidates, temporal combined motion information candidates, spatial scaling combined motion information candidates, combined until the combined motion information candidate number in the combined motion information candidate list reaches the maximum number of merge candidates. The motion information supplement candidates are sequentially added to the combined motion information candidate list to determine the combined motion information candidate list (S195). The detailed operation of determining the combined motion information candidate list will be described later.

(Detailed operation of spatially coupled motion information candidate generation unit 160)
Subsequently, a detailed operation of the spatially coupled motion information candidate generation unit 160 will be described. FIG. 31 is a flowchart for explaining the operation of the spatially coupled motion information candidate generation unit 160. The spatially coupled motion information candidate generation unit 160 generates 0 to 2 spatially coupled motion information candidates. The spatially coupled motion information candidate generation unit 160 repeatedly performs the following processing in the order of block A1, block B1, block C, block E, and block D on candidate blocks included in the spatial candidate block group supplied from the terminal 12 (S200). To S204). Here, the processing order is block A1, block B1, block C, block E, and block D, but the candidate blocks included in the spatial candidate block group only need to be processed at most once, and the present invention is not limited to this. For example, the processing order of the spatial prediction vector candidate generation unit 150 may be the same.

  It is checked whether the candidate block is valid (S201). The candidate block is valid when at least one of the reference index of the L0 prediction and the L1 prediction of the candidate block is 0 or more. If the candidate block is valid (Y in S201), the motion information of the candidate block is determined as a spatially combined motion information candidate (S202). If the candidate block is not valid (N in S201), step S202 and step S203 are skipped and the next candidate block is inspected (S204). Following step S202, it is checked whether the number of spatially coupled motion information candidates is a predetermined number (S203). Here, the predetermined number is four. In the first embodiment, the predetermined number is four, but the predetermined number may be one or more and the number of candidate blocks included in the spatial candidate block group, and is not limited to this. If the determined number of spatially coupled motion information candidates is not a predetermined number (N in S203), the next candidate block is examined (S204). If the determined number of spatially coupled motion information candidates is a predetermined number (Y in S203), the process ends.

(Configuration of time combination motion information candidate generation unit 161)
Next, a detailed configuration of the time combination motion information candidate generation unit 161 will be described. FIG. 32 is a diagram for explaining the configuration of the time-coupled motion information candidate generation unit 161. The temporal combination motion information candidate generation unit 161 includes a prediction direction setting unit 180, a temporal prediction vector candidate generation unit 151, and a temporal combination motion information candidate determination unit 181. The terminal 21 is connected to the combined motion information candidate list determination unit 164.

(Detailed operation of time combination motion information candidate generation unit 161)
Hereinafter, the function and operation of each unit will be described. FIG. 33 is a flowchart for explaining the operation of the time combination motion information candidate generation unit 161. The prediction direction setting unit 180 sets the prediction direction of the temporally combined motion information candidate to bi-prediction (S210). Next, the temporal prediction vector candidate generation unit 151 calculates an L0 prediction motion vector of the temporally coupled motion information candidate (S211). Next, the temporal prediction vector candidate generation unit 151 calculates an L1 prediction motion vector of the temporally combined motion information candidate (S212). Next, the temporally combined motion information candidate determination unit 181 sets the reference index for L0 prediction to the predetermined value Ref_idx_TSscale and the reference index for L1 prediction to the predetermined value Ref_idx_TSscale, and sets the bidirectional prediction direction, the motion vector for the L0 prediction, The motion vector for the L1 prediction, the reference index for the L0 prediction, and the temporally coupled motion information candidate that is the reference index for the L1 prediction are determined (S213), and the temporally coupled motion information candidate is supplied to the terminal 21.

  As described above, by making the calculation of the motion vector of the temporally combined motion information candidate and the motion vector of the temporal prediction vector candidate the same, it becomes easy to share the arithmetic unit for scaling between the merge mode and the prediction vector mode. Is possible. Even when the calculation unit for scaling is shared, either the calculated motion vector of the L0 prediction and the motion vector of the L1 prediction are used, or one of the motion vector of the L0 prediction and the motion vector of the L1 prediction is used. Depending on the use, the higher one of the encoding efficiency of the merge mode and the prediction vector mode can be selected.

(Configuration of Spatial Scaling Combined Motion Information Candidate Generation Unit 162)
Next, a detailed configuration of the spatial scaling combined motion information candidate generation unit 162 will be described. FIG. 34 is a diagram for explaining the configuration of the spatial scaling combined motion information candidate generation unit 162. The spatial scaling combined motion information candidate generation unit 162 includes a prediction direction setting unit 185, a spatial scaling prediction vector candidate generation unit 152, and a spatial scaling combined motion information candidate determination unit 186.

(Detailed Operation of Spatial Scaling Combined Motion Information Candidate Generation Unit 162)
Hereinafter, the function and operation of each unit will be described. FIG. 35 is a flowchart for explaining the operation of the spatial scaling combined motion information candidate generation unit 162. The prediction direction setting unit 185 sets the prediction direction of the spatial scaling combined motion information candidate to bi-prediction (S220). Next, the spatial scaling prediction vector candidate generation unit 152 calculates an L0 prediction motion vector of the spatial scaling combined motion information candidate (S221). Next, the spatial scaling prediction vector candidate generation unit 152 calculates the L1 prediction motion vector of the spatial scaling combined motion information candidate (S222). Next, the spatial scaling combined motion information candidate determination unit 186 sets the reference index for L0 prediction to the predetermined value Ref_idx_SSscale and the reference index for L1 prediction to the predetermined value Ref_idx_SSscale, and sets the bidirectional prediction direction and the motion vector for the L0 prediction. Then, the motion vector of the L1 prediction, the reference index of the L0 prediction, and the spatial scaling combined motion information candidate that is the reference index of the L1 prediction are determined (S223), and the spatial scaling combined motion information candidate is supplied to the terminal 21.

  As described above, the motion vector calculation of the spatial scaling combined motion information candidate and the motion vector calculation of the spatial scaling prediction vector candidate are made the same, thereby making it easy to share the arithmetic unit for the merge mode and the prediction vector mode scaling. It becomes possible to do. Even when the calculation unit for scaling is shared, either the calculated motion vector of the L0 prediction and the motion vector of the L1 prediction are used, or one of the motion vector of the L0 prediction and the motion vector of the L1 prediction is used. Depending on the use, the higher one of the encoding efficiency of the merge mode and the prediction vector mode can be selected.

(Detailed operation for determining the combined motion information candidate list)
Subsequently, a detailed operation for determining the combined motion information candidate list will be described. FIG. 36 is a flowchart for explaining the operation of determining the combined motion information candidate list. The combined motion information candidate list determination unit 164 adds the spatial combined motion information candidate to the combined motion information candidate list (S230). Next, the temporally combined motion information candidate is added to the combined motion information candidate list (S231). Next, it is checked whether there are a plurality of the same combined motion information candidates in the combined motion information candidate list. If there are a plurality of combined motion information candidates, the first combined motion information candidate is left and the rest is deleted (S232). Next, it is checked whether the number of combined motion information candidates in the combined motion information candidate list is the maximum number of merge candidates (S233). If the number of combined motion information candidates in the combined motion information candidate list is the maximum number of merge candidates (Y in S233), the combined motion information candidate list is determined, and the process is terminated by skipping steps S234 to S237. If the number of combined motion information candidates in the combined motion information candidate list is not the maximum number of merge candidates (N in S233), the spatial scaling combined motion information candidate is added to the combined motion information candidate list (S234). Subsequent to step S234, it is checked whether there are a plurality of the same combined motion information candidates in the combined motion information candidate list. If there are a plurality of combined motion information candidates, the first combined motion information candidate is left and the rest is deleted (S235). Following step S235, it is checked whether the combined motion information candidate number in the combined motion information candidate list is the maximum number of merge candidates (S236). If the number of combined motion information candidates in the combined motion information candidate list is the maximum number of merge candidates (Y in S236), the combined motion information candidate list is confirmed, and the process is terminated by skipping step S237. If the number of combined motion information candidates in the combined motion information candidate list is not the maximum number of merge candidates (N in S236), the combined motion information supplement candidate is added to the combined motion information candidate list (S237), and the combined motion information candidate list is displayed. Confirm and end the process.

(Configuration of moving picture decoding apparatus 200)
Next, the moving picture decoding apparatus according to the first embodiment will be described. FIG. 37 shows the moving picture decoding apparatus 200 according to the first embodiment. The video decoding device 200 is a device that generates a playback image by decoding the code string encoded by the video encoding device 100.

  The moving picture decoding apparatus 200 is realized by hardware such as an information processing apparatus including a CPU (Central Processing Unit), a frame memory, and a hard disk. The moving picture decoding apparatus 200 realizes functional components described below by operating the above components. Note that the position information and the prediction block size of the prediction block to be decoded are shared in the video decoding device 200 and are not shown.

  The moving picture decoding apparatus 200 according to Embodiment 1 includes a code string analysis unit 201, a prediction error decoding unit 202, an addition unit 203, a motion information reproduction unit 204, a motion compensation unit 205, a frame memory 206, and a motion information memory 207.

(Operation of the video decoding device 200)
Hereinafter, the function and operation of each unit will be described. FIG. 38 is a flowchart for explaining the operation of the moving picture decoding apparatus 200. The code string analysis unit 201 analyzes the code string supplied from the terminal 30 and compares the prediction error encoded data, the merge flag, the merge index, the prediction direction of motion compensation prediction, the reference index, the difference vector, and the prediction vector index. Entropy decoding is performed according to the tax (S290). Entropy decoding is performed by a method including variable length coding such as arithmetic coding or Huffman coding. Then, the prediction error encoded data is transferred to the prediction error decoding unit 202, and the merge flag, the merge index, the prediction direction of the motion compensated prediction, the reference index, the difference vector, and the prediction vector index are transferred to the motion information reproducing unit. 204.

  The motion information reproduction unit 204 includes a merge flag, a merge index, a prediction direction of motion compensation prediction, a reference index, a difference vector, and a prediction vector index supplied from the code string analysis unit 201, and candidates supplied from the motion information memory 207. Motion information is reproduced from the block group (S291), and the motion information is supplied to the motion compensation unit 205 and the motion information memory 207. A detailed configuration of the motion information reproducing unit 204 will be described later.

  The motion compensation unit 205 generates a prediction signal by performing motion compensation on the reference image indicated by the reference index in the frame memory 206 based on the motion vector based on the motion information supplied from the motion information reproducing unit 204 (S292). . If the prediction direction is bi-prediction, an average of the prediction signals of the L0 prediction and the L1 prediction is generated as a prediction signal, and the prediction signal is supplied to the adding unit 203.

  The prediction error decoding unit 202 performs a process such as inverse quantization or inverse orthogonal transform on the prediction error encoded data supplied from the code string analysis unit 201 to generate a prediction error signal (S293). The error signal is supplied to the adding unit 203.

  The adding unit 203 adds the prediction error signal supplied from the prediction error decoding unit 202 and the prediction signal supplied from the motion compensation unit 205 to generate a decoded image signal (S294), and the decoded image signal is framed. This is supplied to the memory 206 and the terminal 31.

  The frame memory 206 and the motion information memory 207 have the same functions as the frame memory 110 and the motion information memory 111 of the video encoding device 100. The frame memory 206 stores the decoded image signal supplied from the adding unit 203 (S295). The motion information memory 207 stores the motion information supplied from the motion information reproducing unit 204 in units of the minimum predicted block size (S296).

(Detailed configuration of the motion information playback unit 204)
Next, a detailed configuration of the motion information reproducing unit 204 will be described. FIG. 39 shows the configuration of the motion information playback unit 204. The motion information playback unit 204 includes an encoding mode determination unit 210, a motion vector playback unit 211, and a combined motion information playback unit 212. The terminal 32 is connected to the code string analysis unit 201, the terminal 33 is connected to the motion information memory 207, and the terminal 34 is connected to the motion compensation unit 205.

(Detailed operation of the motion information playback unit 204)
Hereinafter, the function and operation of each unit will be described. The encoding mode determination unit 210 determines whether the merge flag supplied from the code string analysis unit 201 is “0” or “1”. If the merge flag is “0”, the motion compensation prediction direction, the reference index, the difference vector, and the prediction vector index supplied from the code string analysis unit 201 are supplied to the motion vector reproduction unit 211. If the merge flag is “1”, the merge index supplied from the code string analysis unit 201 is supplied to the combined motion information reproduction unit 212.

  The motion vector reproduction unit 211 obtains motion information from the prediction direction, the reference index, the difference vector, and the prediction vector index of the motion compensated prediction supplied from the coding mode determination unit 210 and the candidate block group supplied from the terminal 33. Reproduce and supply to terminal 34. Details of the motion vector reproducing unit 211 will be described later.

  The combined motion information reproduction unit 212 reproduces the motion information from the merge index supplied from the encoding mode determination unit 210 and the candidate block group supplied from the terminal 33 and supplies the motion information to the terminal 34. A detailed configuration of the combined motion information reproducing unit 212 will be described later.

(Detailed Configuration of Motion Vector Reproducing Unit 211)
Next, a detailed configuration of the motion vector reproduction unit 211 will be described. FIG. 40 shows the configuration of the motion vector playback unit 211. The motion vector reproduction unit 211 includes a prediction vector candidate list generation unit 220, a prediction vector determination unit 221, and an addition unit 222. The terminal 35 is connected to the encoding mode determination unit 210.

(Detailed operation of the motion vector reproduction unit 211)
Hereinafter, the function and operation of each unit will be described. FIG. 41 is a flowchart for explaining the operation of the motion vector reproducing unit 211. The motion vector reproduction unit 211 performs the following processing for L0 prediction if the prediction direction of motion compensation prediction is L0 prediction, and performs the following processing for L1 prediction if the prediction direction of motion compensation prediction is L1 prediction. If the prediction direction of motion compensation prediction is BI prediction, the following processing is performed for L0 prediction and L1 prediction.

  The prediction vector candidate list generation unit 220 has the same function as the prediction vector candidate list generation unit 130 of the video encoding device 100 and performs the same operation as the prediction vector candidate list generation unit 130 of the video encoding device 100. A prediction vector candidate list is generated (S300), and the prediction vector candidate list is supplied to the prediction vector determination unit 221.

  The prediction vector determination unit 221 selects a prediction vector candidate indicated by the prediction vector index supplied from the terminal 35 from the prediction vector candidate list supplied from the prediction vector candidate list generation unit 220 and determines a prediction vector. (S301), the prediction vector is supplied to the adding unit 222.

  The addition unit 222 adds the difference vector supplied from the terminal 35 and the prediction vector supplied from the prediction vector determination unit 221 to calculate a motion vector (S302), and supplies the motion vector to the terminal 34.

(Detailed Configuration of Combined Motion Information Reproducing Unit 212)
Next, a detailed configuration of the combined motion information reproduction unit 212 will be described. FIG. 42 shows the configuration of the combined motion information playback unit 212. The combined motion information reproduction unit 212 includes a combined motion information candidate generation unit 230 and a combined motion information selection unit 231.

(Detailed operation of the combined motion information reproduction unit 212)
Hereinafter, the function and operation of each unit will be described. FIG. 43 is a flowchart for explaining the operation of the combined motion information reproducing unit 212. The combined motion information candidate generation unit 230 has the same function as the combined motion information candidate list generation unit 140 of the video encoding device 100, and the same operation as the combined motion information candidate list generation unit 140 of the video encoding device 100. To generate a combined motion information candidate list (S310), and supplies the combined motion information candidate list to the combined motion information selection unit 231.

  The combined motion information selection unit 231 selects the combined motion information candidate indicated by the merge index supplied from the terminal 35 from the combined motion information candidate list supplied from the combined motion information candidate generation unit 230, and combines motion information (S311), and the combined motion information is supplied to the terminal 34.

(Modification of Embodiment 1)
The first embodiment can be modified as follows.

  In the first modification of the first embodiment, the operation of the prediction vector candidate list generation unit 130 is different from the basic example of the first embodiment. FIG. 44 is a flowchart for explaining the operation of the prediction vector candidate list generation unit 130 in the first modification of the first embodiment. In the flowchart of FIG. 44, steps S320 to S322 are added to the flowchart of FIG. Hereinafter, step S320 to step S322 will be described.

  Following step S140, the prediction vector candidate list generation unit 130 checks whether the prediction block size is larger than a predetermined size (S320). The predetermined size is 16 pixels × 16 pixels. Here, the predetermined size is set to 16 pixels × 16 pixels, but it may be less than the maximum coding block, and is not limited to this. If the prediction block size is larger than the predetermined size (Y in S320), the maximum number of temporal prediction vector candidates is set to 2, and the maximum number of spatial scaling prediction vector candidates is set to 0 (S321). If the prediction block size is not larger than the predetermined size (N in S320), the maximum number of temporal prediction vector candidates is set to 1, and the maximum number of spatial scaling prediction vector candidates is set to 1 (S322).

  If the predicted block size is equal to or larger than the predetermined size, the operation of the temporal prediction vector candidate generation unit 151 is different from the basic example of the first embodiment, and step S165 in FIG. Generate.

  In general, when the prediction block size is large, the processing target block has a high correlation with the spatial candidate block or the temporal candidate block, so that the effectiveness of the spatial scaling prediction vector candidate is relatively lowered. Therefore, when the prediction block size is large, the number of temporal prediction vector candidates is increased, and the number of spatial scaling prediction vector candidates is decreased, so that relatively reliable spatial prediction vector candidates are added to the prediction vector candidate list. Thus, the encoding efficiency of the prediction vector index can be improved.

[Embodiment 2]
First, the syntax of the second embodiment will be described. FIG. 45 is a diagram for describing an example of the syntax of the prediction block according to the second embodiment. The syntax of the prediction block in Embodiment 1 includes the prediction vector index (mvp_idx_l0 and mvp_idx_l1), the difference vector (mvd_l0 [0], mvd_l0 [1], mvd_l1 [0], mvd_l1 [1]), and the reference index ( The order of ref_idx_l0 and ref_idx_l1) is different. Further, when the prediction vector index is the maximum value of the prediction vector index, the reference index is not encoded and decoded. MAX_MVP_IDX in FIG. 45 indicates the maximum value of the prediction vector index. When the maximum number of prediction vector candidates is 2, the maximum value of the prediction vector index is 1.

  Next, restrictions in the second embodiment will be described. The predetermined value Ref_idx_TSscale used in the temporal prediction vector candidate generation unit 151 and the predetermined value Ref_idx_SSscale used in the spatial scaling prediction vector candidate generation unit 152 are the same value. Hereinafter, the predetermined value is referred to as Ref_idx_CSscale.

(Moving picture encoding apparatus according to Embodiment 2)
The configuration of the moving picture encoding apparatus according to the second embodiment is the same as that of the moving picture encoding apparatus 100 according to the first embodiment. The functions and operations of the code sequence generation unit 104, the prediction vector mode determination unit 120, and the prediction vector candidate list determination unit 154 are different from those of the moving image encoding apparatus 100 according to the first embodiment. Hereinafter, differences from Embodiment 1 in the functions and operations of code string generation section 104, prediction vector mode determination section 120, and prediction vector candidate list determination section 154 in Embodiment 2 will be described.

(Code string generation unit 104)
The code string generation unit 104 generates a code string in the order of the prediction vector index, the difference vector, and the reference index for each of the L0 prediction and the L1 prediction. Further, when the prediction vector index is the maximum value of the prediction vector index, the reference index is not encoded.

(Predicted vector mode determination unit 120)
The operation of the prediction vector mode determination unit 120 will be described. FIG. 46 is a flowchart for explaining the operation of the prediction vector mode determination unit 120 according to the second embodiment. In the flowchart of FIG. 46, steps S250 to S253 are added to the flowchart of FIG.

  Subsequent to step S120, the prediction vector determination unit 131 checks whether the reference index of the L0 prediction supplied from the terminal 13 is a predetermined value Ref_idx_CSscale (S250). If the L0 prediction reference index is the predetermined value Ref_idx_CSscale (Y in S250), the prediction vector determination unit 131 selects one prediction vector candidate from the prediction vector candidate list of the L0 prediction supplied from the prediction vector candidate list generation unit 130. It selects as a prediction vector of L0 prediction, determines the prediction vector index of L0 prediction (S121), and supplies the prediction vector of the said L0 prediction to the subtraction part 132.

  If the reference index of the L0 prediction is not the predetermined value Ref_idx_CSscale (N in S250), the prediction vector determining unit 131 uses the temporal prediction vector candidate and the space from the prediction vector candidate list of the L0 prediction supplied from the prediction vector candidate list generation unit 130. One prediction vector candidate is selected as a prediction vector for L0 prediction from prediction vector candidates excluding the scaling prediction vector candidate, a prediction vector index for L0 prediction is determined (S251), and the prediction vector for the L0 prediction is subtracted. To the unit 132.

  Subsequent to step S124, the prediction vector determination unit 131 checks whether the reference index of the L1 prediction supplied from the terminal 13 is the predetermined value Ref_idx_CSscale (S252). If the reference index of L1 prediction is the predetermined value Ref_idx_CSscale (Y in S252), the prediction vector determination unit 131 selects one prediction vector candidate from the prediction vector candidate list of L1 prediction supplied from the prediction vector candidate list generation unit 130. It selects as a prediction vector of L1 prediction, determines the prediction vector index of L1 prediction (S125), and supplies the prediction vector of the said L1 prediction to the subtraction part 132.

  If the reference index of the L1 prediction is not the predetermined value Ref_idx_CSscale (N in S252), the prediction vector determination unit 131 determines the temporal prediction vector candidate and the space from the prediction vector candidate list of the L1 prediction supplied from the prediction vector candidate list generation unit 130. One prediction vector candidate is selected as a prediction vector for L1 prediction from prediction vector candidates excluding the scaling prediction vector candidate, a prediction vector index for L1 prediction is determined (S253), and the prediction vector for the L1 prediction is subtracted. To the unit 132.

  As described above, when the reference index supplied from the terminal 13 is not the predetermined value Ref_idx_CSscale, the reference image supplied from the terminal 13 and indicated by the reference index used for motion compensation and the reference image used for calculating the scaling are used. From the increase in the code amount of the difference vector due to the mismatch, the selection rate of the prediction vector candidate accompanied by the scaling process decreases. Therefore, when the reference index supplied from the terminal 13 is not 0, the processing related to candidate selection can be reduced by excluding the temporal prediction vector candidate accompanied by the scaling process and the spatial scaling prediction vector candidate. .

(Predicted vector candidate list determination unit 154)
The operation of the prediction vector candidate list determination unit 154 will be described. FIG. 47 is a flowchart for explaining the operation of the prediction vector candidate list determination unit 154 according to the second embodiment. The flowchart in FIG. 47 is different from the flowchart in FIG. 26 in that step S260 and step S261 are added.

  Subsequent to step S181, it is checked whether the number of prediction vector candidates in the prediction vector candidate list is “maximum number of prediction vector candidates−1” (S260). If the number of prediction vector candidates in the prediction vector candidate list is “maximum number of prediction vector candidates−1” (Y in S260), the temporal prediction vector candidate is added to the prediction vector candidate list (S182). If the number of prediction vector candidates in the prediction vector candidate list is not “maximum number of prediction vector candidates−1” (N in S260), until the number of prediction vector candidates in the prediction vector candidate list reaches “maximum number of prediction vector candidates−1”. The prediction vector supplement candidate is added to the prediction vector candidate list (S261).

  As described above, if the number of prediction vector candidates in the prediction vector candidate list is not “maximum number of prediction vector candidates−1”, the number of prediction vector candidates in the prediction vector candidate list reaches “maximum number of prediction vector candidates−1”. By adding the prediction vector supplement candidate to the prediction vector candidate list, the prediction vector index of the prediction vector candidate accompanied by the scaling process can be fixed to the maximum value of the prediction vector index. Here, the prediction vector index of the prediction vector candidate accompanied by the scaling process is fixed to the maximum value of the prediction vector index, but it is only necessary to be able to fix it to a predetermined value, and the present invention is not limited to this.

(Moving picture decoding apparatus according to Embodiment 2)
The configuration of the moving picture decoding apparatus according to the second embodiment is the same as that of the moving picture decoding apparatus 200 according to the first embodiment except for the function of the code string analysis unit 201.

  The code string analysis unit 201 analyzes the code string supplied from the terminal 30 and compares the prediction error encoded data, the merge flag, the merge index, the prediction direction of motion compensation prediction, the reference index, the difference vector, and the prediction vector index. Decrypt according to the tax. When the prediction vector index is the maximum value of the prediction vector index, the reference index is set to a predetermined value Ref_idx_CSscale. Then, the prediction error encoded data is transferred to the prediction error decoding unit 202, and the merge flag, the merge index, the prediction direction of the motion compensated prediction, the reference index, the difference vector, and the prediction vector index are transferred to the motion information reproducing unit. 204.

  As described above, in the video decoding device according to the second embodiment, when the prediction vector index is the maximum value of the prediction vector index, the reference index that is not decoded is regarded as the predetermined value Ref_idx_CSscale and supplied to the motion information reproduction unit 204. Thus, it is possible to generate a reproduced image that is consistent with the moving picture encoding apparatus of the second embodiment.

  As described above, in the video encoding apparatus and video decoding apparatus according to Embodiment 2, when the prediction vector index is the maximum value of the prediction vector index, it is not necessary to encode the reference index, so that the motion information The amount of codes can be reduced.

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

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

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

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

  DESCRIPTION OF SYMBOLS 100 moving image encoder, 101 prediction block image acquisition part, 102 subtraction part, 103 prediction error encoding part, 104 code stream production | generation part, 105 prediction error decoding part, 106 motion compensation part, 107 addition part, 108 motion vector detection , 109 motion information generation unit, 110 frame memory, 111 motion information memory, 120 prediction vector mode determination unit, 121 merge mode determination unit, 122 prediction coding mode determination unit, 130 prediction vector candidate list generation unit, 131 prediction vector determination , 132 subtraction unit, 140 combined motion information candidate list generation unit, 141 combined motion information selection unit, 150 spatial prediction vector candidate generation unit, 151 temporal prediction vector candidate generation unit, 152 spatial scaling prediction vector candidate generation unit, 153 Prediction vector candidate supplement unit, 154 Prediction vector candidate list determination unit, 160 Spatial joint motion information candidate generation unit, 161 Temporal joint motion information candidate generation unit, 162 Spatial scaling joint motion information candidate generation unit, 163 Joint motion information candidate supplement unit, 164 combined motion information candidate list determination unit, 170 reference vector determination unit, 171 reference index setting unit, 172 scaling unit, 175 reference vector determination unit, 176 reference index setting unit, 177 scaling unit, 180 prediction direction setting unit, 181 time combination Motion information candidate determination unit, 185 prediction direction setting unit, 186 spatial scaling combined motion information candidate determination unit, 200 video decoding device, 201 code string analysis unit, 202 prediction error decoding unit, 203 addition unit, 204 motion information Playback unit, 205 motion compensation unit, 206 frame memory, 207 motion information memory, 210 encoding mode determination unit, 211 motion vector playback unit, 212 combined motion information playback unit, 220 prediction vector candidate list generation unit, 221 prediction vector determination unit 222 addition unit, 230 combined motion information candidate generation unit, 231 combined motion information selection unit.

Claims (9)

An image decoding apparatus that performs motion compensation prediction,
A code string analysis unit that acquires information for specifying a reference image to be used in motion compensation of a decoding target block from an encoded stream;
A prediction vector candidate generation unit for generating a prediction vector candidate of a motion vector of the decoding target block,
The prediction vector candidate generation unit
A reference vector determination unit that determines a reference motion vector from among the motion vectors of decoded blocks adjacent to the block to be decoded;
A reference image information setting unit for setting information for specifying a reference image for scaling;
A scaling unit that scales the reference motion vector based on information for specifying the reference image for scaling,
The reference image information setting unit determines the reference image for scaling without depending on a reference image used for motion compensation of the decoding target block.
An image decoding apparatus characterized by that. The reference image information setting unit determines the reference image for scaling based on a reference image used for motion compensation of a decoded block adjacent to the decoding target block.
The image decoding apparatus according to claim 1. An image decoding apparatus that performs motion compensation prediction,
A prediction vector candidate list generation unit that generates a prediction vector candidate list by selecting a block including a motion vector from a plurality of blocks adjacent to a decoding target block;
A combined motion information candidate list generation unit that generates a combined motion information candidate list by selecting a block including motion information including at least reference image information and a motion vector from a plurality of blocks adjacent to the decoding target block;
A prediction mode selection unit that selects which one of the first prediction mode that uses the prediction vector candidate list and the second prediction mode that uses the combined motion information candidate list;
Information for specifying a prediction mode is obtained from the encoded stream, and when the prediction mode is the first prediction mode, a prediction vector indicating the position of the prediction vector in the prediction vector candidate list is obtained from the encoded stream. Information for specifying, a difference vector, and information for specifying a reference image of the decoding target block are acquired, and when the prediction mode is the second prediction mode, the combined motion information candidate from the encoded stream A code string analyzer that acquires information for specifying motion information indicating the position of the motion information in the list;
Based on information for specifying the prediction vector, a prediction vector selection unit that selects a prediction vector of the block to be decoded from prediction vector candidates included in the prediction vector candidate list;
A motion vector reproduction unit that adds the prediction vector and the difference vector to reproduce the motion vector of the decoding target block;
Based on information for specifying the motion information, a combined motion information selection unit that selects motion information of the decoding target block from among motion information candidates included in the combined motion information candidate list;
When the prediction mode is the first prediction mode, a prediction signal is generated using the reference image specified by the information for specifying the reference image and the reproduced motion vector, and the prediction mode is the second prediction mode. A motion compensation unit that generates a prediction signal using a reference image specified by reference image information included in the selected motion information and a motion vector included in the selected motion information when the mode is selected;
A scaling unit that scales a motion vector of a block that is a decoded block adjacent to the decoding target block and that is included in an image that is temporally different from the image including the decoding target block;
The motion vector scaled by the scaling unit is shared by the first prediction mode and the second prediction mode.
An image decoding apparatus characterized by that. An image decoding apparatus that performs motion compensation prediction,
A code string analysis unit that acquires information for specifying a prediction vector from the encoded stream;
A spatial prediction vector candidate generation unit that inspects a plurality of blocks adjacent to a decoding target block in a first order and uses a motion vector of a block including a motion vector as a spatial prediction vector candidate;
A spatial scaling prediction vector candidate generation unit which examines a plurality of blocks adjacent to the decoding target block in a second order and sets a scaling motion vector obtained by scaling a motion vector of a block including a motion vector as a spatial scaling prediction vector candidate; ,
A candidate list generating unit that generates a candidate list including at least the spatial prediction vector candidates and the spatial scaling prediction vector candidates;
Based on information for specifying a prediction vector acquired from the encoded stream, a prediction vector selection unit that selects a prediction vector of the decoding target block from prediction vector candidates included in the candidate list;
An image decoding apparatus comprising: An image decoding apparatus that performs motion compensation prediction,
A candidate list generating unit that generates a candidate list by selecting a block including a motion vector from a plurality of blocks adjacent to a decoding target block;
A code string analysis unit that acquires information for specifying a prediction vector indicating a position of a prediction vector in the candidate list from a coded stream, a difference vector, and information for specifying a reference image of the decoding target block;
Based on information for specifying the prediction vector, a prediction vector selection unit that selects a prediction vector of the decoding target block from prediction vector candidates included in the candidate list;
A motion vector reproducing unit that calculates the motion vector of the block to be decoded by adding the prediction vector and the difference vector;
When the information for specifying the prediction vector is a predetermined value, the information for specifying the reference image is omitted.
An image decoding apparatus characterized by that. An image decoding method for performing motion compensation prediction,
Obtaining information for identifying a reference image to be used in motion compensation of a decoding target block from an encoded stream;
Generating a prediction vector candidate of a motion vector of the decoding target block, and
The step of generating the prediction vector candidate includes
Determining a reference motion vector from motion vectors of decoded blocks adjacent to the decoding target block;
Setting information for identifying a reference image for scaling;
Scaling the reference motion vector based on information for identifying the reference image for scaling,
The step of setting information for specifying the reference image for scaling determines the reference image for scaling without depending on the reference image used for motion compensation of the decoding target block.
An image decoding method characterized by the above. An image decoding method for performing motion compensation prediction,
Selecting a block including a motion vector from a plurality of blocks adjacent to the decoding target block to generate a prediction vector candidate list;
Selecting a block including motion information including at least reference image information and a motion vector from a plurality of blocks adjacent to the decoding target block to generate a combined motion information candidate list;
Selecting which prediction mode to use, the first prediction mode using the prediction vector candidate list or the second prediction mode using the combined motion information candidate list;
Information for specifying a prediction mode is obtained from the encoded stream, and when the prediction mode is the first prediction mode, a prediction vector indicating the position of the prediction vector in the prediction vector candidate list is obtained from the encoded stream. Information for specifying, a difference vector, and information for specifying a reference image of the decoding target block are acquired, and when the prediction mode is the second prediction mode, the combined motion information candidate from the encoded stream Obtaining information for identifying motion information indicating the position of motion information in the list;
Selecting a prediction vector of the decoding target block from prediction vector candidates included in the prediction vector candidate list based on information for specifying the prediction vector;
Adding the prediction vector and the difference vector to reproduce the motion vector of the decoding target block;
Selecting motion information of the decoding target block from motion information candidates included in the combined motion information candidate list based on information for specifying the motion information;
When the prediction mode is the first prediction mode, a prediction signal is generated using the reference image specified by the information for specifying the reference image and the reproduced motion vector, and the prediction mode is the second prediction mode. Generating a prediction signal using a reference image specified by reference image information included in the selected motion information and a motion vector included in the selected motion information when the mode is selected;
Scaling a motion vector of a block that is a decoded block adjacent to the decoding target block and is included in an image temporally different from the image including the decoding target block;
The scaled motion vector is shared by the first prediction mode and the second prediction mode.
An image decoding method characterized by the above. An image decoding program for performing motion compensation prediction,
Processing for acquiring information for specifying a reference image used in motion compensation of a decoding target block from an encoded stream;
A process of generating motion vector prediction vector candidates of the decoding target block, and causing the computer to execute,
The process of generating the prediction vector candidate is
A process of determining a reference motion vector from motion vectors of decoded blocks adjacent to the decoding target block;
A process for setting information for specifying a reference image for scaling;
Causing the computer to perform a process of scaling the reference motion vector based on information for specifying the scaling reference image,
The process of setting information for identifying the reference image for scaling determines the reference image for scaling without depending on the reference image used for motion compensation of the decoding target block.
An image decoding program characterized by the above. An image decoding program for performing motion compensation prediction,
A process of selecting a block including a motion vector from a plurality of blocks adjacent to a decoding target block to generate a prediction vector candidate list;
A process of generating a combined motion information candidate list by selecting a block including motion information including at least reference image information and a motion vector from a plurality of blocks adjacent to the decoding target block;
A process of selecting which prediction mode to use, the first prediction mode using the prediction vector candidate list or the second prediction mode using the combined motion information candidate list;
Information for specifying a prediction mode is obtained from the encoded stream, and when the prediction mode is the first prediction mode, a prediction vector indicating the position of the prediction vector in the prediction vector candidate list is obtained from the encoded stream. Information for specifying, a difference vector, and information for specifying a reference image of the decoding target block are acquired, and when the prediction mode is the second prediction mode, the combined motion information candidate from the encoded stream Processing for acquiring information for identifying motion information indicating the position of motion information in the list;
Based on information for specifying the prediction vector, a process of selecting a prediction vector of the decoding target block from prediction vector candidates included in the prediction vector candidate list;
A process of adding the prediction vector and the difference vector to reproduce the motion vector of the decoding target block;
Based on the information for specifying the motion information, a process of selecting motion information of the decoding target block from motion information candidates included in the combined motion information candidate list;
When the prediction mode is the first prediction mode, a prediction signal is generated using the reference image specified by the information for specifying the reference image and the reproduced motion vector, and the prediction mode is the second prediction mode. A process for generating a prediction signal using a reference image specified by reference image information included in the selected motion information and a motion vector included in the selected motion information when the mode is selected;
A process of scaling a motion vector of a block that is a decoded block adjacent to the decoding target block and is included in an image temporally different from the image including the decoding target block;
The scaled motion vector is shared by the first prediction mode and the second prediction mode.
An image decoding program characterized by the above.

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