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Re: Multichannel and AU
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Re: Multichannel and AU


  • Subject: Re: Multichannel and AU
  • From: Urs Heckmann <email@hidden>
  • Date: Mon, 3 May 2004 13:33:23 +0200

Hi Hans,

Sorry, I must correct myself 8-(

You keep the 8 output Busses, but, as described in /Developer/Documentation/CoreAudio/AudioUnits/ IOChannelConfigurations.rtf ChannelInfo must return { 0, 16 }, because this adds up the total number of channels for all Busses.

Then, you must make your BusCount property writable ("It is illegal to publish a channel info using this semantic of a total number of channels and not to have that scope's element count writable."). The host can guess from the initial setting how many Busses there are at maximum. It's more or less clearly explained in the HTML docs for kAudioUnitProperty_BusCount: "Other units, such as Mixer units, may have already allocated the necessary state to accept a number of inputs, so this call can be used to determine that limit. "

I think, the explicit semantics must be negotiated between host and plugin when setting the ChannelLayout property (which I havn't explored so far...)

Then, the host should give you a Render Call for each Output.

(I hope I got it correct this time)

Cheers,

;) Urs



Am 27.04.2004 um 14:21 schrieb Hans Mvller:

Thanks Urs.

This is probably the solution, but how can the plugin work in Logic(I forgot to mention this in the last mail)?

/Hans
tisdagen den 27 april 2004 kl 13.25 skrev Urs Heckmann:

Hiya Hans,

at first glimpse: 8 Stereo outs equal 8 Busses.

Set the Output Scope Elements count in the MusicDevice derived constructor to 8 rather than 16...

The ChannelInfo Property should only return a stereo pair { 0, 2 }, which then counts for all busses (If I'm not completely mistaken)

Hope this helps,

;) Urs


Am 27.04.2004 um 12:39 schrieb Hans Mvller:

Hello

Im trying to get a multichannel(8 stereo channels) AU to work in Motu DP 4.1 and Garageband. The probelm is that is not shown.

Im also get the following error message in au validation tool.

--------------------------------------------------
VERIFYING DEFAULT SCOPE FORMATS:
Input Scope Bus Configuration:
Default Bus Count:0
Output Scope Bus Configuration:
Default Bus Count:16
Default Format: AudioStreamBasicDescription: 2 ch, 44100 Hz, 'lpcm' (0x0000002B) 32-bit big-endian float, deinterleaved
ERROR: Default Format of unit does not match reported Channel handling capabilities
* * FAIL

urs heckmann
email@hidden
www.u-he.com
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