Re: AudioUnit/MusicDevice example without the SDK
Re: AudioUnit/MusicDevice example without the SDK
- Subject: Re: AudioUnit/MusicDevice example without the SDK
- From: Marc Poirier <email@hidden>
- Date: Thu, 13 Nov 2003 11:11:00 -0600 (CST)
On Thu, 13 Nov 2003, Marc Poirier wrote:
>
On Thu, 13 Nov 2003, Mark's Studio wrote:
>
>
> "Audio Units are created when a Component with appropriate type,
>
> subType and manufactureID is opened.
>
> In the underlying implementation this will create a C++ object -
>
> the open component calls can viewed as the basic allocation of the
>
> unit's basic resources."
>
>
>
> I am a bit confused about the whole AudioUnit thing.
>
>
>
> If i look at AudioUnit.Framework headers files
>
> it look like there are some 20 C functions / callbacks.
>
>
>
> Is the AUPublic SDK a wrapper around both the Component Manager,
>
> and the AudioUnit.Framework?
>
>
Yes.
>
>
> Would it not be possible to make a AudioUnit component,
>
> that just implemented the functions in the AudioUnit.Framework?
>
>
No, you need to implement the Component interface, too.
Actually, I wasn't thinking/writing too clearly there, so I think that I
may have been misleading. Basically it is all a Component interface
(aside from the callbacks) with some extended selectors. All of the
functions in AudioUnit.framework like AudioUnitInitialize, AudioUnitReset,
AudioUnitSetParameter, AudioUnitGetProperty, etc. are actually just
convenience wrapper functions for "raw" Component calls with specific
selectors (kAudioUnitInitializeSelect, kAudioUnitGetPropertySelect, etc.).
So if you are going to make an AU "from scratch" basically you are going
to be handling a bunch of different selectors, the common Component ones
plus these Audio Unit ones, with varying sorts of parameters passed
depending on the selector. But they all pass through one function, which
is your Component dispatcher. Except for some of the other callbacks that
get installed like the Render callback.
By the way, I'm just curious: why does this seem more appealing than
using the SDK?
Marc
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