Multichannel output

Special Interest Groups Recording Techniques
1

I was considering Audacity in order to output to an array of speakers (from 10 to 16) arranged as a circle around the listeners, with various effects such as a sound circling around the audience, and 3D effects.

Is it possible to use Audacity for multiple outputs, say with a motu 828 firewire? Does it allow independent outputs? Also, are there any spatial filters/effects?

2

Audacity does not currently support multiple outputs.

3

So the next question is how difficult will this be to implement? Is the code nicely laid out where one might attempt in doing this as an addon or mod?

4

Pretty tricky I would guess. Audacity uses portaudio to communicate with the the sound system, and I don’t think that portaudio supports multi-channel output.

With Audacity 1.3 you can Export multi-channel files, so it may be easier to Edit in Audacity, but use another application to play it.

5

Thanks! I dug some conflicting info. Does anyone have more?

http://osdir.com/ml/audio.portaudio.devel/2007-02/msg00056.html

6

Ah yes, if you can harness ASIO, then you are in with more of a chance. Audacity does not support ASIO by default due to licensing restrictions, but it is possible to build Audacity with ASIO support. (see here for more information http://wiki.audacityteam.org/index.php?title=ASIO_Audio_Interface ).

I’m not a programmer myself, but I know that the Audacity developers are quite fastidious about having the code laid out nicely so that it is readable for other programmers. I’m guessing that this will still be a tough project.

An alternative approach that you could possibly take (if developing on Linux) would be to “graft in” per channel ports for Jackd.

This is really beyond the scope of this help forum, but you can obtain the Audacity source code from here: http://audacityteam.org/download/beta_source
If having studied that you are still wanting to give it a shot you may be better to speak directly to the Audacity developers by joining their mailing list: http://audacityteam.org/community/developers

7

Jamh wrote (to feedback_AT_audacityteam_DOT_ORG)

I was thinking of using Audacity for performance, but I need
multichannel output support for 10 to 20 speakers. Is this doable at
all? Say through jackd on linux?

Please see:
Multichannel output

and:
Multi channel output - Linux - Ardour >

Audacity doesn’t support multi-channel output (even if you compile 1.3.7 Beta with ASIO support), though this is a definite aim longer term. No work can be done on multi-channel output until we have finished bugfixing the Beta code and released it as a new Stable 2.0 version. This should be done towards the end of this year.

Also Audacity cannot record from multiple sound devices, though it has limited support for recording multiple channels from one device (this usually requires ASIO on WIndows). See:
http://audacityteam.org/wiki/index.php?title=Multichannel_Recording

Like Steve said, if you would like to offer your help towards implementing multi-channel output, please subscribe to and introduce yourself on our developers’ mailing list:

Thanks


Gale