Methods and apparatus for signaling spatial relationships for point cloud multimedia data tracks

A method for encoding video data, the method comprising:

• encoding at least a portion of point cloud video data comprising encoding:
• a plurality of groups of tracks that are separate from each other in carrying different bitstreams, wherein:
• the point cloud video data is divided into a plurality of source regions, wherein:
• each source region corresponds to a different spatial portion of the point cloud video data;
• and
• at least one source region of the plurality of source regions is further divided into a plurality of sub-regions;
• and
• each of the plurality of groups of tracks comprises video data of an associated portion of the point cloud video data;
• each of the different bitstreams are encoded as separate point cloud content bitstreams that are not multiplexed into one point cloud content bitstream;
• and
• spatial relationship metadata specifying, for each of the plurality of groups of tracks, which one of the plurality of source regions, and which one of the plurality of sub-regions, when applicable, the video data of the group of tracks is associated with;
• the encoding comprising:
• determining a first source region of the plurality of source regions of a point cloud video data, wherein the first source region comprises the plurality of sub-regions;
• and
• determining a sub-region of the plurality of sub-regions of the first track in the first source region, comprising determining data indicative of a spatial position of video data in the first source region;
• and
• encoding, based on the determined first source region and the determined sub-region of the first track, the point cloud video data comprising:
• encoding the video data in the first track, wherein the first track is of a first group of tracks of the plurality of groups of tracks;
• and
• encoding first metadata of the spatial relationship metadata of the first rack comprising metadata specifying the first source region and the sub-region.

An apparatus configured to decode video data, the apparatus comprising a processor in communication with memory, the processor being configured to execute instructions stored in the memory that cause the processor to perform:

• receiving at least a portion of point cloud video data, comprising receiving:
• a plurality of groups of tracks that are separate from each other in carrying different bitstreams, wherein:
• the point cloud video data is divided into a plurality of source regions, wherein:
• each source region corresponds to a different spatial portion of the point cloud video data;
• and
• at least one source region of the plurality of source regions is further divided into a plurality of sub-regions;
• and
• each of the plurality of groups of tracks comprises video data of an associated portion of the point cloud video data;
• each of the different bitstreams are received as separate point cloud content bitstreams that are not multiplexed into one point cloud content bitstream;
• and
• spatial relationship metadata specifying, for each of the plurality of groups of tracks, which one of the plurality of source regions, and which one of the plurality of sub-regions, when applicable, the video data of the group of tracks is associated with;
• accessing first metadata from the spatial relationship metadata of a first track of a first group of tracks of the plurality of groups of tracks, the first metadata specifying:
• a first source region of the plurality of source regions of the point cloud video data, wherein the first source region comprises the plurality of sub-regions;
• and
• a sub-region of the plurality of sub-regions of the first track in the first source region comprising data indicative of a spatial position of video data of the first track in the first source region;
• and
• generating, based on the first metadata, point cloud media for the sub-region of the first source region using the video data of the first track.