[whatwg] On implementing videos with multiple tracks in HTML5

Ian Hickson ian at hixie.ch
Mon Apr 30 21:27:01 PDT 2012

On Fri, 20 Aug 2010, Silvia Pfeiffer wrote:
> Three issues I have taken out of this discussion that I think are still 
> open to discuss and potentially define in the spec:
> * How to expose in-band extra audio and video tracks from a multi-track 
> media resource to the Web browser? I am particularly thinking here about 
> the use cases Lachlan mentioned: offering stereo and surround sound 
> alternatives, audio descriptions, audio commentaries or multiple 
> languages, and would like to add sign language tracks to this list. This 
> is important to solve now, since it will allow the use of audio 
> descriptions and sign language, two important accessibility 
> requirements.

I think this is now resolved. Let me know if there's still something open 

> * How to associate and expose such extra audio and video tracks that are 
> provided out-of-band to the Web browser? This is probably a next-version 
> issue since it's rather difficult to implement in the browser. It 
> improves on meeting accessibility needs, but it doesn't stand in the way 
> of providing audio descriptions and sign language - just makes it easier 
> to use them.

I'm not sure what you mean here.

> * Whether to include a multiplexed download functionality in browsers 
> for media resources, where the browser would do the multiplexing of the 
> active media resource with all the active text, audio and video tracks? 
> This could be a context menu functionality, so is probably not so much a 
> need to include in the HTML5 spec, but it's something that browsers can 
> consider to provide. And since muxing isn't quite as difficult a 
> functionality as e.g. decoding video, it could actually be fairly cheap 
> to implement.

I agree that this seems out of scope for the spec.

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

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