[foms] Proposal: adaptive streaming using open codecs

Chris Pearce chris at pearce.org.nz
Thu Nov 4 21:13:32 PDT 2010

  Sorry for coming late to the party as well, I've been busy with 
Firefox 4 blockers, but have caught up with all these threads today. I'm 
on Mozilla's <video> team.

On 4/11/2010 11:26 p.m., Philip Jägenstedt wrote:
> On Fri, 29 Oct 2010 15:47:58 +0200, Timothy B. Terriberry
> <tterribe at xiph.org>  wrote:
>>> It does require more work from browser developers though, so not sure
>>> if this would be preferred.
>> This is something we've talked about doing, and I there are a lot of
>> reasons to want to be able to do something like this, but the
>> implementation is also very complicated. We get faces filled with horror
>> from the New Zealand folks every time it's brought up. I'm sure Philip
>> would agree.
> Yes, it's something that goes against the current architecture with
> completely independent decoding pipelines for each<video>. However, I'm
> not sure if we can avoid doing this eventually, as it may be required for
> accessibility (sign-language video and audio descriptions). The jury is
> still out.

Muxing on the client seems to make sense to enable adaptive streaming, 
so funny faces aside, we may have to bite the bullet and end up 
implementing it for that reason, in addition to the reason Philip 
outlines above.

Making the stream-switching logic optionally overridable in JS seems 
reasonable, given that the different big video sites would likely want 
to customize their buffering logic. It must work without custom logic in 
JS of course.

I think some kind of model where the decoding pipeline gets passed 
keyframe-aligned byte-ranges from possibly different resources seems 
reasonable. We'd probably not want the media data from the chunks to be 
exposed to JS, we'd be better off passing "handles" to chunks around in 
JS instead.

Chris Pearce.

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