[whatwg] Video, Closed Captions, and Audio Description Tracks

John Foliot foliot at wats.ca
Wed Nov 14 21:53:10 PST 2007

Silvia Pfeiffer wrote:
> Sorry to be getting back to this thread this late, but I am trying to
> catch up on email. 
> I'd like to contribute some thoughts on Ogg, CMML and Captions and
> will cite selectively from emails in this thread. 

>> This would be problematic when downloading the video for offline use
>> or further distribution. This is also different from how this
>> currently works for DVDs, iPod, and the like as far as I can tell. It
>> also makes authoring more complicated in the cases where someone
>> hands a video to you as you'd have to separate the closed caption
>> stream from it first and point to it as a separate resource.
> Think it through: when you currently download a video from
> bittorrent, you download the subtitle file with it - mostly inside a
> zip file for simplicity even. Downloading a separate caption file  is
> similar to how you currently have to download the images separately
> for a Web page. It's no big deal really as long as there is a
> connection that can be automatically identified (e.g. through a link
> to the other inside the one, or through a zip-file, or through a
> description file).       
> Actually for the authoring, I completely disagree. Authoring a
> captioning file inside a text editor is much simpler than needing a
> special application to author the captions directly inside a video
> file.   
> In any case: I don't think it's a matter of one or the other. I
> believe firmly that it should be both, no matter what caption format
> and video format is being used.  

Actually, having the media transcript separate from the media itself is far
superior than "embedded" captioning from the perspective of indexing and
SEO.  Full text transcripts external to their media extends the shelf life
of videos beyond what simple meta-data alone can provide.  A number of
proof-of-concept examples have emerged that even go so far as to use the
caption/transcription file's time-stamping to 'surgically' arrive at a
specific point in a video (in the example I saw, a lecture), allowing for
precise search and retrieve capacity.  While support for both external and
embedded captioning might be of value, encouragement of the external method
should be encouraged.


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