[whatwg] Proposal: Media element - add attributes for discovery of playback rate support

[Brendan Long]

On 07/18/2013 03:17 PM, Eric Carlson wrote:
> Even a DVR, however, won't always let you change the playback speed.
> For example it isn't possible to play at greater than 1x past the
> current time when watching a live stream. If I am watching a live
> stream and I try to play past the end of the buffered video, my DVR
> drops back to 1x and won't let me change the speed. It doesn't
> automatically pause and buffer for a while so it can play at a faster
> rate. It isn't always possible to play a media stream at an arbitrary
> speed. It is foolish to pretend otherwise as the current spec does. 
That makes sense, but we also don't want to limit ourselves to playback
speeds that a server supports when the client /does/ have data buffered.

What if we added a "supportedPlaybackRates" attribute, which holds an
array of playback rates supported by the server, plus (optionally) any
rates the user agent can support due to the currently buffered data
(possibly requiring that the user agent have enough data buffered to
play at that speed for some amount of time).