BACKGROUND

1. Field of the Invention

The present invention relates to a technology of coding and decoding moving pictures by using motion compensation prediction and, more particularly, to a moving picture coding device, a moving picture coding method and a moving picture coding program, and a moving picture decoding device, a moving picture decoding method and a moving picture decoding program that code and decode motion information used in motion compensation prediction.

2. Description of the Related Art

Motion compensation prediction is used in commonly-used moving-picture compression coding. Motion compensation prediction is a technology of partitioning a target picture into small blocks and generating, as a prediction signal, a signal located a position moved from a target block of the target picture to a reference block of a reference picture based on the amount of motion indicated by a motion vector, the reference picture being a decoded picture. Motion compensation prediction includes uni-prediction performed using a single motion vector and bi-prediction performed using two motion vectors.

Regarding motion vectors, a motion vector of a coded block neighboring a target block is set to be a motion vector predictor (also simply referred to as “vector predictor”), and a difference between a motion vector of the target block and the vector predictor is obtained and transmitted as a coding vector so as to improve compression efficiency.

Moving-picture compression coding such as MPEG-4AVC/H.264 (hereinafter, MPEG-4AVC) allows for highly-accurate motion compensation prediction by making the size of a block used for motion compensation to be small with variations. On the other hand, there is a problem that the code size of a coding vector becomes large when reducing the size of the block.

Thus, in MPEG-4AVC, the continuity of motion in a temporal direction is focused, and motion compensation prediction in a temporal direct mode is used where motion compensation is achieved, without transmitting coding vectors, by scaling a motion vector of a block on a reference picture that is located at the same position as a target block according to an inter-frame distance and using the scaled motion vector as a motion vector of the target block, the reference picture being a processed picture different from a target picture on which the target block is located. This allows for a reduction in a code size of a motion vector, achieving improvement in coding efficiency.

Also, focusing on the continuity of motion in a spatial direction, Patent document 1 discloses a method of achieving motion compensation prediction, without transmitting coding vectors, by using a motion vector of a processed block neighboring a target block as a motion vector of the processed block.

[Patent document 1] JP 10-276439

In the derivation of a motion vector in a temporal direction such as that defined in the above-stated MPEG-4AV, scaling is required at the time of the derivation, and complicated operations thus become necessary. In the method described in Patent document 1, a motion vector of a processed block neighboring a target prediction block is used as a motion vector of the target prediction block, and in the case of performing motion compensation prediction collectively on a plurality of neighboring prediction blocks, a parallel motion prediction process may not be performed.

SUMMARY

Accordingly, a purpose of the present invention is to provide a moving picture coding and moving picture decoding technology capable of efficiently achieving parallel processing of motion compensation prediction that performs motion compensation prediction collectively on a plurality of neighboring prediction blocks while using a motion vector of a processed block neighboring a target prediction block in the generation of a motion block of the target prediction block.

A picture coding device according to one embodiment of the present invention includes: a temporal merging motion information candidate generation unit (161) configured to derive, when information indicating whether or not to derive a temporal merging motion information candidate shared for all prediction blocks in the coding block is information indicating the derivation of a temporal merging motion information candidate shared for all the prediction blocks in the coding block, a temporal merging motion information candidate shared for all the prediction blocks in the coding block from a prediction block of a coded picture different from a picture having a prediction block subject to coding; a merging motion information candidate generation unit configured to generate a plurality of merging motion information candidates including the temporal merging motion information candidate; a merging motion information selection unit (141) configured to select one merging motion information candidate from the plurality of merging motion information candidates and to use the selected merging motion information candidate as motion information of the prediction block subject to coding; and a coding unit configured to code an index for specifying the selected merging motion information candidate as a candidate specifying index.

Another embodiment of the present invention also relates to a moving picture coding device. The device is a moving picture coding device adapted to partition a coding block into a plurality of prediction blocks and perform motion compensation, including: a temporal merging motion information candidate generation unit (161) configured to generate a temporal merging motion information candidate shared in any one of prediction blocks in the coding block from a block of a coded picture different from a picture having a prediction block subject to coding; a merging motion information candidate generation unit configured to generate a plurality of merging motion information candidates including the temporal merging motion information candidate; a merging motion information selection unit (141) configured to select one merging motion information candidate from the plurality of merging motion information candidates and to set the selected merging motion information candidate to be motion information of the prediction block subject to coding; and a coding unit configured to code an index for specifying the selected merging motion information candidate as a candidate specifying index.

Yet another embodiment of the present invention relates to a picture coding method. This method is a moving picture coding method for coding a coding block consisting of greater than or equal to one prediction block, including: deriving, when information indicating whether or not to derive a temporal merging motion information candidate shared for all prediction blocks in the coding block is information indicating the derivation of a temporal merging motion information candidate shared for all the prediction blocks in the coding block, a temporal merging motion information candidate shared for all the prediction blocks in the coding block from a prediction block of a coded picture different from a picture having a prediction block subject to coding; generating a plurality of merging motion information candidates including the temporal merging motion information candidate; selecting one merging motion information candidate from the plurality of merging motion information candidates and using the selected merging motion information candidate as motion information of the prediction block subject to coding; and coding an index for specifying the selected merging motion information candidate as a candidate specifying index.

A moving picture decoding device according to one embodiment of the present invention is a moving picture decoding device adapted to decode a decoding block consisting of greater than or equal to one prediction block, including: a decoding unit configured to decode, from a bitstream in which an index for specifying a merging motion information candidate used in a prediction block subject to decoding is coded as a candidate specifying index, the candidate specifying index; a temporal merging motion information candidate generation unit (161) configured to derive, when information indicating whether or not to derive a temporal merging motion information candidate shared for all prediction blocks in the decoding block is information indicating the derivation of a temporal merging motion information candidate shared for all the prediction blocks in the decoding block, a temporal merging motion information candidate shared for all the prediction blocks in the decoding block from a prediction block of a decoded picture different from a picture having a prediction block subject to decoding; a merging motion information candidate generation unit configured to generate a plurality of merging motion information candidates including the temporal merging motion information candidate; and a merging motion information selection unit (231) configured to select one merging motion information candidate from the plurality of merging motion information candidates based on the candidate specifying index and to use the selected merging motion information candidate as motion information of the prediction block subject to decoding.

Another embodiment of the present invention also relates to a moving picture decoding device. This device is a moving picture decoding device adapted to partition a decoding block into a plurality of prediction blocks and perform motion compensation, including: a decoding unit configured to decode, from a bit stream in which an index for specifying a merging motion information candidate used in a prediction block subject to decoding is coded as a candidate specifying index, the candidate specifying index; a temporal merging motion information candidate generation unit (161) configured to generate a temporal merging motion information candidate shared in any one of prediction blocks in the coding block from a block of a decoded picture different from a picture having a prediction block subject to decoding; a merging motion information candidate generation unit configured to generate a plurality of merging motion information candidates including the temporal merging motion information candidate; and a merging motion information selection unit (231) configured to select one merging motion information candidate from the plurality of merging motion information candidates based on the candidate specifying index and to set the selected merging motion information candidate to be motion information of the prediction block subject to decoding.

Another embodiment of the present invention relates to a moving image decoding method. This method is a moving picture decoding method for decoding a decoding block consisting of greater than or equal to one prediction block, including: decoding, from a bitstream in which an index for specifying a merging motion information candidate used in a prediction block subject to decoding is coded as a candidate specifying index, the candidate specifying index; deriving, when information indicating whether or not to derive a temporal merging motion information candidate shared for all prediction blocks in the decoding block is information indicating the derivation of a temporal merging motion information candidate shared for all the prediction blocks in the decoding block, a temporal merging motion information candidate shared for all the prediction blocks in the decoding block from a prediction block of a decoded picture different from a picture having a prediction block subject to decoding; a merging motion information candidate generation module configured to generate a plurality of merging motion information candidates including the temporal merging motion information candidate; and selecting one merging motion information candidate from the plurality of merging motion information candidates based on the candidate specifying index and using the selected merging motion information candidate as motion information of the prediction block subject to decoding.

Optional combinations of the aforementioned constituting elements and implementations of the invention in the form of methods, apparatuses, systems, recording mediums, and computer programs may also be practiced as additional modes of the present invention.

