Re: Audio Unit suggestions
Re: Audio Unit suggestions
- Subject: Re: Audio Unit suggestions
- From: Marc Poirier <email@hidden>
- Date: Sat, 27 Jul 2002 00:28:40 +0200 (CEST)
>
In general, you are free to define a parameter whose type is "generic"
>
which internal to your DSP code may end up changing something in a
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non-linear way.
A la VST and its limitation of 0 to 1 for every parameter. I guess that
will be fine once custom GUIs are possible...
>
1. Always publish a frequency parameter units as Hertz. Then, the UI
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or other controlling code would be required to do the appropriate
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logarithmic scaling before calling AudioUnitSetParameter().
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This is what our "generic" AudioUnit view does when it creates a slider
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for a parameter of type Hertz. You can also use our functions
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AUParameterValueFromLinear() and AUParameterValueToLinear() in
>
Jaguar's AudioUnitUtilities.h to do this type of conversion.
...but those those parameter utilities sound much better, good to hear!
>
2. Create a new type of frequency parameter called "AbsoluteCents"
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where differences of 100 AbsoluteCents correspond to one semi-tone
>
change in frequency (1200 corresponds to an octave change). There
>
would be then need to be an "anchor" point to establish the frequency
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value of say middle C in absolute cents. One way to do this is simply
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take the MIDI note number corresonding to a particular frequency and
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multiply it times 100. AbsoluteCents then are useful both for musical
>
pitch and filter frequencies...
>
>
Internally, we've decided on solution (1) above. Although personally
>
I much prefer (2). There's actually no reason both methods couldn't
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be used. Let us know what you think...
Yeah, method 2 could definitely be used as things are now, since it's
linear. Both are useful, I agree that cents/semitones makes more musical
sense, but I think it depends on the application. An EQ, for example,
will probably make more sense to people when expressed with Hz simply
because that's how every other EQ presents its parameters.
>
There is a parameter type kAudioUnitParameterUnit_Indexed which can
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be used for menues, etc. The value *is* still an integer, but names
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can be assigned to each integer value. See the
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kAudioUnitProperty_ParameterValueStrings property in Jaguar's
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AudioUnitProperties.h
That sounds perfect, great! I guess we just have to wait a month now...
Thanks,
Marc
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