Ambisonic micing


#1

Has any one done any ambisonic recording using a usb mic under supercollider? I’m getting a Twirling 720 lite mic and would like to experiment with using the ATK in a live environment.


#2

I’ve done comparable things with Zoom - IIRC ATK has encoders that can handle the zoom capsule configuration as input, so it’s very easy. Without knowing how the the 720’s audio channels are configured, it’s tough to say how easy it will be to get it into proper B-format. If the input format of the mic is particularly unusual, I would suggest talking to Joe Anderson (ATK’s creator) or @mike for tips on how to create a new encoder for this particular device.


#3

The first question to answer would be whether the 720 can output b-format (ambisonics) in realtime, or if it can only function in a-format (raw mic feeds) in realtime.

A quick look at the documentation, it shows it can output a number of formats, including:

The Twirling720 recorder is accompanied with our versatile post-processing software Twirling720 Studio. This software converts raw 4-channel recordings into a variety of output formats.

  • First Order Ambisonic B format SN3D
  • First Order Ambisonic B format FuMa

But they may just be the output of their post-processing software. If this can happen in realtime, you’ll want to use B format FuMa with the ATK. Then you’re already in native ambisonics and off to the races. If for some reason you can only get SN3D format output, you’d need to first go through FoaEncoderMatrix: *newAmbix1 to get it to FuMa format.

If it can only output a-format in realtime, because the mic is in a tetrahedral configuration, you can use FoaEncoderMatrix: *newAtoB to bring it in to b-format, then you’re ready to go. Have a look at the help docs for newAtoB to select the proper capsule order. The argument options are pretty well documented. Send any questions if you hit snags along the way.