[alsa-devel] [Alsa-user] Metallic recording in cs46xx on Thinkpad T22

Rene Herman rene.herman at keyaccess.nl
Wed Mar 12 17:39:48 CET 2008

On 12-03-08 15:43, Takashi Iwai wrote:

> At Tue, 11 Mar 2008 23:01:39 +0100,
> Rene Herman wrote:
>> On 11-03-08 08:24, Gadi Oron wrote:
>>> I am trying to record sound on an old Thinkpad T22 that uses the cs46xx 
>>> sound driver.
>>> Each time you start to record you have a 10% chance of having the 
>>> recording completely distorted and having a metallic sound. When you 
>>> look at the waveform it looks as though there are small segments with 
>>> sharp transitions between them, a little like if these segments were 
>>> moved a little from their correct place.
>> No insights, but I confirm the bug with a TerraTec DMX XFire 1024 (CS4624).
> Hm, cs46xx driver hasn't been much changes since long time ago (around
> year 2005).  The only big change was about some PM fixes, and I don't
> think it's relevant...  Could you run als-info.sh to get the status?



Script was run just after repeating the problem. I have two of these same 
cards (TerraTec DMX XFire 1024) by the way and the same thing happens on 
both. If desperately need be, I can also test a CS4630 in the form of a 
TerraTec SiXPack 5.1+.

This may indeed have been broken for a long time. I (sometimes) use this 
card in a little P1-133 machine in my living room to feed music to my 
regular amp and, seldomly, use it to record from for example LP.

Last time that I did was some 2 months ago and I experienced the problem and 
at the time I remembered seeing that problem before, which may well have 
been 2005. As said, it doesn't happen each time and I use recording on that 
card seldomly...

I expect this is going to be difficult to debug. It's no doubt a timing 
problem and yes, Gadi's description matches. This is what a bad capture 
sounds like:


(a good capture is just, well, good)

Didn't report it before since when I'm recording on that thing I'm recording 
for someone else and when I'm busy trying to do something _with_ a computer 
instead of _to_ a computer, all those pesky little linux problems just get 
on my nerves so incredibly bad at times...


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