[whatwg] Reporting mid-stream resolution change on <video>

Ian Hickson ian at hixie.ch
Thu Dec 12 12:04:56 PST 2013

On Thu, 12 Dec 2013, Ami Fischman wrote:
> Today the <video> tag exposes video{Width,Height} attributes that allow 
> the page to discover the resolution of the playing media once 
> metadataloaded has fired.  However there is no way for the page to find 
> out that the media resolution has changed mid-stream (short of polling 
> the tag constantly, which is obviously unappealing).
> Examples where mid-stream resolution change can happen include:
> - WebRTC up/down-scaling a video stream at the source to adhere to
> available bandwidth or other requirements
> - MSE shifting between quality levels of source material
> - Static/VOD/classic video files that change resolution mid-stream b/c of
> different source material being concatenated together.
> One way to enable this would be to add a "metadatachange" event to the 
> list of media elements events ( 
> http://www.whatwg.org/specs/web-apps/current-work/multipage/the-video-element.html#event-definitions 
> ).
> (this has come up recently in a public-webrtc 
> thread<http://lists.w3.org/Archives/Public/public-webrtc/2013Dec/0040.html>, 
> and previously in private discussions)

Seems reasonable. Done. (I used the 'resize' event since it is well 
established as the appropriate event to use when dimensions change.)

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

More information about the whatwg mailing list