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Re: [whatwg] Feature Request for the-video-element to support audiochannel descriptions

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Wed, 17 Jul 2013 11:07:09 +1000
Message-ID: <CAHp8n2n5Jp=ppCRk2WcXmzbmt6KaPjmUeO9t7ZmAKRuM4SLuuQ@mail.gmail.com>
To: Ian Hickson <ian@hixie.ch>
Cc: "whatwg@lists.whatwg.org" <whatwg@lists.whatwg.org>, Christian Horn <chorn1@my.uno.edu>
Note that Mozilla have introduced .mozChannels for this:
https://developer.mozilla.org/en-US/docs/Web/API/HTMLMediaElement .

The Web Audio API have created what is called an AudioNode, which
includes the number of channels:
https://dvcs.w3.org/hg/audio/raw-file/tip/webaudio/specification.html#AudioNode-section
There is a whole section on how to do up/down mixing:
https://dvcs.w3.org/hg/audio/raw-file/tip/webaudio/specification.html#UpMix-section

You need to use createMediaElementSource  to get an
MediaElementAudioSourceNode which is a kind of AudioNode and should
thus have a channelCount attribute.
(see http://updates.html5rocks.com/2012/02/HTML5-audio-and-the-Web-Audio-API-are-BFFs
for an example)


Is this too much mucking around to just get information about the
channel count of an audio track? I don't know... I guess if every use
case involves manipulating audio, then the use of the Web Audio API is
appropriate. If it's just to display to users more information about
the quality of their media files... maybe this is overkill and a
simpler interface directly on HTMLMediaElement like .mozChannels would
be better.

Silvia.


On Wed, Jul 17, 2013 at 9:39 AM, Ian Hickson <ian@hixie.ch> wrote:
> On Wed, 23 Jan 2013, Christian Horn wrote:
>>
>> Hello to everybody, unknowingly,
>>
>> It would be nice to see audioTrack.channels added to the-video-element
>> for media resources with multiple media tracks.
>>
>> It should return the number of channels in the audio track (1 = mono, 2
>> = stereo, 6 = surround, etc).
>>
>> A use case can be: A user has an encoded video with multiple audio
>> tracks. Track 1 and 2 are both English, but one is stereo, one is
>> surround.
>
> Can you elaborate on the use case? Wouldn't the browser be the one in the
> best position to know which to pick, in that case?
>
> --
> Ian Hickson               U+1047E                )\._.,--....,'``.    fL
> http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
> Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Wednesday, 17 July 2013 01:07:53 UTC

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