Dolby surround downmix

[MyC sPiTTa]

Hi,

I use GKnot to encode but I use OggMachine to make OGG files for the audio track. OggMachine lets you choose to output surround (Dolby Prologic) or surround2, which is fine coz I have a prologic stereo. But should I check the dolby downmix box in DVD2AVI when I make the project or leave it with the "raw" 2 channels and let OggMachine figure it out?

Cheers.

[hakko504]

Unless you have a 4.0 or 5.1 stream, checking the 'Dolby Downmix' won't do anything. But the way you describe it you should check it when you have a 4.0 or 5.1 stream.

[MyC sPiTTa]

I would say usually they are 5.1 surround seeing as they come from the DVD vobs. Saving the project in DVD2AVI leaves me with a file which can be frameserved in Gordian Knot and a large audio file (ac3 I think) which I encode with OggMachine. So hopefully the flow is going something like this:
Vobs(5.1) --DVD2AVI--> ac3(downmixed to 2ch) --OggMachine--> ogg(2ch with surround information).