Re: AU parameter names and units
Re: AU parameter names and units
- Subject: Re: AU parameter names and units
- From: William Stewart <email@hidden>
- Date: Fri, 16 Feb 2007 12:21:39 -0800
On 16/02/2007, at 12:06 PM, Sophia Poirier [dfx] wrote:
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.
Yes, thats it (same mechanism as we use for getting parameter info
for a particular parameter)
Bill
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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