[alsa-devel] ad1988 spdif crackling (includes patch)

Raymond Yau superquad.vortex2 at gmail.com
Sun Nov 4 02:02:54 CET 2012

> 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


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
    rates [0x7e0]: 44100 48000 88200 96000 176400 192000
    bits [0xe]: 16 20 24
    formats [0x5]: PCM AC3
  Connection: 1
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'


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.




0n those P5Q deluxe (ad1989b), there are coaxial and spdif out ports but no

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 ?

More information about the Alsa-devel mailing list