Channel Mapping and Audio Input
Channel Mapping and Audio Input
- Subject: Channel Mapping and Audio Input
- From: Mark Coniglio <email@hidden>
- Date: Tue, 27 Feb 2007 08:06:54 +0100
I am using AUHAL for audio input, and have a question about mapping.
The hardware source is a two channel device.
I've set the output format of the audio input
(kAudioUnitScope_Output, element 1) to four channels. I would like to
be able to route input 1 and 2 from the hardware, to any of the four
ourput channels. My tests show this:
Case 1: Channel map { 0, 1, 0, 1 } = all four output channels have sound.
Case 2: Channel map { -1, 1, 0, 1 } = first output chan = no sound,
remaining channels have sound
Case 3: Channel map { 1, -1, 0, 1 } = second output chan = no sound,
remaining channels have sound
Case 4: Channel map { -1, -1, 0, 1 } = no channels have sound!
It would seem that in case 4, I am telling channels 3 and 4 of the
output to receive data from channels 0 and 1 of the input device. But
instead I get no audio at all.
It seems that as long as position 1 or 2 of the map has a valid
source, i.e., 0 or 1, I get the correct mapping. But if position 1
and 2 of the map are both -1, then I get nothing.
Am I doing something wrong? Does AUHAL get confused if I set the
audio output stream for the input device to 4 output channels ?
Thank in advance for the help,
Mark
--
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Mark Coniglio, Artistic Co-Director | email@hidden
Troika Ranch Dance Theater | http://www.troikaranch.org
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