

Stereo to Mono Using the Side Channel - theandrewbailey
http://theandrewbailey.com/article/160/Stereo-to-Mono-Using-The-Side-Channel

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ireflect
The observation that an average sounds flat is a good one. The relative phase
of sounds in each channel could do weird things and cancel each other out when
averaged. However, most modern music is mastered in such a way that the stereo
channels are highly correlated, so averaging is usually the best way to get a
mono version.

That said, the solution in the article isn't really doing much...

given two tracks: L and R

    
    
      side channel = (L - R)/4dB
      mid channel = (L + R)/4dB
      final = (L - R)/4dB + (L + R)/4dB = 2L/4dB ≈ 1.26L
    

Since dB is a logarithmic scale, 4dB corresponds to around 1.58 times power.
2dB corresponds to around 1.26 times power. Audacity may be attenuating it
further in each of the "Mix and Render" steps depending on how it's summing is
implemented.

In the end, it looks like you'll up with just the left channel. And as a
practical solution to the original problem, this isn't that bad of a result!

Edit: formatting

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FlyingAvatar
Isn't this exactly the same as what you were doing before, averaging the
channels and then amplifying?

