[LAU] Sound issues with videos

Grant emailgrant at gmail.com
Wed Jul 13 01:10:57 UTC 2011


I listen to music with mpd and send the audio straight to my USB DAC like this:

audio_output {
  type  "alsa"
  name  "Wavelength Proton"
  device  "hw:0,0"
}

It sounds great, a lot better than letting dmix resample to any rate I
have tried, even with libsamplerate's best algorithm.  I've tried
doing the same thing with mplayer:

mplayer -ao alsa:device=hw=0.0 -format s24le video.mkv

but the result is a somewhat muddy sound, especially with Blu-Rays.
It sounds like dmix has gotten involved.  Last night I tested mplayer,
gmplayer, and vlc with The Princess Bride on Blu-ray.  The sound was
muddy with mplayer and vlc.  gmplayer sounded crisp and clear but the
dialog was missing, I could only hear the movie's soundtrack.  After
that I realized the 6-channel movie audio must be downmixed for my
2-channel DAC which must be where the sound is being fouled up.  Does
anyone have any suggestions?  I like to leave the digital audio
untouched but I suppose 6 channels need to be downmixed to 2 channels
digitally.

- Grant


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