Re: Value of currentTime

Hi Joseph,

Thanks for your answer. I really know how to start two sources at specific time. It is more that I would like to know how it works because I didn't find nothing about that in the specification. :-)

Thank you,

Arnau

On 27 mai 2014, at 17:17, Joseph Berkovitz <joe@noteflight.com> wrote:

> Hi Julia,
> 
> Setting aside the part of your post that relates to the rate at which currentTime is updated, I wanted to note that it is easy to start two sources at a specific time:
> 
> On May 27, 2014, at 10:06 AM, Arnau Julia <Arnau.Julia@ircam.fr> wrote:
>> Therefore, as I understand, if I want to start two sources at a specific time I can't do something like this,
>> 
>> function start(){
>> 	source1.start(audioContext.currentTime+1);
>> 	source2.start(audioContext.currentTime+1);
>> }
>> 
>> because it's not possible to guarantee that the currentTime for these two instructions will be the same.
> 
> 
> You could, however, do this, if you wanted to be completely sure:
> 
> function start(){
> 	var t = audioContext.currentTime+1;
> 	source1.start(t);
> 	source2.start(t);
> }
> 
> Overall I don’t think it is a good idea (even if it were possible) to rely on sample-accurate ("a-rate") updates of the currentTime clock in the main thread, because there is always some unpredictability in the thread’s timing, and it’s likely to be large relative to the duration of a sample frame. The main browser thread can yield CPU time to other interrupt-driven processes (including things outside the browser) at some point between acquiring currentTime’s value and employing that value for scheduling purposes.
> 
> .            .       .    .  . ...Joe
> 
> Joe Berkovitz
> President
> 
> Noteflight LLC
> Boston, Mass.
> phone: +1 978 314 6271
> www.noteflight.com
> "Your music, everywhere"
>