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Re: Newbie questions re:kAudioUnitProperty_ParameterList
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Re: Newbie questions re:kAudioUnitProperty_ParameterList


  • Subject: Re: Newbie questions re:kAudioUnitProperty_ParameterList
  • From: Robert Grant <email@hidden>
  • Date: Wed, 12 Nov 2003 19:55:33 -0500

First customer for:
http://www.mat.ucsb.edu:8000/CoreAudio/101

:-)

The nature of an element changes based on the context, but it's basically the atomic thing in that context. In your situation the elements are the individual parameters. If you don't care about the element set it to 0.

And check out Bill and Jeff's excellent PublicUtiltity class CAAudioUnit in the example code (if you're using Panther)

file:///Developer/Examples/CoreAudio/PublicUtility/CAAudioUnit.h

Robert.

On Nov 12, 2003, at 7:13 PM, joel pigdon wrote:

I am very much a CoreAudio/Audio Units newbie and I
have a few question about the way that the operation
of the AudioUnitGetProperty function. I am trying to
build a findUnits like program in C to gain a greater
understanding of audioUnits however I am unsure as to
how to go about using The AudioUnitsGetProperty
function. I have an AUnit and I just want to start off
by using the global scope. The first question is that
the documentation talks about an Element of which I
can find absolutely no information. If someone can
explain to me what an element is I would greatly
appreciate. I understand that the AudioUnitParameterID
is a Uint32 type so I am trying to put the result into
a UInt32. By setting the outData to NULL I can get the
data size being returned but I cannot seem to get the
actual data out. If I am being returned a pointer to
an UInt32 when I debug the out size is always 0 and
the UInt is always 0 also please help attached is code
snippet, I realise the dirtyness of this code:
ComponentDescription desc,temp;
Component current;
ComponentInstance auInst;
UInt32 paramsize;
Boolean wtable;
Handle name;
OSStatus error;
ConstStr255Param actualName;
UInt32 numBusses,size;
Float64 out;


desc.componentType = 'aufx';
desc.componentSubType = 0;
desc.componentManufacturer = 0;
desc.componentFlags = 0;
desc.componentFlagsMask = 0;

current = FindNextComponent(0,&desc);

while(current != NULL)
{
OpenAComponent(current,&auInst);
name = NewHandle(sizeof(void*));

GetComponentInfo(current,&temp,name,NULL,NULL);
HLock(name);
actualName = (ConstStr255Param)(*name);

// AudioUnitGetProperty(auInst,kAudioUnitProperty_ParameterList,0,0,&numBu sses,&size);

AudioUnitGetProperty(auInst,kAudioUnitProperty_ParameterList,1,0,&numBu sses,&size);

// AudioUnitGetProperty(auInst,kAudioUnitProperty_ParameterList,2,0,NULL,& size);

// AudioUnitGetProperty(auInst,kAudioUnitProperty_ParameterList,3,0,NULL,& size);

NSLog(@"out %s",actualName);
NSLog(@"busses %l",numBusses);
DisposeHandle(name);
current = FindNextComponent(current,&desc);
}
Thanks for any assistance you may be able to provide
Joel Pigdon
email@hidden




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References: 
 >Newbie questions re:kAudioUnitProperty_ParameterList (From: joel pigdon <email@hidden>)

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