Sound quality in linux?

sawsedge · n00b Joined: 19 Apr 2002 Posts: 20 Location: Boston

I have 2 systems with SB Live cards, same labtec speakers on each. One runs Gentoo, one runs Windows 2000. I compiled sound support into the 2.4.22 kernel as a module. XMMS runs, sounds work. However, the sound quality is noticably better in Windows, running either iTunes or winamp. Running the same files, XMMS sounds hollow and "tinny". I'm not sure if the lower quality in Linux comes from the kernel driver, the configuration, or something else. Are there any audiophiles out there that could help me troubleshoot? I'm not sure where to search.

dmesg:
Creative EMU10K1 PCI Audio Driver, version 0.20a, 07:38:39 Jan 8 2004
PCI: Found IRQ 5 for device 00:11.0
emu10k1: EMU10K1 rev 8 model 0x8027 found, IO at 0xb800-0xb81f, IRQ 5
ac97_codec: AC97 Audio codec, id: 0x8384:0x7609 (SigmaTel STAC9721/23)

bash-2.05b# lsmod
Module Size Used by Not tainted
emu10k1 74248 0
ac97_codec 10376 0 [emu10k1]
sound 58260 0 [emu10k1]

I have these installed:

alsa-driver-0.9.8
esound-0.2.32
libao-0.8.3-r1
libsdl-1.2.6-r3

I don't have: alsa-utils, alsamixergui, much else.

Thanks for any suggestions.

G-Style · Posted: Thu Feb 19, 2004 2:38 am Post subject:

Try lowering your PCM and raising your Master levels.
I think that should make somewhat of a difference.

Slyde · Guru Joined: 14 Jul 2003 Posts: 314

Play around with all your alsamixer settings. Like G-Style said, mess with your PCM and Master, also with Bass/Treble. I have noticed that if you PCM is at 1005, sound gets disorted. Try running everything at 90%.

Woody · Guru Joined: 30 Nov 2002 Posts: 592 Location: Milwaukee

Also, that card probably does some internal
resampling. Try opening it at 48Khz and do some
tests with just a wav file and aplay.

sawsedge · n00b Joined: 19 Apr 2002 Posts: 20 Location: Boston

Thanks for the suggestions.

I'll look further and let you know what I find

Eamon Nerbonne · n00b Joined: 16 Feb 2004 Posts: 45

I had the same problem and it's definitely the PCM volume as previous posters mentioned. You probably would not encounter this if you removed alsa. Apparently the alsa mixer can set the volume too high; distorting the sound (when it exceeds the 16bit range).

The 48000 vs. 44100 Hz issue exists as well (in that the SBLive! uses a bad internal resampler to resample everything to 48000 Hz). However I've only ever been able to hear that in really artificial samples: additionally, this problem exists in windows as well. (As a matter of fact I've never tested it in linux, so it's even remotely possible that the driver works around it). The resampling issue appears most strongly when listening to high (above 10KHz), pure, tonal, sine waves, (it'll be aliased AFAIK).

lunarg · Posted: Thu Feb 19, 2004 3:58 pm Post subject:

However.....

Unlike the majority of onboard chips (intel8x0, via-whatz-the-number, ...), SB Live and Audigy can playback sound at something else than 48khz. The internal resampling you refer to, can be bypassed (tweaking the module source and/or parameters).
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sawsedge · n00b Joined: 19 Apr 2002 Posts: 20 Location: Boston

Hmmm, saw no errors installing alsamixergui, but it won't run:

alsamixer: function snd_ctl_open failed for default: no such device

I did not have /dev/snd. I read some other threads on the error, and made sure I added alsasound to boot. now dmesg shows

ALSA seq_oss.c:223: can't register device seq

and stopping/starting the service:
/etc/init.d/alsasound stop
* WARNING: you are stopping a boot service.
* Unloading ALSA...
* Storing ALSA Mixer Levels
/usr/sbin/alsactl: save_state:1061: No soundcards found...
* Unloading modules [ ok ]

/etc/init.d/alsasound start
* Loading ALSA drivers...
* Unable to find any ALSA drivers. Have you compiled alsa-drivers correctly?
* Using ALSA OSS emulation
* Loading: snd-seq-oss
/lib/modules/2.4.22-gentoo-r3/kernel/sound/acore/seq/oss/snd-seq-oss.o: init_module: Device or resource busy
Hint: insmod errors can be caused by incorrect module parameters, including invalid IO or IRQ parameters.
You may find more information in syslog or the output from dmesg
/lib/modules/2.4.22-gentoo-r3/kernel/sound/acore/seq/oss/snd-seq-oss.o: insmod /lib/modules/2.4.22-gentoo-r3/kernel/sound/acore/seq/oss/snd-seq-oss.o failed
/lib/modules/2.4.22-gentoo-r3/kernel/sound/acore/seq/oss/snd-seq-oss.o: insmod snd-seq-oss failed
* Loading: snd-pcm-oss
* Running card-dependent scripts
* Restoring Mixer Levels
* No mixer config in /etc/asound.state, you have to unmute your card! [ !! ]
[ ok ]

So it looks like I need to re-read the directions and recompile the kernel

pppZero · n00b Joined: 26 Apr 2003 Posts: 30 Location: Australia

sawsedge · n00b Joined: 19 Apr 2002 Posts: 20 Location: Boston

thanks

ENABLE_TONE_CONTROL=yes was already set,
playing with aumix helps some, but not a tremendous amount.

sklettke · Guru Joined: 05 Nov 2002 Posts: 352 Location: Madison, WI

You could also try emerge xmms-mad.

It uses libmad, a higher quality MPEG audio decoder, http://www.underbit.com/products/mad/

Scott
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