Table of Contents
Mixed Sound with ARTS and ALSA
A small HOWTO found at http://wiki.splitbrain.org/alsa and which I edited according to my own views. It explains to configure your system to play sounds from various applications simultanously. Think of applications like XMMS, GAIM, MPlayer and Firefox (with Flashplugin).
ALSA comes with a method to mix multiple sound streams which is called dmix. ALSA-enabled applications should be able to all access the device at the same time when it is set up. To do this you'll need to set up either a system-wide /etc/asound.conf
or a ~/.asoundrc
file in your home directory.
1.0.9b
, alsa-lib 1.0.9
and alsa-utils 1.0.9a
so I can't guarantee it will work out of the box. Slackware 11.0 howeverwill definitely not need the setup as described below!
/etc/asound.conf (1st version)
Here is an example /etc/asound.conf
which I took from http://alsa.opensrc.org/index.php?page=Dmix+Kde+-+arts%2C+ESD+and+SDL+quick+and+dirty+HOWTO . It works for me, but you might also want to have a look at the rest of this page.
pcm.ossmix { type dmix ipc_key 1027 # must be unique! slave { pcm "hw:0,0" # you cannot use a "plug" # device here, darn. period_time 0 period_size 1024 buffer_size 4096 #format "S32_LE" #periods 128 # dito. rate 44100 # with rate 8000 you *will* # hear, if ossmix is used :) } bindings { 0 0 # from 0 => to 0 1 1 # from 1 => to 1 } } pcm.!default { type plug slave.pcm "ossmix" } # mixer0 like above ctl.mixer0 { type hw card 0 }
/etc/asound.conf (2nd version)
The instructions at http://alsa.opensrc.org/index.php?page=asym are the source of what follows on the rest of this page. If the above does not work for you, you might want to take a look at the story below.
This is what /etc/asound.conf
could look like also:
#asym fun start here. we define one pcm device called "dmixed" pcm.dmixed { ipc_key 1025 type dmix slave { pcm "hw:0,0" period_time 0 period_size 1024 buffer_size 8192 rate 48000 } } #one called "dsnooped" for capturing pcm.dsnooped { ipc_key 1026 type dsnoop slave.pcm "hw:0,0" } #and this is the real magic pcm.asymed { type asym playback.pcm "dmixed" capture.pcm "dsnooped" } #a quick plug plugin for above device to do the converting magic. saves #typing when settng the pcm name in an alsa app pcm.pasymed { type plug slave.pcm "asymed" } #a ctl device to keep xmms happy ctl.pasymed { type hw card 0 } #here we try to point the aoss script to our asymed device pcm.dsp0 { type plug slave.pcm "asymed" } ctl.mixer0 { type hw card 0 } #this sets the default device pcm.!default { type plug slave.pcm "asymed" }
It's pretty much the same as decribed in the given link. However, a problem is to get applications to work with it that do not support ALSA.
ARTS
The solution to the above mentioned problems is to use a sound daemon, like KDE's ARTS.
Arts needs to be started on login. You can do that for instance from your ~/.xsession
file. Just add the following line before your the where your windowmanager gets started:
/opt/kde/bin/artsd -b 16 -r 48000 -a alsa -D asymed &
Application Setup
Firefox
To make firefox use the ARTS daemon we use a library wrapper called artsdsp
- so for running Firefox with ARTS just run the following command:
artsdsp firefox
To be sure it works install the Flash Plugin and try any Flash animation - like this cute kitten. If you don't hear sound then something is wrong.
XMMS
For xmms, you need to select the aRts-Output as output plugin in your Preferences.
GAIM
Also easy - in the Sound preferences tab, select Automatic as the Sound Method.
MPlayer
The MPlayer documentation says there is an arts
driver. Running
mplayer -ao help
shows something like this:
Available audio output drivers: mpegpes Mpeg-PES audio output oss OSS/ioctl audio output alsa9 ALSA-0.9.x audio output esd EsounD audio output sdl SDLlib audio output null Null audio output pcm RAW PCM/WAVE file writer audio output plugin Plugin audio output
Now the dmix feature configured above comes in handy again. We just use the asymed
device which is able to mix multiple sources. So it's possible to have both - ARTS with multiple Soundsources and MPlayer - accessing the same ALSA device.
Just add this to the ~/.mplayer/config
ao=alsa9:asymed #or ao=alsa1x ... srate=48000