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Consider an adaptation set AS and representations R1-R4 as follows.
AS in period A:
R1
R2
R3
AS in period B:
R1 (connected to period A)
R2 (connected to period A)
R4 (not connected)
Is this AS period-connected?
DASH does not explicitly state this, as far as I can tell. I would guess clients would not expect connectivity to apply if only a subset of representations are connected, so I suggest DASH-IF notify MPEG of this ambiguity and propose to constrain it to only cases where all the contents of an adaptation set are connected.
The text was updated successfully, but these errors were encountered:
Question answered in IOP call: connectivity is an adaptation set level concept, there should not be nonconnected representations appearing/disappearing. This will be integrated into timing model text as part of Dash-Industry-Forum/Guidelines-TimingModel#2
Answer was found but I leave this issue open as reminder that we should ask MPEG to clarify this.
Here is a scenario where representation-level is desirable:
I encounter segment loss between encoder and packager. The 720p representation has a gap!
I do not want gaps in my MPD, so I remove the 720p representation. All others remain connected and I want to signal this.
But oh no, I cannot signal this if adaptation set level continuity is expected (all representations must exist).
From this viewpoint, I can see a valuable use case for allowing the set of representations to be different, as long as the difference is not additive (no new decoder requirements in the period that follows).
Consider an adaptation set AS and representations R1-R4 as follows.
AS in period A:
AS in period B:
Is this AS period-connected?
DASH does not explicitly state this, as far as I can tell. I would guess clients would not expect connectivity to apply if only a subset of representations are connected, so I suggest DASH-IF notify MPEG of this ambiguity and propose to constrain it to only cases where all the contents of an adaptation set are connected.
The text was updated successfully, but these errors were encountered: