[Alsa-user] Distorted line capture with ICH4 ALC655/snd_intel8x0 - tinny sound

[Burt H. <bu...@co...>]

Hello -
I am having some sound quality problems.  Any ideas of things to try =
would really be appreciated.  I have links to some audio file samples =
below for the good and bad cases I have recreated.

System Background:
- Commell LV-670 (per documentation audio is Intel ICH4 with Realtek =
ALC650 AC97)
- CentOS4, updated kernel to 2.6.17
- ALSA version 1.0.11rc4
- I have played with the alsamixer settings without progress.  I even =
have tried PCM, line, and all the other settings down below 10%.
- lspci shows: 'Multimedia audio controller: Intel Corporation =
82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) AC'97 Audio Controller (rev 02)

Problem:
I am attempting to capture video and audio via the Real Networks =
realproducer v10.  According to Real, the OSS compatibility APIs are =
used, and ALSA may work but is not supported.  When I use the above =
mentioned ALSA driver, the audio has a horrible sound  when played back =
in RealPlayer.  While capturing, the PCM output to the speakers sounds =
great, as does playing wav files.  I can successfully use arecord and =
aplay as well.
- Here is a link to the "bad sounding file" - =
http://www.thehurffs.com/bad_alsa.rm

The problem only seems to be when audio is captured through the OSS =
interface (assuming I have the terms correct based upon Real's =
statements about OSS and ALSA support).  I am not very smart on the =
ALSA/OSS compatibility...

Additionally, I downloaded the commercial OSS driver from =
http://www.opensound.com/.  This driver works flawlessly through =
realproducer, as well as straight arecord, etc.  While this driver is an =
option, I would much rather not have to purchase the driver and deal =
with future support.  I'd like to just use the standard distro ALSA =
drivers.  Since the OSS driver works, it leads me to believe it is =
simply an issue with my ALSA driver config, maybe a modprobe parameter, =
sampling rate, alsamixer setting, or something of that sort.  I looked =
at the intel module parameters and tried the rate one, to no avail.
- Here is a link to the "good sounding file" - =
http://www.thehurffs.com/good_oss.rm

Are there known issues with this chip?  Or do you think it is an issue =
of RealProducer/OSS/and the chip all together?  I have seen a lot of =
references to the nForce clock rate issues referring to 44.1 KHz vs 48 =
KHz, resampling issues, etc.  But the suggestions have not really made a =
difference.  Do the files I linked sound like a sampling issue, or =
something else?

Thanks SO much in advance!
Burt