[MPlayer-users] [BUG?] 5.1 channel ogg audio

[陆然]

Hi,

I have a movie with 5.1 channel ogg audio, and my output device is  a stereo 
headphone, When I try to play it with alsa ao, I got a error message:

alsa-init: 1 soundcard found, using: surround51
ALSA lib pcm.c:1959:(snd_pcm_open_conf) Invalid type for PCM surround51 
definition (id: surround51, value: cards.pcm.surround51)
alsa-init: playback open error: Invalid argument

I searched the mail list and it looks like a alsa's bug, then I used oss to 
play it. I can hear sound, but it looks like it just used the first two 
channel and dropped others, unfortunately xiph people seem use a different 
channel order, for 5.1 it is front left, front center, front right, rear 
left, rear right, LFE, so I got front left on the left and front center on 
the right. 

I tried to use the channels filter to direct the front right channel to the 
right place. I got the front left on the left and front right on the right, 
but then I found the dialog sound is stored in the front center channel, so 
at last I get all the sound effect but no dialog.

I don't know if it should be a mplayer's bug or an libogg's bug, In the ideal 
situation, 5.1 ogg should be handled like ac3, get the output device 
information from the ao, and try to downmix to the correct channel if it's 
necessary.

-- 
Best Regards,
LR