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#1 2009-04-15 08:36:32

onguarde
Member
Registered: 2008-09-14
Posts: 144

Switching from ALSA to OSS - Audigy2

I decided to try switching to OSS firstly because my sound suddenly stopped working(which I later figured out is not the fault of ALSA but of PCI loose connection). Researching on the problem, I heard good stuff(better quality sound and lower cpu usage) about the new open sourced OSS driver. Sadly, the switch is far from simple...

Summary of OSS/AlSA history - worth noting that it states excellent OSS support for SBLive(NOT Audigy)
http://www.linuxhardware.org/article.ph … /06/179255

lscpi output

02:05.0 Multimedia audio controller: Creative Labs SB Audigy (rev 03)
02:05.1 Input device controller: Creative Labs SB Audigy Game Port (rev 03)

Following the wiki instructions, I initially got hard freezes(no mouse/keyboard) immediately upon kde4 login. This is traced to putting oss right after kdm in rc.conf. Fixed this by placing oss first.

Running lsmod,

Module                  Size  Used by

oss_usb               109004  1
oss_sblive             82544  1
osscore               536020  4 oss_usb,oss_sblive

emu10k1_gp              2452  0
gameport               10112  2 emu10k1_gp

Note: I also stumbled upon the dreaded ipv6 module! No wonder my internet connection seems a bit too slow... Disabled as per wiki.

Running ossinfo,

Version info: OSS 4.1 (b 1052/200903241101) (0x00040100) GPL
Platform: Linux/i686 2.6.29-ARCH #1 SMP PREEMPT Wed Apr 8 12:47:56 UTC 2009 (AZCOM)

Number of audio devices:        6
Number of audio engines:        10
Number of mixer devices:        1


Device objects
 0: osscore0 OSS core services
 1: oss_sblive0 SB Audigy2 interrupts=25106 (25106)
 2: oss_usb0 USB audio core services


Mixer devices
 0: SB Audigy2 (STAC9721) (Mixer 0 of device object 1)

Audio devices
SB Audigy2 main                   /dev/oss/oss_sblive0/pcm0  (device index 0)
SB Audigy2 front out              /dev/oss/oss_sblive0/pcm1  (device index 1)
SB Audigy2 side out               /dev/oss/oss_sblive0/pcm2  (device index 2)
SB Audigy2 center/lfe out         /dev/oss/oss_sblive0/pcm3  (device index 3)
SB Audigy2 raw S/PDIF (output only)  /dev/oss/oss_sblive0/pcm4  (device index 4)
SB Audigy2 5.1 output device      /dev/oss/oss_sblive0/pcm5  (device index 5)

  /dev/dsp -> /dev/oss/oss_sblive0/pcm0
  /dev/dsp_in -> /dev/oss/oss_sblive0/pcm0
  /dev/dsp_out -> /dev/oss/oss_sblive0/pcm0
  /dev/dsp_ac3 -> /dev/oss/oss_sblive0/pcm0
  /dev/dsp_mmap -> /dev/oss/oss_sblive0/pcm0
  /dev/dsp_multich -> /dev/oss/oss_sblive0/pcm5

However, running osstest, and ossxmix in user mode, I see volume activity bars fluctuating when the test is running but no sound out of the speakers.

TROUBLESHOOTING
I tried changing plugging the speaker connection to the other jacks(5 colours in total) besides the green one. Surprisingly, fuzzy, noisy, garbled, static, hardly-discernable sound started coming out of the speakers. Later I figured out the first jack(orange) is supposedly for analog/digital output.

I figured I should try switch to analog somehow since that worked perfectly in alsa. Following the website below, I changed the setting below and restarted the service.
http://manuals.opensound.com/usersguide/oss_sblive.html

vi /usr/lib/oss/conf/oss_sblive.conf

# Sets the SPDIF/Analog combo output to audio or spdif mode
# Values: 1 = Digital, 0=Analog Default: 0
#
#
sblive_digital_din = 0
#
#
# Sets the SPDIF/Analog combo output to analog or spdif mode
# Values: 1 = Digital, 0 = Analog Default: 1
#
audigy_digital_din = 0

At this point, the sound status regresses to no sound at all! Changing the jacks back to green and other colors doesn't work either. Neither does rebooting.

Searching around I found this,
http://4front-tech.com/forum/viewtopic. … light=live
It offerred a tip about testing the devices one by one. Also learnt that 5.1 surround is non-existant. Good thing I don't need that.

ossplay -d/dev/oss/sblive0/<follow_ossinfo> <some_test_file>.wav
eg. ossplay -d/dev/oss/oss_sblive0/pcm5

Sadly, still no sound. The last device even hung the whole system!

Pretty much stumped here... Either garbled digital sound quality or no sound at all. I guess I'll just go back to ALSA...

Last ditch effort would be to try rebuilding it according to instructions below. And installing the mercurial(svn) version from aur.
http://www.4front-tech.com/forum/viewto … 84a8259cb0

Any ideas?

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#2 2009-04-16 01:31:00

brebs
Member
Registered: 2007-04-03
Posts: 3,742

Re: Switching from ALSA to OSS - Audigy2

The Audigy2 itself *remixes* to 48khz, even if the input is the same. There's no way to turn it off that I've ever heard about, and no-one cares except musicians.

ALSA knows that the card does hardware-mixing, so doesn't attempt to waste CPU cycles on software-mixing.

I've tried opensound on my Audigy4 and current X-fi, with varying levels of success. Its support, as you've seen, is crap. There's like ONE GUY supporting opensound.

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#3 2009-04-16 10:53:39

onguarde
Member
Registered: 2008-09-14
Posts: 144

Re: Switching from ALSA to OSS - Audigy2

Hmm.. I guess I'm going back to ALSA. I tried the svn mercurial version to no avail. The rebuilding tip mentioned above might work but its too troublesome.

Its just too bad I have to go through all that of testing cos I can't find any good resource on how well  it's supported.

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