[html5] Autoplay and preload insufficient for proper video playback.
eric.carlson at apple.com
Thu Aug 26 21:21:27 PDT 2010
On Aug 26, 2010, at 1:40 PM, Rik Sagar wrote:
> What is the prescribed behavior with "autoplay"? When should the UA start play?
> - "canplay"
> - "canplaythrough"
> - "HAVE_FUTURE_DATA"
> - "HAVE_ENOUGH_DATA"
It is all in the spec: http://www.w3.org/TR/html5/video.html#dom-media-have_enough_data
HAVE_ENOUGH_DATA (numeric value 4)
All the conditions described for the HAVE_FUTURE_DATA state are met, and, in addition, the user agent estimates that data is being fetched at a rate where the current playback position, if it were to advance at the rate given by the defaultPlaybackRate attribute, would not overtake the available data before playback reaches the end of the media resource.
If the new ready state is HAVE_ENOUGH_DATA ... if the autoplaying flag is true, and the paused attribute is true, and the media element has an autoplay attribute specified ... then the user agent may also set the paused attribute to false, queue a task to fire a simple event named play, and queue a task to fire a simple event named playing.
User agents are not required to autoplay, and it is suggested that user agents honor user preferences on the matter. Authors are urged to use the autoplay attribute rather than using script to force the video to play, so as to allow the user to override the behavior if so desired.
In any case, the user agent must finally queue a task to fire a simple event named canplaythrough.
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