Multiple Output Music Device
Multiple Output Music Device
- Subject: Multiple Output Music Device
- From: Art Gillespie <email@hidden>
- Date: Thu, 16 Oct 2003 23:16:39 -0400
Ignoring the hacks I've had to use get multiple output AUs working in
the past,
I'm a bit curious as to whether I've got how it's *supposed* to work
right:
- Audio Unit reports the number of outputs to MusicDeviceBase
constructor, this
number corresponds to the number of output busses (elements on
the output
scope).
- Audio Unit reports the total number of channels via
SupportedNumChannels().
For example, if I had two stereo pairs and two mono outs, I'd
report 4 as my
number of outputs, and { 0, 6 } in response to
SupportedNumChannels()
- Host interrogates the Audio Unit for number of output busses
via
kAudioUnitProperty_BusCount
- For *each* output bus (element on the output scope), Host
interrogates the
Audio Unit for the element's StreamFormat via
kAudioUnitProperty_StreamFormat
- During render, AU calls GetOutput(n) to get the
AudioBufferList for the nth
bus. Each buffer list's mNumberBuffers member should
correspond with the
CAStreamBasicDescription.mChannelsPerFrame member returned by
kAudioUnitProperty_StreamFormat.
Is this right? Am I missing anything?
Best,
Art
>>0xBA
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