Lame and surround Options

[Fr4nz]

Hi guys. I've read many past threads about Lame and encoding movies soundtracks from AC3 to Dolby Surround1/2. While many people claim that Lame preserves the phase informations thanks to its safe joint stereo mode, in this thread http://www.hydrogenaudio.org/forums/index....t=0&#entry47454 it's stated that only at very high bitrates (for e.g. --alt-preset extreme or insane(!!)) Lame can conserve surround infos in a decent way.

Anyway i've encoded lots of movie soundtracks with Lame, and the --alt-preset standard setting seems quite good to me for surround1/2 tracks.

Thanks for any answer!

Fr4nz

[2Bdecided]

So guys --nsmsfix 1.0 is the way to go for encoding surround tracks?

Well, maybe, but you missed three points:

1. In a movie soundtrack intended for Dolby Pro-logic decoding, it's unlikely that you will find the combinations of sounds which cause a problem. That's just my guess though, and it's only a guess. This discussion should be shared with doom9 to get some experts on board!

2. --nsmsfix 1.0 might make things worse elsewhere. Again, that's a guess - I'm not trying to give answers in this post - I'm trying to get other people to test this, and those involved to remember what the issues were when this was tweaked.

3. I'm still not sure it's a 100% solution for the most serious surround problems. It sounds fine to me, but I don't have a propper surround system to test it on, and there are people with better ears here. What I can see it doing to the surround channel in spectral view makes me suspect that there may well be some audible problems remaining.


I'll ask again - is it possible to make lame (or mpc) view the Side channel as a real channel, and perform psychoacoustic calculations on it; rather than viewing it as something that can be dumped? That would be much better than an nsmsfix hack in lame, or than using ms 15 in mpc. I'm happy to help with the algorithm (but not the coding!) because I think some of the spatial masking measurements I made in 1999 might be a good starting point.

Cheers,
David.