Re: Recording for 5.1
 

OK Gary, thanks. I'm quite confident in those formulas because I use them at least weekly if not more often when working on old phono recordings or cleaning noise in other sources.

I sometimes need to cut out a very tiny bit of audio (I'm talking of a few msec) to get rid of some noise which otherwise can't be removed. I want to cut on zero crossings, but the info in the two channels does not cross at the same point in time. So I convert to M/S, cut on the zero crossing of the M channel, ignore the S channel and do a very brief gain dip to zero at the edit point if necessary, and finally convert from M/S back to L/R. (Actually it's more complex than that, but that's a reasonable summary.)

Of course, come to think of it, that editing technique would work with your formulas too, except that the M channel would appear in the usual R channel space, rather than the usual L channel space. Hmmm.

But I have checked a few references, and the formulas are correct as given.

Carry on!