Difference between revisions of "Open Sound System"

From ArchWiki
Jump to navigation Jump to search
m (add link to spanish ver)
Line 6: Line 6:
{{i18n_entry|简体中文|OSS (简体中文)}}
{{i18n_entry|简体中文|OSS (简体中文)}}
{{i18n_entry|Français|OSS (Français)}}
{{i18n_entry|Français|OSS (Français)}}
{{i18n_entry|Español|Open Sound System (Español)}}
{{i18n_entry|Türkçe|OSS (Türkçe)}}
{{i18n_entry|Türkçe|OSS (Türkçe)}}

Revision as of 00:20, 13 December 2009

Template:I18n links start Template:I18n entry Template:I18n entry Template:I18n entry Template:I18n entry Template:I18n entry Template:I18n links end This article will show you how to install and configure the Open Sound System (OSS) on you computer.


The Open Sound System is an alternative sound architecture for Unix-like and POSIX-compatible systems. OSS version 3 was the original sound system for Linux and is in the kernel but was superceded by ALSA in 2002 when OSS version 4 became proprietary software. OSSv4 became free software again in 2007 when 4Front Technologies released it's source code and provided it under the GPL license.

Comparisions with ALSA

Some advantages and disadvantages compared to using the Advanced Linux Sound Architecture.

OSS Advantages (users)

  • Includes a transparent software mixer (vmix in kernel space). Having a transparent software mixer means that multiple applications can access the sound device at the same time.
  • Control for each application sound volume.
  • Some legacy cards are supported better (e.g. Creative X-Fi).
  • Initial response time in sound applications is usually better.
  • Better support for applications that use the OSS API. Many applications still use this API, and doe not require an emulation layer like ALSA uses.

OSS Advantages (developers)

  • Cleaner and easier to use API, and better API documentation.
  • Support for drivers in userspace.
  • Accesibility. OSS runs on BSDs and Solaris.
  • Portability. OSS is easier to port to other operating systems.

ALSA Advantages

  • Better support for USB audio devices. With OSS output is experimental, input is not implemented.
  • Support for Bluetooth audio devices.
  • Support for AC'97 and HDAudio dial-up soft-modems such as Si3055.
  • Better support for MIDI devices. With OSS you'll have to use a software synthesizer such as Timidity or Fluidsynth.
  • Support for suspend. OSS and associated programs will need to be closed first.
  • Better support for jack detection. On some HD motherboards users will need to turn down the speaker volume when plugging in their earphones.


Install OSS by running:

# pacman -S oss

This will install the OSS files and run the OSS install script that will temporarily disable the ALSA modules, and install the OSS kernel modules. Since ALSA is enabled by default in the boot scripts, you need to disable it for it not to conflict with OSS when booting. You can do this by editing Template:Filename and adding:

MODULES=(!soundcore ...

Then add the OSS module:

MODULES=(!soundcore ... oss)

If your user is not part of the audio group, add your user by:

# gpasswd -a username audio

Then start OSS by:

# /etc/rc.d/oss start

In the case OSS is not able to detect your card when starting it, run:

# ossdetect -v

Then Template:Codeline to reactivate it.


Beware the default volume is very loud, avoid using earphones and physically lower the volume of your speakers (if possible) before running the test.

Test OSS by running:

$ osstest

You should be able to hear music during the test process. If there is no audio, try to adjust the volume or refer to the troubleshooting section.

See which devices are detected by running:

$ ossinfo

You should be able to see your devices listed under Device objects or Audio Devices. If the device that you want to use is not at the top on Audio devices or Device objects sections, /usr/lib/oss/etc/installed_drivers needs to be edited. The driver for the device that needs to be used should be at the very top. A soundoff, soundoff is probably required. If this does not work, comment all drivers listed that are not your preferred device.

Volume Control

To control the volume of various devices, mixers levels will need to be set. The command line mixer is called Template:Codeline. It's very like the BSD audio mixer (mixerctl). The graphical mixer is called Template:Codeline and will require Template:Package Official to be installed.

The basic ossxmix controls:

 / High Definition Audio ALC262 \    --------------------------------> 1
|                                                                 \
| [x] vmix0-enable [vmix0-rate: 48.000kHz]      vmix0-channels    |--> 2
|                                               [ Stereo [v] ]    |
|                                                                 |
|  __codec1______________________________________________________ |
| |  _jack______________________________________________________ ||--> 3
| | |  _int-speaker_________________   _green_________________  |||
| | | |                             | |                       | |||
| | | |  _mode_____ | |             | |  _mode_____   | |     | |||
| | | | [ mix [v] ] o o [x] [ ]mute | | [ mix  [v] ]  o o [x] | |||
| | | |             | |             | |               | |     | |||
| | | |_____________________________| |_______________________| |||
| | |___________________________________________________________|||
| |______________________________________________________________||
| ___vmix0______________________________________________________  |
| |  __mocp___  O O   _firefox_  O O  __pcm7___  O O            | |--> 4
| | |         | O O  |         | x x |         | O O            | |
| | | | |     | x O  | | |     | x x | | |     | O O            | |
| | | o o [x] | x x  | o o [x] | x x | o o [x] | O O            | |
| | | | |     | x x  | | |     | x x | | |     | O O            | |
| | |_________| x x  |_________| x x |_________| O O            | |
| |_____________________________________________________________| |
  1. One tab for each sound card
  2. The vmix (virtual mixer) special configurations appear at the top. These include sampling rate and mixer priority.
  3. These are your sound card jack configurations (input and output). Every mixer control that is shown here is provided by your sound card.
  4. Application vmix mixer controls and sound meters. If the application isn't actively playing a sound it will be labeled pcm08, pcm09..., when the application is playing the application name will be shown.

Color Definitions

For high definition (HD) audio, Template:Codeline will color jack configurations by their pre-defined jack colors:

Color Type Connector
green front channels (stereo output) 3.5mm TRS
black rear channels (stereo output) 3.5mm TRS
grey side channels (stereo output) 3.5mm TRS
gold center and subwoofer (dual output) 3.5mm TRS
blue line level (stereo input) 3.5mm TRS
pink microphone (mono input) 3.5mm TS

Saving Mixer Levels

Mixer levels are saved when you shut off your computer. If you want to save the mixer level immediately, as root:

# savemixer

Template:Codeline can be used to write mixer levels to a file with the Template:Codeline switch and restore by the Template:Codeline switch.

Other Mixers

Other mixers that have support for OSS:

  • GNOME - Gnome volume control
  • KDE - Kmix - OSS support is being developed.

Configuring Applications for OSS


The skype package only includes support for ALSA. To get an OSS-capable Skype, install the skype-oss package:

# pacman -S skype-oss

If you are using x86_64, you can get the bin32-skype-oss package from AUR.


  • Run winecfg.
$ winecfg
  • Go to the Audio tab.
  • Select OSS Driver.


By default Gajim uses Template:Codeline to play a sound. To change this go in Advanced Settings and search for the Template:Codeline variable. The ossplay program included in the oss package is a good replacement:



To use MOC with OSS v4.1 you must change section OSSMixerDevice to OSSMixerDevice==/dev/ossmix in your config (located in /home/yourusername/.moc). And now MOC should work with OSS v4.1. Or you can compile moc-svn package from AUR (he got support for new vmix). For issue with interface change OSSMixerChannel===to OSSMixerChannel===Any channel and after start mocp press w (change to sofware mixex) that will help and you can change the volume power.

Applications that use Gstreamer

Remove pulseaudio and gstreamer*-pulse programs and libraries.

To change the gstreamer setting to output the sound to OSS instead of the default ALSA, run:


Change the Default Output plugin to custom and the change the pipeline to:


For the input:

Note: It's not certain that the input will sound better with oss4src compared to osssrc, so change this only if it improves your input sound. < confirmation on this please >

If you are using phonon with the gstreamer backend you will need to set the environmental variable. To add to your current user:

export PHONON_GST_AUDIOSINK=oss4sink

Add this to your Template:Filename to be loaded on login.

Firefox >=3.5

Firefox 3.5 introduces the <video> and <audio> tag support and can play ogg media out of the box. However, it currently can't be compiled with ALSA and OSS support at the same time. So you need to install the xulrunner-oss package.

1. Stop firefox.
2. Remove the xulrunner package without dependency check: sudo pacman -Rd xulrunner
3. Install xulrunner-oss package from AUR using yaourt or ABS.
4. Start firefox.


If you are using gui (smplayer etc.) you will find the oss output at the audio settings. Using on cli you should specify the sound output: mplayer -ao oss /some/file/to/play.mkv If you don't want to brother typing it over and over again add "ao=oss" to your config file. (/home/$USER/.mplayer/config)

Other applications


Troubleshooting HDAudio devices

Understanding why problems arise

If you have a HDAudio sound device, it's very likely that you will have to adjust some mixer settings before your sound works.

HDAudio devices are very powerful in the sense that they can contain a lot of small circuits (called widgets) that can be adjusted by software at any time. These controls are exposed to the mixer, and they can be used, for example, to turn the earphone jack into a sound input jack instead of a sound output jack.

However, there is a side effect, mainly because the HDAudio standard is more flexible than it perhaps should be, and because the vendors often only care to get their official drivers working.

Then, when using HDAudio devices, you often find disorganized mixer controls, that doesn't work at all by default, and you are forced to try every mixer control combination, until it works.

How to solve

Open ossxmix and try to change every mixer control in the middle area, that contains the sound card specific controls, as explained in the previous "The mixer" section.

You'll probably want to setup a program to record/play continously in the background (e.g. Template:Codeline for recording or Template:Codeline for playing), while changing mixer settings in ossxmix in the foreground.

  • Raise every volume control slider.
  • In each option box, try to change the selected option, trying all the possible combinations.
  • If you get noise, try to lower and/or mute some volume controls, until you find the source of the noise.

Please note again that you do not need to change any controls in the top area nor in the bottom area, as they are virtual vmix-related mixer controls.

  • Editing Template:Codeline uncommenting and changing hdaudio_noskip=0 to a value from 0-7 can give you more jack options in ossxmix

I had to edit mine to hdaudio_noskip=7 for my sub/rear speaker to work on my laptop, restart oss for the changes to take effect Template:Codeline

MMS sound cracking in totem

If your stream sounds with cracks or strange noise in totem like it did with me then you could try to play it with another backend like ffmpeg (mplayer). That "fixed" the issue for me. This will not fix the issue that somehow pops up in gstreamer when playing MMS streams but it will give you the option to play it with good sound quality. Playing it in mplayer is simple:

# mplayer mmsh://yourstreamurl

Microphone playing through output channels

OSS by default plays back the microphone through the speakers. To disable this in ossxmix find the misc section. Check off every "input-mix-mute" to disable this.

Troubleshooting other issues

  • If you get distorted sound, try lowering some volume control sliders.
  • If you need to change the default sound card, look at here.
  • If you have another issues, try searching or asking for help at the 4front forums.

Tips and tricks

Using multimedia keys with OSS

An easy way to mute/unmute and increase/decrease the volume is to use the Template:Codeline script available in AUR.

Once you installed it try to toggle the sound:

$ ossvol -t

Type Template:Codeline for the other commands.

If you don't know how to assign commands to your multimedia keys, see Extra Keyboard Keys.

Template:Codeline troubleshooting

If you get an error like:

Bad mixer control name(987) 'vol'

you need to edit the script (Template:Filename) and change the value of the Template:Codeline variable which is at the beginning of the script. For example mine is Template:Codeline.

  • Note if you are using xbindkeys for your multimedia keys adding this
"ossmix vmix0-outvol -- +1"

raise volume

"ossmix vmix0-outvol -- -1"

lower volume

to the raise/lower volume section of your .xbindkeysrc file is an easy way to adjust the volume

Changing the Sample Rate

Changing the output sample rate is not obvious at first. Sample rates can only be changed by the superuser and vmix must be unused by any programs when a change is requested. Before you follow any of these steps, ensure you are going through a receiver/amplifier and using quality speakers and not simply computer speakers. If you are only using computer speakers, don't bother changing anything here as you won't notice a difference.

By default the sample rate is 48000hz. There are several conditions in which you may want to change this. This all depends on your usage patterns. You want the sample rate you are using to match the media you use the most. If your computer has to change the sampling rate of the media to suit the hardware it is likely, though not guaranteed that you will have a loss in audio quality. This is most noticable in downsampling (ie. 96000hz → 48000hz). There is an article about this issue in "Stereophile" which was discussed on Apple's "CoreAudio API" mailing list if you wish to learn more about this issue.

Some example sample rates:

  • 44100hz - Sample rate of standard Red Book audio cds.
  • 88000hz - Sample rate of SACD high definition audio discs/downloads. It is rare that your motherboard will support this sample rate.
  • 96000hz - Sample rate of most high definition audio downloads. If your motherboard is an AC'97 motherboard, this is likely to be your highest bitrate.
  • 192000hz - Sample rate of BluRay, and some (very few) high definition downloads. Support for external audio reciever equipment is limited to high end audio. Not all motherboards support this. An example of a motherboard chipset that would support this includes Intel HDA audio.

To check what your sample rate is currently set to:

  1. Run "ossmix | grep rate".

You are likely to see "vmix0-rate <decimal value> (currently 48000) (Read-only)".

If you do not see a "vmix0-rate" (or "vmix1-rate", etc.) being outputted, than it probably means that vmix is disabled. In that case, OSS will use the rate requested by the program which uses the device, so this section doesn't apply. Exception: envy24(ht) cards have a setting envy24.rate which has a similiar function (see "oss_envy24" manpage). You can follow these steps, but at step 2, change with ossmix the value of "envy24.rate" as well.

Steps to affect the change:

  1. First, make sure your card is able to use the new rate. Run "ossinfo -v2" and see if the wanted rate is in the "Native sample rates" output.
  2. As root, run "/usr/lib/oss/scripts/killprocs.sh". Be aware, this will close any program that currently has an open sound channel (examples being media players, Firefox as of 3.5 if you have xulrunner-oss installed, and the gnome volume control).
  3. After all programs occupying vmix are terminated, run as root: "vmixctl rate /dev/dsp 96000" replacing the rate with your desired sample rate.
  4. Run "ossmix | grep rate" and check for "vmix0-rate <decimal value> (currently 96000) (Read-only)" to see if you were successful.

Changing the Default Sound Output

When running osstest, the first test passes for the first channel, but not for the stereo or right channel, it sounds distorted/hisses. If this is what your sound is like, then it's set to the wrong output.

      *** Scanning sound adapter #-1 ***
      /dev/oss/oss_hdaudio0/pcm0 (audio engine 0): HD Audio play front
      - Performing audio playback test... 
      <left> OK <right> OK <stereo> OK <measured srate 47991.00 Hz (-0.02%)> 

The left sounded good, the right and stereo were the distorted ones.

Let the test continue until you get a working output:

      /dev/oss/oss_hdaudio0/spdout0 (audio engine 5): HD Audio play spdif-out 
      - Performing audio playback test... 
      <left> OK <right> OK <stereo> OK <measured srate 47991.00 Hz (-0.02%)> 

If this passed the test on all left, right and stereo, proceed to next step.

So from here: Changing_the_default_sound_output you get the command to change the default output; change according to what works for you

      sudo ln -sf /dev/oss/oss_hdaudio0/spdout0 /dev/dsp_multich

With 5.1 surround, chose dsp_multichannel; with 2 channel, dsp should work.

Creative Sound Blaster X-Fi Surround 5.1 SB1090 USB

This information is completely from 4front-tech.com ; courtesy of kristian and Maxa. Thanks!!

It's surprising to learn that the external card does not work just because of a missing true return value in the function write_control_value(...) in ossusb_audio.c.

To fix this, a recompile of oss is nessasary, for now.

1. Grab the latest oss from the Arch Repo


2. Extract it

3. cd to the folder, I renamed the folder to oss

4. run makepkg --nobuild

5. cd to src/kernel/drv/oss_usb/ ; edit the ossusb_audio.c ; add a Return 1 ; should look like so and SAVE

  static int
 write_control_value (ossusb_devc * devc, udi_endpoint_handle_t * endpoint,
            int ctl, int l, unsigned int v)
   return 1;

6. do a makepkg --noextract

Now you must install the package with pacman -U ; remove oss first if already installed (pacman -Rd oss)

A simple systray applet

Want a applet to control volume like in GNOME? Form here I got a usable one.

Download this script and rename whatever you want, e.g.: ossvolctl. run the following command:

$chmod +x ossvolctl
#cp ossvolctl /usr/bin/ossvolctl


#install -Dm755 ossvolctl /usr/bin/ossvolctl

Start ossxmix docked to systray on startup


Create an application launcher file named ossxmix.desktop in you local application launchers directory (~/.local/share/applications/ then enter:

[Desktop Entry]
Name=Open Sound System Mixer
GenericName=Audio Mixer
Exec=ossxmix -b

To add it to autostart when loading the desktop environment:

System Settings > Advanced tab > Autostart. Then click add program and choose it from the 'Multimedia' list.


  • As Root create a file /usr/local/bin/ossxmix_bg with the following content:
exec /usr/bin/ossxmix -b

Goto System > Preferences > Start Up Applications

  • Click Add, Type OSSMIX in Name field and /usr/local/bin/ossxmix_bg in Command field then click Add button.
  • Login and Logout to see the changes.

Record sound output from a program

Suspend and Hibernation

OSS does not automatically support suspend meaning that OSS must be manually stopped prior to suspending or hibernating.

OSS provides soundon and soundoff to enable and disable OSS, although any processes that use sound must be terminated first.

The following script is a rather basic method of automatically unloading OSS prior to suspending and reloading afterwards.




case "$1" in
 *) exit $NA

Save the contents of the script (as root) into Template:Filename and make it executable. Template:Filename

Note: This script is rather basic and will terminate any application directly accessing OSS, save your work prior to suspending/hibernating.

OSS does not support suspending but we don't care or better s2ram works fine without stopping OSS. Just create a nice suspend script to /sbin/suspend and make it executable.


 if [ [ $EUID -ne 0 ] ]; then
 ## Checking if you are a root or not
   echo "This script must be run as root" 1>&2
   exit 1

 s2ram -f

 sleep 2

 /etc/rc.d/oss restart 2>/tmp/oss.txt

 if [ $? -gt 0 ]; then
 echo "OSS restart failed check /tmp/oss.txt for advice"

 exit 0

That's all your apps are fine and suspend works. \o/

Note: If you are using Opera you must kill operapluginwrapper before suspend. To do this add PID=`pidof operapluginwrapper`;kill -9 $PID before s2ram -f.

ALSA emulation

You can instruct alsa-lib to use OSS as its audio output system. This works as a sort of ALSA emulation.

Note, however, that this method may introduce additional latency in your sound output, and that the emulation is not complete and doesn't work with all applications. It doesn't work, for example, with programs that try to detect devices using ALSA.

So, as most applications support OSS directly, use this method only as a last resort.

In the future, more complete methods may be available for emulating ALSA, such as libsalsa and cuckoo.


  • Install the alsa-plugins package.
# pacman -S alsa-plugins
pcm.oss {
   type oss
    device /dev/dsp

pcm.!default {
    type oss
    device /dev/dsp

ctl.oss {
    type oss
    device /dev/mixer

ctl.!default {
    type oss
    device /dev/mixer
Note: If you don't want to use OSS anymore, don't forget to revert changes that you do here in Template:Filename.

Experimental packages

Mercurial repository version

There is a oss-mercurial package in AUR. This package compiles and installs the latest OSS development version direcly from the Mercurial repository.

You can try this package if you want to contribute code to OSS or if only a very recent change in OSS code introduced support to your sound device.

If you want oss to take care of your flash sound you will need to install libflashsupport:

# pacman -S libflashsupport