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Extracting side information of a stereo file.
Old 9th November 2018
  #1
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Extracting side information of a stereo file.

As we know, the Mid and Side information of a stereo file is achieved by sum and difference but the side information will always cancel out when summed to mono due to the algorithm of the Mid-Side process.

These means that if an instrument is panned hard Left or Right, within a stereo file it will still be cancelled out if it is separated using M/S.

My question is can the stereo part of a stereo file be separated into its true Left/Right state which will be mono compatible?
For instance, if I have a Congo panned hard left and a Tom panned hard right with a kick in the centre, I would have a Side signal where the Congo and Tom would collapse to mono and still be heard within the mix. M/S separation would phase those two instruments.

Is this why why have true stereo files as opposed to dual mono and stereo?

Thanks.
Old 9th November 2018
  #2
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Old 9th November 2018
  #3
Logically impossible.

And we don’t have “true stereo, stereo and dual mono”.

We have stereo and mono. “Dual mono” is just the same thing in both sides of a stereo file - ie mono. And there’s only one type of stereo. The only time I’ve heard “true stereo” used is regarding synth patches, where a stereo patch might actually be a “big mono” patch - ie a mono sound with a big chorus or verb on it.
Old 9th November 2018
  #4
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Quote:
Originally Posted by MUSICMUSIC View Post
.

Is this why why have true stereo files as opposed to dual mono and stereo?

Thanks.
The term dual mono is usually used in situations where two mono processors/engines are used to each process one half of a stereo signal.
This method requiring to set the parameters on each processor as similar possible to the other, in order to maintain stereo coherence.

True stereo is/was used to make a distinction between a signal that truly contains stereo information and a mono source made to sound artificially "wider" by adding stereo chorus and other phase tricks to it (also called fake/pseudo stereo).

When all these terms get used interchangeably and in the inappropriate situations it becomes a source of confusion and debate.
Old 9th November 2018
  #5
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Quote:
Originally Posted by psycho_monkey View Post
Logically impossible.

The only time I’ve heard “true stereo” used is regarding synth patches, where a stereo patch might actually be a “big mono” patch - ie a mono sound with a big chorus or verb on it.
Yes I guess what I’m asking for has to be two separate files. One for the MID and one for the STEREO info.
I guess if you record an acoustic guitarist using the Mid/Side technique their will be slight frequency and amplitude differences in each channel (the side info) which will not cancel each other out when collapsed to mono. Using Mid/Side decoding on a stereo signal with Mid information is different.
Old 10th November 2018
  #6
Quote:
Originally Posted by MUSICMUSIC View Post
Yes I guess what I’m asking for has to be two separate files. One for the MID and one for the STEREO info.
I guess if you record an acoustic guitarist using the Mid/Side technique their will be slight frequency and amplitude differences in each channel (the side info) which will not cancel each other out when collapsed to mono. Using Mid/Side decoding on a stereo signal with Mid information is different.
I think a fundamental lack of understanding of waveform theory (I think that’s what you’d call it) is pushing this.

Mid + stereo doesn’t make sense. The stereo file would include the mid information. That’s why it’s mid side. Sum and difference. L+R and L-R. The single channel side signal contains the information on the left in phase and the information on the right out of phase - that’s how you can reconstruct the left AND the right wide information out of a single mono file.

You don’t need 2 “stereo” files.

This is going a bit like your pan law thread!
Old 10th November 2018
  #7
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There are some very neat engineering tricks interwoven in the history of audio that are not easy to learn and understand. Phantom powering. The use of the same cabling (and sometimes connectors) to send either unbalanced stereo signals or balanced mono signals WHICH ARE NOT COMPATIBLE. The elements of a two channel “stereo” signal which can place an instrument or vocal anyplace in the stereo spread, or outside of it. And that’s just the surface of a fairly deep study.
Old 10th November 2018
  #8
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Quote:
Originally Posted by psycho_monkey View Post

This is going a bit like your pan law thread!



Plugins give you a choice to separate Mid and side now, and I’m just commenting on how a signal that is hard panned, when separated by Mid/Side will be lost in mono, which makes it useless when mixing, hence my question.

Put Mid/Side on a panned mono signal and it will appear in both channels.

I do understand waveforms but sorry if I do your head in

Using samples which are quite rich with instruments can cause a great mess when you don’t have control over them.

I get it so I won’t go on. I won’t do that to you.
Old 10th November 2018
  #9
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Quote:
Originally Posted by MUSICMUSIC View Post
I’m just commenting on how a signal that is hard panned, when separated by Mid/Side will be lost in mono, which makes it useless when mixing, hence my question.

Put Mid/Side on a panned mono signal and it will appear in both channels.
Psycho Monkey isn’t just randomly picking on you. Your statements are factually incorrect. If no one responds to point that out, you may confuse and confound people who are reading this forum.
Old 10th November 2018
  #10
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Quote:
Originally Posted by Bushman View Post
Psycho Monkey isn’t just randomly picking on you. Your statements are factually incorrect. If no one responds to point that out, you may confuse and confound people who are reading this forum.
I know he’s not and I appreciate his input. Where am I factually incorrect? In Ableton you have a utility which can give you just the side information of a file. It always cancels out when mono’d because it is a differential algorithm. That means if you have a hard panned signal it will still cancel out due to the Mid/Side agorithm.

A normal stereo signal with a hard panned instrument will just centre it when it’s collapsed to mono. A very different process.

It’s turning into the Mid/Side post Psycho!

I will post some sound bites showing what M/S does to a panned signal within the stereo field........
Old 10th November 2018
  #11
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"In this specific context, the terms "Mid" and "Side" are miss-leading, as EQing the "Mid" channel (i.e. the stereo sum) will also affect hard panned sounds, i.e. not just the stereo center as most people intuitively assume."

Quoted here by Fabien:

MID / Side "real" center channel.
Old 10th November 2018
  #12
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I don’t have Abelton, so I can’t replicate your examples. But...
Mid-Side is not an algorithm. It is a recording and mixing technique that has a reality outside software. Your software should be modeling what Mid-Side hardware does. You seem to think that people use Mid-Side to “separate” the two signals to use as separate elements in a mix. Then you say that if you separate the two signals, Side will “collapse” in mono. Of course it will. The Side signal is the “difference” signal, composed of everything that is not present at all in the mono signal. So of course it doesn’t even exist in mono. There isn’t anything wrong or inferior in that fact. You are not understanding Mid-Side or using it’s possibilities effectively BECAUSE you do not understand how it works and how it should be used. Changing the relative levels of the two signals, or using compression or EQ on one or both can do some interesting things to a stereo instrument, buss or mix.
Old 10th November 2018
  #13
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Quote:
Originally Posted by MUSICMUSIC View Post
As we know, the Mid and Side information of a stereo file is achieved by sum and difference but the side information will always cancel out when summed to mono due to the algorithm of the Mid-Side process.
Come again?
Old 10th November 2018
  #14
Quote:
Originally Posted by MUSICMUSIC View Post


Plugins give you a choice to separate Mid and side now, and I’m just commenting on how a signal that is hard panned, when separated by Mid/Side will be lost in mono, which makes it useless when mixing, hence my question.

Put Mid/Side on a panned mono signal and it will appear in both channels.

I do understand waveforms but sorry if I do your head in

Using samples which are quite rich with instruments can cause a great mess when you don’t have control over them.

I get it so I won’t go on. I won’t do that to you.
The side signal cancels out, because it’s the same thing in opposite polarity.

But it’s easily verified that a hard panned element in a stereo mix doesn’t disappear in mono isn’t it. It’ll still be present in the mono component, albeit at a quieter level.

Mid/side is a way to record, and a way to process. But the final delivery is still a 2 channel stereo file which behaves when summed to mono in the usual way.

Try it for yourself - get the bx_digital freebie mid/side plugin. Hard pan something, then solo the mid component of the mix buss. You’ll still hear the hard panned element!

The “mid” component is not just things panned to the middle. Even something panned hard left still appears in the mid signal.
Old 12th November 2018
  #15
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Quote:
Originally Posted by psycho_monkey View Post
Mid/side is a way to record, and a way to process. But the final delivery is still a 2 channel stereo file which behaves when summed to mono in the usual way.

Try it for yourself - get the bx_digital freebie mid/side plugin. Hard pan something, then solo the mid component of the mix buss. You’ll still hear the hard panned element!

The “mid” component is not just things panned to the middle. Even something panned hard left still appears in the mid signal.
Brainworx is the reason I posted. A hard panned mono signal falls centre when passed through brainworx mid/Side, which appears in both channels. So if I solo mid or side the hard panned instrument still can be heard. I thought stereo information would disappear when soloing mono. I guess it’s the nature of the beast.

Mine was discontinued for my soundcard after version 2 btw.
Old 12th November 2018
  #16
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Quote:
Originally Posted by Jeff Hayat View Post
Come again?
Q. How does Mid-Sides encoding/decoding actually work? |

The side information is actually created by phasing the left and right of a stereo signal in my case. This cancels to zero when using a printed stereo file but in the real world, with spaced mics, you will have differences (amplitude, timbre, room) which won’t cancel out eacother.
Old 12th November 2018
  #17
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Quote:
Originally Posted by MUSICMUSIC View Post
Q. How does Mid-Sides encoding/decoding actually work? |

The side information is actually created by phasing the left and right of a stereo signal in my case. This cancels to zero when using a printed stereo file but in the real world, with spaced mics, you will have differences (amplitude, timbre, room) which won’t cancel out eacother.
In sentence one you seem to be confusing “phasing” with polarity reversal. Sentence two is an incoherent mishmash that seems to be saying that “a printed stereo file” behaves differently in MS processing than do “real world” tracks. Real world stereo tracks become printed stereo files. Both will behave the same in processing because they are the same. It doesn’t seem like you are trying to learn anything, and it also doesn’t seem that you have anything to teach. I wish you would stop posting (and you probably feel the same about me).
Old 12th November 2018
  #18
Quote:
Originally Posted by MUSICMUSIC View Post
Brainworx is the reason I posted. A hard panned mono signal falls centre when passed through brainworx mid/Side, which appears in both channels. So if I solo mid or side the hard panned instrument still can be heard. I thought stereo information would disappear when soloing mono. I guess it’s the nature of the beast.

Mine was discontinued for my soundcard after version 2 btw.
There’s always a mono component to in phase but panned information.

You’ll find your hard panned source will also appear in the sides signal.

The only thing which won’t appear in both is a signal hard panned, where an equal and opposite polarity signal appears in the other side - this would then sum to zero when collapsed to mono.

The “mid” signal generated by a M/S matrix is just L+R, the same as mono-ing signals any other time.
Old 12th November 2018
  #19
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Quote:
Originally Posted by psycho_monkey View Post
There’s always a mono component to in phase but panned information.

You’ll find your hard panned source will also appear in the sides signal.

The only thing which won’t appear in both is a signal hard panned, where an equal and opposite polarity signal appears in the other side - this would then sum to zero when collapsed to mono.

The “mid” signal generated by a M/S matrix is just L+R, the same as mono-ing signals any other time.
Yes I’m aware of that Psycho. Using M/S for mastering, I guess, would never be used for LCR mixes.That would mess everything up.

Thanks for input.
Old 12th November 2018
  #20
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Quote:
Originally Posted by Bushman View Post
In sentence one you seem to be confusing “phasing” with polarity reversal. Sentence two is an incoherent mishmash that seems to be saying that “a printed stereo file” behaves differently in MS processing than do “real world” tracks. Real world stereo tracks become printed stereo files. Both will behave the same in processing because they are the same. It doesn’t seem like you are trying to learn anything, and it also doesn’t seem that you have anything to teach. I wish you would stop posting (and you probably feel the same about me).
You seem offended, and I don’t know why? You can post as much as you like, but it seems you are trying to make me look stupid and I’m not here to teach.

Your are technically correct when saying polarity and phase are different but a 180 degree phase at zero seconds is the same as a polarity reverse.

Maybe it’s bad for a reputable DAW to use phaze when it means polarity, but maybe it’s the process they use for attaining a polarity shift:

1001 Uses of Ableton Live's Utility Device - Part 1

Maybe you can’t undestand my point, which says that if an audio signal appears in one channel it shouldn’t cancel out when the mix is mono’d. M/S processing won’t do that, as Psycho started, but stereo wideners do.

If you have an issue with people asking questions I don’t see the point of this forum. Isn’t that what it’s for?
Old 12th November 2018
  #21
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Quote:
Originally Posted by MUSICMUSIC View Post
Maybe you can’t undestand my point, which says that if an audio signal appears in one channel it shouldn’t cancel out when the mix is mono’d. M/S processing won’t do that, as Psycho started, but stereo wideners do.
I apologize if this thread has become about my inability to understand your point.
So, your point was that you are trying to understand the difference between stereo wideners and M/S processing? That isn’t in your first post at all.
If you just stated your point now, how could anyone have understood your point before your last post?
In an intellectual sense, yes, your posts are offensive. They don’t make sense. They don’t ask a clear question that can be answered, and they don’t offer useful information.
I will leave you to whatever you think this is.
psycho_monkey, as a moderator, may be required to hang with you. God bless him for his patience.
Old 12th November 2018
  #22
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Quote:
Originally Posted by Bushman View Post
I apologize if this thread has become about my inability to understand your point.
So, your point was that you are trying to understand the difference between stereo wideners and M/S processing? That isn’t in your first post at all.
If you just stated your point now, how could anyone have understood your point before your last post?
In an intellectual sense, yes, your posts are offensive. They don’t make sense. They don’t ask a clear question that can be answered, and they don’t offer useful information.
I will leave you to whatever you think this is.
psycho_monkey, as a moderator, may be required to hang with you. God bless him for his patience.
Hard for you to understand you mean!!

You can't be a very good teacher if you can't understand a simple question and the processes applied. That's so many people fail at school, due to bad teaching and good students are ones that ask many questions.

Waves has a plugin which separates L/R/C (which i know now and which you didn't mention).M/S is a different process and Ableton's Utility also has different processes.

Maybe you need to learn about digital more to understand people's questions.
If you don't understand what I'm saying then please don't comment.

There's many things digital can do that analogue can't, and many things are done in different ways, so it's hard to explain to somebody that isn't aware of this.
Old 12th November 2018
  #23
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Old 13th November 2018
  #24
Quote:
Originally Posted by MUSICMUSIC View Post
Yes I’m aware of that Psycho. Using M/S for mastering, I guess, would never be used for LCR mixes.That would mess everything up.

Thanks for input.
Why not? It’s still a stereo mix at the end of the day - and why does the method matter? Unless you’re literally creating a stereo field by panning mono sources hard left and right, there’s always going to be a mix of sources across the stereo field.

Quote:
Originally Posted by MUSICMUSIC View Post
Hard for you to understand you mean!!

You can't be a very good teacher if you can't understand a simple question and the processes applied. That's so many people fail at school, due to bad teaching and good students are ones that ask many questions.

Waves has a plugin which separates L/R/C (which i know now and which you didn't mention).M/S is a different process and Ableton's Utility also has different processes.

Maybe you need to learn about digital more to understand people's questions.
If you don't understand what I'm saying then please don't comment.

There's many things digital can do that analogue can't, and many things are done in different ways, so it's hard to explain to somebody that isn't aware of this.
I’d respectfully suggest you have a fair bit to learn here, and it may not be best to insult others’ attempts to help! A lot of your questioning is a bit confused - that’s why there’s not a lot of clear answers. You seem to have quite a unique way of analysing things, and I think it’s leading you down some confusing and innacurste paths.

I’m not sure which waves plugin you’re referring to, but you can’t really split a signal into L/C/R components. As I’ve said, something hard panned still has a mid component, the only way to remove this is to put it 180degrees out of phase left and right - and that gives you pure “side” signal.
Old 13th November 2018
  #25
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Quote:
Originally Posted by psycho_monkey View Post



I’m not sure which waves plugin you’re referring to, but you can’t really split a signal into L/C/R components. As I’ve said, something hard panned still has a mid component, the only way to remove this is to put it 180degrees out of phase left and right - and that gives you pure “side” signal.
Center - Stereo Enhancer Plugin for Mastering | Waves

This plugin has a different process to M/S and my question is based on audio files and plugins, not Mic techniques.

A stereo file has two channels but there are three positions L/C/R. As you've said a panned signal still has a Mid component. A M/S process deals with the side information differently to Ableton's utility which seems to separate the sides differently. Then you have Waves Centre which is based on a phantom centre and the separation of L/R which do not cancel out when the mix is mono'd.

That's why I've asked on the different processes of how to extract instruments. We know how to cancel out the information which is dead centre but side information is confusing for me because each process which I've explained above, does different things to the signal.

Thanks for your help
Old 13th November 2018
  #26
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Quote:
Originally Posted by MUSICMUSIC View Post
A stereo file has two channels but there are three positions L/C/R. As you've said a panned signal still has a Mid component. A M/S process deals with the side information differently to Ableton's utility which seems to separate the sides differently. Then you have Waves Centre which is based on a phantom centre and the separation of L/R which do not cancel out when the mix is mono'd.
I think you would do well to be a bit careful with how you use nomenclature. If you're not careful people (including you) will get confused and talk past each other.

A stereo file has two channels and really only ever has "two positions". Something exists either in the one channel or the other, or both. There is no "C" in a stereo audio file. You should be careful when talking about this because some engineers actually deal with three-channel LCR files where there is an actual dedicated center channel available. So, there's room for confusion here if you're not careful.

Sorry for being picky.
Old 13th November 2018
  #27
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Quote:
Originally Posted by mattiasnyc View Post
I think you would do well to be a bit careful with how you use nomenclature. If you're not careful people (including you) will get confused and talk past each other.

A stereo file has two channels and really only ever has "two positions". Something exists either in the one channel or the other, or both. There is no "C" in a stereo audio file. You should be careful when talking about this because some engineers actually deal with three-channel LCR files where there is an actual dedicated center channel available. So, there's room for confusion here if you're not careful.

Sorry for being picky.
Yes of course. Some terms and used very loosely. We do hear in L/C/R and also with depth, which is another conversation.
Old 14th November 2018
  #28
Quote:
Originally Posted by MUSICMUSIC View Post
Center - Stereo Enhancer Plugin for Mastering | Waves

This plugin has a different process to M/S and my question is based on audio files and plugins, not Mic techniques.

A stereo file has two channels but there are three positions L/C/R. As you've said a panned signal still has a Mid component. A M/S process deals with the side information differently to Ableton's utility which seems to separate the sides differently. Then you have Waves Centre which is based on a phantom centre and the separation of L/R which do not cancel out when the mix is mono'd.

That's why I've asked on the different processes of how to extract instruments. We know how to cancel out the information which is dead centre but side information is confusing for me because each process which I've explained above, does different things to the signal.

Thanks for your help
Centre is an M/S based plugin. The “phantom centre” is just the mid component of the stereo file, played back between 2 speakers (as opposed to the C part of a 5.1 file, which is a dedicated mono audio file played back from a dedicated speaker).

There’s other controls, but in essence it splits the signal into mid and side, and you’ve got controls and eq applied to each.

There’s never “3 positions”. It’s always 2 mono channels providing the L/R feeds. Something in the centre will appear in both - something hard left will only appear in the left channel. But both will have mono components and will appear in the Mid. There is no way of splitting a L/R stereo file into LCR components, where hard panned things do not appear in the C channel. That’s not how audio works, and you’re confusing yourself by thinking it does. You’re still not fundamentally understanding how M/S works - it’s nothing to do with mics (the miking technique is based on the mathematical process and the fact that a fig8 mic captures in phase from one side, out of phase from the other - you could approximate it with 3 mics and a polarity flip).

Mid is L+R of a stereo signal (ie mono sum); Side is L - R (or polarity reverse R and sum to mono). Anything that’s not 100% mono panned in the mix appears in the side signal, in phase to the original if on the left, and out of phase if on the right. Then to recombine them, you just need to pan the Side signal left, copy and polarity flip it and pan it right. Turn them down 3dB (I think? Don’t quote me there...might be 6dB!) and you have your original signal, which will null 100%. Try it yourself.

I’m sorry to keep lecturing, but your arguments aren’t making sense - if you truly understood the physics of stereo and summing audio (it’s nothing to do with digital btw, it’s physics) you’d understand why this idea of LCR separation doesn’t make sense outside of multichannel audio.
Old 14th November 2018
  #29
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Quote:
Originally Posted by psycho_monkey View Post
Centre is an M/S based plugin. The “phantom centre” is just the mid component of the stereo file, played back between 2 speakers (as opposed to the C part of a 5.1 file, which is a dedicated mono audio file played back from a dedicated speaker).

There’s other controls, but in essence it splits the signal into mid and side, and you’ve got controls and eq applied to each.

There’s never “3 positions”. It’s always 2 mono channels providing the L/R feeds. Something in the centre will appear in both - something hard left will only appear in the left channel. But both will have mono components and will appear in the Mid. There is no way of splitting a L/R stereo file into LCR components, where hard panned things do not appear in the C channel. That’s not how audio works, and you’re confusing yourself by thinking it does. You’re still not fundamentally understanding how M/S works - it’s nothing to do with mics (the miking technique is based on the mathematical process and the fact that a fig8 mic captures in phase from one side, out of phase from the other - you could approximate it with 3 mics and a polarity flip).

Mid is L+R of a stereo signal (ie mono sum); Side is L - R (or polarity reverse R and sum to mono). Anything that’s not 100% mono panned in the mix appears in the side signal, in phase to the original if on the left, and out of phase if on the right. Then to recombine them, you just need to pan the Side signal left, copy and polarity flip it and pan it right. Turn them down 3dB (I think? Don’t quote me there...might be 6dB!) and you have your original signal, which will null 100%. Try it yourself.

I’m sorry to keep lecturing, but your arguments aren’t making sense - if you truly understood the physics of stereo and summing audio (it’s nothing to do with digital btw, it’s physics) you’d understand why this idea of LCR separation doesn’t make sense outside of multichannel audio.
Great explanation thanks. I’m confusing myself by not just concentrating on what a stereo file is rather than the audio itself.

Thanks for your patience and tact. You’d make a great teacher
Old 14th November 2018
  #30
Quote:
Originally Posted by MUSICMUSIC View Post
Great explanation thanks. I’m confusing myself by not just concentrating on what a stereo file is rather than the audio itself.

Thanks for your patience and tact. You’d make a great teacher
Thank you! (as it happens, I do the occasional teaching gig, so that's good reassurance )

And also - attempting to explain things has solidified my own knowledge/thinking, so that's helpful to me too!
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