[alsa-devel] Intel HD: ALC662 noise-bug on FitPC2i

[Takashi Iwai]

At Wed, 12 Dec 2012 19:30:58 +0100,
Bent Bisballe Nyeng wrote:
> 
> On 12/12/12 15:51, Takashi Iwai wrote:
> > At Wed, 12 Dec 2012 15:45:46 +0100,
> > Bent Bisballe Nyeng wrote:
> >>
> >> On 12/12/12 15:25, Takashi Iwai wrote:
> >>> At Wed, 12 Dec 2012 14:14:57 +0100,
> >>> Bent Bisballe Nyeng wrote:
> >>>>
> >>>> On 12/12/12 14:05, Clemens Ladisch wrote:
> >>>>> Bent Bisballe Nyeng wrote:
> >>>>>> When recording, audible clicking sounds are present in the resulting
> >>>>>> audio data.
> >>>>>>
> >>>>>> The corruption are composed of approximately 10 samples, and the
> >>>>>> nature of the corrupted values are such that they could come from an
> >>>>>> earlier buffer (the corrupted data resemble wav forms).
> >>>>>
> >>>>> This looks like a problem with your HDA controller; either the memory
> >>>>> bus is overloaded so that some writes are dropped, or the hardware is
> >>>>> just buggy.
> >>>>>
> >>>>>
> >>>>> Regards,
> >>>>> Clemens
> >>>>
> >>>> I tried to record some audio using windows 7 and here the noise was not
> >>>> present indicating that it is not buggy hardware.
> >>>>
> >>>> Also, the system was not under load when the arecord call was made so if
> >>>> the memory bus was overloaded I need another way to verify this.
> >>>>
> >>>> Are there any additional (useful) debugging info I can subtract from the
> >>>> system that will help aiding the debugging process?
> >>>
> >>> Which sound backend are you using at all?  Does the problem appear if
> >>> you run with -Dhw for arecord?
> >>>
> >>> If it's using dsnoop or PulseAudio, the accuracy of DMA position
> >>> reporting plays a big role.  In that case, changing position_fix
> >>> option cures often.
> >>>
> >>> Takashi
> >>
> >> There are no sound servers installed on the pc in question (it is a
> >> 'lean' pc) so arecord should be using the hardware directly already.
> > 
> > If you are using alsa-lib as is, it must be using dsnoop as default,
> > which is pretty different from hw.
> > 
> > 
> > Takashi
> 
> Running arecord with -Dhw did not solve the issue.
> 
> I played around with the buffer-size and have concluded that even with a
> very large buffer the ticks are still present, precisely one tick per
> buffer. This results in fever ticks with greater buffer sizes, but ticks
> non-the-less.
> 
> Are there any special kernel parameters that I should set in order to
> make audio smooth?

As I wrote, check position_fix option.


Takashi