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Clarification of 2-D video stream encapsulation #19

Closed laurilo closed 5 months ago

laurilo commented 6 months ago

It’s not clear from the draft how the 2-D video streams (H.264, H.265, and H.266) are encapsulated or associated with the V3C stream. Are these streams’ NAL units encapsulated inside V3C NAL units, or are the streams sent separately and then somehow correlated? I think from reading the document that it’s the former, but this could definitely be clearer

laurilo commented 5 months ago

Seems some further clarification in the specification is in order. The 2D video streams are using the respective video payload specifications, they are not re-encoded into V3C NAL units. "V3C NAL units" are reserved for atlas data only, i.e. the metadata that describes how the 2D video streams can be converted into a 3D representation.

The association with the atlas data NAL units and the 2D video NAL units is done by grouping the media lines inthe SDP that create a V3C representation. Then the right pairs of NAL units between the streams can be identified using timestamps, decoding order numbers or sequence number.

laurilo commented 5 months ago

Addressed in commit https://github.com/laurilo/draft-ilola-avtcore-rtp-v3c/commit/2167a87f56aa925697d1048eebdb0271e286c6da