[whatwg] Using <video> as a source for canvas.drawImage
Oliver Hunt
oliver at apple.com
Mon Aug 18 18:48:58 PDT 2008
On Aug 18, 2008, at 5:58 PM, Robert O'Callahan wrote:
> On Tue, Aug 19, 2008 at 11:24 AM, Oliver Hunt <oliver at apple.com>
> wrote:
> Cool -- I wonder though if it would be better if it were placed in a
> different method, drawFrame or something (very much an up in the air
> sort of question)
>
> drawImage is already overloaded, so why not carry on with that,
> unless we change the API as you suggest below.
I'm not sure that drawImage overloading was a good idea in the first
place *but* canvas and image are fairly similar in both image-like,
whereas video is quite clearly different. I was also thinking it
would work better given the additional frame argument, however...
>
> AFAIK we'd basically have to implement that by creating a second
> video stream, seeking it and then capturing the frame, and you
> really don't want to do that synchronously! Then we'd want to cache
> that stream so that another drawFrame with a nearby frame index was
> efficient ... ick. So I suggest not offering that API. Authors can
> always use a second, hidden video element to achieve the same effect.
... I had failed to consider streaming content (where random seeking
may not be possible) :-/
I still think it would be useful to be able to specify an exact frame,
but as you say it may not be really feasible
--Oliver
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