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<?xml version="1.0" encoding="UTF-8"?>
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<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/alsa-guide.xml,v 1.42 2004/10/31 18:57:00 cam Exp $ -->
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<!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
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<guide link="/doc/en/alsa-guide.xml">
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<title>Gentoo Linux ALSA Guide</title>
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<author title="Author">
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<mail link="zu@pandora.be">Vincent Verleye</mail>
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</author>
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<author title="Author">
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<mail link="g2boojum@gentoo.org">Grant Goodyear</mail>
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</author>
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<author title="Author">
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<mail link="agenkin@gentoo.org">Arcady Genkin</mail>
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</author>
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<author title="Author">
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<mail link="eradicator@gentoo.org">Jeremy Huddleston</mail>
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</author>
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<author title="Editor"><!-- zhen@gentoo.org -->
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John P. Davis
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</author>
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<author title="Editor">
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<mail link="swift@gentoo.org">Sven Vermeulen</mail>
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</author>
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<author title="Editor">
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<mail link="bennyc@gentoo.org">Benny Chuang</mail>
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</author>
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<author title="Editor">
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<mail link="blubber@gentoo.org">Tiemo Kieft</mail>
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</author>
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<author title="Editor">
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<mail link="erwin@gentoo.org">Erwin</mail>
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</author>
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<abstract>
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This guide will show you how to set up the Advanced Linux Sound Architecture
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(ALSA) on Gentoo Linux. In addition to the Gentoo Linux Desktop Configuration
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Guide, this guide is supposed to give you more information on this subject.
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</abstract>
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<license/>
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<version>1.5.5</version>
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<date>2004-10-31</date>
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<chapter>
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<title>The Advanced Linux Sound Architecture</title>
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<section>
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<title>What is ALSA?</title>
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<body>
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<p>
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ALSA is the <e>Advanced Linux Sound Architecture</e>, a project dedicated to the
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development of a high-quality Linux sound subsystem. It has replaced OSS
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(<e>Open Sound System</e>) as default sound subsystem in the 2.6 kernel series.
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</p>
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<p>
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ALSA provides efficient support for all types of audio interfaces, is fully
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modularized, is SMP and thread-safe and provides a high-quality user space
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library called <e>alsa-lib</e> to simplify application programming. It also
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provides a backwards compatibility layer with OSS.
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</p>
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</body>
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</section>
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</chapter>
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<chapter>
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<title>Installing ALSA</title>
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<section>
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<title>USE Flags</title>
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<body>
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<p>
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Gentoo provides an <c>alsa</c> USE flag which you should set in
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<path>/etc/make.conf</path> to allow our available packages to compile with
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ALSA support. If you have <c>oss</c> in your USE variable as well, ALSA will
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compile with OSS backward compatibility.
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</p>
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</body>
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</section>
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<section>
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<title>Kernel Modules</title>
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<body>
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<p>
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First of all, before continuing, make sure your kernel has <e>Sound Card
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Support</e> enabled. If you used <c>genkernel</c> to build your kernel, then
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this is automatically true. Otherwise reconfigure your kernel.
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</p>
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<p>
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If you use a 2.6 kernel you can skip the rest of this section and continue with
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<uri link="#alsa-utils">Installing the ALSA Utils</uri> as 2.6 already has the
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necessary ALSA drivers in it. Of course, don't forget to enable support for the
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sound card you have when configuring your kernel.
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</p>
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<p>
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Users of 2.4 kernel sources will have to install the necessary ALSA drivers for
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their soundcard. First find out what soundcard you have. An easy trick is to
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search for "audio" in the output of the <c>lspci</c> command. You can install
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it with <c>emerge pciutils</c>.
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</p>
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<pre caption="Finding out the soundcard type">
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# <i>lspci | grep -i audio</i>
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Multimedia audio controller: VIA Technologies, Inc. VT82C686 AC97 Audio Controller (rev 64).
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</pre>
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<p>
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Now go to the <uri link="http://www.alsa-project.org/alsa-doc">ALSA Soundcard
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Matrix</uri> and search for your soundcard. In the above example you should go
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to the "VIA" manufacturer. You will receive a table with the known chipsets of
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that vendor. The chipset in the above example is "via82c686"; the "Details" link
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then informs me that the driver is called <path>via82xx</path>. This is all the
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information you need, so you can safely discard the rest of that document.
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</p>
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<p>
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Based on this information we can now install the <c>alsa-driver</c> for our
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soundcard. First edit <path>/etc/make.conf</path> and <e>add</e> a new option
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called ALSA_CARDS to it. Inside this variable you declare the soundcard driver
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you want to use:
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</p>
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<pre caption="Editing /etc/make.conf for ALSA_CARDS">
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ALSA_CARDS="via82xx"
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</pre>
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<p>
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Now install <c>alsa-driver</c>:
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</p>
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<pre caption="Installing ALSA Drivers">
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# <i>emerge alsa-driver</i>
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</pre>
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<impo>
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Whenever you (re)compile your kernel sources, chances are that the ALSA drivers
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will be overwritten. It is therefore adviseable to rerun <c>emerge
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alsa-driver</c> every time you (re)compile your kernel <e>after</e> having
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rebooted into the new kernel.
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</impo>
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</body>
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</section>
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<section id="alsa-utils">
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<title>Installing the ALSA Utils</title>
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<body>
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<p>
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If you want backwards compatibility with OSS, you need to install
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<c>alsa-oss</c>:
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</p>
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<pre caption="Installing the ALSA OSS compatibility layer">
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# <i>emerge alsa-oss</i>
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</pre>
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<p>
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Now install the ALSA Utils on your system (this is mandatory):
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</p>
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<pre caption="Installing ALSA Utils">
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# <i>emerge alsa-utils</i>
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</pre>
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<p>
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Now that the utils are installed, it is time to configure ALSA...
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</p>
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</body>
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</section>
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</chapter>
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<chapter>
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<title>Configuring ALSA</title>
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<section>
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<title>Automatically Loading the Kernel Modules</title>
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<body>
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<p>
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If you use a modular kernel (such as when using <c>genkernel</c>) you have to
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edit <path>/etc/modules.d/alsa</path> so that it activates the necesary modules
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at boot time. For the soundcard in our example:
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</p>
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<pre caption="/etc/modules.d/alsa">
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alias snd-card-0 snd-via82xx
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<comment># The following is only needed when you want OSS compatibility</comment>
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alias sound-slot-0 snd-card-0
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alias /dev/mixer snd-mixer-oss
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alias /dev/dsp snd-pcm-oss
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alias /dev/midi snd-seq-oss
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</pre>
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<p>
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Now run <c>modules-update</c> to save the changes you made to the
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<path>alsa</path> file into <path>/etc/modules.conf</path>:
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</p>
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<pre caption="Running modules-update">
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# <i>modules-update</i>
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</pre>
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</body>
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</section>
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<section>
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<title>Verifying the Device Files</title>
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<body>
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<p>
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If you use DevFS (which is the default for Gentoo installations) make sure that
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<path>/etc/devfsd.conf</path> has the ALSA devices and permissions correctly
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registered:
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</p>
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<pre caption="/etc/devfsd.conf">
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# ALSA/OSS stuff
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# Comment/change these if you want to change the permissions on
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# the audio devices
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LOOKUP snd MODLOAD ACTION snd
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LOOKUP dsp MODLOAD
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LOOKUP mixer MODLOAD
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LOOKUP midi MODLOAD
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REGISTER sound/.* PERMISSIONS root.audio 660
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REGISTER snd/.* PERMISSIONS root.audio 660
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</pre>
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</body>
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</section>
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<section>
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<title>Having ALSA Activated at Boot</title>
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<body>
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<p>
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To activate ALSA support at boot, add the <c>alsasound</c> init script to the
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boot runlevel:
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</p>
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<pre caption="Adding alsasound to the boot runlevel">
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# <i>rc-update add alsasound boot</i>
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# <i>/etc/init.d/alsasound start</i>
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</pre>
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</body>
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</section>
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<section>
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<title>Unmute the Channels</title>
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<body>
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<p>
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By default, all sound channels are muted. To fix this, run <c>amixer</c>:
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</p>
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<pre caption="Running amixer">
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# <i>amixer</i>
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</pre>
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<p>
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If <c>amixer</c> produces lots of output then you're ready to unmute the
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channels. If you receive an error, doublecheck that your soundcard module is
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started.
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</p>
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<p>
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Now unmute the <e>Master</e> and <e>PCM</e> channels. If this isn't sufficient,
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also unmute the <e>Center</e> and <e>Surround</e> channels.
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</p>
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<pre caption="Unmuting the sound channels">
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# <i>amixer set Master 100 unmute</i>
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# <i>amixer set PCM 100 unmute</i>
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<comment>(Only if the above isn't sufficient:)</comment>
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# <i>amixer set Center 100 unmute</i>
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# <i>amixer set Surround 100 unmute</i>
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</pre>
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<p>
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To check if your sound works, play a wave file (using <c>aplay</c>), mp3 (using
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<c>mpg123</c> or even <c>mplayer</c>) or any other sound file for that matter.
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</p>
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<p>
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To fine-tune the sound channel settings you can use the <c>alsamixer</c>
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application.
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</p>
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</body>
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</section>
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</chapter>
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<chapter>
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<title>Activating MIDI Support</title>
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<section>
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<title>Installing the Necessary Packages</title>
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<body>
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<p>
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Some soundcards come with onboard MIDI synthesizers. To use them, you must first
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install the <c>awesfx</c> package:
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</p>
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<pre caption="Installing the awesfx package">
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# <i>emerge awesfx</i>
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</pre>
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<p>
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If you have a collection of sound fonts somewhere, place them in
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<path>/usr/share/sfbank</path>. For instance, the SBLive has a sound font file
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called <path>8MBGMSFX.SF2</path> or <path>CT4GMSFX.SF2</path>.
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</p>
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<p>
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After copying over the sound font, select them using <c>asfxload</c>:
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</p>
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<pre caption="Loading the sound font">
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# <i>asfxload /usr/share/sfbank/8MBGMSFX.SF2</i>
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</pre>
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<p>
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You must have this command run every time you boot, so it is adviseable to add
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it to <path>/etc/conf.d/local.start</path> as well.
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</p>
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<p>
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If you can't find soundfonts on your driver CD you can download some online from
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<uri>http://www.parabola.demon.co.uk/alsa/awe64.html</uri>.
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</p>
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</body>
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</section>
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<section>
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<title>Timidity++ Virtual Synthesizer</title>
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<body>
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<p>
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If your sound card does not come with a hardware synthesizer (or you don't want
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to use it), you can use <c>timidity++</c> to provide you with a virtual
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synthesizer. Start by emerging this package:
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</p>
|
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<pre caption="Installing Timidity++">
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# <i>emerge timidity++</i>
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</pre>
|
| 347 |
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| 348 |
<p>
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| 349 |
For timidity to play sounds, it needs a soundfont. If you do not have any,
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install <c>timidity-eawpatches</c> which will give you some soundfonts.
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</p>
|
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<pre caption="Installing timidity-eawpatches">
|
| 354 |
# <i>emerge timidity-eawpatches</i>
|
| 355 |
</pre>
|
| 356 |
|
| 357 |
<p>
|
| 358 |
Don't forget to add <c>timidity</c> to the default runlevel.
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| 359 |
</p>
|
| 360 |
|
| 361 |
<pre caption="Adding timidity to the default runlevel">
|
| 362 |
# <i>rc-update add timidity default</i>
|
| 363 |
# <i>/etc/init.d/timidity start</i>
|
| 364 |
</pre>
|
| 365 |
|
| 366 |
</body>
|
| 367 |
</section>
|
| 368 |
<section>
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| 369 |
<title>Testing MIDI Support</title>
|
| 370 |
<body>
|
| 371 |
|
| 372 |
<p>
|
| 373 |
You can use <c>aplaymidi</c> from the ALSA Utils to test your MIDI
|
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configuration.
|
| 375 |
</p>
|
| 376 |
|
| 377 |
<p>
|
| 378 |
To see what MIDI output ports are available on your system, use the <c>-l</c>
|
| 379 |
option:
|
| 380 |
</p>
|
| 381 |
|
| 382 |
<pre caption="Viewing the MIDI output ports">
|
| 383 |
# <i>aplaymidi -l</i>
|
| 384 |
</pre>
|
| 385 |
|
| 386 |
<p>
|
| 387 |
If all looks fine, try playing a MIDI file to make sure everything works. With
|
| 388 |
the <c>-p</c> option you define what MIDI port you want to use.
|
| 389 |
</p>
|
| 390 |
|
| 391 |
<pre caption="Playing a MIDI file">
|
| 392 |
# <i>aplaymidi -p 65:0 "Final Fantasy 7 - Aerith' Theme.mid"</i>
|
| 393 |
</pre>
|
| 394 |
|
| 395 |
</body>
|
| 396 |
</section>
|
| 397 |
</chapter>
|
| 398 |
<chapter>
|
| 399 |
<title>Final Remarks</title>
|
| 400 |
<section>
|
| 401 |
<title>Tools and Firmware</title>
|
| 402 |
<body>
|
| 403 |
|
| 404 |
<p>
|
| 405 |
Some specific sound cards can benefit from certain tools provided by the
|
| 406 |
<c>alsa-tools</c> and <c>alsa-firmware</c> packages. If you need
|
| 407 |
<c>alsa-tools</c>, be sure to define the ALSA_TOOLS variable in
|
| 408 |
<path>/etc/make.conf</path> with the tools you require. For instance:
|
| 409 |
</p>
|
| 410 |
|
| 411 |
<pre caption="Selecting ALSA Tools in /etc/make.conf">
|
| 412 |
ALSA_TOOLS="as10k1 ac3dec"
|
| 413 |
</pre>
|
| 414 |
|
| 415 |
<p>
|
| 416 |
Then install the <c>alsa-tools</c> (and/or <c>alsa-firmware</c>) package(s):
|
| 417 |
</p>
|
| 418 |
|
| 419 |
<pre caption="Installing ALSA Tools">
|
| 420 |
# <i>emerge alsa-tools</i>
|
| 421 |
</pre>
|
| 422 |
|
| 423 |
</body>
|
| 424 |
</section>
|
| 425 |
<section>
|
| 426 |
<title>Activating Joystick Support</title>
|
| 427 |
<body>
|
| 428 |
|
| 429 |
<p>
|
| 430 |
If your soundcard has a joystick plug, you might be interested in activating
|
| 431 |
joystick support for your soundcard. If so, start by verifying if your soundcard
|
| 432 |
driver has a joystick parameter. You can verify this by running <c>modinfo</c>
|
| 433 |
against your kernel module. For instance, for the <c>snd-via82xx</c>:
|
| 434 |
</p>
|
| 435 |
|
| 436 |
<pre caption="Running modinfo">
|
| 437 |
# <i>modinfo snd-via82xx</i>
|
| 438 |
filename: /lib/modules/2.4.22-ck2/snd-via82xx.o
|
| 439 |
description: "VIA VT82xx audio"
|
| 440 |
author: "Jaroslav Kysela <perex@suse.cz>"
|
| 441 |
license: "GPL"
|
| 442 |
parm: index int array (min = 1, max = 8), description "Index value for
|
| 443 |
VIA 82xx bridge."
|
| 444 |
parm: id string array (min = 1, max = 8), description "ID string for VIA
|
| 445 |
82xx bridge."
|
| 446 |
parm: enable int array (min = 1, max = 8), description "Enable audio part
|
| 447 |
of VIA 82xx bridge."
|
| 448 |
parm: mpu_port long array (min = 1, max = 8), description "MPU-401 port.
|
| 449 |
(VT82C686x only)"
|
| 450 |
<i>parm: joystick int array (min = 1, max = 8), description "Enable
|
| 451 |
joystick. (VT82C686x only)"</i>
|
| 452 |
parm: ac97_clock int array (min = 1, max = 8), description "AC'97 codec
|
| 453 |
clock (default 48000Hz)."
|
| 454 |
parm: dxs_support int array (min = 1, max = 8), description "Support for
|
| 455 |
DXS channels (0 = auto, 1 = enable, 2 = disable, 3 = 48k only, 4 =
|
| 456 |
no VRA)
|
| 457 |
</pre>
|
| 458 |
|
| 459 |
<p>
|
| 460 |
If it has the <c>joystick</c> parameter, append <c>joystick=1</c> to your
|
| 461 |
<c>options</c> line in <path>/etc/modules.d/alsa</path>. For instance:
|
| 462 |
</p>
|
| 463 |
|
| 464 |
<pre caption="Adding the joystick parameter">
|
| 465 |
alias snd-card-0 snd-via82xx
|
| 466 |
options snd-via82xx joystick=1
|
| 467 |
</pre>
|
| 468 |
|
| 469 |
</body>
|
| 470 |
</section>
|
| 471 |
<section>
|
| 472 |
<title>Resources</title>
|
| 473 |
<body>
|
| 474 |
|
| 475 |
<ul>
|
| 476 |
<li><uri link="http://www.alsa-project.org">The ALSA Project</uri></li>
|
| 477 |
<li><uri link="http://www.djcj.org">ALSA Howto's and FAQs</uri></li>
|
| 478 |
<li><uri link="http://linux-sound.org">Linux Sound/MIDI Software</uri></li>
|
| 479 |
</ul>
|
| 480 |
|
| 481 |
</body>
|
| 482 |
</section>
|
| 483 |
</chapter>
|
| 484 |
</guide>
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