.................. I made a test with +matrix-- code written by Tom Erbe.
http://tinyurl.com/yo5duf
Maybe someone can figure out something I'm doing wrong, or maybe
someone will find ways to do a "perfect reversal" when non default
plug settings are used. I hope so, because there are many useful
applications. Rob D.
JL- I recon (not 100% sure) if you set the decode with the same gain on=
both M&S, unity say. Then boosted / attenuated as needed the L&R output
channels by the inverse of the amount used on the En-Code, you may (poss)
get back where you started. Or as likely the only way you can change the
relative gains of the LR outputs is via a panpot just leave it centrally
panned and see if you've created 2 signals/mono files that are hopefully
identical to the original in all bar level. A null test with the noted
boost/cut you originally used should work.
BTW your original file is odd in that there is more S than M, IE unless you=
reduced the amount of S in the de-code your LR stereo will contain quite
some amount of out of phase info - but that's odd and not relevant to why
your not getting perfect reversal.
It's not clear to me why you chose to use 6dB of gain ** on the decode mix=
bus? It's just possible there could be some rounding or other mathematical=
errors [stuff like plugin being 24bit & I assume Logic uses 32float
internally]
Rob, you could you try the following
Take 2 mono files of, I suggest, Noise (any colour) & sine tone
Use these as your MS inputs & encode to MS (sum & difference) note setting=
of non unity gain gain controls
Decode - you need to be able to listen to just the L or the right output
Whilst listenining to one speaker (as it were) adjust level of either chan=
till you get just noise or tone. Note gain setting & tell us.
** I recon it may have to do with Max's point
"MS to LR" is exactly the same as "LR to MS", except that you loose 6 dB o=
f
gain in the latter.
Well this is not some universal truth/rule but has some sense to it and is=
for example the way CEP/Audition does things. They quite reasonably decided=
that when one adds the L to R in a worst case if the mix were in fact doubl=
e
mono the sum would be 6dB louder - so to be safe reduce the level by 6dB so=
it doesn't clip. Unfortunately their clear thinking didn't extend to their=
de-code preset but if you work in 32bit Float as I do you can normalise any=
greater than 100% modulation back to what regular integer PCM can handle.
best
John L
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