Hi everyone, here's my problem — and sorry if it sounds a bit basic for you...

I have a number of Stereo recordings which were originally MS, and have been converted to LR by mistake. Original M and S signals are lost. I HAVE to get the M back.

So what I need is to extract the only part of the signal that's strictly phase-correlated between Left and Right...

[ I tried to do the maths back, like the good old sum-difference trick used in mastering for stereo enhancement and so forth, but it won't do; probably because the original S signal is from an actual fig-8 mic, therefore the signal from the negative end is far from being the inverted positive end; in other words: S ≠ - (-S) ]

So my guess is that I need some fft processing that could eliminate everything that's non phase-correlated, maybe like fft—>cartopol—>unknown math ? dunno.

I'm sure most of you signal-processing-experts have done it already, or you can figure it out pretty quick.. Thanks a LOT. Best,

Olivier