Removing center stereo information....

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ScuzzyEye
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13 Apr 2015

I do this (well, with the stereo content instead of the mono) all the time with JP's Anansi. https://shop.propellerheads.se/product/ ... de-router/

Set it up like this:
Image 
That is the Mid-Send wired into the Mid-Return, and the Side-Send into the Side-Return (you can put other things in those loops if you want more processing than just dialing back the mono content).

Image 
Now, you can use the Mid/Side switches to turn off the mono or stereo content. Or if you don't wan to be as extreme, you can use the Balance control to just dial it back a little. In your case, you'd be turning off the M switch, or turning the Balance more to the S side.
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ScuzzyEye
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14 Apr 2015

Cool. Yeah, that looks like it does the same thing.

I use it a lot when remixing vocal stems. Removing the stereo component doesn't get rid of all of the reverb, and effects, but it does usually make the vocal much more dry sounding, so I can build it back up from there with my own stuff.

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ScuzzyEye
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14 Apr 2015

Oh, and one thing you might want to check. I believe routing a device back to itself like that introduces a 64-sample delay. If you think you're running into a phasing problem when using this trick in parallel, that's the first place you should look. Otherwise 64 samples isn't so much that you need to worry when matching up with other tracks.

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14 Apr 2015

So does this effectively remove the sound in the center, while leaving the side material?? And if so, is there a way to do the opposite and leave ONLY center material. And if this is also true, is there a way to eliminate individual sides (left or right) of audio in Reason???
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ScuzzyEye
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15 Apr 2015

Yeah, it works exactly the same for the Side content. Just turn off the the Side switch or turn the knob the other way on JP's, or turn the Side gain down on Quad's.

Because of how the Pan control works in Reason's Mixer, if you leave the Width set to full, and pan all the way to one side or the other, you'll actually lose the other side's content (it's only blended in if the width is decreased).

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BPGeez
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15 Apr 2015

ScuzzyEye wrote: Because of how the Pan control works in Reason's Mixer, if you leave the Width set to full, and pan all the way to one side or the other, you'll actually lose the other side's content (it's only blended in if the width is decreased).
Thats fuckin insane my man!!! Thank you! Now is there a way you can get the isolated content back to center without undoing what you've just done??
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ScuzzyEye
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15 Apr 2015


Rather than messing with the pan control, which as you said, while removing one channel's audio, leaves the other one silent. That's fine if you don't want to remove all of one side, and are willing to bus to another channel re-center the audio. If you want either the left or right audio only here's what I do:
Image 
That's wiring one side (either left or right) of the insert send to the left return. This has the added benefit or making the channel appear to be mono, and allowing you to bounce mono stems (if you tell it to ignore the fader section).
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BPGeez
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15 Apr 2015

Life saver Scuzzy!!! Many Thanks Bro
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Gulale
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15 Apr 2015

Stereo splitter from quadelectra manual is not updated I really wanted to understand what the added signal path are. I always tend to use the older version way in order to process the mid and the side separately with two combinators. And then I apply effects as needed individually. 
can I do that without using the combinator? my intention is not to put a gain up or down when I use mid-side splitter I love to manipulate the signal individually. Thanks for you help 
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ScuzzyEye
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15 Apr 2015

I've never used the Quadelectra device. I already had JP's, and didn't really like the way they used "stereo" outputs, and relied upon the mixing of those signals to reconstruct the original. I'll give them props for some innovative thinking on that point, but when I want to work with M/S I'm expecting two mono signals.

Looking at the current device, with its Inserts section, that's exactly what has been added. A way to use it like a more traditional M/S encoder/decoder.

So yeah, you use the Mid-Send to make a mono signal that's just the mid content, and you can process how you like, and then you return it to the Mid-Return jack next to the send. You can then do the same with the Side jacks. Just remember the signal has to come back to the device, which is how M/S encoders/decoders usually work, instead of using a mixer to recombine the signal. Also the mid and side signals are to be treated as separate, mono sources. You don't want to put both the mid and side into one stereo device.

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selig
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15 Apr 2015

ScuzzyEye wrote:I've never used the Quadelectra device. I already had JP's, and didn't really like the way they used "stereo" outputs, and relied upon the mixing of those signals to reconstruct the original. I'll give them props for some innovative thinking on that point, but when I want to work with M/S I'm expecting two mono signals.

Looking at the current device, with its Inserts section, that's exactly what has been added. A way to use it like a more traditional M/S encoder/decoder.

So yeah, you use the Mid-Send to make a mono signal that's just the mid content,
Wait a sec - the mid signal is not JUST the mid content (if indeed that's what you meant to say) - it's the ENTIRE stereo spectrum reduced to mono, sides AND mids (just to be clear). The Mid and Side signal BOTH contain the sides, FWIW, as it's only the side signal that has anything "removed". 

AFAIK, it's impossible to have JUST the mid signal in mono, or just the sides in stereo (with a  hole in the middle) - Mid/Side doesn't work like that (to answer a previous question). 
:)
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MAL9000
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15 Apr 2015

What about the MID/SIDE Mastering patches in the FSB. Would they be similar to this method?

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selig
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15 Apr 2015

MAL9000 wrote:What about the MID/SIDE Mastering patches in the FSB. Would they be similar to this method?
If it says "Mid/Side", then yes. The only other use of the term is for a microphone technique which is based on similar concepts, but of course can only apply when you are recording with microphones. :)
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ScuzzyEye
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15 Apr 2015

selig wrote:Wait a sec - the mid signal is not JUST the mid content (if indeed that's what you meant to say) - it's the ENTIRE stereo spectrum reduced to mono, sides AND mids (just to be clear). The Mid and Side signal BOTH contain the sides, FWIW, as it's only the side signal that has anything "removed".
OK, yeah. What I meant to say, is if you remove the mid signal from a M/S encoded pair, and then decode it back to stereo, you'll be left with only the stereo content, the middle will be gone. Which is what my original solution does. Similarly, if you remove the side information, and then decode, you will be left with only middle. The decode part is important.

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15 Apr 2015

selig wrote:Wait a sec - the mid signal is not JUST the mid content (if indeed that's what you meant to say) - it's the ENTIRE stereo spectrum reduced to mono, sides AND mids (just to be clear). The Mid and Side signal BOTH contain the sides, FWIW, as it's only the side signal that has anything "removed".
ScuzzyEye wrote: OK, yeah. What I meant to say, is if you remove the mid signal from a M/S encoded pair, and then decode it back to stereo, you'll be left with only the stereo content, the middle will be gone. Which is what my original solution does. Similarly, if you remove the side information, and then decode, you will be left with only middle. The decode part is important.
as someone with very little grasp on the M/S process, how exactly do you "decode" it? I thought the "decoding" process was simply adding the two split signals back together. if you remove the mid channel entirely, is there really a way to build the stereo signals back up without it? I thought they were dependent on each other

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selig
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15 Apr 2015

selig wrote:Wait a sec - the mid signal is not JUST the mid content (if indeed that's what you meant to say) - it's the ENTIRE stereo spectrum reduced to mono, sides AND mids (just to be clear). The Mid and Side signal BOTH contain the sides, FWIW, as it's only the side signal that has anything "removed".
ScuzzyEye wrote: OK, yeah. What I meant to say, is if you remove the mid signal from a M/S encoded pair, and then decode it back to stereo, you'll be left with only the stereo content, the middle will be gone. Which is what my original solution does. Similarly, if you remove the side information, and then decode, you will be left with only middle. The decode part is important.
Not exactly, as the signal won't decode properly without both Mid AND Side information. What you end up with in that situation (dropping the mid signal) is the mono "sides" signal on one side, and the inverted mono "sides" signal on the other (which will totally disappear in mono). An instrument panned hard left will not appear hard left in this scenario because there's no Mid signal to recreate the original panning. Any change to either the side or mid signal will in some way destroy the original stereo image…  Similarly, if you drop the sides you are NOT left with just the middle - you are left with a mono version of the original STEREO signal (sides included). 

What I wanted to make clear is that the mid signal is simply a mono version of the entire stereo signal, not "just the mid panned signals". This part often gets overlooked by those thinking this process actually separates the mid signals from the sides. Possibly this effect's name isn't as accurate as intended, mainly because the name comes from the microphone technique where the "mid" signal does indeed represent mostly the middle panned sources in the stereo field. And btw, the "side" signal is also potentially misleading since it is mono - meaning it's not actually the stereo signal with the middle missing.
:)
(where's the "condescending smiley" when you need one)
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selig
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15 Apr 2015

lowpryo wrote:
selig wrote:Wait a sec - the mid signal is not JUST the mid content (if indeed that's what you meant to say) - it's the ENTIRE stereo spectrum reduced to mono, sides AND mids (just to be clear). The Mid and Side signal BOTH contain the sides, FWIW, as it's only the side signal that has anything "removed".
ScuzzyEye wrote: OK, yeah. What I meant to say, is if you remove the mid signal from a M/S encoded pair, and then decode it back to stereo, you'll be left with only the stereo content, the middle will be gone. Which is what my original solution does. Similarly, if you remove the side information, and then decode, you will be left with only middle. The decode part is important.
lowpryo wrote:
as someone with very little grasp on the M/S process, how exactly do you "decode" it? I thought the "decoding" process was simply adding the two split signals back together. if you remove the mid channel entirely, is there really a way to build the stereo signals back up without it? I thought they were dependent on each other
Yes they are totally dependent on each other to recreate the original stereo image, so removing the mid signal leaves you with a mono side signal (or two mono side signals panned hard L/R with one being polarity inverted - not a "pretty" sound IMO).

Decoding is done by mixing the mid and side signal thusly: mid gets panned center, side gets duplicated with one channel panned hard left and one hard right (and one of these two channels needs to have it's polarity inverted). :)
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15 Apr 2015

I've been playing around since my last post. JP's Anasi does what I'd expect when turning off the "side" switch, it leaves only the center (in Dolby Pro-Logic terms, i.e. the mono content). But turning on the side switch, with the mid off, doesn't produce the surround channel, as I was expecting (i.e. only the stereo content). It does what Giles was expecting, and produces the phase inverted left/right audio. Yeah, it isn't pleasing when listening on stereo speakers (unless you like out of phantom, out-of-phase imaging).

What I ended up doing, is using the center information from a mid only Anasi, and phase inverting that, then combining it with another Anasi that had both switches on (this was needed to get a 64 sample delay to match the first one). That produced the expected stereo-only signal.

I'm not sure if the Side gain knob on the Quadelectra's device works as I was expecting Anansi to or not. I should probably trial it, and see.

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selig
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15 Apr 2015

ScuzzyEye wrote:I've been playing around since my last post. JP's Anasi does what I'd expect when turning off the "side" switch, it leaves only the center (in Dolby Pro-Logic terms, i.e. the mono content). But turning on the side switch, with the mid off, doesn't produce the surround channel, as I was expecting (i.e. only the stereo content). It does what Giles was expecting, and produces the phase inverted left/right audio. Yeah, it isn't pleasing when listening on stereo speakers (unless you like out of phantom, out-of-phase imaging).

What I ended up doing, is using the center information from a mid only Anasi, and phase inverting that, then combining it with another Anasi that had both switches on (this was needed to get a 64 sample delay to match the first one). That produced the expected stereo-only signal.

I'm not sure if the Side gain knob on the Quadelectra's device works as I was expecting Anansi to or not. I should probably trial it, and see.
Can you give an example of what you mean above? What exactly are you mixing the mid signal with, the decoded or un-decoded side signal? I can't get the results you describe and need a little help here. :frown:
Flipping the polarity of the mid signal will only cause the stereo image to 'flip' as expected - what am I missing here (this is something I've always considered impossible to do with M/S)?
:)
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ScuzzyEye
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15 Apr 2015

I'm wrong again. :frown: After trying the Quadelectra's, and not getting the results I thought I was getting with JP's I went back to make sure I was right, and I wasn't. I should just go back to bed, today's not my day. :P (Turns out the track I was playing with (not my handiwork, a 3rd party's stems) had a lot of out-of-phase content masquerading as stereo, so when I went into mid-only it was removing itself, it wasn't Anansi's doing.)

But I'm not giving up. I'm going to build a proper center/surround extractor. :)

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selig
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15 Apr 2015

ScuzzyEye wrote:I'm wrong again. :frown: After trying the Quadelectra's, and not getting the results I thought I was getting with JP's I went back to make sure I was right, and I wasn't. I should just go back to bed, today's not my day. :P (Turns out the track I was playing with (not my handiwork, a 3rd party's stems) had a lot of out-of-phase content masquerading as stereo, so when I went into mid-only it was removing itself, it wasn't Anansi's doing.)

But I'm not giving up. I'm going to build a proper center/surround extractor. :)
This is a puzzle I've tried to solve my entire adult life, to no avail - hopefully you'll see it from a fresh perspective and maybe find something others have missed!

I'm rooting for you here because this would be seriously useful, but at the moment it's a bit of a "holy grail" as far as I can tell. Cue Monty Python references… ;)
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lowpryo
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15 Apr 2015

ScuzzyEye wrote:I'm wrong again. :frown: After trying the Quadelectra's, and not getting the results I thought I was getting with JP's I went back to make sure I was right, and I wasn't. I should just go back to bed, today's not my day. :P (Turns out the track I was playing with (not my handiwork, a 3rd party's stems) had a lot of out-of-phase content masquerading as stereo, so when I went into mid-only it was removing itself, it wasn't Anansi's doing.)

But I'm not giving up. I'm going to build a proper center/surround extractor. :)
selig wrote:
This is a puzzle I've tried to solve my entire adult life, to no avail - hopefully you'll see it from a fresh perspective and maybe find something others have missed!

I'm rooting for you here because this would be seriously useful, but at the moment it's a bit of a "holy grail" as far as I can tell. Cue Monty Python references… ;)
wow that is such a brain wrinkler. it's one of those things that for some reason, it intuitively feels obtainable. but no, you just can't cancel out the signal that's shared in both the L and R channels while still keeping the L & R separate. you just can't. right? ugh

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ScuzzyEye
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15 Apr 2015

lowpryo wrote:wow that is such a brain wrinkler. it's one of those things that for some reason, it intuitively feels obtainable. but no, you just can't cancel out the signal that's shared in both the L and R channels while still keeping the L & R separate. you just can't. right? ugh
Yeah, I think this is going to take more than a Thor. :)

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BPGeez
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15 Apr 2015

@Selig.. so what technically happens in a plugin like Waves "Center"? To my ears (acknowledging they're probably nowhere as good as urs), it sounds as if this effectively isolates "center" and "side" components of an audio file.
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selig
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16 Apr 2015

dannyF wrote: LOL. I think we've gotten a bit lost here folks. It doesn't need to be this cerebral.
We are just speaking mostly about appearances, or what seems to be ( or what is ) generally percieved.
But, if you want to turn it into a university paper by all means.....
The important thing is "did any of this answer your original question"?
:)
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