Picture coding supporting block partitioning and block merging
A further coding efficiency increase may be achieved if for a current block of a picture, for which the bit stream signals one of supported partitioning patterns, a reversal of the partitioning by block merging is avoided. In particular, if the signaled one of the supported partitioning patterns specifies a subdivision of the block into two or more further blocks, a removal of certain coding parameter candidates for all further blocks, except a first further block of the further blocks in a coding order, is performed. Particularly, those coding parameter candidates are removed from the set of coding parameter candidates for the respective further block, the coding parameters of which are the same as coding parameters associated with any of the further blocks which, when being merged with the respective further block, would result in one of the supported partitioning pattern. This avoids redundancy between partitioning coding and merging coding.
1 . A decoder configured to decode a bitstream signaling one of supported partitioning patterns for a current block of a picture, wherein:
if the signaled one of the supported partitioning patterns specifies a subdivision of the current block into a plurality of sub-blocks, the decoder is configured to:
determine coding parameter candidates for a current sub-block of the plurality of sub-blocks,
check whether a total number of the determined coding parameter candidates is equal to a predetermined number of coding parameter candidates needed to complete a set of coding parameter candidates for the current sub-block, and
based on an indication from the check that the total number of the determined coding parameter candidates is not equal to the predetermined number of coding parameter candidates, provide one or more ancillary coding parameter candidates including a zero motion vector parameter to the set of coding parameter candidates to complete the set, wherein:
the current sub-block is not a first sub-block of the plurality of sub-blocks in a coding order, and
a coding parameter candidate associated with any candidate sub-block is excluded from the set of coding parameter candidates for the current sub-block if the candidate sub-block, when being merged with the current sub-block, results in one of the supported partitioning patterns.
2 . The decoder according to claim 1 , wherein the one or more ancillary coding parameter candidates include parameters of neighboring partitions of temporally neighboring and previously coded pictures.
3 . The decoder according to claim 1 , wherein the one or more ancillary coding parameter candidates include a combined coding parameter candidate obtained by combination of coding parameters associated with previously decoded blocks neighboring the current sub-block.
4 . The decoder according to claim 1 , wherein the decoder is configured to, depending on a total quantity of coding parameter candidates in the set of coding parameter candidates being greater than one, decode a syntax element from the bitstream specifying which of the predetermined number of coding parameter candidates is to be used for merging.
5 . The decoder according to claim 1 , wherein the picture has associated therewith a depth map as additional information.
6 . The decoder according to claim 1 , wherein the picture includes sample arrays related to different planes of the picture.
7 . The decoder according to claim 6 , wherein the different planes of the picture are coded independently from each other.
8 . An encoder configured to encode a picture into a bitstream, the encoder being configured to:
signal, within the bitstream, one of supported partitioning patterns for a current block of the picture; and
if the signaled one of the supported partitioning patterns specifies a subdivision of the current block into a plurality of sub-blocks,
determine coding parameter candidates for a current sub-block of the plurality of sub-blocks,
check whether a total number of the determined coding parameter candidates is equal to a predetermined number of coding parameter candidates needed to complete a set of coding parameter candidates for the current sub-block, and
based on an indication from the check that the total number of the determined coding parameter candidates is not equal to the predetermined number of coding parameter candidates, provide one or more ancillary coding parameter candidates including a zero motion vector parameter to the set of coding parameter candidates to complete the set, wherein:
the current sub-block is not a first sub-block of the plurality of sub-blocks in a coding order, and
a coding parameter candidate associated with any candidate sub-block is excluded from the set of coding parameter candidates for the current sub-block if the candidate sub-block, when being merged with the current sub-block, results in one of the supported partitioning patterns.
9 . The encoder according to claim 8 , wherein the one or more ancillary coding parameter candidates include parameters of neighboring partitions of temporally neighboring and previously coded pictures.
10 . The encoder according to claim 8 , wherein the one or more ancillary coding parameter candidates include a combined coding parameter candidate obtained by combination of coding parameters associated with previously decoded blocks neighboring the current sub-block.
11 . The encoder according to claim 8 , wherein the picture has associated therewith a depth map as additional information.
12 . The encoder according to claim 8 , wherein the picture includes sample arrays related to different planes of the picture.
13 . The encoder according to claim 12 , wherein the different planes of the picture are coded independently from each other.
14 . The encoder according to claim 8 , wherein the encoder is configured to derive at least one coding parameter candidate of the set based on a combination of coding parameters of two previously coded blocks.
15 . A method for decoding a data stream, comprising:
obtaining, in the data stream, data signaling one of supported partitioning patterns for a current block of a picture;
determining that the signaled one of the supported partitioning patterns specifies a subdivision of the current block into a plurality of sub-blocks;
determining coding parameter candidates for a current sub-block of the plurality of sub-blocks;
checking whether a total number of the determined coding parameter candidates is equal to a predetermined number of coding parameter candidates needed to complete a set of coding parameter candidates for the current sub-block; and
based on an indication from the check that the total number of the determined coding parameter candidates is not equal to the predetermined number of coding parameter candidates, providing one or more ancillary coding parameter candidates including a zero motion vector parameter to the set of coding parameter candidates to complete the set, wherein:
the current sub-block is not a first sub-block of the plurality of sub-blocks in a coding order, and
a coding parameter candidate associated with any candidate sub-block is excluded from the set of coding parameter candidates for the current sub-block if the candidate sub-block, when being merged with the current sub-block, results in one of the supported partitioning patterns.
16 . The method according to claim 15 , wherein the one or more ancillary coding parameter candidates include parameters of neighboring partitions of temporally neighboring and previously coded pictures.
17 . The method according to claim 15 , wherein the one or more ancillary coding parameter candidates include a combined coding parameter candidate obtained by combination of coding parameters associated with previously decoded blocks neighboring the current sub-block.
18 . The method according to claim 15 , wherein the picture has associated therewith a depth map as additional information.
19 . The method according to claim 15 , wherein the picture includes sample arrays related to different planes of the picture, wherein the different planes are coded independently from each other.
20 . A method for encoding a picture into a data stream, comprising:
signaling, within the data stream, one of supported partitioning patterns for a current block of the picture; and
if the signaled one of the supported partitioning patterns specifies a subdivision of the current block into a plurality of sub-blocks,
determining coding parameter candidates for a current sub-block of the plurality of sub-blocks,
checking whether a total number of the determined coding parameter candidates is equal to a predetermined number of coding parameter candidates needed to complete a set of coding parameter candidates for the current sub-block, and
based on an indication from the check that the total number of the determined coding parameter candidates is not equal to the predetermined number of coding parameter candidates, providing one or more ancillary coding parameter candidates including a zero motion vector parameter to the set of coding parameter candidates to complete the set, wherein:
the current sub-block is not a first sub-block of the plurality of sub-blocks in a coding order, and
a coding parameter candidate associated with any candidate sub-block is excluded from the set of coding parameter candidates for the current sub-block if the candidate sub-block, when being merged with the current sub-block, results in one of the supported partitioning patterns.
21 . A method, comprising storing, on a digital storage medium, a data stream into which a picture is encoded by a method according to claim 20 .