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Re: AudioUnitSetParameter question
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Re: AudioUnitSetParameter question


  • Subject: Re: AudioUnitSetParameter question
  • From: Chris Rogers <email@hidden>
  • Date: Fri, 15 Feb 2002 02:58:09 -0800

John,

You're not doing anything wrong. There is a bug particular to the reverb
AudioUnit which makes it ignore parameter changes. You still can set
a particular preset of the reverb with the kAudioUnitProperty_ReverbRoomType
property using one of the enums from AudioUnitProperties.h

enum {
kReverbRoomType_SmallRoom = 0,
kReverbRoomType_MediumRoom = 1,
kReverbRoomType_LargeRoom = 2,
kReverbRoomType_MediumHall = 3,
kReverbRoomType_LargeHall = 4,
kReverbRoomType_Plate = 8
};

Sorry about the trouble. We expect this will be fixed.

Some other improvements to the reverb, perhaps improved quality, etc.
may be coming as well...

Chris Rogers
CoreAudio


I'm trying to use AudioUnitSetParameter to set some of the options on the built-in reverb audio unit, and I must be doing something wrong because it doesn't seem to be working.

First, I use AudioUnitGetProperty with kAudioUnitProperty_ParameterList, and then AudioUnitGetProperty with kAudioUnitProperty_ParameterInfo to get the list of parameters that the reverb audio unit supports.

So, as an example, "decay time" has a parameter ID of 0, min value of .1, and max value of 5. I see by the flags that it is in the global scope and both readable and writable.

If I try to do the following, however, it doesn't seem to be working:
theStatus = AudioUnitSetParameter(reverbAU, 0, kAudioUnitScope_Global, 0, [sender floatValue], 0);

When I say "doesn't seem to be working," I mean that I can't hear any difference between the max value, the min value, or anything in between. (The same goes for all the other properties.) There are no errors reported from the calls as far as I can tell.

The things that I think might be wrong in that call are the inElement value, and the inBufferOffsetInFrames (arguments 4 and 6). Should they be something other than zero?

If anyone has ideas on why this isn't working, I would appreciate hearing about it.

--john
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References: 
 >AudioUnitSetParameter question (From: John Cramp <email@hidden>)

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