[whatwg] TextTrack and addCue

Philip Jägenstedt philipj at opera.com
Thu Sep 27 01:47:29 PDT 2012

On Thu, 27 Sep 2012 10:35:26 +0200, Cyril Concolato  
<cyril.concolato at telecom-paristech.fr> wrote:

> Hi Philip,
> Le 9/27/2012 10:30 AM, Philip Jägenstedt a écrit :
>> On Wed, 26 Sep 2012 21:41:34 +0200, Cyril Concolato  
>> <cyril.concolato at telecom-paristech.fr> wrote:
>>> Hi all,
>>> Has it been considered adding another method to add cues to a track?  
>>> Something like addCues(DOMString text) where the text is not only one  
>>> cue (like in the TextTrackCue ctor) but where the text would be  
>>> multiple cues as written in a WebVTT file? My use case is that I'm  
>>> getting WebVTT content from a server using XHR and I'd like to add  
>>> that easily to the track, without having to parse them myself.  
>>> Ideally, I would like to push the WebVTT content to the track a bit  
>>> like the Media Source Extension API. Another option (less ideal) would  
>>> be to have a WebVTTParser object with a parseFromString method  
>>> returning a TextTrackList (a bit like the DOMParser object). Each cue  
>>> could be added one by one.
>>> Comments?
>>> Cyril
>> You can parse WebVTT using a dummy video+track element and then move  
>> the cues to the actual track, why is this less than ideal?
> I did not think about that option. It could do the trick. Thank you. By  
> less than ideal, I meant that if I can push content to a buffer and let  
> the browser parse the text and add the cues to the track, it seems  
> easier/more elegant than having either to parse in JS or to create dummy  
> elements and move cues around.

Yeah, creating that temporary document is one step more than is needed to  
parse HTML by setting innerHTML. If constructing text tracks  
piece-by-piece in this fashion is something that a lot of people will need  
to do, I think a utility method could be considered. It certainly wouldn't  
be hard to implement, it's just a bigger API that the Web will have to  
support forever :)

Philip Jägenstedt
Core Developer
Opera Software

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