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Re: SetParameter
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Re: SetParameter


  • Subject: Re: SetParameter
  • From: William Stewart <email@hidden>
  • Date: Fri, 21 Sep 2007 19:59:38 -0700

And to add to this:

AUEffectBase::SetParameter is the call that is made in your AU in response to someone using your AU and calling AudioUnitSetParameter

We do not expect that the audio unit itself notify listeners of changes to the parameter values. Rather the code that is calling this API should do so. So I think in this case the problem is that your view is just calling AudioUnitSetParameter when it should be calling AUParameterSet that will itself do two things:
Call AudioUnitSetParameter on your AU to set the value of the parameter
Call the notification mechanism to tell other listeners that the value of this parameter has changed.


HTH

Bill

On 20/09/2007, at 9:07 PM, Sophia Poirier [dfx] wrote:

What in that document leads you to believe that AUEffectBase::SetParameter() is supposed to notify listeners? I don't see anything that says anything like that, but maybe I'm not catching something in there.

At any rate, what Eric told you and you've found are correct: that AUEffectBase::SetParameter() will not post notification. AUParameterSet() will (in addition to setting the value for the parameter), or alternately you can use AUParameterListenerNotify() to only post a change notification without setting a value.

Sophia



On Sep 19, 2007, at 10:19 AM, Paul Tapper wrote:

Thanks for the help.


I am calling AUEffectBase::SetParameter(paramID, value); which the Audio Unit Programming Guide seems to suggest would then notify the listeners (which would presumably include the host - see http://developer.apple.com/documentation/MusicAudio/Conceptual/ AudioUnitProgrammingGuide/index.html?http://developer.apple.com/ documentation/MusicAudio/Conceptual/AudioUnitProgrammingGuide/ TheAudioUnit/chapter_4_section_4.html)


But, for me, AUEffectBase::SetParameter just seems to call AUElement::SetParameter which doesn't seem to feed through into AUParameterSet anywhere. Maybe I'm just using this wrong somehow.

Paul

Use AUParameterSet to set an AudioUnit parameter value and notify
listeners.

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