[whatwg] <source> media attribute behavior, static or dynamic ?
padenot+whatwg at mozilla.com
Thu May 10 14:03:15 PDT 2012
Currently implementing the media attribute of the source element in
Gecko, we are unsure about what the specification requires us to do there.
Considering this example :
<source src="lowres.webm" media="max-width:500px">
what is the expected behavior of a page containing such code being
loaded, in a page that is 1000px width, and then being resized to be
Should the media currently playing change? Is the media attributes and
the multiple <source> attribute only taken into account when the page is
The spec  says :
> Dynamically modifying a source element and its attribute when the
> element is already inserted in a video or audio element will have no
> effect. To change what is playing, just use the src attribute on the
> media element directly, possibly making use of the canPlayType()
> method to pick from amongst available resources. Generally,
> manipulating source elements manually after the document has been
> parsed is an unncessarily complicated approach.
which seems to indicate that the <source> element are only used at load
time. Since |canPlayType()| is mentioned, |matchMedia()| is possibly the
right approach here, but it is unclear to us what the spec exactly
requires. We think the spec needs clarification here.
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