Dolby Pro-Logic II

[Ste]

I was wondering if there is an advanced audio encoder that could optimize stereo signals for use with Dolby Pro-Logic II. I know a lot of Nintendo Gamecube games are optimized for Pro-Logic II, so I thought maybe it was possible to encode SVCDS/VCDS in such a manner. I think I recall seeing someone post about this in the past, but I could be mistaken. If there is no such program, then what would be the best audio encoder to encode for regular Dolby Pro-Logic I? I'm trying to get the best out of my new surround system.

[Oracle]

Give Besweat a go, excellent encoder, +freeware.

With be-sweat you can optimise for Pro-logic I or Pro-logic II

When using a 5.1 source (AC3 or DTS) you get excellent results with PLII.
Dont go below 224K when encoding the mp2 file as you will start losing the surround infos.(the seperation between the 5 chanels will not be as good)

This is from the guy that wrote the program.........

Dolby Pro Logic (1 or 2 or whatever) is a decoding algorithm.
unlike in mp3/ogg/aac/etc', when the "brain" is mostly placed in the encoder, and each encoder has his own way of encoding audio samples into the mp3/etc format, and all mp3/etc decoders basicly does the very same thing. in Dolby Pro Logic (DPL), the brain is placed inside the decoder.

DPL decoder is about interpolating more than two channels out of a 2ch track. (like in a 2.0 --> 5.1 process).
the DPL/DPL2 implements an adaptive 2x5 matrix :
[Lt Rt]*MTX=[L R C SL SR LFE]'.
the left channel output, L, would be equal in this case to : Lt*MTX(1,1)+Rt*MTX(2,1).
(and so on for R,C,SL,..)

this matrix is adaptive, and that means that the coefficients changes from time to time, according to the input data.
the dpl algorithm doesn't "care" if the source is a dolby surround material or a plain stereo track.

let's think of this very primitive process with a statix dpl-like matrix.
given a 5.1 source L,R,C,SL,SR,LFE, we would create a 2ch downmixed track with channels Lt&Rt:
Lt=L+C+(SL+SR)
Rt=R+C-(SL+SR)
the (static) decoding process would look like :
Lr=Lt;
Rr=Rt;
Cr=(Lr+Lt)/2; [=L+C+(SL+SR)+R+C-(SL+SR)=L+R+C]
Sr=(Lr-Lt)/2; [=L+C+(SL+SR)-R-C+(SL+SR)=(L-R)/2+(SL+SR)]

creating Lt&Rt is principly what Dolby Surround Downmix is about, and creating Lr,Rr,Cr,Sr is principly what Dolby Pro Logic is about.


as mentioned before, the (adaptive) DPL algorithm can reproduce 4/5/6 channels out of ANY 2ch source, but in case the source was encoded as Dolby Surround, the decoded track would be very close to the original.

as you can now understand, Dolby Surround "encoding" is a very simple process of simply weighted summings of 5.0/5.1 channels into two channels.

as for DPL2 & Dolby Surround 2,
in Dolby Surround (1), we would sum the surround channels into one mono channel, and treat them just like in the example as "(SL+SR)", while in Dolby Surround 2 we would "help" DPL2 seperating them back by giving different weights to each channel. for instance :
Lt=L+C+SL+0.5*Sr
Rt=R+C-SR-0.5*Sl

that's it.

[Ste]

Most excellent. Thanks man.