[ardour-users] Multi Channel Bus Panning Behaviour

[Jesse Chappell]

Iain Young wrote on Fri, 07-Jan-2005:

 > Hi Everyone,
 > 
 > I recently got a 5.1 Soundcard (actually its built in on the EPIA MII
 > 12000 board), and thought I'd start playing with multi (5.1 mainly)
 > channel audio via jack and ardour.
 > 
 > I can play 5.1 audio, and route it out via ac3jack, and the S/PDIF
 > connector with no problem. 

Cool, i'm glad ac3jack works for you.  It needs some fixing up, and I
plan integrate parts of ac3dec into it so you don't need to pipe
it.
 
 > I then created a 6 channel bus in the mixer window of Ardour. I noted
 > the Panner area had (what I guess are loudspeakers), and 6 "pucks".
 > 
 > I'm confused as to how these work. I could understand a single
 > puck (eg the listener), but a puck for each channel seems strange to
 > me. Can anyone explain it to me ?
 
First of all, our multichannel XY panner just plain sucks.  We
know this, and we intend to improve that dramatically in the future,
by providing different panner types, etc (probably taking a few
tips from sonar, cubase, etc).

It will make more sense for you to have a multichannel bus that
you treat like a master bus, and bypass the panner on it (in context
menu for panner, or middle click).

Then create new Tracks that have 1 input port (maybe 2) but 5 (or 6) output ports.
To do this create the track initially as a mono track, then add
output ports in the i/o editor for the track.  This will make
more sense because then you are panning that single source into
the multiple outputs.  Connect those outputs to your multichannel
master bus.

 > 
 > Now...when I fed a stereo feed into that bus, the bus itself appeared
 > to do some processing of the signal to create a surround effect - or
 > at least judging by the level meters it did.
 > 
 > Is there a way to have a multi channel bus not do any surround processing,
 > but just Pre/Post/Fader processing ? Or is it just going to be easier
 > for me to use 3 stereo busses ?

Yes, just bypass the panner (context menu option, or middle-click).

 > One thing I've done (outside ardour) is combine L&R signals to create the
 > Centre channel, pass that through a LPF out to the LFE channel, and delay
 > the rear surround channels slightly. Trying to implement this within
 > Ardour would seem to require 3 seperate busses.

Yes, it would either probably require separate busses, or a custom multichannel plugin
to be implemented that treats the the channels specially and does
the processing you want.

 > One thing that I'd also like to be able to do is route certain signals
 > to the front/centre/speakers only as I choose (eg incoming phone calls,
 > gated audio from a real audio stream etc), but again, this looks like its
 > going to need 3 stereo faders.

You might be able to use inserts to accomplish this.  I'm not
totally sure i understand your setup....

 > 
 > Finally, can anyone confirm which of the 5/6/7/8 channels would respond
 > to which Loudspeaker in a surround sound setup ?
 
I don't really understand your question here, our panner is totally nonstandard
and unrelated to reality.  whatever outputs you connect to your
output (be that ac3jack, or actual alsa_playback ports) is where
the audio will go.

You are pushing the boundaries of current ardour usability...
although multichannel support is there, it is not user friendly
in the real world yet.

jlc