Determination of a maximum number of merge candidates in subblock based merge candidate lists

An apparatus for video encoding, comprising:

• processing circuitry configured to:
• calculate a maximum number of candidates in subblock based merge candidate lists for coding a video bitstream,
• determine a parameter corresponding to the coded video bitstream based on the calculated maximum number of candidates, the parameter being in a range from 0 to 5-sps_sbtmvp_enabled_flag, wherein the sps_sbtmvp_enabled_flag equal to 1 specifies that subblock based temporal motion vector predictors are used in decoding of pictures with slices having slice type not equal to I (intra coded) in a coded video, and wherein the sps_sbtmvp_enabled_flag equal to 0 specifies that the subblock based temporal motion vector predictors are not used in the coded video;
• and
• in response to a current block being in a subblock based prediction mode, encode samples of the current block based on a candidate selection from a constructed subblock based merge candidate list of the current block, the constructed subblock based merge candidate list of the current block being constrained by the maximum number of candidates in the subblock based merge candidate lists.

A non-transitory computer-readable medium storing instructions which, when executed by a computer for video encoding, cause the computer to perform:

• calculating a maximum number of candidates in subblock based merge candidate lists for coding a video bitstream;
• determining a parameter corresponding to the coded video bitstream based on the calculated maximum number of candidates, the parameter being in a range from 0 to 5-sps_sbtmvp_enabled_flag, wherein the sps_sbtmvp_enabled_flag equal to 1 specifies that subblock based temporal motion vector predictors are used in encoding of pictures with slices having slice type not equal to I (intra coded) in a coded video, and wherein the sps_sbtmvp_enabled_flag equal to 0 specifies that the subblock based temporal motion vector predictors are not used in the coded video;
• and
• in response to a current block being in a subblock based prediction mode, encoding samples of the current block based on a candidate selection from a constructed subblock based merge candidate list of the current block, the constructed subblock based merge candidate list of the current block being constrained by the maximum number of candidates in the subblock based merge candidate lists.