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Undo a M/S matrix recording

Discussion in 'Recording' started by huntson, Apr 16, 2011.

  1. huntson

    huntson Active Member

    Recently I bought a new device, the H4n and I turned on the M/S Matrix feature. I did not know it applied to the XLR inputs so I M/S Matrixed a source that was already perfect stereo. I know there is a way through inversion and all sorts of other stuff to create an M/S mix after the fact. Is there any wya to undo an M/S mix to get the original stuff back? Just to be clear I fed my VP-88 into a unit that thought it was receiving an M/S microphone input and properly (improperly in this case) decoded the M/S information. Since the VP-88 mic already does this this second step was not helpful at all. How do I reverse this?
     
  2. TheJackAttack

    TheJackAttack Distinguished Member

    Yes. MSED Audio mid-side encoder-decoder plugin (AU, VST) - MSED - Voxengo

    It can reverse the encoding.
     
  3. huntson

    huntson Active Member

    Free?

    Since it is free...is it that good?
     
  4. TheJackAttack

    TheJackAttack Distinguished Member

    Yes. MS encoding/decoding is not exactly rocket science. I have several mastering plugs that can extract just a center channel as well. In your case however you just need a straight decode.
     
  5. huntson

    huntson Active Member

    SO exactly what option do I have to hit on this thing. I know it is probably obvious but I do request your patience.
     
  6. TheJackAttack

    TheJackAttack Distinguished Member

    Click on where it says <mode>. It will give you a drop down that asks whether you want to <encode> or <decode>
     
  7. RemyRAD

    RemyRAD Well-Known Member

    Utilizing MS matrixing can be very effective in processing all kinds of stereo information. You can either create the MS matrix or decode the MS matrix. Many pieces of software such as Adobe Audition & many others include a " channel mixing" feature for stereo tracks. These usually include some kinds of presets to go to or from MS. This technique was not only used for microphone recording but also to encode FM stereo & special analog NAB, continuous loop cartridge recorders. This technique for analog recording prevented certain head azimuth alignment problems On playback. There are certain situations when you're given a stereo feed that isn't correct. Sometimes mistakes are made and you might find a soloist in your left or right channel instead of stereo center. Utilizing MS encoding or decoding can certainly straighten out a crooked and/or lopsided stereo mix.

    Back slashed & white washed
    Mx. Remy Ann David
     
  8. huntson

    huntson Active Member

    OK. So I selected decode and now the left channel is much higher than the right - I am quite sure that all of the action at the venue I was at was just on the left. Any ideas?
     
  9. BobRogers

    BobRogers Well-Known Member

    I would not use a plugin. The sum of the left and right should give you the "center" channel. The difference (sum of the right plus the inverted left) should give you the "side" (or its inverse). You will have to mess with the phase (polarity) of the side and perhaps its volume.
     
  10. TheJackAttack

    TheJackAttack Distinguished Member

    Of course now that it is un-encoded you could just flip the polarity.
     
  11. huntson

    huntson Active Member

    Care to explain
     
  12. TheJackAttack

    TheJackAttack Distinguished Member

    What part?
     
  13. huntson

    huntson Active Member

    Of course now that it is un-encoded you could just flip the polarity. ​
     
  14. huntson

    huntson Active Member

    I have gotten it pretty close with the plugin but the volume is really off
     
  15. TheJackAttack

    TheJackAttack Distinguished Member

    Well within either Stuido One or Logic or whatever DAW is a button that says phase or polarity or something like that. If you hit that the left right image will be reversed. That was your main concern. Within in many editors you can split a stereo track into it's left right components. This makes it much easier to deal with too. Then there are numerous stereo plugins that can do similar things.

    Now, if you think the image was reversed then you had the VP88 pointed 180 degrees reversed. Generally the "side" microphone points to the left as the audience looks at the stage. This is also known as stage right.

    One of the reasons many of us manually decode MS within a DAW is to control all the variables ourselves rather than rely on the mic or recorder matrix.
     
  16. huntson

    huntson Active Member

    So I have been using the suggested filter and i think I got it. The only issue is that the "side" - right channel is much lower than the left. If I boost it then the correlation meter goes to hell. Any ideas?
     
  17. TheJackAttack

    TheJackAttack Distinguished Member

    Use your ears and not a meter.
     
  18. huntson

    huntson Active Member

    I have been told this before and I usually do but I don't want to shoot myself in the foot and find out everything is wrong later becuase of it
     
  19. TheJackAttack

    TheJackAttack Distinguished Member

    Ok. Here's the deal. When you are using a mid side microphone or two near coincident microphones as mid side, you aren't going to get perfectly equal levels. How could you. In one ear you have mid and in the other you have side. One preamp knob only controls the center or mid. One preamp knob covers the side. Basically three channels but you can't adjust left to right during the recording. That has to be done after the fact just like you are doing. If the sound stage was not centered on the microphone then either left or right will HAVE to be hotter than the other side. Logic.
     
  20. huntson

    huntson Active Member

    I understand this but there is a significant difference (I believe i mentioned this above) than what was at the location. There were variances but we are talking over 20db
     

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