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HOWTO: Working with B-format recordings - 2

2010-10-17

UPDATE:

I wrote this tutorials a few days after having figured out how to do it, and had forgotten some details in the meantime. Logic and the Logic project shoudl not be set to 4-channel LCRS or Quadrophonics. The SoundField AudioUnit will refuse to load with these settings, as it requires 6 channels out. Instead ITU 5.1 should be used. This will give you a 6-channel audio file after the bounce. Two of the channels will be silent, and will need to be removed using e.g. Amadeus Pro.

However, since then I have found that it is easier and faster to do the conversion in Wave Editor instead of Logic Pro. The details of how to do this are explained in a more recent blog post.

 
 

So, here is the second half of this tutorial/note to self. I had a really hard time figuring out how to do this and rather would not like to start from scratch next time.

The problem is caused by Logic, as most other DAWs, being geared towards standard consumer formats such as stereo or ITU 5.1. The closest it gets to 4-channel B-format is the 4-channel Logic LCRS setup and Quadrophonic setups, but both of these cause problems with the SPS200 AudioUnit plug-in as it is 6 channels in and 6 channels out. Hence it won’t load in a 4-channel strip.

I did try loading the A-format recordings and the plugin in a 6 channel surround strip, but returned channels from the plug-in just didn’t make any sense.

The workaround is to load Plogue Bidule as a plug-in, and then load the SoundField plugin inside Bidule.

:-P

Anyway, here we go:

 

First we need to set Logic to four channel surround. In Logic preferences > Audio set surround to Quadrophonic:

Logic_proscreensnapz002

 

Next we go to File > Project Settings > Audio and set Surround Format to Quadrophonic in much the same way.

 

I’ve had great difficulties loading the SPS200 AudioUnit plug-in due to the fact that it is 6 channels in and out. The VST version is 4 in and 8 out, but Logic don’t support VST at all. So, the workaround is to launch Bidule as an insert effect at the channel strip. It will show up as 4-in and 4-out.

Logic_proscreensnapz003

 

Now add the SPS200 AudioUnit and patch as follows:

Logic_proscreensnapz004

 

Next double click the SPS200 bidule to bring up the user interface for the plugin. Set output format to B-format, and set “Invert” and “End Fire” according to the positioning of the mic during recording. Please refer to the manual for the mic for further details:

Logic_proscreensnapz005

 

Finally, we are ready to import A-format recordings into the channel strip and start converting to B-format.

Phew!

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