Polarity Maximizer in Ardour?

Watching Harrison’s Youtube channel (as it shares many features with Ardour), I saw the video about the “Polarity Maximizer” feature:

I found it very interesting, as I’m working on a project where there’s a drum set recorded with several mics.
When trying to use that function, I noticed that Ardour does not include “Polarity Maximizer”. I haven’t found anything about it in Ardour’s manual either.
Is that because it hasn’t been considered interesting by the developers? Or is it a proprietary Harrison technology?

I am currently using Ardour 6.3, downloaded from https://community.ardour.org/download on Debian 10 stable

The DSP is proprietary. It was developed by Prof. Jim Davis, Dept. Computer Science & Engineering at Ohio State University and licensed to Harrison. There is also a plugin version of that algorithm available from https://www.audiomere.com/polarity.html

Ah! Ok Robin. I already assumed that the algorithm would not be free (libre).
Thanks for the clarification!
Unfortunately, the plugin version is only available for Mac and Windows :pensive:

It’s also more cumbersome compared to the tight integration into Mixbus. You’ll have to add plugins to all tracks and play the whole song though once. While in MIxbus the analysis happens offline, faster than realtime on a range selection.

If someone was to write a free software equivalent analysis plugin we could also add this feature to Ardour.

Very very interesting feature

I hacked together a quick python script to do this on a set of soundfiles.

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Mmmmm… interesting…
How to use it? As a plugin? Can it be integrated in any way into Ardour?
I’m not a computer expert… :sweat:
Anyway, thanks for your contribution

No, it’s not a plugin, although it could perhaps be integrated in some way via a lua script? It’s just a command-line script which analyzes a set of audio files and tests the phase permutations. Multi-channel files are split to mono first.

Thus, in a directory of stems from a session:

python3 phaseanalyze 0005-v* 0005-room_KM184_ortf.wav
................................

 Channel                          Phase
-------------------------------  -------
0005-viola_U87.wav               ø
0005-violin_ii_MK4.wav
0005-violin_i_MK4.wav
/tmp/1_0005-room_KM184_ortf.wav
/tmp/2_0005-room_KM184_ortf.wav  ø

Unchanged RMS -77.62 dB
Optimized RMS -62.46 dB

16 phase permutations calculated.

Which tells you that by flipping the polarity on the viola and right channel of the room pair, 15dB of RMS gain can be achieved.

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How cool!
A question for the developers: could the algorithm developed by Mark be implemented in Ardour, as the Mixbus function? (with Mark’s permission, of course :wink:)
If so, should I make the proposal in tracker.ardour.org?

Ardour doesn’t do any DSP. Ideally it would be implemented as VAMP plugin, just like Mixbus’ Polmax feature.