Re: Getting parameter info on StereoMixers
Re: Getting parameter info on StereoMixers
- Subject: Re: Getting parameter info on StereoMixers
- From: William Stewart <email@hidden>
- Date: Thu, 5 Jan 2006 16:35:51 -0800
Parameter Info gives you meta-information about a parameter (min,
max, default values for instance). Parameters are presumed to be
consistent across all elements in a scope, so the element argument is
irrelevant (that's why we use the paramID here)
If you want to get the current value of a parameter, or set it, then
you should be looking at the AudioUnitGet/SetParameter calls.
Bill
On 05/01/2006, at 3:58 PM, Stephen Shaw wrote:
A little more info on my question...
In
ComponentResult AudioUnitGetPropertyInfo(
AudioUnit ci,
AudioUnitPropertyID inID,
AudioUnitScope inScope,
AudioUnitElement inElement,
UInt32* outDataSize,
Boolean* outWritable
)
It appears that inElement typically refers to the bus id that you are
talking about. But in the sample I found in CAAUParameter.cpp (
CAAUParameter::Init)
it is called with:
OSStatus err = AudioUnitGetProperty(au,
kAudioUnitProperty_ParameterInfo,
scope,
param,
&mParamInfo,
&propertySize);
Which looks like it is using the 3rd param as a parameter select
instead of
a bus select. If this is the case, then using the stereo mixer,
how do you
specify the correct parameter (volume) of the bus of the mixer (in
this case
0)?
Thanks,
Stephen
On 1/5/06 2:21 PM, "Stephen Shaw" <email@hidden> wrote:
I'm a little confused on the usage of
kAudioUnitProperty_ParameterInfo, I'm
trying to get the min / max range of the volume & Pan of the mixer
I can get / set parameters using
AudioUnitGetParameter(mMixerUnit, kStereoMixerParam_Volume,
kAudioUnitScope_Input, theBusId,&vol);
But with kAudioUnitProperty_ParameterInfo, how do I specify the
Parameter I'm
talking about?
AudioUnitParameterInfo paramInfo;
UInt32 size = sizeof (AudioUnitParameterInfo);
AudioUnitGetProperty (mMixerUnit, // AudioUnit
kAudioUnitProperty_ParameterInfo, // AudioUnitPropertyID
kAudioUnitScope_Input, // AudioUnitScope
theBusId, // AudioUnitElement
¶mInfo,
&size);
As always, any help is greatly appriciated :)
-Stephen
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