[LAD] Mixing audio: Implementing pan and balance

Fons Adriaensen fons at linuxaudio.org
Tue Mar 12 21:22:39 UTC 2013

On Tue, Mar 12, 2013 at 04:24:49PM -0400, Tim E. Real wrote:

> Interesting about the crossover bit. 
> Wow, I considered adding selectable pan laws but didn't realize crossovers. 

The rationale behind this is that at LF the L and R signals will add more 
or less in phase, while at HF the phases are random and what gets added is
the power.

The mixer app I've been developing has only Ambisonic panning. If you
want stereo, you use a first order horizontal only bus (3 channels),
use the -45 to +45 degrees range of the panner, and decode to stereo
in the master strip. Then it's that decoder that determines the relative
center gain of the panner, and it's no problem to make it frequency
dependent so you get -6 dB at LF and -3 dB at HF.
> I will look at having separate pan controls for each channel on one strip, 
>  as I'm reminded from talking to Paul that Ardour has this :)

A2 had this, but no way to change the relative gains of L and R.
The full matrix from L,R to L',R' has four coefficients. One of
those factors out as channel gain, so three remain. So a really
universal stereo -> stereo 'panner' must have three independent



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