[MPlayer-users] Dolby AC3 question

[Corey Hickey]

Rohit Sharma wrote:
> Hi there,
> 
> I have a small collection of DVDs but I prefer to be able to keep the
> .avi files on my computer.
> 
> When I encode a DVD movie, I ensure that in .mplayer/config
> 
> channels=6

There are two things I should mention here:

1. The mencoder config file is ~/.mplayer/mencoder
2. The channels option doesn't have any effect with -oac copy -- the
audio stream is copied without being altered, so all the original
channels remain.

Those don't actually have any bearing on your problem, but I wanted to
point them out.

> is a line and while encoding stream, I always do -oac copy to retain the
> AC3 track. I have trust dolby digital soundcard with optical out and a
> good receiver which can decode dolby digital signal via optical/fiber
> input.
> 
> When I do a "file movie.avi", it shows me dolby digital [2ch, 48000 hz]
> instead of 6 channels.
> 
> What may I be doing wrong? Should I not expect to see a 3+2+1 or 6ch
> dolby digital, 48000 Hz ?

There are usually several audio tracks on a DVD, some of which are
6-channel and some are 2-channel. I'm guessing that when you use '-oac
copy' it's copying one of the 2-channel tracks. Offhand, I don't know of
any reason why that would be a different channel from the one you get
when you play the DVD. ...except if you use 'mplayer dvd://1
-dumpstream' to copy the movie to your hard disk before encoding it,
which you didn't mention.

Anyway, send us the _entire_ output of the following commands (change
dvd://1 and movie.avi to whatever they really should be).

$ mplayer dvd://1 -identify -frames 0
$ mplayer movie.avi -identify -frames 0

-Corey