vorbis light lossy vs. lossless on dolby pro logic

[canadian_fbi]

hey, has there been any consensus as to whether or not light lossy encoding in ogg vorbis degrades the dolby pro logic signal compared to lossless? i did a search here in the forums and found lots of good stuff talking about how LAME joint stereo maintains dpl info, but not much definitive on ogg... i'm inclined to believe that light lossy won't harm dpl, but perhaps someone's done some actual testing so we'll know for sure and not just on a hunch :)

[MaTTeR]

I can tell you that anything other than light lossy or lossless is definitely hearable to my ears. I remember awhile back sending an email to Dark Avenger about this subject and was complaining that Vorbis didn't maintain the DPL info very well.

Of course his response was to experiment with the channel couplings. So right now I'm pleased with using light lossy.

[canadian_fbi]

yeah, i wouldn't go any more lossy than light. basically i want to up the bitrate from 4.99 for a particularly compressible, short movie (dark city), but i don't think there's much to gain from doing the automatic switch to lossless at 5.0. so i used headac3he to stay at light lossy at -q 5.5 and ended up with a nice 139 kbps file that should sound quite nice without being overly huge. won't be able to test it on a surround sound system for another couple of months though, so i can't test whether or not going to lossless coupling would have added anything (other than about 40 kbps).

[MaTTeR]

One of my favorite movies of all time, in fact I liked it better than Matrix:)

With the settings you mention, I have a feeling it's overkill for DPL FX. Well at least it would be overkill on my home theater. I've found that the surround doesnt really get much better above q3, again this is on my system;)

[canadian_fbi]

well, there are two main speakers i'm interested in improving the quality on too. ;) basically i just wasn't sure if light lossy really damaged the phase information at all. from the search i did it seems that lame joint stereo doesn't, and so i was wondering if light lossy was similar. i think that it should be, and it seems like you've had no problems with it, so i don't feel bad taking lossless out of the picture for now.

interestingly enough, i was testing the audio track now to see how it sounded, and the bitrate during the music at the end credits went as high as 211 kbps at one point. so it's at least trying for high quality if nothing else. i'm excited now to watch this movie tomorrow when it's finished encoding to see how it turned out. in addition to this audio, the video is at 640x272, mpeg quant (xvid of course), neutral bicubic... should be good :)