Picture coding supporting block partitioning and block merging

A method for decoding a bitstream signaling one of supported partitioning patterns for a current block of a picture, the method comprising:

• if the signaled one of the supported partitioning patterns specifies a subdivision of the current block into two sub-blocks,
• removing, for each of the sub-blocks except a first sub-block of the sub-blocks in a coding order, from a set of coding parameter candidates for the respective sub-block, a coding parameter candidate associated with a candidate block, which when merged with the respective sub-block, results in one of the supported partitioning patterns;
• determining coding parameter candidates for a current sub-block of the sub-blocks;
• checking whether a total number of determined coding parameter candidates is equal to a fixed number of coding parameter candidates needed to complete the set of coding parameter candidates for the current sub-block;
• and
• based on an indication from the check that the total number of determined coding parameter candidates is less than the fixed number of coding parameter candidates, providing one or more ancillary coding parameter candidates to the set of coding parameter candidates to complete the set.

An encoder configured to encode a picture into a bitstream, the encoder being configured to:

• signaling, within a bitstream, one of supported partitioning patterns for a current block;
• and
• if the signaled one of the supported partitioning patterns specifies a subdivision of the current block into two sub-blocks,
• remove, for each of the sub-blocks except a first sub-block of the sub-blocks in a coding order, from a set of coding parameter candidates for the respective sub-block, a coding parameter candidate associated with a candidate block, which when merged with the respective sub-block, results in one of the supported partitioning patterns,
• wherein the encoder is configured to:
• determine coding parameter candidates for a current sub-block of the sub-blocks,
• check whether a total number of determined coding parameter candidates is equal to a fixed number of coding parameter candidates needed to complete the set of coding parameter candidates for the current sub-block, and
• based on an indication from the check that the total number of determined coding parameter candidates is less than the fixed number of coding parameter candidates, provide one or more ancillary coding parameter candidates to the set of coding parameter candidates to complete the set.

A non-transitory computer-readable medium for storing video data, comprising:

• a data stream stored in the non-transitory computer-readable medium and comprising data signaling one of supported partitioning patterns for a current block of a picture, and wherein the data stream is decoded by executing operations using a processor, the operations including:
• if the signaled one of the supported partitioning patterns specifies a subdivision of the current block into two sub-blocks,
• removing, for each of the sub-blocks except a first sub-block of the sub-blocks in a coding order, from a set of coding parameter candidates for the respective sub-block, a coding parameter candidate associated with a candidate block, which when merged with the respective sub-block, results in one of the supported partitioning patterns;
• determining coding parameter candidates for a current sub-block of the sub-blocks;
• checking whether a total number of determined coding parameter candidates is equal to a fixed number of coding parameter candidates needed to complete the set of coding parameter candidates for the current sub-block;
• and
• based on an indication from the check that the total number of determined coding parameter candidates is less than the fixed number of coding parameter candidates, providing one or more ancillary coding parameter candidates to the set of coding parameter candidates to complete the set.