Problems with Export to AC3

[andrewb]

Im trying to create a new audio for DVD by combining English in right channel and German in left channel. That done, I try to export to an AC3 file. The file is created, but when I play it, the two channels are (at least a bit) mixed, i.e. there is always some german in the right channel (right should correspond to english). Prior to export, the file behaves as I would expect: pan to the right and you get the english< pan to the left and you get german. Im using Audacity1.3.13 beta (unicode) under Wndows XP. The FFmpeg library version F(52.64.2),C(52.7.2),U(50.15.1).

If I export with the same settings, except to MP3 (using LAME) the result is perfect.

Any ideas what may be wrong? I need the file in AC3 format to do the DVD reauthoring that I need to do.

Thanks.

[kozikowski]

Dolby AC3 is not a conventionally compressed format. They play a lot of tricks to get 5.1 sound channels into a small file. One of the tricks is to mess with the separation -- which in your case doesn't work so well. With natural video, nobody would ever know. That and the dynamic range bump, the "fake" bass channel, etc, etc, are all encoding options, and yes, they drive video producers nuts.

You may find that AC3 efficiency goes way down when you start dedicating individual channels. The dialog[s] may not fit on the disk any more.

You might consider using the Separate Language/Layer option on the DVD/Blu-Ray. That's what they're there for.

Koz

[andrewb]

Thanks Koz,

What I'm trying to do is create a DVD of a lecture that can be played to two different audiences at the same time. The english would be on one channel which would be ported to the TV/data projector, the german the other channel (taking the left channel and porting it into a device that transmits to headphones). The conference hall has a dvd player, not a blue-ray.

I guess this would only work if the dvd player has 5.1 playback as a stereo playback device partly blends the two stereo tracks together (or am I wrong on all counts??)

Any ideas?

Thanks.