Conformance constraint for collocated reference index in video coding

An apparatus configured to encode video data, the apparatus comprising:

• a memory configured to store a current picture of video data;
• and
• one or more processors configured to:
• encode a current picture of video data;
• generate a respective collocated reference picture index syntax element for one or more slices of the current picture;
• and
• perform a bitstream conformance check only for slices of the one or more slices that do not have an intra slice type and also for which a temporal motion vector predictor is enabled, the bitstream conformance check constrains the values of the respective collocated reference picture index syntax elements such that each respective collocated reference picture index syntax element points to the same picture and does not reference the current picture itself.

A non-transitory computer-readable storage medium storing instructions that, when executed, causes one or more processors of a device configured to encode video data to:

• encode a current picture of video data;
• generate a respective collocated reference picture index syntax element for one or more slices of the current picture;
• and
• perform a bitstream conformance check only for slices of the one or more slices that do not have an intra slice type and also for which a temporal motion vector predictor is enabled, the bitstream conformance check constrains the values of the respective collocated reference picture index syntax elements such that each respective collocated reference picture index syntax element points to the same picture and does not reference the current picture itself.

An apparatus configured to decode video data, the apparatus comprising:

• a memory configured to store an encoded current picture of video data;
• and
• one or more processors configured to:
• receive the encoded current picture of video data;
• receive a respective collocated reference picture index syntax element for one or more slices of the encoded current picture;
• and
• perform a bitstream conformance check only for slices of the one or more slices that do not have an intra slice type and also for which a temporal motion vector predictor is enabled, the bitstream conformance check determining if each respective collocated reference picture index syntax element points to the same picture and does not reference the encoded current picture itself.