Re: Script Processor onaudioprocess() gives up the ghost?

Hey Lonce,

I've hit this problem before as well. The key is that you're defining your
scriptProcessor and the onaudioprocess callback within a function namespace
because of require.js, so the variables don't land on the global namespace.
This becomes problematic because the garbage collector will swing by and
clean your node and listener up after your code finishes referencing it.
Somebody listed a bug in Chrome to avoid garbage collecting event listeners
like this, but I can't find it... Maybe it's been fixed since I last played
around with it, in which case I'm not sure what the problem is :)

You should be able to fix it by binding the scriptprocessor or the callback
to the window to prevent garbage collection:
https://github.com/nick-thompson/flow/blob/master/public/js/flow.js#L96

Best,
Nick



On Tue, Feb 19, 2013 at 5:11 AM, lonce <lonce.wyse@zwhome.org> wrote:

>
> Hi -
>
>     What might cause callbacks to  onaudioprocess()  for
> ScriptProcessorNode to suddenly cease?
>
> I have the simplest architecture:
>      ScriptProcessorNode (generating random noise)  -> Gain node ->
> audioContext.destination
>
> When left to run, I get anywhere from 150 to 1500 successsive callbacks to
> onaudioprocess(), and then it just quits (leaving a dirty buffer for the
> gain node to read)
>
> You can hear/see it here:
> http://animatedsoundworks.com/**jsaSound/<http://animatedsoundworks.com/jsaSound/>(select "JS Node Test" from the drop-down menu, and hit "play" and let it
> run)
>     You can see the callbacks to onaudioprocess() logged in the console
> window. Sometime in the first minute, they just stop.
>
> The core code:
>
>             // ScriptProcessor to generate noise
>             var noiseNode = config.audioContext.**
> createScriptProcessor(config.**k_bufferLength, 1, 1);
>             noiseNode.onaudioprocess = function (e) {
>                 var outBuffer = e.outputBuffer.getChannelData(**0);
>                 for (var i = 0; i < outBuffer.length; i += 1) {
>                     outBuffer[i] = Math.random() * 2 - 1;
>                 }
>             }
>
>             var gainLevelNode = config.audioContext.**createGainNode();
>
>             // Connect graph
>             noiseNode.connect(**gainLevelNode);
>             gainLevelNode.connect(config.**audioContext.destination);
>             gainLevelNode.gain.value = .1;
>
> To "start" and "stop" the sound, I just set the gain level.
>
> If I am not doing something properly, I would be glad to know about it!
> Thanks,
>                  - lonce
>
>
>