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US 2017/0302957 A1Published application
Motion vector calculation method
AssigneePanasonic Intellectual Property Corporation of America
InventorsSatoshi KONDO, Shinya KADONO, Makoto HAGAI, Kiyofumi ABE
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Abstract
When a block (MB22) of which motion vector is referred to in the direct mode contains a plurality of motion vectors, 2 motion vectors MV23 and MV24, which are used for inter picture prediction of a current picture (P23) to be coded, are determined by scaling a value obtained from averaging the plurality of motion vectors or selecting one of the plurality of the motion vectors.
Claims2
A picture decoding method for decoding a bit stream corresponding to coded data of a decoding target block included in a decoding target picture in direct mode, wherein the bit stream is generated by the following steps:
- a step of specifying, when a co-located block has two motion vectors, only one motion vector out of the two motion vectors, the co-located block being located in a second picture at the same position that a coding target block is located in a coding target picture, the second picture being a B-picture following the coding target picture in display order;
- a step of determining a first motion vector and a second motion vector of the coding target block, using the specified one motion vector;
- a step of generating a first predictive image of the coding target block using the first motion vector of the coding target block and a second predictive image of the coding target block using the second motion vector of the coding target block;
- a step of generating a predictive image of the coding target block based on the first predictive image and the second predictive image;
- a step of generating a difference image between the coding target block and the predictive image of the coding target block;
- and
- a step of coding the difference image to obtain a coded difference image of the coding target block,
- the picture decoding method comprising:
- specifying, when a co-located block has two motion vectors, only one motion vector out of the two motion vectors, the co-located block being located in a second picture at the same position that the decoding target block is located in the decoding target picture, the second picture being a B-picture following the decoding target picture in display order;
- determining a first motion vector and a second motion vector of the decoding target block, using the specified one motion vector;
- generating a first predictive image of the decoding target block using the first motion vector of the decoding target block and a second predictive image of the decoding target block using the second motion vector of the decoding target block;
- generating a predictive image of the decoding target block based on the first predictive image and the second predictive image;
- decoding a coded difference image of the decoding target block to obtain a decoded difference image of the decoding target block;
- and
- reconstructing the decoding target block by adding the decoded difference image of the decoding target block and the predictive image of the decoding target block,
- wherein, in the case where the co-located block is motion compensated using two motion vectors which refer to a same one reference picture preceding the second picture in display order, one motion vector among the two motion vectors of the co-located block which appears earlier in a bit stream is specified as the only one motion vector of the co-located block in said specifying.
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A picture decoding apparatus that decodes a bit stream corresponding to coded data of a decoding target block included in a decoding target picture in direct mode, wherein the bit stream is generated by using the following units:
- a specifying unit configured to specify, when a co-located block has two motion vectors, only one motion vector out of the two motion vectors, the co-located block being located in a second picture at the same position that the coding target block is located in a coding target picture, the second picture being a B-picture following the coding target picture in display order;
- a motion vector determining unit configured to determine a first motion vector and a second motion vector of the coding target block, using the specified one motion vector;
- a first and second predictive image generating unit configured to generate a first predictive image of the coding target block using the first motion vector of the coding target block and a second predictive image of the coding target block using the second motion vector of the coding target block;
- a predictive image generating unit configured to generate a predictive image of the coding target block based on the first predictive image and the second predictive image;
- a difference image generating unit configured to generate a difference image between the coding target block and the predictive image of the coding target block;
- and
- a difference image coding unit configured to code the difference image to obtain a coded difference image of the coding target block,
- the picture decoding apparatus comprising:
- a specifying unit configured to specify, when a co-located block has two motion vectors, only one motion vector out of the two motion vectors, the co-located block being located in a second picture at the same position that the decoding target block is located in the decoding target picture, the second picture being a B-picture following the decoding target picture in display order;
- a motion vector determining unit configured to determine a first motion vector and a second motion vector of the decoding target block, using the specified one motion vector;
- a first and second predictive image generating unit configured to generate a first predictive image of the decoding target block using the first motion vector of the decoding target block and a second predictive image of the decoding target block using the second motion vector of the decoding target block;
- a predictive image generating unit configured to generate a predictive image of the decoding target block based on the first predictive image and the second predictive image;
- a difference image decoding unit configured to decode a coded difference image of the decoding target block to obtain a decoded difference image of the decoding target block;
- and
- a block image reconstructing unit configured to reconstruct the decoding target block by adding the decoded difference image of the decoding target block and the predictive image of the decoding target block,
- wherein, in the case where the co-located block is motion compensated using two motion vectors which refer to a same one reference picture preceding the second picture in display order, one motion vector among the two motion vectors of the co-located block which appears earlier in a bit stream is specified by said specifying unit, as the only one motion vector of the co-located block.
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Dependencies are inferred from the claim text.