File format signaling of error mitigation in sub-picture bitstream based viewport dependent video coding

A video coding device comprising:

• a receiver configured to receive a plurality of sub-picture tracks containing a plurality of video bitstreams including a plurality of sub-picture video signals each containing a sequence of sub-pictures mapped to a spherical video signal, wherein the plurality of sub-picture tracks are compatible with multi-bitstream merging for reconstruction of the spherical video signal or a part thereof, wherein the plurality of sub-picture tracks are compatible with a multi-bitstream merging when no sample values outside a sub-picture are referenced for inter-prediction, motion vectors are restricted to point to full-sample locations inside the sub-picture and to fractional-sample locations that employ only full-sample locations inside the sub-picture for interpolation, and inter-prediction is restricted so motion vector candidates for temporal motion vector prediction are not derived from blocks outside the sub-picture;
• and
• a processor coupled to the receiver and configured to:
• parse one or more track level mergable indications from the bitstream for each of the sub-picture tracks, the track level mergable indications indicating whether a video bitstream carried in a current sub-picture track can be merged with a video bitstream carried in the sub-picture tracks in a same track group;
• and
• decode the plurality of sub-picture tracks based on the track level mergable indications.

A non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to:

• receive a plurality of sub-picture tracks containing a plurality of video bitstreams including a plurality of sub-picture video signals each containing a sequence of sub-pictures mapped to a spherical video signal, wherein the plurality of sub-picture tracks are compatible with a multi-bitstream merging for reconstruction of the spherical video signal or a part thereof, wherein the plurality of sub-picture tracks are compatible with a multi-bitstream merging when no sample values outside a sub-picture are referenced for inter-prediction, motion vectors are restricted to point to full-sample locations inside the sub-picture and to fractional-sample locations that employ only full-sample locations inside the sub-picture for interpolation, and inter-prediction is restricted so motion vector candidates for temporal motion vector prediction are not derived from blocks outside the sub-picture;
• parse one or more track level mergable indications from the bitstream for each of the sub-picture tracks, the track level mergable indications indicating whether a video bitstream carried in a current sub-picture track can be merged with a video bitstream carried in the sub-picture tracks in a same track group;
• and
• decode the plurality of sub-picture tracks based on the track level mergable indications.