[linux-audio-user] bad sound quality (under a non-libre OS good)

Miernik miernik at ctnet.pl
Tue Jan 20 06:53:56 EST 2004

I am installin Debian GNU/Linux on a Sony PCG-C1MV notebook computer.
The owner of this computer is very picky aboud audio quality. I cannot
make it work so the sound quality would be as good as in some non-libre
operating system, which Sony has installed on it. I am playing exactly
the same sound wav file, and under Debian GNU/Linux the audio quality is
much worst than under the non-libre OS. 

The sound card is a PCI card like this: 

00:06.0 Multimedia audio controller: ALi Corporation M5451 PCI AC-Link Controller Audio Device (rev 02)
	Subsystem: Sony Corporation: Unknown device 80ec
	Flags: bus master, medium devsel, latency 64, IRQ 9
	I/O ports at 1800 [size=256]
	Memory at e8100000 (32-bit, non-prefetchable) [size=4K]
	Capabilities: [dc] Power Management version 2

I am using ALSA with the snd_ali5451 driver, but I also tried Knoppix
and Gnoppix, (which autodetects and installs the trident OSS driver) and
the problem is more or less the same, maybe a little better, but maybe
not, hard to tell.			

I must say that for me the difference is very tiny, and I would not even
notice that something is wrong, and I can only notice that there is a
difference if I play on one OS and the immidiately reboot to Debian and
listen to the same file. Otherwise I simply forget that it should be any

The bad quality doesn't look like any extra noise, it looks more like
some kind of distortion. 

It doesn't depend on video usage, moving windows, etc. 

Just in case, the video card is:
00:0c.0 VGA compatible controller: ATI Technologies Inc Radeon Mobility M6 LY (prog-if 00 [VGA])
	Subsystem: Sony Corporation: Unknown device 80ec
	Flags: stepping, medium devsel, IRQ 9
	Memory at f0000000 (32-bit, prefetchable) [size=128M]
	I/O ports at 2800 [size=256]
	Memory at e8110000 (32-bit, non-prefetchable) [size=64K]
	Expansion ROM at <unassigned> [disabled] [size=128K]
	Capabilities: [50] Power Management version 2
The card doesn't use DMA:

venezia:~# cat /proc/dma 
 4: cascade
The same under Knoppix. Also while playing a sound file. 						

I've read the Audio-Quality-HOWTO for Linux at
http://www.linuxdj.com/audio/quality/ but it didn't help. I've tried
booting with the no-hlt option, no difference. 

I use the 2.6.0-2 kernel from Debian. 
What to do to make the audio quality as good as in the non-libre OS?

    Miernik         ________________________ jabber:miernik at amessage.info
___________________/__ tel: +48608233394 __/      mailto:miernik at ctnet.pl
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