Re: AudioUnit : how to communicate from DSP to GUI ?
Re: AudioUnit : how to communicate from DSP to GUI ?
- Subject: Re: AudioUnit : how to communicate from DSP to GUI ?
- From: Bill Stewart <email@hidden>
- Date: Mon, 14 Oct 2002 12:10:02 -0700
on 12/10/02 10:25 PM, Benjamin Golinvaux wrote:
>
well...... I'm sorry to have used this "hack". After all, i'm not
>
really proud of it and I'd like to find something better.
>
>
The main question then is : is it possible to have a private api
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between a view and an audiounit based on parameters, but do NOT allow
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to display those parameters in a host "generic" view ? (even in
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"advanced" mode (i've seen this flag in the param infos) )
Sure - if you take a look through the SDK classes, you'll see how the
parameters are published. The generic view is calling the
kAudioUnitProperty_ParameterList property to get the list of *public*
parameters (and then calls the info on each parameter ID)
This ends up calling GetParameterList which goes through the elements,
etc....
If you're private parameters are not visible through this code path, then
they won't get published...
And of course, same with properties - we've marked in the headers the ranges
we're reserving for the standard properties, but there is a legitimate use
and need for private properties - just stay out of the public range.
I'd echo Chris' comments as well - if these are pointing to areas that are
of general utility, then we should look at adding these as public properties
with a standard means of use and support.
Bill
>
On the other hand, having properties in the audiounit (that the view
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continuously reads) means polling must be used for every visual
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attribute, right ? What if we want to display a virtual key being
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pressed when the audio unit receives a "note on" event ? Is there an
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easy way to solve this using a read-only protocol ? Maybe use
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properties on the view side, too ?
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>
>
Benjamin Golinvaux
>
Arboretum Systems, Inc.
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www.arboretum.com
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>
>
>
On Sunday, October 13, 2002, at 02:38 AM, Chris Rogers wrote:
>
>
> These vu-meters, clipping LED, etc. should all be reported as read-only
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> parameters accessible via the ordinary property APIs for AudioUnits.
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> The internal DSP of the AudioUnit may set these parameters in real-time
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> for the UI to display. What we want to avoid is people adding extra
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> hacks like accessing C++ objects directly or adding C APIs.
>
> If there's something we've neglected in the standard APIs, then lets
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> address the issue cleanly.
>
>
>
> Chris Rogers
>
> Core Audio
>
> Apple Computer
>
>
>
>
>
>>> Hmmm...
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>>>
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>>> We'll, I'd be careful here. [...]
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>>
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>> The situation that I describe is a reality. Great numbers of existing
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>> market plugins provides vu-meters, clipping led, that are computed to
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>> a particular stage of dsp processing.
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>>
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>> It appears then to me that this should become as a standard part of
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>> the SDK, isn't it ?
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>> Suppose that Apple decide to run the dsp code in another process (as
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>> it is done in BeOS for efficiency) ; the solution that we are talking
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>> about would not work then...
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>>
>
>> Raphael
>
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