Re: Schedule arbitrary callback at future time

Hey Josh-

The real problem with this approach is that you simply can't "get" a
callback at a precise time in audio-clock time.  JavaScript, in a nutshell,
just isn't a real-time language - the main thread may be busy with layout
for a number of milliseconds, or it may be delayed by garbage collection.
 The best approach is what Web Audio does most of the time - scheduling
events that are more bounded (i.e. don't call arbitrary JavaScript that may
have side effects) for precise times in the future, which are calculated
and executed on a separate thread.

If a recorder node is added to Web Audio at some point, I would expect its
"start recording" method to have a time parameter; however, in the mean
time, you should pretty easily be able to replicate one by using a script
processor node and just calculate where you are in the buffer (based on the
.playbackTime on the audio processing event), and just grab a part of a
buffer.


On Tue, May 7, 2013 at 11:24 AM, Josh Nielsen <josh@joshontheweb.com> wrote:

> Hi all, this is my first time posting to the group, please let me know if
> I am breaking any etiquette.  I'm very excited to see the webaudio api
> shaping up!
>
> I think I have seen this brought up before but I want to throw my vote in
> for a way to schedule callbacks to fire at a future time.  I am in the
> process of building a synthesizer/loop recorder and I need to do things
> like start recording audio at a specific time in the future.  Currently I
> am using a javascript node's onaudioprocess  callback (as per suggested her
> in the past) to get close enough but the granularity is based on the buffer
> length and it is not exact. It would be really handy to bind a callback to
> be fired in the future just like you can with an oscillators .start().  You
> can see a prototype of what I'm talking about here
> http://grooveclock.com/synth.html
>
> tl;dr - +1 for arbitrary callbacks scheduled at a future time
>
> --
> Thanks,
> Josh Nielsen
> @joshontheweb <http://twitter.com/joshontheweb>
> joshontheweb.com
>