[MPlayer-users] Getting the best sound from mplayer

[Vladimir Mosgalin]

Hi Grant!

 On 2011.07.19 at 12:18:15 -0700, Grant wrote next:

> >> downmix.  I just tried -channels 6 -af
> >> pan=2:.8:0:0:.8:.4:0:0:.4:.6:.6:.2:.2 and the results are great.  I
> >
> > Note that this pan line is VERY wrong as it puts too much volume into
> > two channels, you have to reduce coefficients to normalize volume
> > properly. When loud sounds from all channels occur, often happens for
> > explosions and stuff, for example, it will exceed maximum volume level
> > which will be clipped to max, it's a very heavy distortion that's quite
> > unpleasant to your ears.
> 
> You're right again.  I noticed your pan was superior to mine last
> night while watching a movie, even during normal volume passages.  I
> guess you want each channel to total 1?

Yes, otherwise when there is loudest sound on many/all channels,
calculated volume for stereo channels will be more than max possible,
it'll be clipped to max with nasty distortions.

> I'd like to keep experimenting with it.  Can the numbers be defined to
> 2 decimal places?

Of course. Also, to answer question about converting from 6.1 and 7.1:
try default mplayer downmix pan filter settings for these, from
libaf/af.c.  Clément Bœsch did a nice work on implementing downmix in
mplayer, check out this email for two good sets of pan settings:
http://lists.mplayerhq.hu/pipermail/mplayer-dev-eng/2010-September/066308.html

The first one you see there is the one that made it to mplayer; but also
check another one, it's based on Dolby recommendations IIRC; it gets
less sound from FL/FR and more from rear/side channels and sounds quite
different, its up to you which to prefer.

PS btw, there are some blu-rays with nice stereo sound track added,
premuxed from multichannel. You might enjoy these.

-- 

Vladimir