In delivering a 2.0 mix that is not dolby pro logic a network wants the channel assignment to reflect Lt,Rt or LoRo. Since we are not doing any dolby matrixing on the mix the channels are really just stereo left and right. I will therefore slate them as Lo,Ro. It just seems to me that the Lo,Ro is for a downmix or fold down which we haven't really done and seems inaccurate to label them Lo,Ro. Is there any difference in Lo,Ro and stereo left,right?
Here is what I found so far:
Left total/Right total (Lt/Rt)
Lt/Rt is a downmix suitable for decoding with a Dolby Pro Logic upmixer to obtain 5.1 channels again. Lt/Rt is also suitable for stereophonic sound playback on a hi-fi or on headphones as it is.
Lt = L + -3dB*C + -3dB*(-Ls -Rs)
Rt = R + -3dB*C + -3dB*(Ls + Rs)
(where Ls and Rs are phase shifted 90°)
[edit] Left only/Right only (Lo/Ro)
Lo/Ro is a downmix suitable when mono compatibility is required. Lo/Ro destroys front/rear channel separation information and thus a Dolby Pro Logic upmixer will not be able to properly extract 5.1 channels again.
Lo = L + -3dB*C + att*Ls
Ro = R + -3dB*C + att*Rs
(where att = -3dB, -6dB, -9dB or 0)
John Moore
Barking Trout Productions
Studio City, CA
bigfish@pacbell.net
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