does adobe audition 2.0 do phase cancellations?

hi!  i need help before i drop $$$$$ on some new software

i'm looking for a program that will do this....

take a stereo recording with 3 instruments, one panned hard left (L) one panned dead center (C) and one panned hard left (L)
and spit out these signals .....

>an OOPS signal (out of phase between left and right) resulting in only L +  R
>a 'center' signal (out of phase bet the first OOPS signal and a mono sum of the original stereo signal) resulting in only C
> a 'discrete right' signal (out of phase between the center signal and the right channel from the original stereo signal) resulting in olnly R
> a 'discrete left' signal (out of phase between the center signal and the left channel from the original stereo signal) resulting in olnly L

i know somebody out there has software that does this from all of the 5.1 upmixes that people do from stereo sources......

i've heard adobe has 'center channel extractor' or something like that.....can it do the rest of the phase cancellations and variations in the stereo spectrum?

i just like to hear isolated tracks to learn songs and amuse myself for hours


thanks in advance for your help!!!!!!!!!!!!!!!1
michael richardson
fort worth tx

i've heard adobe has 'center channel extractor' or something like that.....can it do the rest of the phase cancellations and variations in the stereo spectrum?

If you really have signals split the way you say, then Audition could do what you want very easily - and you wouldn't even need the Center Channel Extractor - just a sum and difference conversion will do what you want for the centre channel, and a little file manipulation will do for the rest.

thanks for replying, steve!!!

so i take it in adobe audition you can make a sum of two tracks, as well as the phase cancellation of two tracks?

follow this logic and tell me if it is realistic....and if so could i do this with audition?

SCENARIO:

guitar > panned hard left
vocal > panned dead center
piano > panned hard right

OOPS between L and R gives you (guitar and piano)    = VARIATION ONE
summing L and R gives you (guitar and vocal and piano) = VARIATION TWO
L by itself contains (guitar and vocals)
R by itself contains (piano and vocals)
OOPS between ONE and TWO gives you (vocal)  = VARIATION THREE
OOPS between L and THREE gives you (guitar)
OOPS between R and THREE gives you (piano)

I wasn't thinking quite straight earlier  - the sum signal will still have all of the L & R information in it.

so i take it in adobe audition you can make a sum of two tracks, as well as the phase cancellation of two tracks?

Let's put it like this; there isn't a single operation of this sort that you could wish to do to a file that Audition can't do - easily. Including a whole load that generally, you wouldn't want to do to a file... but whether this will help you is another matter altogether.

follow this logic and tell me if it is realistic....and if so could i do this with audition?

SCENARIO:

guitar > panned hard left
vocal > panned dead center
piano > panned hard right

OOPS between L and R gives you (guitar and piano)    = VARIATION ONE
summing L and R gives you (guitar and vocal and piano) = VARIATION TWO
L by itself contains (guitar and vocals)
R by itself contains (piano and vocals)
OOPS between ONE and TWO gives you (vocal)  = VARIATION THREE
OOPS between L and THREE gives you (guitar)
OOPS between R and THREE gives you (piano)

No, unfortunately that won't work. If you have the two stereo channels out of phase, you will cancel the vocal - the common-mode signals, which you'd want to add, have been subtracted, so the common-mode (centre) disappears. This automatically screws your other two options as well. If it was that easy, everybody would do it!

What you have described is the classic 'vocal remove' technique as far as it goes - you have to play the result in mono, but the vocal, if it's dead centre and the only thing there, will be considerably reduced in amplitude.

Your best chance is to use the Centre Channel Extractor - this works on an entirely different principle, but the options in it will give you the best chance you'll get.

If you want to try it your way, download the trial of Audition, and experiment with the channel mixer in Effects>Amplitude. In one hit, you can determine the new contents of either channel from what is existing, either as a positive or negative (algebraic) addition, and also swap the relative or absolute phase - there's nothing it won't do. But unfortunately, despite this, it won't do what you want, because whatever you do to get a difference signal will cancel the signal that's common between the channels, which you want on its own. That's where the Center Channel Extractor comes in...

with my scenario, the simple left minus right gives you the guitar and piano with no vocals whatsoever
i do this all of the time just wiring my speakers out of phase......i like doing this with purple haze and foxey lady, you get just the vocals (all instruments are in mono, vocals are panned hard left or right).....

so with the center channel extractor.....

does it extract the center as cleanly as simple out of phase extracts the panned instruments??

like with my above scenario, simple out of phase would give you the guitar/piano cleanly with no vocal
would the center channel extractor give you vocals cleanly with no guitar/piano?

thanks!!!!!!!!!!!!!!

with my scenario, the simple left minus right gives you the guitar and piano with no vocals whatsoever
i do this all of the time just wiring my speakers out of phase......i like doing this with purple haze and foxey lady, you get just the vocals (all instruments are in mono, vocals are panned hard left or right).....

Yes, that would be correct - although generally it doesn't work too well.

so with the center channel extractor.....

does it extract the center as cleanly as simple out of phase extracts the panned instruments??

like with my above scenario, simple out of phase would give you the guitar/piano cleanly with no vocal
would the center channel extractor give you vocals cleanly with no guitar/piano?

thanks!!!!!!!!!!!!!!

I'm afraid that the answer is 'it depends'...  it uses a completely different method, because it has to. And since that method is autocorrelative, it's never going to be perfect anyway. The advantage is that it leaves the rest of the stereo field intact, so you can easily get the extreme L and R. If there really is nothing between the centre signal and the extremes, it will be as clean as it can be. The only real way to find out is to try it, though.

The free trial version runs for a month, and is completely unrestricted - it's just the same as having the registered version.

with my scenario, the simple left minus right gives you the guitar and piano with no vocals whatsoever
i do this all of the time just wiring my speakers out of phase......i like doing this with purple haze and foxey lady, you get just the vocals (all instruments are in mono, vocals are panned hard left or right).....

Yes, that would be correct - although generally it doesn't work too well.

 in my experience, hard wiring your speakers totally cancels out the center perfectly.

so with the center channel extractor.....

does it extract the center as cleanly as simple out of phase extracts the panned instruments??

like with my above scenario, simple out of phase would give you the guitar/piano cleanly with no vocal
would the center channel extractor give you vocals cleanly with no guitar/piano?

thanks!!!!!!!!!!!!!!

I'm afraid that the answer is 'it depends'...  it uses a completely different method, because it has to. And since that method is autocorrelative, it's never going to be perfect anyway. The advantage is that it leaves the rest of the stereo field intact, so you can easily get the extreme L and R. If there really is nothing between the centre signal and the extremes, it will be as clean as it can be. The only real way to find out is to try it, though.

The free trial version runs for a month, and is completely unrestricted - it's just the same as having the registered version.
[/quote]


thanks for all of your help, advice, and patience.....i'm eager to give it a try!!!

in my experience, hard wiring your speakers totally cancels out the center perfectly.

So does adding the left and right channels together, 180º out of phase. 

I think the point SteveG was trying to get across is that this doesn't always (in fact, it seems to me, quite rarely) work because there is often a stereo element attached to a centred vocal (stereo reverb or other FX returns) and this does not cancel.  Thus there is nearly always a vestigal signal left over from the summing exercise.  Still, as he says, the best thing to do is to download the demo and see how well it works for you.

hi graeme!!

i don't care about eliminating vocals in particular......i understand about reverb signals being panned and such....what i'm saying is that L-R perfectly eliminates center panned elements in a stereo mix, for example songs that have the music totally in mono, and the vocals panned hard (puple haze, foxy lady by hendrix, obladi oblada, birthday, by beatles) if you L-R it you get a perfect extraction, the music is cancelled perfectly and you get vocals, or whatever else is panned by itsself  (manic depressions is awesome too....guitar panned hard, the rest is in mono, so you get hendrix's marshall in your face!!!)

i'm wondering if if the center extraction is as clean as this.....like in my above example i'm wondering why you can't take the simple out of phase signal (a mono signal containing L & R only) and run it out of phase with a summed stereo signal (containg L, C, and R) and get the difference in those two, being a perfect C.......

In your original scenario, you wanted to extract all three signals separately, but you still won't be able to do this, because when you subtract the two stereo channels from each other, you end up with all the music in a mono channel - which means that you can't isolate the two hard right/left music tracks.

every signal that you get as a result of a phase cancel is a mono signal derived from two other mono signals.........

when you subtract the two stereo channels from each other you end up a mono signal that contains only L and R

if you add these two stereo channels into a mono signal, you'll have L and C and R

i'm suggesting running those two mono signals out of phase with each other, and cancelling out the L and R to get C


if you can get a C by itself, you could get discreet left and right by running C out of phase with either of the 2 original mono signals (the left channel containing L and C, or the right channel containing R and C)

[and out of phase]

every signal that you get as a result of a phase cancel is a mono signal derived from two other mono signals.........

Each mono signal contains a common part and a difference part...
(L+C) + (R+C) = L + R + 2C in one file.

when you subtract the two stereo channels from each other you end up a mono signal that contains only L and R

Mixed together, and out of phase:
(L+C) - (R+C) = L-R (the +C's cancel)

if you add these two stereo channels into a mono signal, you'll have L and C and R

I've just demonstrated that you don't - you get no isolated C.

i'm suggesting running those two mono signals out of phase with each other, and cancelling out the L and R to get C

if you can get a C by itself, you could get discreet left and right by running C out of phase with either of the 2 original mono signals (the left channel containing L and C, or the right channel containing R and C)

You now have a file with L+R+2C in it, and a file with L-R in it. Let's try either subtracting or adding, and see what we get:

(L+R+2C) + (L-R) = 2L + 2C
(L+R+2C) - (L-R) = 2R + 2C

In other words, any file you get by this method contains right plus centre, or left plus centre, at +6dB.

You cannot, by any manipulation you perform, isolate the centre from the L and R by this method. If you could, then there would be no need for the Center Channel Extractor. And if you think that David Johnson went to all the trouble to figure out a rather complicated way to approximately achieve this when all he needed to do was a little algebraic manipulation, then you have considerably underestimated him.

It simply doesn't work the way you suggest at all. Not only that, but you don't even have to take my word for it - you can download Audition and try it yourself. Do it with widely separated tone - that way you can check each stage accurately. I've done this before, and this is the only  possible result.

ohhhhhhhhhhhhhhhhhhhhhhhhhhhhh.........

that makes it make sense to me now.....

i guess my mindset was that once you have the original OOPS (just the L and the R with the C removed), you
ended up with L + R instead of L - R..............

so  (L +2C + R) - (L + R) = 2C       is how I was seeing it

i guess in my mind, once you did the original OOPS it was basically the discreet L signal PLUS the discreet R signal.... even though
you get (L - R) when you do the math, in my mind it was L + R

damn

so when all of these people 'upmix' 5.1 mixes from stereo sources, the only true signals they can get by phase cancellation are the orignal OOPS cancellations?

Which is why most upmixing from stereo sounds really bad... unless "new" information were to be added through effects processing.  Then it still sounds bad, in a hollow, manufactured sort of way.  I sound like a broken record with this stuff, but honestly, the Dolby Pro Logic II music mode is pretty brilliant for what it is.

If you really needed to do this, and were forced to record three signals to two tracks, then all is solved if you invert the "center" signal on one track, so Lt = (L, C) and Rt = (-C, R).  This would take a little bit of careful mixer set up, and a mult.   Then
(L,C)+(-C,R) = L,R
(L,C)-(-C,R) = L,2C,-R

(L,R)+(L,2C,-R)=2L,2C
(L,R)-(L,2C,-R)=-2C,2R      ....oops, that does NOT work.

(L,C)-(L,R) = C,-R
(C,-R)+(-C,R) = 0               hee hee hee

(L,R)+(L,C)=2L,R,C
(2L,R,C)+(L,2C,-R)= 3L,3C
(2L,R,C)-(L,2C,-R) = L,-C,2R

(L,2C,-R)+(-C,R)=L,C           nope

You know, has anyone mentioned that there's absolutely no way to do this?

Get more tracks!  Get a studio master!  Use the Center Channel Extractor!

Hmm... I think that you should have realised half way through that you'd just ended up with the result that I did... and that the rest follows inevitably!