[a52-dev] Quiet AC3 with 2-speaker setup

[<Jef...@ac...>]

My apologies if this comes through twice.  The first time, I signed up for
the list using an incorrect e-mail address.

First off, I want to thank the devs for their hard work.  For the most
part, this library just works, and lets me play DVDs on my Mandrake box.
In researching the behavior I'm relating below, I've done some googling and
searching of the archives for this list, but I'm either using the wrong
search terms, or this question hasn't been asked before.

Most of my experience is with MPlayer, but I've noticed the same behavior
with Xine.

When I play a ripped VOB, and MPlayer gives this in its output (this is
most of my DVDs):

AC3: 5.1 (3f+2r+lfe)  48000 Hz  448.0 kbit/s

The output volume is very quiet.  If I turn up the stereo loud enough to
hear dialog, I start getting a lot of background hiss.

When I play a ripped VOB, and MPlayer gives this in its output (this is
rare -- mostly a few Baby Einstein titles I ripped for my son):

AC3: 2.0 (stereo)  48000 Hz  192.0 kbit/s

The output volume is at a level I would expect.  I can set the volume
reasonably, and what little dialog I can find is clear, without any kind of
background noise.

I assume that the observed behavior is an artifact of the downmixing
process done by liba52.  This process is probably doing everything
correctly -- it's just not quite working for the way I have my system set
up.  One solution I can think of is to find a way to skip the 5.1 track
altogether and use the stereo audio track provided on most DVDs, but if I'm
going to rip anything for posterity (Children's DVDs come to mind in a few
years -- no way I'm going to buy the same disc multiple times because the
first one was broken/scratched/smeared with jelly), I'd like to be able to
preserve the full 5.1, in case my set-top box ever becomes 5.1-capable.  So
I'd love to hear about some sort of tweak or configuration I can do to make
my current output (straight stereo from a cheap sound card) play 5.1 at the
volume I get from the rarer stereo-only DVDs.

Thanks in advance for any help.

-Jeff