[whatwg] <video> feedback

Silvia Pfeiffer silviapfeiffer1 at gmail.com
Wed Feb 10 15:11:59 PST 2010

On Thu, Feb 11, 2010 at 3:01 AM, Brian Campbell <lambda at continuation.org> wrote:
> On Feb 9, 2010, at 9:03 PM, Ian Hickson wrote:
>> On Sat, 7 Nov 2009, Silvia Pfeiffer wrote:
>>> I use timeupdate to register a callback that will update
>>> captions/subtitles.
>> That's only a temporary situation, though, so it shouldn't inform our
>> decision. We should in due course develop much better solutions for
>> captions and time-synchronised animations.
> The problem is, due to the slow pace of standards and browser development, we can sometimes be stuck with a temporary feature for many years. How long until enough IE users support HTML6 (or whatever standard includes a time-synchronization feature) for it to be usable? 10, 15 years?

Even when we have a standard means of associate captions/subtitles
with audio/video, we still want to allow for overriding the default
presentation of these and do it all in JavaScript ourselves.

I have just been pointed to a cool lyrics demo at
http://svg-wow.org/audio/animated-lyrics.html which uses an audio file
and essentially a caption file to display the lyrics in sync in svg.
Problem is: they are using setInterval and setTimeout on the audio and
that breaks synchronisation for me - probably because loading the
audio over the distance takes longer than "no time".

Honestly, you cannot use setInterval for synchronising with a/v. You
really need timeupdate.

Maybe one option for pages that need a higher event firing rate than
the default of the browser is to introduce a javascript api that lets
it be set to anything between once per frame (25Hz) and every 250ms
(4Hz)? I'm just wary what it may do to the responsiveness of the
browser and whether the browser could refuse if it knew it would kill
the performance.


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