W3C home > Mailing lists > Public > public-html-a11y@w3.org > April 2011

Re: text track associations

From: David Singer <singer@apple.com>
Date: Mon, 18 Apr 2011 09:56:18 -0700
Cc: Ian Hickson <ian@hixie.ch>, Silvia Pfeiffer <silviapfeiffer1@gmail.com>, Mark Watson <watsonm@netflix.com>, Eric Carlson <eric.carlson@apple.com>, "public-html-a11y@w3.org" <public-html-a11y@w3.org>
Message-id: <17C9350B-A3B8-45E0-90A9-CB45AFB5F149@apple.com>
To: Sean Hayes <Sean.Hayes@microsoft.com>

On Apr 13, 2011, at 6:39 , Sean Hayes wrote:

> Interesting approach. It's a somewhat misnamed use of a video element to supply audio and captions but not video.

Hm, not sure I agree.  I think 'audio' is for multimedia presentations with no visual aspect, and 'video' for everything else.  Captions need to be visual :-)

> Audio files don't work today in two of the major browsers; and It's also far from clear to me that it the spec currently allows it, but if you say as editor it does, then I guess it could be made to work. 
> 
> I think we will need to change the spec to indicate more clearly that the <video> element is supposed to work if there is no video data supplied.
> 
> For example, change:
> "A video element is used for playing videos or movies."
> To
> "A video element is used for playing videos or movies or audio".
> 
> And  replacing
> "The video element is a media element whose media data is ostensibly video data, possibly with associated audio data"
> 
> With
> "The video element is a media element whose media data is ostensibly video data, audio data or possibly video data with associated audio data."
> 
> I'm also not clear if the section on "Media elements", which is indicated to 'apply equally to video and audio', means that if I supply a video to an audio element; that is supposed to play the audio data from it? Can I create a display rectangle with CSS for an audio element to display video data?
> 
> One interesting side effect of this approach is that it gives the ability to make free standing timed text elements, since I can just do <video src=24hrsOfSilence.mp3> <track src=captions.cues ></video>. Would be nicer to have a shorthand <cues> element for that, but I guess not much point trying to make HTML logical at this stage.
> 
> -----Original Message-----
> From: Ian Hickson [mailto:ian@hixie.ch] 
> Sent: 12 April 2011 01:03
> To: Sean Hayes
> Cc: Silvia Pfeiffer; Mark Watson; Eric Carlson; public-html-a11y@w3.org
> Subject: Re: text track associations
> 
> On Fri, 8 Apr 2011, Sean Hayes wrote:
>> 
>> In a multitrack API, since caption tracks are essentially the audio for 
>> Deaf and HoH use, we will need some way for these to follow the selected 
>> audio asset.
>> 
>> If I have a presentation, with the option of switching to different a 
>> different audio resource (e.g director commentary which is longer, 
>> starts before and ends after the main movie). The captions for it need 
>> to be timed to the commentary audio, and so if it's in a markup element, 
>> live in that element. If the user has captions turned on and wants the 
>> commentary audio, then the captions for the commentary soundtrack will 
>> need to replace the captions for the original audio track, and render 
>> into the rectangle allotted for the main video.
>> 
>> I'm not seeing how I would create this.
> 
> Use <video> element for the commentary audio, with the appropriate 
> captions specified, and layer it on top of the main <video>.
> 
> -- 
> Ian Hickson               U+1047E                )\._.,--....,'``.    fL
> http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
> Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
> 
> 

David Singer
Multimedia and Software Standards, Apple Inc.
Received on Monday, 18 April 2011 16:56:49 UTC

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