Ardour and IEM ambisonics plugins suite

I’m revisiting in Ardour a 3rd order ambisonics setup that works quite well in Pure Data, using the IEM plugins suite ( last version) and the [vstplugin~] object.
It is very simple :

  • 4 StereoEncoder to go from stereo to ambi3
  • 1 ambisonics bus with, in order, Omnicompressor, SceneRotator, SimpleDecoder, MultiEq, DistanceCompensator
  • Each StereoEncoder output goes to to the ambi bus.
  • Input tracks have 2 inputs and 16 outputs.
  • Ambi bus has 16 inputs and 7 outputs (regular hexagon + sub)
  • there is also an ambi to binaural bus and an fx ambi bus

IEM plugins default to 64 channels width. Then you can set the ambisonics order, then the plugin tells you if the bus it belongs to is wide enough.

It seems like i can’t reliably replicate my Pd setup in Ardour with these plugins, under Windows or Mint 20.3 and Ardour 7.1 (IIRC i also tried with 6.x versions and older versions of the plugins).
Just to be sure before posting here, i tried with Reaper and it’s been a breeze.

I’d like to ask if someone versed into ambisonics could replicate -or already did- this kind of setup in Ardour. If not, what would be the right way to work with this kind of setup/plugin in Ardour, regarding selection of flexible/strict IO setting, unplugging of unused pins to hopefully save CPU, setting the bus width in the plugins before or after the number of io of the track…

Be nice with me if it’s working right away for you (and send me your session), i tried too many times already :sweat_smile:

Thanks a LOT.

*edit : for the lulz, i include a screen capture of the aforementioned Pd patch.

Why not? Where are you stuck?

People have been doing ambisonics with Ardour since over 15 years (although most sessions use fons’ ambdec not the IEM suite).

Erm, sorry for not including a step-by-step to my issue.

  • create a custom width audio bus, flexible IO
  • insert a SimpleDecoder post fader → Bus gets 64 outputs
  • bypass the panner
  • add inputs to the bus up to 16
  • set the bus VU to “output”
  • set SimpleDecoder to 3rd order and load my config (regular hexagon) ->plugin warns that the bus is too small

This, already, is weird and sometimes leads to a crash, but let’s go on

  • add a custom width track, flexible IO
  • add a StereoEncoder post-fader to the track
  • bypass the panner
  • set the plugin to 3rd order → no bus size warning
  • route the first 16 outputs to the bus
  • play some sound from the track input into the bus, pan the sound around and watch the bus output meters → there is sound in outs 1 and 2, but none from 3 to 6.

I was testing under windows, and now i can’t even get past the simpleDecoder insertion, Ardour crashes.

I know that Ardour works well with multichannel setups, i actually use it with a similar setup but in WFS, where i have 4 WFS panners and a 8-channel wide WFS bus. This one is working ok. That is what led me to revisit the ambi setup.

Are you using the VST3 variant of the plugins?

Ardour currently only support a single optional bus for VST3. Until this is addressed, prefer the LV2 (or VST2) variant.

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I’m using VST3 indeed.
I’ll test again and let you know.
Thanks a lot !

That was it. Shouldn’t Ardour warn the user where they’re trying to create optional busses ?

Thanks ! Reverting to VST2 for now.

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Those busses (additional outputs) should not show up in the first place.
Anyway, the plan is to add full support for them during the Ardour 7.x release cycle.

Thanks for checking back, and great to hear that you have it working.

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