[MPlayer-users] Movie Surround Downmixing

[Rashkae]

I've noticed that an increasing number of videos have their sound 
recording levels such that speech often gets drowned out by surrounding 
sound/noise.  And if volume is increased to levels where it's easy to 
hear what actors are saying, the volume of everything else will seem 
disproportionately loud.  With some research, I've found that the common 
wisdom is to increase the volume of the center channel of your surround 
system.  Not such an easy feat with 2 speaker sound system/headphones.

After studying Mplayer documentation and source code, I've come with the 
following options:.


-channels 6 -af pan=2:0.4:0:0:0.4:0.2:0:0:0.2:0.5:0.5:0.1:0.1

(Note, the mplayer default for downmixing puts the volume level of 
center channel at .3, here I've boosted that to .5)

In theory, increasing the volume of center channel without decreasing 
everything else runs the risk of total volume being too high and sound 
clipping as a result.  In practice, every soundtrack I've tested has 
more than enough headroom for this extra boost and overall, sounds much 
better in stereo.  I believe this is what most set top dvd/bd players do 
when playing Surround to stereo.

Question: Any more experienced mplayer users/devs have different insight?


Suggestion: If this problem is something that affects people (besides 
myself), it might be good to have an option to boost center channel when 
downmixing.  Manually tweaking the pan filter isn't really something I 
would expect people to do who just want to watch a movie.