From alsa-user-owner@alsa.jcu.cz  Wed Dec 16 12:17:03 1998
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Date: Wed, 16 Dec 1998 23:02:24 +1300
From: Bryce McKinlay <bryce@albatross.co.nz>
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To: Jaroslav Kysela <perex@jcu.cz>
CC: alsa-user@alsa.jcu.cz
Subject: Re: CS4236B: Loud "popping" sound every time a sound is played
References: <Pine.LNX.3.96.981216094434.5089A-100000@entry.jcu.cz>
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Jaroslav Kysela wrote:

> On Wed, 16 Dec 1998, Bryce McKinlay wrote:
>
> > Hi all,
> >
> > My work machine is a Dell Optiplex GXa with an integrated CS4236B chip.
> > I have using the $20 OSS drivers for some time with no problems, but got
> > sick of having to download a new version with each kernel release (and
> > incompatibility with .acX kernel patches) so I thought I'd try the
> > alternatives.
> >
> > The problem: Whenever a sound FINISHES playing (and the app releases the
> > sound card) I get a very loud clicking/popping noise. I have tried
> > virtually every possible combination of ports, IRQs, DMAs, and buffer
> > sizes but I allways get this annoying sound. MUTING the master channel
> > does prevent the problem (but then, obviously, I dont get any sound!!)
> >
> > Anyone have any ideas what might be causing this?
>
> I'm author of CS423X drivers. Clicking can have two reasons:
>
> 1) wrong data at end of stream which is send to CS423X
>    - maybe we can skip this - AudioPCI driver works without clicking with
>      same midlevel code
> 2) CS423X chips needs probably some workaround to prevent clicking at
>    end and possibly start of playing
>    - driver mutes internaly PCM channel, but seems that this doesn't help

Yes, It seems unlikely that 1) is the problem - the clicking sound occurs even
when the PCM channel is muted. Changing the master volume, however, does
effect the volume of the "click"

> I welcome any help.. I'm accepting patches.. For me have this problem very
> low priority.. Datasheets from Crystal Semiconductors and my code is
> available for debugging.

Unfortunatly I have no kernel or driver development experience, so I don't
think I can be of much help here. However I will offer my services for rapid
and thorough testing of any patches people can offer. I would *love* to see
this fixed.

regards

  [ bryce ]



