Re: still image on <video> (was: width='' and height='' on <video>)

At 11:25  +0200 10/10/07, Håkon Wium Lie wrote:
>Also sprach Henri Sivonen:
>  > The <video> element currently lacks width and height attributes on 
>  > the grounds that:
>  >   1) They'd be presentational.
>  >   2) YouTube and the like put all videos in the same box.
>  >   3) Different dimensions are called for different media, so the 
>  > <div><style scoped media='...'> video { width: ...; height: ...; } </
>  > style><style scoped media='...'> video { width: ...; height: ...; } </
>  > style><video>...</video></div> would encourage media-independence 
>  > while <video width='...' height='...'>...</video> would not.
>  >
>  > And, yet, for *practical* purposes, authors seem to *expect* to have 
>  > width and height attributes at their disposal. (Based on expectations 
>  > voiced on IRC.) I suggest adding width and height attributes to <video>.
>I support this.
>While on the subject of pragmatic attributes, I would also like to
>propose another attribute -- still -- to point to an image that is
>shown until the video itself is played. The current specification
>indicates that the first frame of the video should be used for this.
>Often, the first frame will be black or otherwise not representative
>for the video that follows.

I certainly don't think we should mandate the 
first frame, agreed;  QuickTime files even have a 
field "poster time" which tells QT what time is a 
good one to get a poster still from.

>Being able to explicitly set a still image
>is a basic function in my DVD recorder; this is very useful as the
>first frame of my home video snippets are often blank. Wikimedia have
>started using the <video> element on their pages, but they start out
>as <img> elements:
>That is, they don't instantiate the <video> element until the user has
>pressed play. A simple attribute would address their needs:
>    <video src="foo.ogg" still="foo.jpg">
>Other names for the attribute could be "img" or "index".
>>From a performance perspective, it seems simpler to fetch a small
>still image of fixed length rater than fetching a part of the video
>file and hoping that a full frame is included.
>>From an authoring perspective, it seems simpler to use the attribute
>rather than editing the video file (e.g., by inserting the desired
>still image in the beginning of the file).
>I don't think the proposed attribute add any new accessibility issues
>as the still image -- one must assume -- is taken from within the video.
>An alternative approach is to specify a time -- say, "3.5s" -- into
>the video from where the still should be fetched.
>The HTML5 spec, in section 3.4.6 has an example 
>showing how to encode still images:
>   <p>
>    <input type="image" src="frame.png" alt="Play Video"
>      onclick="   if (nextSibling.load) nextSibling.load();
>                  disabled = true;
>                  return false;"
>    ><video src="video.ogg" controls="" irrelevant=""
>      onloadedfirstframe="
>                  irrelevant = false;
>                  previousSibling.irrelevant = true;
>                  autoplay = true"
>      onerror="   parentNode.irrelevant = true;
>                  parentNode.nextSibling.irrelevant = false">
>    </video>
>   </p><p irrelevant="">
>    Playback unavailable.
>    <a href="video.ogg">Download Video</a>
>   </p>
>This seems complex to me; I'm a simple person.
>-h&kon (who only speaks for himself on this issue)
>               Håkon Wium Lie                          CTO °þe®ª

David Singer

Received on Wednesday, 10 October 2007 17:11:43 UTC