[whatwg] VIDEO Timeupdate event frequency.

[Simon Fraser]

On Sep 10, 2010, at 10:07 AM, Tab Atkins Jr. wrote:

> On Fri, Sep 10, 2010 at 9:58 AM, Simon Fraser <smfr at me.com> wrote:
>> The problem with a 'newFrame' callback is what to do if the callback
>> takes longer than the duration of a single frame. Does the video engine
>> start dropping frames, or does the video lag?
> 
> Dropping frames would be the better solution, for all the uses I'd put
> it to.  (Or rather, dropping newFrame events.)
> 
> 
>> In WebKit on Mac, video playback is hardware-accelerated, and the
>> presentation of video frames is disconnected from the web page
>> drawing machinery. A newFrame callback would force us to drop
>> back into software rendering, which is significantly more CPU intensive.
>> I don't support the general use of a 'newFrame' callback except in
>> the context of video processing via canvas.
> 
> In general, video processing via canvas is going to require dropping
> into software rendering, right?  I think that's what I was hearing
> from our dudes putting hardware-accelerated video into Chrome.  So at
> least in the case that I can see this often being put towards, you
> don't lose anything.

My concern would be pages registering for newFrame events just
to do stuff like updating a controller, which will vastly increase CPU
usage.

Simon