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Re: Determining if a SMIL presenation has captions and an auditory description.

From: Charles McCathieNevile <charles@w3.org>
Date: Wed, 23 Feb 2000 22:45:48 -0500 (EST)
To: Wendy A Chisholm <wendy@w3.org>
cc: w3c-wai-er-ig@w3.org
Message-ID: <Pine.LNX.4.20.0002232238320.25610-100000@tux.w3.org>
Also, because text is much more lightweight than video, any text that is
intended to form part of the presentation may be shipped as such. In that
case it will most likely not have a system-captions set.

Charles McCN

On Wed, 23 Feb 2000, Wendy A Chisholm wrote:

  I took an action item on the 14 February call to find out how to determine 
  tracks in SMIL.  It's very straightforward.  Consider the following example 
  from the SMIL access note [1]:
  <par>
      <audio alt="Interview with Harvey, English audio"
             src="audio.rm"/>
      <video alt="Interview with Harvey" src="video.rm"/>
      <textstream alt="English captions for interview with Harvey"
                  src="closed-caps.rt"/>
  </par>
  
  This will play an audio track, a video track and a text track (captions).
  
  Therefore, it is fairly simple to determine if a text track is associated 
  with the audio/video tracks.  However, this text track *could* be language 
  subtitles.
  
  Consider the following example:
  <par>
      <audio alt="My Favorite Movie, English audio" src="audio.rm"/>
      <video alt="My Favorite Movie" src="video.rm"/>
      <textstream alt="Stock ticker" src="stockticker.rt"/>
      <textstream alt="English captions for My Favorite Movie"
                  system-captions="on"
                  src="closed-caps.rt"/>
  </par>
  
  It uses the "system-captions" attribute to indicate to a SMIL player that 
  if the user wants captions this is the track to play.  I don't know if we 
  want to get into repairing SMIL, but if we find a SMIL presentation without 
  the "system-captions" flag we could raise a warning.
  
  SMIL 1.0 does not have a similar flag for auditory descriptions, although 
  it is being discussed for the next release.  Multiple audio tracks can be 
  included, but they could be used for language overdubbing.
  
  Therefore, checking for captions is currently more straightforward than 
  checking for an auditory description, but there are clues that you can use 
  to make a guess and ask the author for confirmation.
  
  --wendy
  
  [1] http://www.w3.org/TR/SMIL-access/
  --
  wendy a chisholm
  world wide web consortium
  web accessibility initiative
  madison, wi usa
  tel: +1 608 663 6346
  /--
  

--
Charles McCathieNevile    mailto:charles@w3.org    phone: +61 (0) 409 134 136
W3C Web Accessibility Initiative                      http://www.w3.org/WAI
Location: I-cubed, 110 Victoria Street, Carlton VIC 3053
Postal: GPO Box 2476V, Melbourne 3001,  Australia 
Received on Wednesday, 23 February 2000 22:45:49 GMT

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