Hi!
For nearly three years, a bug has been known to cripple SPDIF output on certain hardware. It might work fine for a while, but will randomly break, showing two symptoms: PCM audio is distorted (similar to clipping) while compressed audio (AC3 or DTS) will not work at all.
can you post the output of alsa-info.sh ?
do turn off this switch help ?
Simple mixer control 'IEC958 Default PCM',0 Capabilities: pswitch pswitch-joined penum Playback channels: Mono Mono: Playback [on]
are your application using hw:0,0 , iec958:0 or hw:0,1 for digital output ?
http://support.asus.com/Search/KDetail.aspx?SLanguage=en&no=BFFD12B9-125...
the supported rates of device 0 is restricted to the supported rates of node 0x02 when the above switch is ON and the driver don't protect the switch when the application is playing
Default PCM: rates [0x7ff]: 8000 11025 16000 22050 32000 44100 48000 88200 96000 176400 192000 bits [0xe]: 16 20 24 formats [0x1]: PCM Default Amp-In caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1 Default Amp-Out caps: ofs=0x27, nsteps=0x27, stepsize=0x05, mute=0 Node 0x02 [Audio Output] wcaps 0x30311: Stereo Digital PCM: rates [0x7e0]: 44100 48000 88200 96000 176400 192000 bits [0xe]: 16 20 24 formats [0x5]: PCM AC3 Connection: 1 0x1d Node 0x03 [Audio Output] wcaps 0x405: Stereo Amp-Out Amp-Out caps: ofs=0x27, nsteps=0x27, stepsize=0x05, mute=0 Amp-Out vals: [0x27 0x27] Power: 0x0
it seem that those paths from ADC to SPDIF does not exist
Simple mixer control 'IEC958 Playback Source',0 Capabilities: enum Items: 'PCM' 'ADC1' 'ADC2' 'ADC3' Item0: 'PCM'
http://support.asus.com/Search/KDetail.aspx?SLanguage=en&no=9b4f722c-dd8...
AD1988 does not support Mic to SPDIF.
Muting an unmuting the master channel may temporarily fix it.
This affects at least all Asus P5B and P6B mainboards.
http://support.asus.com/Search/KDetail.aspx?SLanguage=en&no=02A7151F-D59...
http://git.kernel.org/?p=linux/kernel/git/tiwai/hda-emu.git;a=tree;f=codecs;...
http://www.asus.com/Motherboards/Intel_Socket_775/P5Q_Deluxe/#specifications
0n those P5Q deluxe (ad1989b), there are coaxial and spdif out ports but no hdmi
ADI® AD2000B 8-channel High Definition Audio CODEC - Coaxial/Optical S/PDIF out ports at back I/O
The solution is a simple one-liner, and has been known for a year: http://fjerhammer.dk/ad1988_spdif_crackling.patch (credits go to Javeed Shaikh for the patch and fjerhammer for hosting it). I can verify that it fixes all issues on my setup. Please apply it.
See also: https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/359361
do the bug affect all ad198x since the two reporters who posted the codec info are using ad1984 ?