Re: Paremeter changes by the user
Re: Paremeter changes by the user
- Subject: Re: Paremeter changes by the user
- From: William Stewart <email@hidden>
- Date: Wed, 16 Jun 2004 11:15:34 -0700
On 16/06/2004, at 9:31 AM, Aristotel Digenis wrote:
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Hello,
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>
I have recently started to learn programming for AudioUnits. I have
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been using the SampleEffectUnit example that comes with the SDK to
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make a few changes and experiment with things. I have now come to an
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absolute state of confusion.
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I have a parameter on the default GUI with a range between 0.0 and 1.0
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with the default value at 0.0. I would like to make a simple gain
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effect for the sake of learning about parameter control. I have
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declared a "gainValue" float and i want when the slider is moved, that
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value to be passed to the "gainvalue" float. gainValue will be used in
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the processing section of the code to apply it to the samples as
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amplitude (sample = sample * gainValue).
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Does the getParameter() function automatically get called when the
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user moves a slider in the default GUI just like it happens in VSTs?
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Having read the documentation of the SDK it seems I need to use
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Listeners. And this is where it gets confusing. There is a list of
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listener related functions int eh documentation, then there posts in
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this mailing lists which suggest the API is changing to a new method
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of dealing with events. then there is the AUPropertiesPostPanther.h
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file which seems to play a role in this change, yet I cannot compile
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my code if that header is included ( i get tons of errors).
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Could somebody explain how the AudioUnit knows when a slider has
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moved?Is it event listener? or parameter listener?
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The UI calls your Audio Unit's SetParameter call, to set the new value
of a parameter. Your AU doesn't need to know anything about listeners -
that is for host-UI communication (at least in this case)
All that your AU does in its Render call is to get the current value of
the parameter and apply it - thus, you'd get the value of the gain
parameter.
You'd need to make sure that the AU is publishing the parameter
correctly - so I'd suggest the first thing to do is to run the
AUValidation Tool on the AU that you've made - you can see there that
the parameter is published, etc... (The AUV can be downloaded from
http://developer.apple.com/audio)
Bill
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Thank you in advance
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>
--
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Aristotel Digenis
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email@hidden
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http://www.digenis.ws
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