On 30/12/06, Andrew Lyon <[EMAIL PROTECTED]> wrote: > Hi, > > I am using iec958 spdif output on gigabyte ga-965-ds3 motherboard with > onboard hda-intel, kernel 2.6.18.6 alsa 1.0.13, I dont have a > asound.conf or asoundrc. Most of my sound is coming from mythtv (ac3 > and dts passthru enabled), this works really well provided I run the > following commands (just once) before running myth: > > amixer set IEC958 mute > aplay -D spdif /usr/share/sounds/alsa/Front_Center.wav > amixer set IEC958 unmute > > I dont know why that is necessary but without it I get silence or > "helecopter" noises, I think the aplay command actually errors as > well, it certainly doesnt output any sound, which is even stranger.. > > Anyway thats not the problem, the problem is that a small number of > programmes that I watch have mono audio, when myth attempts to play > them back I get the following error and no sound: > > 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 understand why this happens, iec958 does not support mono audio, > either its simply not possible or not supported on my chipset, Ive > tried changing options in myth but it doesnt make any difference, it > always tries to set the channel count to 1. > > I have asked on the myth mailing list but nobody has been able to > help, I wonder if anything can be done from the alsa side of things? > Perhaps alsa could be configured to accept mono audio on the iec958 > and to resample it to 2 channel? > > Andy >
It is a problem with myth. myth should open difference ALSA devices depending on the type of sound being played. I.e. for AC3/DTS is should open the iec958 device. For PCM (stereo or mono) it should open the plug:iec958 device. The plug bit does the resampling and mono->stereo conversions. James ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
