[alsa-devel] Intel HDA digital out distortion
Hi,
a couple of weeks ago, I bought an ASUS mainboard with integrated Intel HDA and an AD1988B codec. Unfortunately, the digital / SPDIF output gets distorted with stock 1.0.14 drivers. It does not matter what the volume levels of the various mixers are set to.
I think I might have found the source for this problem. Maybe it's only a workaround, but it solved the issue and digital out now works fine for me, so I thought I'd share.
In patch_analog.c, in static struct hda_verb ad1988_spdif_init_verbs[], changeing the forth entry
from {0x1d, AC_VERB_SET_AMP_GAIN_MUTE, AMP_IN_UNMUTE(1)},
to {0x1d, AC_VERB_SET_AMP_GAIN_MUTE, AMP_IN_MUTE(1)}
mutes what might be an feedback loop from the analog inputs. The distortion is gone if the input to this widget is muted.
On a side note, the settings for the ADCs with NID:08, 09, and 0F looks fishy, too. According to the functional diagram, those should have no amps, and thus should not be muteable. The driver mutes them anyway...
I'd like to help somebody who really understands this stuff to solve the problem for good. What would the next step be ?
Thanks, Ingmar
Hi Ingmar.
On Monday 23 July 2007 23:09:24 Ingmar Stieger wrote:
a couple of weeks ago, I bought an ASUS mainboard with integrated Intel HDA and an AD1988B codec. Unfortunately, the digital / SPDIF output gets distorted with stock 1.0.14 drivers. It does not matter what the volume levels of the various mixers are set to.
That makes two of us. I've reported similar problems a few weeks back. So the thread "snd-hda-intel, AD 1988b: SPDIF output not working correctly, volume low for analog output" maybe of interest to you too. (I posted a similar patch just a few minutes before your's by the way -g-)
Could you please tell me what board you have...? If you play back analog sound through spdif, do you hear "distortions" in the background like bass-like low frequency pumping and so on...?
Best regards, Matthias Dahl
Hi Matthias,
Matthias Dahl wrote:
That makes two of us. I've reported similar problems a few weeks back. So the thread "snd-hda-intel, AD 1988b: SPDIF output not working correctly, volume low for analog output" maybe of interest to you too. (I posted a similar patch just a few minutes before your's by the way -g-)
I've read through your thread, and I think we might have two seperate problems with this chip ? I am not getting any noise over SPDIF when no sound is playing, but it will inevitably be distorted at any volume level and mixer settings if sound is played through aplay or mplayer. I have not tried with dts, only with wave files, by the way.
Looking at the functional diagram, and trying to mute the various amps that might have something to do with this, then led to the 0x1D one that I mentioned.
Analog out seems to be fine with the stock drivers for me, altough I did not compare the volume level with the levels of a Windows driver. At least it is as loud as my CD player, so I'd say it is ok. It also sounds clean with the stock drivers. No problem here.
Could you please tell me what board you have...? If you play back analog sound through spdif, do you hear "distortions" in the background like bass-like low frequency pumping and so on...?
The board came pre-installed in a bare-bone system, so I only know that it is from ASUS and whatever mainboard they put into their Pundit P2 system. The chipset is a Intel 945G with ICH7.
I can not discern any special background noise, since the distortion is so loud that any background noise that might be there is not audible.
Bye, Ingmar
participants (2)
-
Ingmar Stieger -
Matthias Dahl