[Bug 27487] [MSE] Decode timestamps < 0 should be allowed.

https://www.w3.org/Bugs/Public/show_bug.cgi?id=27487

Aaron Colwell <acolwell@google.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |acolwell@google.com
           Assignee|adrianba@microsoft.com      |acolwell@google.com

--- Comment #4 from Aaron Colwell <acolwell@google.com> ---
(In reply to Jer Noble from comment #1)
> It looks like this line was changed after the 21 May 2014 Editors draft.
> That version read:
> 
> "1.7 If the presentation timestamp or decode timestamp is less than the
> presentation start time, then run the end of stream algorithm with the error
> parameter set to "decode", and abort these steps."
> 
> It seems like the requirement that the presentation timestamp < 0 was
> removed, leaving the requirement that the decode timestamp < 0.  Perhaps
> that decision could be revisited, and instead the decode timestamp < 0
> requirement be removed, and the presentation timestamp < 0 requirement be
> reinstated.

Yes. The presentation timestamp check was removed as part of resolving Bug
25998. The check was redundant because the constraints on appendWindowStart
always make sure presentation timestamp is within bounds. It's a little subtle,
but that is the reason the pts check was removed.

I vaguely remembering having a discussion about this with Matt Wolenetz on the
Chrome team a while ago. I believe I may have just forgotten to file a spec bug
for it. The relevant Chromium code even has this comment in it:

"B-frames may still result in negative DTS here after being shifted by
|timestamp_offset_|." 

:/

I'm fine with dropping the check since I don't believe it will cause any
problems.

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Received on Wednesday, 3 December 2014 06:14:58 UTC