[whatwg] HTML5 video: frame accuracy / SMPTE

Michael Dale dale at ucsc.edu
Fri Jan 21 10:12:53 PST 2011

On 01/13/2011 01:44 AM, Philip Jägenstedt wrote:
> Changing the default at this point wouldn't really hurt since not all
> browsers are doing exact seeking anyway, right? I think that keyframe
> seeking is more often what you want and it'd be better to let the few
> who want frame-exact seeking jump through hoops than having everyone
> who makes a simple seeking UI discover that seeking is a bit slow and
> 20% of them figuring out that it can be fixed by using seek().

Is accurate seeking *that* much slower than keyframe seeking? I would
discourage changing the accurate seek default. If supported at all you
should opt into fuzzy seeking.

Assuming the client can buffer fast enough for real-time playback, a
seek to keyframe + time in the worst case would would take time offset.
But in most cases the data to time ratio after the keyframe is much more
sparse then the keyframe itself. So the ranged request for key + data to
time will normally not be a lot more than keyframe + data for future
playback for seeking to a keyframe. You can see seeking is pretty fast
in the indexed seek firefox demos.


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