[mythtv-users] Mono Audio does not work

[Andrew Lyon]

Hi,

My setup is dvb-t (avermedia 777) and dvb-s (technotrend s1500)
sources, my audio device is onboard hda intel on gigabyte GA_965P_DS3
motherboard using spdif output to a yamaha rx-v630rds, my output and
passthru devices are both set to ALSA: iec958 and I have both ac3 and
dts passthru enabled.

I am running svn 12293.

For some reason I have to do the following after starting the system
in order to get audio working:

amixer set IEC958 mute
aplay -D spdif /usr/share/sounds/alsa/Front_Center.wav
amixer set IEC958 unmute

Somebody else on this list who has the same motherboard found that was
the only way to get passthru working, and it works for me too, stereo
and 5.1 playback works fine, but when I try to watch a program (live
or recorded) which has mono audio e.g. scrapheap challenge I do not
get any sound and the following error is logged:

2006-12-26 16:22:46.258 AFD: Opened codec 0x8979b80, id(MPEG2VIDEO) type(Video)
2006-12-26 16:22:46.258 AFD: Opened codec 0x88a2c80, id(MP3) type(Audio)
2006-12-26 16:22:46.258 AFD: Opened codec 0xa01cee0, id(MP3) type(Audio)
2006-12-26 16:22:46.585 Opening ALSA audio device 'iec958'.
2006-12-26 16:22:46.586 AudioOutput Error: Channels count (1) not
available: Invalid argument
2006-12-26 16:22:46.586 AudioOutput Error: Unable to set ALSA parameters

I really dont know what to do about this, can anybody suggest a workaround?

I guess the ideal solution would be for myth to detect mono audio and
when encountered disable passthru and instead upsample the audio to 2
channels...

Andy