• SONAR
  • Channel Tools - Mid/Side Encoders
2015/06/14 18:20:10
olemon
I was watching a tutorial that used a Pro-Q2 and a Brainworx bx_controller V2, which the author called a Mid-Side Encoder, to analyze a reference mix.
 
Is Channel Tools a Mid-Side Encoder?  Is any plugin that has M/S processing a Mid-Side Encoder?  For example, I have a
T-RackS3 Classic EQ that has M/S.
 
Thanks.
 
 
2015/06/15 13:25:50
olemon
Well, maybe someone will enlighten me.
 
In the meantime, I've found this free plugin:
 
http://www.voxengo.com/product/msed/
2015/06/15 13:52:30
Wookiee
Channel Tools is indeed a Mid Side processor.  But I think it does a bit of both, is so much as it encodes and decodes but I could be wrong.  Page 1597 of the users guide explains channel tools.
 
The Voxengo is a very useful tool.
2015/06/15 14:03:34
wst3
olemon
I was watching a tutorial that used a Pro-Q2 and a Brainworx bx_controller V2, which the author called a Mid-Side Encoder, to analyze a reference mix.

 
I have a sneaking suspicion there is a question buried above, but I'm not sure what it is. I can however answer the next bit.
olemonIs Channel Tools a Mid-Side Encoder?  Is any plugin that has M/S processing a Mid-Side Encoder?  For example, I have a T-RackS3 Classic EQ that has M/S.

 
Channel Tools is a Mid-Side encoder. And any plugin that provides Mid-Side or M/S controls is encoding the Left and Right channels as Mid and Side. I don't own any T-Racks stuff, but if it say it has M/S then it probably does.
 
In case Mid-Side itself has you perplexed...
 
"Normal" stereo recordings have two channels, left and right. Most of the time this is sufficient, but over the years (and we're talking the beginning of Stereo FM broadcasting, so that's a lot of years) there have been applications where left and right channels were not sufficient to preserve the stereo image.
 
Some clever engineers figured out that they could use a matrix to encode and decode the channels so that the mono signal was preserved, and that timing errors between the two channels were minimized. (The timing problem was a real challenge for early stereo broadcasters, and especially those awful broadcast "cart" machines, among others. Oh yeah, that would include the infamous long playing record!)
 
Enough history!
 
The MID channel is the sum of the left and right channels, or all the content.
 
The SIDE channel is the difference between the left and right channels, and for the most part represents the spatial localization information. It is trivial to decode (or encode for that matter) to switch between the two formats.

To convert from L+R to M/S:
route your left and right channels to a single buss - call that MID
route your left channel, and a polarity inverted copy of the right channel to a second buss - call that SIDE
 
To reverse the process:
route MID and SIDE to a single buss, and call that LEFT
route MID and a polarity inverted copy of SIDE to a second buss and call that RIGHT
 
It's a good idea to use channels and busses to get a feel for the process and how it works, but you can also use the included Channel Tools for the same result.

This matrix approach has many applications - Mid/Side and Blumlein microphone configurations are one example, and the old Sonic Hologram (or whatever Carver and Polk called their respective products) is another.
 
Where we use it most, I'd guess, is for signal processing. Compressing the MID while leaving the SIDE alone creates a very different effect than compressing left and right. The same applies to equalization, reverb, even delays and modulated delays. The beauty of MID/SIDE encoders is that once you've encoded you can use the rest of your processors in their old-fashioned configurations - as long as you remember what you did<G>!

Does that help?
 
2015/06/15 14:06:43
olemon
Wookiee
Channel Tools is indeed a Mid Side processor.  But I think it does a bit of both, is so much as it encodes and decodes but I could be wrong.
 
The Voxengo is a very useful tool.



Thanks, Wookiee.
 
In the video, the encoder was ahead of the equalizer.  The technique was to split the stereo track into M/S, then mute one and use the EQ to analyze what was present in the other.
 
I didn't try it yet, but I was fairly sure I could do that with Channel Tools, or even two EQ's.  The EQ with M/S activated would serve as the encoder in the chain.
2015/06/15 14:15:28
olemon
wst3
Does that help?



Yes it does, Bill!
 
I understand M/S, or least what it means on a plugin and I have used the technique a few times.  I just hadn't encountered the encoder/decoder jargon before as it related to M/S.  Thank you for the detailed explanation.  I read about some of what you described, but it wasn't presented that clearly.
2015/06/15 14:22:41
Keni
Interesting...

My use and understanding of mid/side was to use two mics... One which was a figure 8 pattern turned 90degrees off axis to the sound with the other mic (cardioid) directly facing the sound source... Then blending the two...

Is that not part of it?

Keni
2015/06/15 14:31:02
Beepster
Keni
Interesting...

My use and understanding of mid/side was to use two mics... One which was a figure 8 pattern turned 90degrees off axis to the sound with the other mic (cardioid) directly facing the sound source... Then blending the two...

Is that not part of it?

Keni



I think that would be recording Mid-Side from the start. Doing the stuff discussed above would be for turning stereo signals into M/S and vice versa.
 
I'm still very much trying to wrap my head around all this type of stuff (and really should sit down with some tuts and Channel Tools for a while to REALLY get a handle on it all) so this is a cool thread. Methinks I may bookmark it.
2015/06/15 14:33:28
tlw
The two mic system is used to make a recording of an audio source and is one usage of mid/side techniques.

However any stereo audio can be split into its mid and side content then processed as separate mid and side content and finally reassembled into stereo again. One example might be "centreing" the bass frequencies in a stereo track. Convert to mid/side via channel tools or a similar processor then high pass the side to cut the low frequencies while boosting them in the mid channel if necessary.

Re-convert to stereo and there you are, the bass content is now centred.
2015/06/15 14:36:22
scook
Here is a video describing M/S using Pro-Q and a bit of history about M/S recording https://youtu.be/NilfCElGJ2c
 
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