How do I use Ardour's multichannel panning?

Getting Stuff Done How do I .... ?
#1

When I create a multichannel track, let’s say, a track with a mono input and 8 outputs, the standard panning at the bottom of the corresponding mixer strip changes to a box with eight little orange squares (representing the speakers), plus a larger blue square (representing the desired position of my mono sound source, I believe).
The orange dots come by default in a diagonal line descending from the upper-left to the lower-right corner of the box. I realize I can move the orange dots around. I assume this is so that I can arrange them to visually represent my own 8-channel speaker set-up.

I would like to understand exactly how I can use this feature. Here are some questions:

a) Can I automate the movement over time of my mono source (the blue square), or do I have to choose one fixed location for the entire track?

b) If I arrange my 8 orange dots (speakers) in a circle, and place the blue square (source) right in the middle of my 2D space, that is, equally distant from all 8 orange dots, I thought the result should be the sound going with equal volume to all speakers. Similarly, I thought that by placing the blue square on top of, say, speaker number 1, the sound would go out only through output #1; if between 1 and 2, I then it would go out to both 1 and 2, and nothing to the remaining speakers; and so on and so forth. However, that’s not what happens: by moving the blue square close to a certain orange dot, I see from the meters that the signal output is stronger at that speaker, and just slightly weaker at the others, and placing the blue square in the middle doesn’t make for an equal level on all outputs. Am I missing something? How should I interpret and effectively use this feature?

c) This seems to be a bug: in Editor window, with Show Editor Mixer on, the arrangement of the dots does not mirror my manual arrangement made for that track in the Mixer window. Shouldn’t they be always the same?

d) Is it be possible to control the movement of the blue square (my mono source) with an external device such as a joystick? (the idea would be to spatialize a mono source to 8 channels in real time within Ardour; if automation is not possible, I could still bounce it to another 8-channel track).

I know I could work on spatializing my sounds elsewhere (Pd or Max/MSP, for example), but it would be great to have the ability to do simpler spatial movements directly within Ardour.

Thanks for any help,

Bruno
Ardour 2.8
(both Mac & Linux)

#2

The short and disappointing answer is: “don’t”.

If you are doing real multichannel work, I suggest you use Ambisonics, which ardour will handle quite conveniently (certainly much more easily than, say, Logic or Nuendo or ProTools). I will try to post a document on how to do this on the ardour website in the not too-distant future. Otherwise, please use the mailing list (ardour-users) - there are a few experienced ambisonics users there.

#3

Can I have the long answer? If this [1] is still the way ambisonic should work, it seems rather clumsy. Also, I’d like to know how to interpret the multichannel panner in Ardour, because as it is, I’m really confused, as was the topic starter.

I can also find ambisonic encoder and decoder plugins in Ardour, but when I select the B format to stereo decoder, I can’t really seem to pan well and when I select the B format to quad, all I get is noise at maximum signal gain.

Are there also separate panner plugins available for Ardour, which act somewhat better than Ardour’s multichannel panner but less involved than ambisonics?

And a final question, can channel output with ambisonics be as discrete as 5.1, or do you have leakage effects like in Dolby (Pro logic) surround sound?

[1] https://ardour.org/node/2804

#4

The multichannel panner in Ardour is not ambisonics. There is an article on how to use Ambisonics in Ardour on this website(Might have to search for it).

IIUC Ambisonics by its nature is likely not going to give you 5 ‘discreet’ channels, but rather panning will use any and all channels it needs to to accomplish what it is doing. So if you ar trying to purposely route to a single output out of the 5, I would say ambisonics is not thebest answer for that purpose.

   Seablade
#5

I know multichannel panning in Ardour is not ambisonics and I also know that there is an article on the site how to use ambisonics; I linked to it. My question is that I would like to understand how the multichannel panner works, because it doesn’t seem to do what it’s supposed to do.

#6

@halfgaar: you should consider it broken. if it happens to do something useful for you, consider it a special dispensation from the skies. it attempts 2d panning in a plane, distributing each channel in the track/bus between the outputs based on the proximity of the “puck” for that channel to the speakers. this does not correspond to what anybody actually wants, or so we have learned :frowning:

#7

Adding on to what Paul said, I don’t even think THAT works correctly to be honest. He isn’t kidding when he is talking about if it works consider it a dispensation:)

  Seablade
#8

Is it something that is going to change, or is open for patches?

What you describe, Paul, seems to be what I want, but as Seablade says, that doesn’t work. I can’t really tell what it does. Something changes, but not much and the wrong things.

I wonder why that isn’t the way people want the panning done, because it is what I need. Cinelerra does it that way as well.

BTW, are those ambisonics plugins (B-Format to quad, B-Format to stereo) provided by Ardour usable for decoding, or do I have to use that external program?

#9

The plugins are fine for decoding and even encoding.

The Multichannel panner is probably very open for patches is my guess. It probably won’t be worked on till someone steps up and does it(Its somewhere on my TODO list, but then again so are a LOT of things these days).

It is exactly how the audio routing is handled and the performance of the panner that people might disagree with. For instance some people might want to be able to send via the panner exclusively to one channel at a point, however not all algorithms work like that. But I am to asleep to go into much detail right now.

      Seablade
#10

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