[MPlayer-users] Using hrtf with ac3 5.1

[Stephen Mollett]

Hi,

I've come across what, I think, is a minor bug in mplayer. When trying to use 
-af hrtf to mix down 6-channel ac3 audio from a DVD for headphones, the only 
way to get liba52 to output 6 channels is to specify -channels 6. Otherwise, 
the decoder mixes down to stereo itself before the audio reaches the HRTF 
filter. Unfortunately, I don't have a 6-channel sound card in my laptop, so 
the ao layer fails to open any device for output when I do this...

I've worked around it by creating a virtual 6-channel device in my ALSA 
configuration files, with the first two channels going to the soundcard and 
the rest to /dev/null, and this seems to work OK, but really, there needs to 
be some way to get liba52 to output 6 channels independently of the output 
layer's configuration (perhaps a parameter that can be passed to the codec 
that overrides the -channels option).

Regards,
Stephen