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Temporal media fragment for HTML media questions

From: Chris Double <cdouble@mozilla.com>
Date: Tue, 10 May 2011 13:52:11 +1200
Message-ID: <BANLkTi=p5HmgQXffxs4b9pGr6Fi-fjP7BA@mail.gmail.com>
To: Media Fragment <public-media-fragment@w3.org>
I'm working on Mozilla bug 648595 to implement temporal media
fragments on the HTML video and audio elements:
https://bugzilla.mozilla.org/show_bug.cgi?id=648595

I have basic support working but have some questions regarding
behaviour and events. This is how I've currently implemented things:

1) When a temporal fragment is given with a start time, when the
loadedmetadata event on the resource is raised this is the currentTime
of the resource.
2) When an end time is given I do the equivalent of calling 'pause()'
on the media element. I do not raise the 'ended' event.
3) When the media is paused due to reaching the end time and then
'play()' is called, playback continues ignoring the media fragment
times.
4) What do I do with 'loop'? Loop the fragment?

Currently authors fake looping in the absence of the attribute support
by doing something like:

  <video onended='video.play()'></video>

This workaround won't work with fragments as I've implemented them. I
don't raise the ended event. And if I did, 'play()' resumes after the
fragment.

There doesn't seem to be a way to detect 'hit end of fragment', or to
get the fragment start/end times using the DOM without the author
parsing the URL themselves. Is this likely to be a problem in
practice?

5) When a user seeks, or 'currentTime' is set on the DOM object then
the media fragments are ignored. Is this the right approach? Or should
seeks within the fragment range not remove the fragments?

Any feedback appreciated. If other implementors could comment on what
they plan to do (or have already done) in this area I'd appreciate at
it so I can make sure the Firefox implementation is compatible.

Chris.
-- 
http://www.bluishcoder.co.nz
Received on Tuesday, 10 May 2011 01:52:42 UTC

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