Re: Channel Maps and HALOutputUnit
Re: Channel Maps and HALOutputUnit
- Subject: Re: Channel Maps and HALOutputUnit
- From: William Stewart <email@hidden>
- Date: Tue, 10 Feb 2004 15:47:56 -0800
On 10/02/2004, at 3:02 PM, Robert Grant wrote:
Hi Aaron,
Thanks for the info. I'd come to the same conclusion on the input side
I guess I'm wondering how to wire a graph into a multi-channel output
unit.
It sounds like this is yet another good use for the matrix mixer, to
mix say 3 stereo input busses into a single 6 channel output bus?
Yes (same for device input)... the MM has been optimised with this kind
of splitter usage in mind too.
Bill
Thanks,
Robert.
On Feb 10, 2004, at 2:06 PM, Aaron Eppolito wrote:
On Feb 10, 2004, at 10:05 AM, Robert Grant wrote:
If I've got a 6 input - 2 output audio device that I want to bring
into my app as 3 stereo input busses can I do that? Bill's example
focusses on a single stereo bus into a multi-channel device.
You can get all 6 channels in the same call to AudioUnitRender().
Feel free to interpret them as any pairing that you like.
And if I can - how does it affect the input RenderCallback?
It doesn't change the render callback itself, but you will get more
channels in your call to AudioUnitRender().
And I guess the same goes for output too. If I have a 2 input - 6
output device can I configure the output unit so that I can feed it
3 stereo busses?
For input, you'd want to create a SInt32 array something like:
SInt32 inputChannelsAllSixInputs[] = {0, 1, 2, 3, 4, 5};
or SInt32 inputChannelsFourOfTheSixInputs[] = {0, 1, 4, 5};
For output, you'd create the same:
SInt32 outputChannelsOneTwoFiveAndSix[] = {0, 1, -1, -1, 2, 3}
(this would give you four channels, sourced with channels 1, 2, 5 &
6)
Your audio buffer list will need to contain as many buffers of mono
channels as you ask for channels from the device. In your
AudioUnitRender() callback, you will end up with N deinterleaved
buffers, where N is the number of channels specified in the
ChannelMap. Same goes for the callback for output too.
-Aaron
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