[whatwg] [ogg-dev] HTML5 audio tag

[Silvia Pfeiffer]

Yeah, the track attribute of the media fragments specification that
Ralph links will in theory allow to just download the track-related
data. But it still requires implementation - either in the browser,
which will somehow need to identify which bytes belong to which track
and just request those byte ranges that are relevant, or on the
server, which will only deliver the relevant bytes when asked for the
audio track only.

None of this is implemented yet. In fact, the discovery of which bytes
in a Ogg stream belong to which track is a challenge. I am not sure
whether the new Skeleton Index format might actually allow for that...

Cheers,
Silvia.

On Wed, May 12, 2010 at 3:32 AM, Frank Barchard <fbarchard at google.com> wrote:
> FWIW chromium does client side range requests that in theory would request
> only the audio.  But. the ogg demux reads the other tracks and discards
> them.
> A use case I've heard is listening to music videos and discard the video...
> bit of a bandwidth waste.
>
> On Tue, May 11, 2010 at 10:17 AM, Ralph Giles <giles at thaumas.net> wrote:
>>
>> On 11 May 2010 04:24, narendra sisodiya <narendra.sisodiya at gmail.com>
>> wrote:
>>
>> >      It will be very good if HTML5 API specify this. I mean, Say, If we
>> > use
>> > <audio> tag , then It must stream only audio part of the file
>> > irrespective
>> > of the fact that the src field contains a video file.
>>
>> I don't think that's a practical option, since the server must
>> manipulate the file to return an audio-only subset of the data for
>> there to be any bandwidth advantage. That's not something that the
>> HTML5 specification, which documents browser behaviour, can describe.
>>
>> Note that it's completely possible to use a server-size module or
>> script to do this, using a query url in the HTML5 media element's src
>> attribute. It's just part of a custom server config rather than the
>> HTML5 API. The Media Fragments Working Group at the W3C is currently
>> working on a standardized syntax for this. See
>> http://www.w3.org/2008/WebVideo/Fragments/WD-media-fragments-spec/ if
>> you're interested.
>>
>> FWIW,
>>  -r
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