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[Bug 9452] Handling of additional tracks of a multitrack audio/video resource

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Date: Fri, 04 Mar 2011 07:25:53 +0000
To: public-html-bugzilla@w3.org
Message-Id: <E1PvPOb-0002Ca-6r@jessica.w3.org>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=9452

--- Comment #13 from Philip Jägenstedt <philipj@opera.com> 2011-03-04 07:25:52 UTC ---
Quoting Hixie from <http://krijnhoetmer.nl/irc-logs/whatwg/20110304#l-145>: "if
we have a controller + slaves model, you can imagine a model where the
controller doesn't have a timeline, it just controls the velocity"

I just want to point out that for normal playback of a single resource, the
timeline is in practice controlled by the rate of the sound card, not the wall
clock. The reason is that the wall clock and sound card clock might not be in
sync, and audio glitches are much more noticeable. Only if there is no audio
stream is the wall clock used.

I haven't tried implementing sync of two resources, but I think that it would
have to be done by locking both to the sound card clock. If we define a audio-
and video-less controller that drives the pipeline, we need to ensure that it
can still be implemented by syncing to an audio stream of one of the resources.
Actually using the wall clock to drive pipelines with audio streams would
likely give pretty bad results.

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