Re: AU parameter names and units
Re: AU parameter names and units
- Subject: Re: AU parameter names and units
- From: "Sophia Poirier [dfx]" <email@hidden>
- Date: Fri, 16 Feb 2007 15:06:28 -0500
Huh, I have never noticed this kAudioUnitProperty_DependentParameters
before (though I do use the IsGlobalMeta flag for some parameters in
some plugins). Though after reading this and the header notes (which
seem to be pretty much the same), I am left with one question: How
do you know which GlobalMeta parameter is being queried in the
GetPropertyInfo and GetProperty requests? I'm guessing that you look
the inElement argument as a parameter ID, but I just wanted to verify
that.
thanks,
Sophia
On Feb 15, 2007, at 12:58 PM, William Stewart wrote:
You mark the parameter that can change other parameters as a meta
parameter. You should also list the dependencies (there's a property
for describing which parameters are dependent on a meta parameter).
/*!
@struct AUDependentParameter
@abstract Used to represent a dependent parameter that can change
as a result of its parent meta-parameter
changing
*/
typedef struct AUDependentParameter {
AudioUnitScope mScope;
AudioUnitParameterID mParameterID;
} AUDependentParameter;
@constant kAudioUnitProperty_DependentParameters
Scope: any
Value Type: array of AUDependentParameter
Access: read
This property is used for parameters with the
kAudioUnitParameterFlag_IsGlobalMeta
or kAudioUnitParameterFlag_IsElementMeta flags set. Hosts
applications (and the
AudioUnitParameterListener mechanism) can interrogate this
property to determine which parameters
are dependent on a
meta-parameter.
For parameters marked with
kAudioUnitParameterFlag_IsGlobalMeta, any non-global
dependent parameters are assumed to be dependent in every
element of their scope.
For parameters marked with
kAudioUnitParameterFlag_IsElementMeta, then its dependent
parameters must all be the same scope, and are assumed to apply
only within a single element,
not to other instances of the same parameter in other elements.
That's it - the listener mechanism should take care of the rest.
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