From alsa-user-owner@alsa.jcu.cz  Wed Dec 16 10:10:03 1998
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	Wed, 16 Dec 1998 09:54:05 +0100
Date: Wed, 16 Dec 1998 09:54:05 +0100 (CET)
From: Jaroslav Kysela <perex@jcu.cz>
To: Bryce McKinlay <bryce@albatross.co.nz>
cc: alsa-user@alsa.jcu.cz
Subject: Re: CS4236B: Loud "popping" sound every time a sound is played
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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

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.

							Jaroslav

-----
Jaroslav Kysela <perex@jcu.cz>
Academic Computer Centre, University of South Bohemia
Branisovska 31, C. Budejovice, CZ-370 05 Czech Republic


