Re: [css3-transitions] Frame Rate

On Sat, Sep 29, 2012 at 9:57 AM, Boris Zbarsky <bzbarsky@mit.edu> wrote:

> On 9/29/12 12:52 PM, Rik Cabanier wrote:
>
>> Is this 60fps defined in a spec, or is it just accepted practice?
>>
>
> The latter.  Though in many cases I think it's a consequence of tying the
> animation to vsync and the fact that most LCD panels go at 60Hz.
>
>  The flash player allows setting of the frame rate and this is a
>> _*guaranteed*_ number of frames per second. This means that if a script
>>
>> or an animation takes too long, the animation will start skipping frames
>> so things stay in perfect sync (ie if you want to sync audio or video
>> with an animation) but scripts will still run.
>> The event model in browsers is not compatible with this so we'd need a
>> major architecture change if this should be added.
>>
>
> I'm not sure what about browsers is incompatible with this.  I thought the
> whole point of requestAnimationFrame and declarative animations was to
> allow frame skipping as needed in the face of limited compute resources!
>
> Yes, and that's a problem.If 2 animations run in a page with
requestanimationframe, they will each run a 30fps.
If there is a lot of event handling, that rate will go down even more.

In Flash, if you have a callback that is for each frame and the movie
starts falling behind and skip frames, the callback will still be called as
if the frame rate is uninterrupted.

Rik