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Re: mid-side confusion

Subject: Re: mid-side confusion
From: "Borja Marcos" borjamar
Date: Thu Oct 4, 2018 10:06 am ((PDT))
Nothing like writing a quickie while I waited for the bus.

Correct second option will follow tonight. Sorry

Fat fingers and tiny keys

> On 4 Oct 2018, at 18:57, Borja Marcos  [naturerecordis=
ts] <> wrote:
>
>
>> On 4 Oct 2018, at 16:10, Duncan Whitley  [nature=
recordists] <> wrote:
>>
>> 
>> Hi all
>>
>> Wondering if anyone with mid-side knowledge can help me out on this one.=
 I made some recordings last night and in the dark mistakenly plugged the S=
 into the left-channel of my recorder, and the M into the right. Usually th=
is wouldn=92t be problem for me to rectify as I tend to record in MS on dis=
crete mono channels and decode later - however, on this occasion I decoded =
to XY stereo inside the matrix box of the mic.
>>
>
> Fortunately MS encoding/decoding is a linear, reversible operation.
>
> L =3D (M + S)  / 2
>
> R =3D (M - S) / 2
>
> If you have exchanged M and S you have two options.
>
> 1) Reverse the phase of the R you decoded from the exchanged ; and S
>
> 2) You can undo the process by getting the resultant XY decoding back to =
MS. After doing that, exchange M and S and decode again
>
> Something like:
>
> M=97-\.                       /=97=97-\
>         Convert to XY             =97-- Convert to XY again
> S =97-/.                        \=97=97/
>
>
>>
>> Is it possible to recover the original M and S channels from the XY ster=
eo decoded recordings? My intuition says =93no=94, but wondered if anyone h=
ad any knowledge on this.
>>
>> It=92s easy enough to derive the M and S from the XY stereo when the cha=
nnels have been decoded to stereo correctly in the 1st place, but I=92m not=
 sure in this case if it still works.
>>
>> Thoughts?
>>
>> Duncan
>>
>
>








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sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.



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