[whatwg] Scripted <video> query proposal; Query supported formats for media elements

[Eric Carlson]

On Oct 13, 2008, at 4:47 PM, Robert O'Callahan wrote:

> On Tue, Oct 14, 2008 at 12:10 PM, Ian Hickson <ian at hixie.ch> wrote:
> Try to play all the videos you have available, and catch errors:
>
>  <video id=a>
>   <source src="video.mp4" type="video/mp4; codecs="avc1.42E01E,  
> mp4a.40.2"">
>   <source src="video.3gp" type="video/3gpp; codecs="mp4v.20.8,  
> samr"">
>   <source src="video.ogv" type="video/ogg; codecs="theora,  
> vorbis"">
>   <source src="video.mkv" type="video/x-matroska;  
> codecs="theora, vorbis"">
>  </video>
>  <script>
>   document.getElementById('a').load();
>   if (document.getElementById('a').currentSrc == "") {
>     // failed to find a video that would play
>     // do whatever fallback you want to do here
>     ...
>   }
>  </script>
>
> This will reliably work, because load() blocks until a decision about
> which video to play is made.
>
> We may have to change this (e.g. to allow UAs to asynchronously  
> fetch and
> try each video)
>
> We definitely have to change that! Having load() synchronous would  
> be a disaster.
>
   I agree! A truly synchronous load() will result in a terrible user  
experience as a UA may need to download a significant amount of data  
before it knows if a file is playable.

Eric