edit lists

[jpiesing]

This issue is for discussion about what we should do about edit lists, what we should put in the DPCTF spec and what we should test.

Note that the MSE byte stream spec for ISOBMFF only requires support for a very limited subset of edit list functionality.

"The user agent MUST support setting the offset from media composition time to movie presentation time by handling an Edit Box (edts) containing a single Edit List Box (elst) that contains a single edit with media rate one. This edit MAY have a duration of 0 (indicating that it spans all subsequent media) or MAY have a non-zero duration (indicating the total duration of the movie including fragments)."

See also the following DASH-IF IOP issues on edit lists.

• Edit Lists with Bitstream Switching Dash-Industry-Forum/DASH-IF-IOP#168
• When, if ever, are edit lists okay to use and how to they affect timing calculations? Dash-Industry-Forum/Guidelines-TimingModel#27

[haudiobe]

Discussion with Romain:

• we would be interested to know if you provide representative test content with the following options:
  • With edit lists for video and audio.
  • Without edit lists uses negative offsets for video and avoiding audio priming.
  • In the CTA WAVE context, do we have these different options?

Romain Bouqueau: No. I did take care of video. Audio was handled by Resillion.
I'm pretty sure the Resillion streams use edit lists. For video we have no edit list.

[haudiobe]

Actions from f2f IBC

• Generate Questions about edit lists in deployments
  • We need to make sure that the manifest generation takes into account the edit lists
• Create a tests in DPCTF for edit list playback (functional, audio, video, sync, random access)
• We add content validation for edit lists or make sure that it is correctly implemented

[haudiobe]

Draft questions are generated here: https://docs.google.com/document/d/10Nw9MtJprr8qFzN7uERU9Ql7q3KPOLNaP1kM3xScXRs/edit?tab=t.0