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

On Wed, Feb 20, 2013 at 3:04 AM, Lonce Wyse <lonce.wyse@zwhome.org> wrote:

>
> Thanks, Nick! It looks like the global binding does the trick.
> BTW, Kumar has also written brilliantly on this and a collection of
> related issues with ScriptProcessorNode lifetimes:
>
> http://sriku.org/blog/2013/01/30/taming-the-scriptprocessornode/#replacing-gain-node-with-scriptprocessornode
>

You may be interested in starring this Chromium bug: <
https://code.google.com/p/chromium/issues/detail?id=82795>

Regards,

Dominic Cooney


>
> Best,
>              - lonce
>
>
> On 2/20/2013 1:39 AM, Nick Thompson wrote:
>
> 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/ (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
>>
>>
>>
>
>