UHJ Encoder VST Beta

I’ve got 32bit Windows and Mac versions of a UHJ Encoder working. I’m looking for anyone who wants to beta test it. I’m hoping to see how stable it is on other systems (seems fine on mine) and different DAWs (I’ve tested for Reaper and SONAR X1). If you’d like to give it a go then just leave a comment or contact me via email.

Overview of the Plugin

This is an encoding plug in that takes a mono or stereo source and encodes it using the UHJ format. It has three outputs: L, R and T.

It can be used with either two or three of the output channels in a few diff erent confi gurations.

  •  The simplest is to take the L and R channels and use them as the signals to your left and right loudspeakers, as you would with conventional stereo. This raw/undecoded format allows it to work as a stereo panner that uses both amplitude and phase.
  •  The next option is to use it in conjunction with a UHJ decoder as 2D Ambisonic encoder. If used like this then either two or all three output channels can be used and, for an appropriate loudspeaker confi guration, will allow it to function as a surround panner. If all three channels are used it will be equivalent to 1st order 2D B-format. If only the L and R channels are used then the spatial resolution will be reduced.

Please see Signal Flow for the required signal flow required in both cases.

Please Note: At the current time this VST has been compiled for both 32bit
Windows and 32bit OSX. I do intend to make 64bit versions available but unless
there’s some unprecedented demand for them I’ll not be doing them too soon. I’d rather get the B-format Encoder and the SARCoder working efficiently on
both platforms first.

Tips for Raw/Undecoded Processing

Since it can only do 2D rst order surround sound the more interesting properties
of the VST are as a stereo e ffect. Here are two things you can try:

  •  For a mono input signal try turning the Source Angle beyond 90 degrees. You should notice a change in character between sounds in the front and “rear”. For the most obvious example check out the diff erence between a source at 0 degrees and 180 degrees. The one at 180 degrees should be broader or less focused than the one directly in front. This allows a slightly diff erent “flavour” of stereo than conventional amplitude panning.
  •  Using a stereo input signal, leave the Source Angle at 0 degrees, set the input to Stereo in and try changing the Source Width. It will act as a stereo width control that goes from completely mono to full width.

Basis for the VST
This plugin is based on work done by Michael Gerzon. The equations used are
from the appendix of:

Gerzon, M. (1985). Ambisonics in multichannel broadcasting and video. J. Audio Eng. Soc, 33(11), 859-871.

The original version of this VST was made a part of an assignment for the Spatial
Audio module during the MA in Sonic Arts at the Sonic Arts Research Centre
(SARC) at Queen’s University Belfast. It has since been slightly modi ed for
stability and efficiency.

3 responses to “UHJ Encoder VST Beta

  1. Pingback: Thoughts on Ambisonic B-Format Encoder VST | Circle Sounds

  2. Needs a B-Format input. The main use of two-channel UHJ is distribution of surround sound. (It would also be easy to add the fourth UHJ channel, Q, for periphony.)


    • Hi Martin.
      Originally I’d thought of it more as a panner, hence no B-format input. I have a decoder that does B-to-UHJ and therefore didn’t consider putting it into this one when I was designing them.

      However, I think it’s a great idea to have the option to use it as a converter, as well as a panner. I’ll implement that soon for the next revision. (I’ll also be adding the Q-channel as well).

      Thanks for the suggestion 🙂

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