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1	<?xml version='1.0' encoding="UTF-8"?>	1	<?xml version='1.0' encoding="UTF-8"?>
		2	<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/alsa-guide.xml,v 1.83 2009/08/05 15:43:12 nightmorph Exp $ -->
		3
2	<!DOCTYPE guide SYSTEM "/dtd/guide.dtd">	4	<!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
3		5
4	<guide link = "/doc/en/alsa-guide.xml">	6	<guide link="/doc/en/alsa-guide.xml">
5	<title>Gentoo Linux ALSA Guide</title>	7	<title>Gentoo Linux ALSA Guide</title>
6	<author title="Author"><mail link="zu@pandora.be">	8
7	Vincent Verleye</mail>	9	<author title="Author">
		10	<mail link="fox2mike@gentoo.org">Shyam Mani</mail>
8	</author>	11	</author>
9	<author title="Author"><mail link="g2boojum@gentoo.org">	12	<author title="Author">
10	Grant Goodyear</mail>	13	<mail link="nightmorph@gentoo.org">Joshua Saddler</mail>
11	</author>	14	</author>
12	<author title="Author"><mail link="agenkin@gentoo.org">	15	<author title="Contributor">
13	Arcady Genkin</mail>	16	<mail link="flameeyes@gentoo.org">Diego Pettenò</mail>
14	</author>	17	</author>
15	<author title="Editor"><mail link="zhen@gentoo.org">
16	John P. Davis</mail>
17	</author>
18	<author title="Editor"><mail link="swift@gentoo.org">
19	Sven Vermeulen</mail>
20	</author>
21	<author title="Editor"><mail link="bennyc@gentoo.org">
22	Benny Chuang</mail>
23	</author>
24	<author title="Editor"><mail link="blubber@gentoo.org">
25	Tiemo Kieft</mail>
26	</author>
27		18
		19	<abstract>
		20	This document helps a user setup ALSA on Gentoo Linux.
		21	</abstract>
		22
		23	<!-- The content of this document is licensed under the CC-BY-SA license -->
		24	<!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
28	<license/>	25	<license/>
29		26
30	<abstract>
31	This guide will show you how to set up the Advanced Linux Sound Architecture (ALSA) on Gentoo Linux.
32	In addition to the Gentoo Linux Desktop Configuration Guide, this guide is supposed to give you more information on this subject. </abstract>
33
34	<version>1.3.3</version>	27	<version>2.25</version>
35	<date>October 9, 2003</date>	28	<date>2009-08-05</date>
36		29
37	<chapter>	30	<chapter>
38	<title>Introduction</title>	31	<title>Introduction</title>
39	<section>	32	<section>
40	<title>What is ALSA?</title>	33	<title>What is ALSA?</title>
		34	<body>
		35
		36	<p>
		37	ALSA, which stands for <e>Advanced Linux Sound Architecture</e>, provides
		38	audio and MIDI (<e>Musical Instrument Digital Interface</e>) functionality to
		39	the Linux operating system. ALSA is the default sound subsystem in the 2.6
		40	kernel thereby replacing OSS (<e>Open Sound System</e>), which was used in the
		41	2.4 kernels.
		42	</p>
		43
		44	<p>
		45	ALSA's main features include efficient support for all types of audio
		46	interfaces ranging from consumer sound cards to professional sound
		47	equipment, fully modularized drivers, SMP and thread safety, backward
		48	compatibility with OSS and a user-space library <c>alsa-lib</c> to make
		49	application development a breeze.
		50	</p>
		51
41	<body>	52	</body>
42	<p>	53	</section>
43	The Advanced Linux Sound Architecture (ALSA) is a project to improve the Linux sound subsystem by rewriting	54	<section>
44	large chunks of it.	55	<title>ALSA on Gentoo</title>
45	It is anticipated that ALSA will make it into Linux kernel 2.6.x (or 3.x.x -- whichever comes first) as it becomes ready.	56	<body>
		57
46	</p>	58	<p>
47		59	Historically, Gentoo offered two ways to get ALSA up and running: the
		60	<e>in-kernel</e> driver and the external <c>alsa-driver</c> package. The two
		61	solutions essentially do the same thing; this made supporting the external
		62	package extremely difficult and time-consuming. The Gentoo maintainers decided
		63	to discontinue support for the <c>alsa-driver</c> package, concentrating their
		64	resources on the ALSA drivers available within the Linux kernel. This guide will
		65	focus solely on configuring ALSA via the in-kernel driver.
48	<p>	66	</p>
49	ALSA provides audio and MIDI functionality for Linux.	67
50	</p>	68	<p>
51		69	If you still require the <c>alsa-driver</c> package, please email the <mail
		70	link="alsa-bugs@gentoo.org">Gentoo ALSA maintainers</mail> with why the
		71	in-kernel drivers don't work for you. Be sure to include detailed error logs.
52	<p>	72	</p>
53	Quoted from <uri>http://www.alsa-project.org</uri>, ALSA has the following features:	73
54	<ul><li> Efficient support for all types of audio interfaces, from consumer soundcards to professional multichannel audio interfaces.</li>	74	</body>
55	<li> Fully modularized sound drivers.</li>	75	</section>
56	<li> SMP and thread-safe design.</li>	76	</chapter>
57	<li> User space library (alsa-lib) to simplify application programming and provide higher level functionality.</li>	77
58	<li> Support for the older OSS API, providing binary compatibility for most OSS programs.</li>	78	<chapter>
		79	<title>Installing ALSA</title>
		80	<section id="lspci">
		81	<title>Before you proceed</title>
		82	<body>
		83
		84	<p>
		85	First, you need to know what drivers your sound card uses. In most cases, sound
		86	cards (onboard and otherwise) are PCI based and <c>lspci</c> will help you in
		87	digging out the required information. Please <c>emerge sys-apps/pciutils</c> to
		88	get <c>lspci</c>, if you don't have it installed already. In case you have a USB
		89	sound card, <c>lsusb</c> from <c>sys-apps/usbutils</c> <e>might</e> be of help.
		90	For ISA cards, try using <c>sys-apps/isapnptools</c>. Also, the following pages
		91	<e>may</e> help users with ISA based sound cards:
		92	</p>
		93
		94	<ul>
		95	<li>
		96	<uri link="http://www.roestock.demon.co.uk/isapnptools/">The ISAPNPTOOLS
		97	Page</uri>
		98	</li>
		99	<li>
		100	<uri link="http://www2.linuxjournal.com/article/3269">LinuxJournal PnP
		101	Article</uri>
		102	</li>
		103	<li>
		104	<uri link="http://www.tldp.org/HOWTO/Sound-HOWTO/x320.html">TLDP Sound
		105	HowTo</uri>
		106	</li>
59	</ul>	107	</ul>
60	There's lots more to ALSA however, like support for Full Duplex playback and recording, multiple soundcard support,	108
61	hardware mixing of streams, extensive mixer capabilities (to support advanced features of new soundcards), ...	109	<note>
		110	For ease of use/explanation, we assume the user has a PCI based sound card for
		111	the remainder of this guide.
		112	</note>
		113
62	</p>	114	<p>
		115	We now proceed to find out details about the sound card.
		116	</p>
		117
		118	<pre caption="Soundcard Details">
		119	# <i>lspci -v \| grep -i audio</i>
		120	0000:00:0a.0 Multimedia audio controller: Creative Labs SB Live! EMU10k1 (rev 06)
		121	</pre>
		122
		123	<p>
		124	We now know that the sound card on the machine is a Sound Blaster Live! and the
		125	card manufacturer is Creative Labs. Head over to the <uri
		126	link="http://bugtrack.alsa-project.org/main/index.php/Matrix:Main">ALSA
		127	Soundcard Matrix</uri> page and select Creative Labs from the list. You will
		128	be taken to the Creative Labs matrix page where you can see that the SB Live!
		129	uses the <c>emu10k1</c> module. That is the information we need for now. If
		130	you are interested in detailed information, you can click on the link next to
		131	the "Details" and that will take you to the <c>emu10k1</c> specific page.
		132	</p>
		133
		134	<p>
		135	If you intend to use MIDI, then you should add <c>midi</c> to your USE flags in
		136	<path>/etc/make.conf</path> before emerging any ALSA packages. Later in the
		137	guide, we will show you how to set up <uri link="#midi">MIDI support</uri>.
		138	</p>
		139
63	</body>	140	</body>
64	</section>
65	<section>	141	</section>
66	<title>Why use ALSA?</title>	142	<section id="kernel">
67	<body>	143	<title>Configuring the kernel</title>
68	<p>
69	If your soundcard is supported by the Linux kernel sound system or the commercial OSS/4Front sound driver system,
70	which can be found in all 2.4.x Linux kernels, you could just aswell build <e>those modules</e> for use with your soundcard.
71	If you want this, just read through the <uri link="http://www.tldp.org/HOWTO/Sound-HOWTO/index.html">Linux Sound HOWTO</uri>.
72	</p>
73	<p>
74	However, those OSS/4Front drivers have some limitations -- being commercial is one.
75	ALSA is an attempt to go beyond these limitations and to do so in an open source fashion.
76	ALSA is a fully GPL and LGPL'ed sound driver system, that provides a professional quality system for recording, playback,
77	and MIDI sequencing.
78	</p>
79	</body>	144	<body>
80	</section>	145
81	<section>	146	<note>
82	<title>What cards does ALSA support?</title>	147	Since the 2005.0 release, Gentoo Linux uses 2.6 as the default kernel. Please
83	<body>	148	check that your kernel is a 2.6 series kernel. This method will <e>not</e> work
84	<p>	149	on a 2.4 kernel.
85	ALSA tries to support as many (new) cards as possible by providing open-source drivers.	150	</note>
86	However, some vendors may provide binary-only packages.	151
87	</p>	152	<p>
88	<p>To know if your card is supported, you can find a Soundcard Matrix of supported and not-supported cards here:	153	Let us now configure the kernel to enable ALSA.
89	<uri>http://www.alsa-project.org/alsa-doc/</uri>.	154	</p>
		155
		156	<impo>
		157	<c>genkernel</c> users should now run <c>genkernel --menuconfig all</c> and
		158	then follow the instructions in <uri link="#doc_chap2_pre3">Kernel Options for
		159	ALSA</uri>.
		160	</impo>
		161
		162	<pre caption="Heading over to the source">
		163	# <i>cd /usr/src/linux</i>
		164	# <i>make menuconfig</i>
		165	</pre>
		166
		167	<note>
		168	The above example assumes that <path>/usr/src/linux</path> symlink points to
		169	the kernel sources you want to use. Please ensure the same before proceeding.
		170	</note>
		171
90	</p>	172	<p>
		173	Now we will look at some of the options we will have to enable in the 2.6
		174	kernel to ensure proper ALSA support for our sound card.
		175	</p>
		176
		177	<p>
		178	Please note that for ease of use, all examples show ALSA built as modules. It
		179	is advisable to follow the same as it then allows the use of <c>alsaconf</c>
		180	which is a boon when you want to configure your card. Please do <e>not</e> skip
		181	the <uri link="#alsa-config">Configuration</uri> section of this document. If
		182	you still like to have options built-in, ensure that you make changes to your
		183	config accordingly.
		184	</p>
		185
		186	<pre caption="Kernel Options for ALSA">
		187	Device Drivers --->
		188	Sound --->
		189
		190	<comment>(This needs to be enabled)</comment>
		191	<M> Sound card support
		192
		193	<comment>(Make sure OSS is disabled)</comment>
		194	Open Sound System --->
		195	< > Open Sound System (DEPRECATED)
		196
		197	<comment>(Move one step back and enter ALSA)</comment>
		198	Advanced Linux Sound Architecture --->
		199	<M> Advanced Linux Sound Architecture
		200	<comment>(Select this if you want MIDI sequencing and routing)</comment>
		201	<M> Sequencer support
		202	<comment>(Old style /dev/mixer* and /dev/dsp* support. Recommended.)</comment>
		203	<M> OSS Mixer API
		204	<M> OSS PCM (digital audio) API
		205
		206	<comment>(You now have a choice of devices to enable support for. Generally,
		207	you will have one type of device and not more. If you have more than one
		208	sound card, please enable them all here.)</comment>
		209
		210	<comment>(Mostly for testing and development purposes, not needed for normal
		211	users unless you know what you are doing.)</comment>
		212	Generic devices --->
		213
		214	<comment>(For ISA Sound cards)</comment>
		215	ISA devices --->
		216	<comment>(IF you had the Gravis, you would select this option)</comment>
		217	<M> Gravis UltraSound Extreme
		218
		219	<comment>(Move one level back and into PCI devices. Most sound cards today are
		220	PCI devices)</comment>
		221	PCI devices --->
		222	<comment>(We now select the emu10k1 driver for our card)</comment>
		223	<M> Emu10k1 (SB Live!, Audigy, E-mu APS)
		224	<comment>(Or an Intel card would be)</comment>
		225	<M> Intel/SiS/nVidia/AMD/ALi AC97 Controller
		226	<comment>(Or if you have a VIA Card)</comment>
		227	<M> VIA 82C686A/B, 8233/8235 AC97 Controller
		228
		229	<comment>(Move one level back and select in case you have an USB sound card)</comment>
		230	USB Devices --->
		231	</pre>
		232
		233	<p>
		234	Now that your options are set, you can (re)compile the kernel and ALSA support
		235	for your card should be functional once you reboot into the new kernel. Don't
		236	forget to update your GRUB configuration to use the newly built kernel.
		237	You can now proceed to <uri link="#alsa-utilities">ALSA Utilities</uri> and
		238	see if everything is working as it should.
		239	</p>
		240
91	</body>	241	</body>
92	</section>	242	</section>
93	</chapter>	243	</chapter>
94		244
95	<chapter>	245	<chapter>
96	<title>Installation</title>	246	<title>Configuring/Testing ALSA</title>
97	<section>	247	<section id="alsa-utilities">
98	<title>Gentoo USE flags</title>	248	<title>ALSA Utilities</title>
99	<body>
100
101	<p>
102	To compile programs with ALSA-support, be sure to add <e>alsa</e> to
103	your USE-variable. However, several tools don't support alsa yet, and
104	require OSS. ALSA provides OSS-emulation if you define <e>oss</e> in your
105	USE-variable before you start.
106	</p>
107
108	</body>	249	<body>
109	</section>
110		250
111	<section>
112	<title>Kernel modules</title>
113	<body>
114	<p>
115	Since we're still using 2.4.x kernel sources, we'll have to compile kernel modules and ALSA modules separately. People who are using a 2.5.x kernel can do this from within their kernel configuration, since the ALSA modules are included in the kernel sources and should be built there.
116	</p>	251	<p>
		252	<c>alsa-utils</c> forms an integral part of ALSA as it has a truckload of
		253	programs that are highly useful, including the ALSA Initscripts. Hence we
		254	strongly recommend that you install <c>alsa-utils</c>
117	<p>	255	</p>
118	First we'll make sure that our kernel configuration is ready for use with ALSA.	256
119	All you need in your kernel configuration is having Sound Card Support set to be built as a module (M).	257	<pre caption="Install alsa-utils">
120	This will build <c>soundcore.o</c>.	258	# <i>emerge alsa-utils</i>
121	</p>	259	</pre>
122	<p>	260
123	<note>	261	<note>
124	Possibly, this will also work when you built Sound Card Support in the kernel (Y) instead of building it as a module (M).	262	If you did <e>not</e> compile ALSA as modules, please proceed to the <uri
125	However, the official ALSA documentation suggests building it as a module, since ALSA will try loading it.	263	link="#initscript">ALSA Initscript</uri> section. The rest of you need to
		264	configure ALSA. This is made very easy by the existence of the <c>alsaconf</c>
		265	tool provided by <c>alsa-utils</c>.
126	</note>	266	</note>
		267
		268	</body>
		269	</section>
		270	<section id="alsa-config">
		271	<title>Configuration</title>
		272	<body>
		273
127	</p>	274	<p>
128	<p>If you already have a working kernel configuration, make sure you remove all sound drivers (except for Sound Card Support).	275	Recent versions of <c>udev</c> (<c>>=udev-103</c>) provide some degree of
129	If you wish to do this without having to reboot, you could do like this:	276	kernel-level autoconfiguration of your sound card. If possible, try to rely on
130	</p>	277	just letting your kernel automatically setup your sound card for you. Otherwise,
131	<pre>	278	use <c>alsaconf</c> to configure your card, as shown below.
132	# <i>cd /usr/src/linux</i>
133	# <i>cp .config ~/</i>
134	# <i>make mrproper</i>
135	# <i>cp ~/.config .</i>
136	# <i>make menuconfig</i>
137	</pre>
138	<p>	279	</p>
139	Now select <e>Sound Card Support</e> as Module (M) and deselect all other sound drivers.	280
140	Exit and say Y to save your kernel configuration.	281	<note>
141	After that, build the modules:	282	Please shut down any programs that <e>might</e> access the sound card while
142	</p>	283	running <c>alsaconf</c>.
143	<pre>
144	# <i>make dep clean</i>
145	# <i>make modules modules_install</i>
146	</pre>
147	<p>
148	Before installing your new modules, this last line will delete all your previous modules,
149	even the ones from a previous ALSA installation.
150	</p>
151	<p>
152	<impo>
153	This means, whenever you recompile your kernel later on, you MUST recompile <c>alsa-driver</c>.
154	</impo>
155	</p>
156	<p>
157	<note>However, there's no need to reinstall <c>nvidia-kernel</c>, the Nvidia drivers are in a separate directory
158	in <path>/lib/modules/*/video</path> and won't get deleted by a <c>make modules modules_install</c>
159	</note>	284	</note>
		285
160	</p>	286	<p>
161	</body>	287	To configure your sound card just type <c>alsaconf</c> in a shell as root.
162	</section>	288	</p>
163		289
		290	<pre caption="Invoking alsaconf">
		291	# <i>alsaconf</i>
		292	</pre>
		293
		294	<p>
		295	You will now see a neat menu guided interface that will automatically probe
		296	your devices and try to find out your sound card. You will be asked to pick
		297	your sound card from a list. Once that's done, it will ask you permission to
		298	automatically make required changes to <path>/etc/modprobe.d/alsa.conf</path>.
		299	It will then adjust your volume settings to optimum levels, run
		300	<c>update-modules</c> and start the <path>/etc/init.d/alsasound</path> service.
		301	Once <c>alsaconf</c> exits, you can proceed with setting up the ALSA
		302	initscript.
		303	</p>
		304
		305	</body>
164	<section>	306	</section>
165	<title>ALSA modules</title>	307	<section id="initscript">
		308	<title>ALSA Initscript</title>
		309	<body>
		310
		311	<p>
		312	We're now almost all setup. Whichever method you chose to install ALSA, you'll
		313	need to have something load your modules or initialize ALSA and restore your
		314	volume settings when your system comes up. The ALSA Initscript handles all of
		315	this for you and is called <c>alsasound</c>. Add it to the boot runlevel.
		316	</p>
		317
		318	<pre caption="Adding ALSA to the boot runlevel">
		319	# <i>rc-update add alsasound boot</i>
		320	* alsasound added to runlevel boot
		321	* rc-update complete.
		322	</pre>
		323
		324	<p>
		325	Next, just check the <path>/etc/conf.d/alsasound</path> file and ensure that
		326	SAVE_ON_STOP variable is set to yes. This saves your sound settings when you
		327	shutdown your system.
		328	</p>
		329
166	<body>	330	</body>
		331	</section>
		332	<section>
		333	<title>Audio Group</title>
		334	<body>
167		335
168	<p>
169	Now it's time to install the ALSA drivers for your soundcard(s). If your soundcard is PCI, you can find out the name
170	and type of your soundcard by looking at the output of /proc/pci.
171	</p>	336	<p>
		337	Before we move on to testing, there's one last <e>important</e> thing that needs
		338	to be setup. Rule of thumb in a *nix OS: Do not run as root unless needed.
		339	This applies here as well ;) How? Well, most of the times you should be logged
		340	in as a user and would like to listen to music or access your soundcard. For
		341	that to happen, you need to be in the "audio" group. At this point, we'll add
		342	users to the audio group, so that they won't have any issues when they want to
		343	access sound devices. We'll use <c>gpasswd</c> here and you need to be logged in
		344	as root for this to work.
		345	</p>
		346
		347	<pre caption="Adding users to the audio group">
		348	<comment>(Substitute <username> with your user)</comment>
		349	# <i>gpasswd -a <username> audio </i>
		350	Adding user <username> to group audio
172	<pre>	351	</pre>
173	# <i>grep audio /proc/pci</i>
174	</pre>
175		352
		353	</body>
		354	</section>
		355	<section>
		356	<title>Volume Check!</title>
		357	<body>
176		358
		359	<p>
		360	We've completed all the setups and prerequisites, so let's fire up ALSA. If
		361	you ran <c>alsaconf</c>, you can skip this step, since <c>alsaconf</c> already
		362	does this for you.
177	<p>	363	</p>
		364
		365	<pre caption="Start the service">
		366	# <i>/etc/init.d/alsasound start</i>
		367	</pre>
		368
		369	<p>
		370	Now that the required things have been taken care of, we need to check up on
		371	the volume as in certain cases, it is muted. We use <c>alsamixer</c> for this
		372	purpose.
		373	</p>
		374
		375	<pre caption="Starting alsamixer">
		376	<comment>(Opens up a console program. Only required settings are shown)</comment>
		377	# <i>alsamixer</i>
		378	</pre>
		379
		380	<p>
		381	This is how the ALSA Mixer <e>might</e> look the first time you open it. Pay
		382	attention to the Master and PCM channels which both have an MM below them.
		383	That means they are muted. If you try to play anything with <c>alsamixer</c>
		384	in this state, you will not hear anything on your speakers.
		385	</p>
		386
		387	<figure link="/images/docs/alsa-mixermuted.png" short="AlsaMixer Muted" caption="The Alsa Mixer Main Window, Muted"/>
		388
		389	<p>
		390	Now, we shall unmute the channels, and set volume levels as needed.
		391	</p>
		392
178	<warn>	393	<warn>
179	If you had a previous sound setup and there are still non-ALSA sound modules loaded, unload them <e>now</e>.	394	Both Master <e>and</e> PCM need to be unmuted and set to audible volume levels
180	Check with <c>lsmod</c> and use <c>rmmod</c> to unload all sound-related modules on your system.	395	if you want to hear some output on your speakers.
181	</warn>	396	</warn>
182	</p>
183		397
184	<p>	398	<ul>
185	We could simply do an <c>emerge alsa-driver</c> now, this would compile and install <e>all</e> ALSA sound drivers.	399	<li>
186	</p>	400	To move between channels, use your left and right arrow keys. (<-
187	<p>	401	& ->)
188	However, to save some time, lookup the <e>Module Name</e> of your soundcard(s) on the	402	</li>
189	<uri link="http://www.alsa-project.org/alsa-doc">ALSA Soundcard Matrix</uri> by following the <e>Details</e> link in the <e>Driver and Docs</e> column in the row of the chipset of your soundcard.	403	<li>
190	Mine is <c>snd-emu10k1</c>, since I have an SBlive! soundcard, with the <e>EMU10K1</e> chipset.	404	To toggle mute, move to the specific channel, for example Master and press
191	We'll set ALSA_CARDS environment to the value of the module name before emerging (but without the snd prefix), so emerge will only compile the drivers we need.	405	the <e>m</e> key on the keyboard.
192	</p>	406	</li>
		407	<li>
		408	To increase and decrease the volume levels, use the up and down arrow keys
		409	respectively.
		410	</li>
		411	</ul>
193		412
194	<pre>
195	# <i>env ALSA_CARDS='emu10k1' emerge alsa-driver</i>
196	</pre>
197	<note>	413	<note>
198	You can also add this value in <path>/etc/make.conf</path>, so when you have to emerge the alsa-driver later on you can just run <c>emerge alsa-driver</c>.	414	Be careful when setting your Bass and Treble values. 50 is usually a good
199	For example, like this: <c>echo 'ALSA_CARDS="emu10k1"' >> /etc/make.conf</c>	415	number for both. Extremely high values of Bass may cause <e>jarring</e>
		416	on speakers that are not designed to handle them.
200	</note>	417	</note>
201		418
		419	<p>
		420	After you're all done, your ALSA Mixer should look similar to the one below.
		421	Note the 00 instead of the MM and also the volume levels for some optimum
		422	settings.
		423	</p>
		424
		425	<figure link="/images/docs/alsa-mixerunmuted.png" short="AlsaMixer Unmuted" caption="Alsa Mixer ready to roll"/>
		426
		427	</body>
		428	</section>
		429	<section>
		430	<title>Sound Check!</title>
		431	<body>
		432
		433	<p>
		434	Finally. Some music. If everything above is perfect, you should now be able to
		435	listen to some good music. A quick way to test is to use a command line tool
		436	like <c>media-sound/madplay</c>. You could also use something more well known
		437	like <c>mpg123</c>. If you are an ogg fan, you could use <c>ogg123</c> provided
		438	by <c>media-sound/vorbis-tools</c>. Use any player you are comfortable with. As
		439	always, <c>emerge</c> what you need.
		440	</p>
		441
		442	<pre caption="Getting the software">
		443	<comment>(Install the applications you want)</comment>
		444	# <i>emerge madplay mpg123</i>
		445	<comment>(To play .ogg files)</comment>
		446	# <i>emerge vorbis-tools</i>
		447	</pre>
		448
		449	<p>
		450	And then play your favorite sound track...
		451	</p>
		452
		453	<pre caption="Playing Music">
		454	# <i>madplay -v /mnt/shyam/Music/Paul\ Oakenfold\ -\ Dread\ Rock.mp3</i>
		455	MPEG Audio Decoder 0.15.2 (beta) - Copyright (C) 2000-2004 Robert Leslie et al.
		456	Title: Dread Rock
		457	Artist: Paul Oakenfold
		458	Album: Matrix Reloaded
		459	Year: 2003
		460	Genre: Soundtrack
		461	Soundtrack
		462	00:04:19 Layer III, 160 kbps, 44100 Hz, joint stereo (MS), no CRC
		463
		464	# <i>ogg123 Paul\ Oakenfold\ -\ Dread\ Rock.ogg</i>
		465	Audio Device: Advanced Linux Sound Architecture (ALSA) output
		466
		467	Playing: Paul Oakenfold - Dread Rock.ogg
		468	Ogg Vorbis stream: 2 channel, 44100 Hz
		469	Genre: Soundtrack
		470	Transcoded: mp3;160
		471	Title: Dread Rock
		472	Artist: Paul Oakenfold
		473	Date: 2003
		474	Album: Matrix Reloaded
		475	Time: 00:11.31 [04:28.75] of 04:40.06 (200.6 kbps) Output Buffer 96.9%
		476	</pre>
		477
		478	</body>
		479	</section>
		480	<section>
		481	<title>ALSA and USE</title>
		482	<body>
		483
		484	<p>
		485	You can now add the <c>alsa</c> use flag to <path>/etc/make.conf</path> to
		486	ensure that your applications that support ALSA get built with it. Some
		487	architectures like x86 and amd64 have the flag enabled by default.
		488	</p>
		489
		490	</body>
		491	</section>
		492	<section>
		493	<title>Issues?</title>
		494	<body>
		495
		496	<p>
		497	If for some reason you're unable to hear sound, the first thing to do would
		498	be to check your <uri link="#doc_chap3_pre6">alsamixer</uri> settings. 80% of
		499	the issues lie with muted channels or low volume. Also check your Window
		500	Manager's sound applet and verify that volumes are set to audible levels.
		501	</p>
		502
		503	<p>
		504	<path>/proc</path> is your friend. And in this case, <path>/proc/asound</path>
		505	is your best friend. We shall just take a short look at how much info is made
		506	available to us there.
		507	</p>
		508
		509	<pre caption="Fun with /proc/asound">
		510	<comment>(First and foremost, if /proc/asound/cards shows your card, ALSA has
		511	picked up your sound card fine.)</comment>
		512	# <i>cat /proc/asound/cards</i>
		513	0 [Live ]: EMU10K1 - Sound Blaster Live!
		514	Sound Blaster Live! (rev.6, serial:0x80271102) at 0xb800, irq 11
		515
		516	<comment>(This displays the current running ALSA version)</comment>
		517	# <i>cat /proc/asound/version</i>
		518	Advanced Linux Sound Architecture Driver Version 1.0.8 (Thu Jan 13 09:39:32 2005 UTC).
		519
		520	<comment>(ALSA OSS emulation details)</comment>
		521	# <i>cat /proc/asound/oss/sndstat</i>
		522	Sound Driver:3.8.1a-980706 (ALSA v1.0.8 emulation code)
		523	Kernel: Linux airwolf.zion 2.6.11ac1 #2 Wed May 4 00:35:08 IST 2005 i686
		524	Config options: 0
		525
		526	Installed drivers:
		527	Type 10: ALSA emulation
		528
		529	Card config:
		530	Sound Blaster Live! (rev.6, serial:0x80271102) at 0xb800, irq 11
		531
		532	Audio devices:
		533	0: EMU10K1 (DUPLEX)
		534
		535	Synth devices: NOT ENABLED IN CONFIG
		536
		537	Midi devices:
		538	0: EMU10K1 MPU-401 (UART)
		539
		540	Timers:
		541	7: system timer
		542
		543	Mixers:
		544	0: SigmaTel STAC9721/23
		545	</pre>
		546
		547	<!-- TODO: remove this a few months after alsa-driver leaves the tree -->
		548
		549	<p>
		550	The other most common issue users face is the dreaded "Unknown symbol in module"
		551	error. An example of the same is shown below.
		552	</p>
		553
		554	<pre caption="Unknown Symbol in module error">
		555	# <i>/etc/init.d/alsasound start</i>
		556	* Loading ALSA modules ...
		557	* Loading: snd-card-0 ... [ ok ]
		558	* Loading: snd-pcm-oss ...
		559	WARNING: Error inserting snd_mixer_oss
		560	(/lib/modules/2.6.12-gentoo-r6/kernel/sound/core/oss/snd-mixer-oss.ko): Unknown
		561	symbol in module, or unknown parameter (see dmesg) FATAL: Error inserting
		562	snd_pcm_oss
		563	(/lib/modules/2.6.12-gentoo-r6/kernel/sound/core/oss/snd-pcm-oss.ko): Unknown
		564	symbol in module, or unknown parameter (see dmesg)
		565	[ !! ]
		566	* Loading: snd-mixer-oss ...
		567	FATAL: Error inserting snd_mixer_oss
		568	(/lib/modules/2.6.12-gentoo-r6/kernel/sound/core/oss/snd-mixer-oss.ko): Unknown
		569	symbol in module, or unknown parameter (see dmesg)
		570	[ !! ]
		571	* Loading: snd-seq ... [ ok ]
		572	* Loading: snd-emu10k1-synth ... [ ok ]
		573	* Loading: snd-seq-midi ... [ ok ]
		574	* Restoring Mixer Levels ... [ ok ]
		575	</pre>
		576
		577	<p>
		578	And when you take a look at <c>dmesg</c> as suggested, you're quite likely to
		579	see:
		580	</p>
		581
		582	<pre caption="dmesg output">
		583	<comment>(Only relevant portions are shown below)</comment>
		584	# <i>dmesg \| less</i>
		585	ACPI: PCI Interrupt 0000:02:06.0[A] -> Link [APC3] -> GSI 18 (level, low) -> IRQ 209
		586	snd_mixer_oss: Unknown symbol snd_unregister_oss_device
		587	snd_mixer_oss: Unknown symbol snd_register_oss_device
		588	snd_mixer_oss: Unknown symbol snd_mixer_oss_notify_callback
		589	snd_mixer_oss: Unknown symbol snd_oss_info_register
		590	snd_pcm_oss: Unknown symbol snd_unregister_oss_device
		591	snd_pcm_oss: Unknown symbol snd_register_oss_device
		592	snd_pcm_oss: Unknown symbol snd_mixer_oss_ioctl_card
		593	snd_pcm_oss: Unknown symbol snd_oss_info_register
		594	snd_mixer_oss: Unknown symbol snd_unregister_oss_device
		595	snd_mixer_oss: Unknown symbol snd_register_oss_device
		596	snd_mixer_oss: Unknown symbol snd_mixer_oss_notify_callback
		597	snd_mixer_oss: Unknown symbol snd_oss_info_register
		598	</pre>
		599
		600	<p>
		601	The above issue is caused when you switch from the <c>alsa-driver</c> to in-kernel
		602	ALSA because when you unmerge <c>alsa-driver</c> the module files are config
		603	protected and hence get left behind. So, when you switch to in-kernel
		604	drivers, running <c>modprobe</c> gives you a mix of <c>alsa-driver</c> and
		605	in-kernel modules thus causing the above errors.
		606	</p>
		607
		608	<p>
		609	The solution is quite easy. We just need to manually remove the problem causing
		610	directory after you unmerge <c>alsa-driver</c>. Be sure to remove the correct
		611	kernel version and not the current one!
		612	</p>
		613
		614	<pre caption="Removing the alsa-driver modules">
		615	# <i>rm -rf /lib/modules/$(uname -r)/alsa-driver</i>
		616	</pre>
		617
		618	<p>
		619	Another reason for error messages similar to the ones above could be a file in
		620	<path>/etc/modprobe.d</path> supplying a <c>device_mode</c> parameter when it
		621	isn't required. Confirm that this is indeed the issue and find out which file
		622	is the culprit.
		623	</p>
		624
		625	<pre caption="Confirming and searching for device_mode">
		626	<comment>(Check dmesg to confirm)</comment>
		627	# <i>dmesg \| grep device_mode</i>
		628	snd: Unknown parameter `device_mode'
		629	<comment>(Now, to get to the source of the issue)</comment>
		630	# <i>grep device_mode /etc/modprobe.d/*</i>
		631	</pre>
		632
		633	<p>
		634	Usually it is a file called <path>alsa</path> with the line <c>options snd
		635	device_mode=0666</c>. Remove this line and restart the <c>alsasound</c> service
		636	and that should take care of this issue.
		637	</p>
		638
		639	<!-- End of removal notice -->
		640
		641	</body>
		642	</section>
		643	</chapter>
		644
		645	<chapter>
		646	<title>Other things ALSA</title>
		647	<section id="midi">
		648	<title>Setting up MIDI support</title>
		649	<body>
		650
		651	<p>
		652	First, check to make sure that you enabled the <c>midi</c> USE flag in
		653	<path>/etc/make.conf</path>. If you didn't, go ahead and add it now. You will
		654	also need to re-emerge any ALSA packages that use the <c>midi</c> flag, such as
		655	<c>alsa-lib</c> and <c>alsa-utils</c>.
		656	</p>
		657
		658	<p>
		659	If your sound card is one of those that come with on-board MIDI synthesizers
		660	and you would like to listen to some .mid files, you have to install
		661	<c>awesfx</c> which is basically a set of utilities for controlling the AWE32
		662	driver. We need to install it first. If you don't have a hardware synthesizer,
		663	you can use a virtual one. Please see the section on
		664	<uri link="#vsynth">Virtual Synthesizers</uri> for more information.
		665	</p>
		666
		667	<pre caption="Installing awesfx">
		668	# <i>emerge awesfx</i>
		669	</pre>
		670
202	<note>	671	<note>
203	When you want to install ALSA drivers for more than one soundcard, you could set ALSA_CARDS to a space-separated list	672	You will need to copy over SoundFont (SF2) files from your sound card's driver
204	of drivers; like this: <c>env ALSA_CARDS='emu10k1 intel8x0 ens1370' emerge alsa-driver</c>	673	CD or a Windows installation into <path>/usr/share/sounds/sf2/</path>. For
		674	example a sound font file for the Creative SBLive! card would be 8MBGMSFX.SF2.
205	</note>	675	</note>
206		676
207	<note>If you want to have OSS compatibility, make sure to emerge <i>alsa-oss</i>, it is the ALSA/OSS compatibility
208	wrapper. </note>
209
210	<note>If you plan on recompiling your kernels numerous times, it might
211	be adviseable to emerge <c>alsa-driver</c> with <c>--buildpkg</c>. This
212	will create a binary package for it. Later, after recompiling your kernel,
213	you can just do <c>emerge --usepkg alsa-driver</c> which will install the
214	binary package instead of recompiling it completely.</note>
215
216	<p>
217	After this, the ALSA modules should be installed on your system.
218	</p>	677	<p>
219	</body>	678	After copying over the Soundfont files, we can then play a midi file as shown.
220	</section>	679	You can also add the <c>asfxload</c> command to
221	<section>	680	<path>/etc/conf.d/local.start</path>, so that the sound font is loaded
222	<title>Configuration of ALSA</title>	681	every time the system starts up.
223	<body>
224	<p>	682	</p>
225	Let's start configuring now to get ALSA working properly.
226	We'll need to edit some files, to let our system know about the freshly installed ALSA modules.
227	</p>
228		683
229	<p>
230	First, install <c>alsa-utils</c> on your system:
231	</p>
232
233	<pre caption = "Emerging alsa-utils">
234	# <i>emerge alsa-utils</i>
235	</pre>
236
237	<p>
238	Hereafter, we need to edit <path>/etc/modules.d/alsa</path>.
239	</p>
240	<warn>
241	There is no need to edit <path>/etc/modules.conf</path>. Instead, always edit files in <path>/etc/modules.d</path>.
242	</warn>
243	<p>
244	Check the ALSA portion <e>at the bottom of the file</e>.
245	By tweaking this line you can specify the max number of soundcards you have (generally, just one).
246	</p>
247	<pre caption="At the bottom of /etc/modules.d/alsa">
248	<comment>Set this to the correct number of cards.</comment>
249	options snd cards_limit=1
250	</pre>
251	<p>
252	Now we'll specify the sounddriver(s) ALSA should use. In the same file, edit like this:
253	</p>
254	<pre caption="In /etc/modules.d/alsa">
255	## and then run `modules-update' command.
256	## Read alsa-driver's INSTALL file in /usr/share/doc for more info.
257	##
258	## ALSA portion
259	alias snd-card-0 snd-emu10k1
260	<comment>## If you have more than one, add:</comment>
261	## alias snd-card-1 snd-intel8x0
262	## alias snd-card-2 snd-ens1370
263	## OSS/Free portion
264	## alias sound-slot-0 snd-card-0
265	## alias sound-slot-1 snd-card-1
266	##
267	</pre>
268	<note>	684	<note>
269	If you have more than one soundcard, adjust the <c>cards_limit</c> value and add more snd-card aliases to the file.	685	<path>/mnt</path> paths mentioned in the code listing(s) below will <e>not</e>
270	I don't have experience with this, but you can find examples for configurations with two or more soundcards in	686	be the same in your machine. They are just an example. Please be careful to
271	<uri link="http://www.alsa-project.org/alsa-doc/alsa-howto/c1660.htm">Chapter 6</uri>	687	change the path to suit your machine.
272	of the <uri link="http://www.alsa-project.org/alsa-doc/alsa-howto/alsa-howto.html">ALSA Howto</uri>.
273	</note>	688	</note>
274	<p>	689
275	Last thing to do in this file, almost at the end, check if these lines are there and uncommented:	690	<pre caption="Loading Soundfonts">
276	</p>	691	<comment>(First, copy the Soundfont)</comment>
277	<pre caption="Near the end of /etc/modules.d/alsa">	692	# <i>cp /mnt/win2k/Program\ Files/CreativeSBLive2k/SFBank/8MBGMSFX.SF2 /usr/share/sounds/sf2/</i>
278	alias /dev/mixer snd-mixer-oss	693	<comment>(Or get it from your SoundBlaster CD)</comment>
279	alias /dev/dsp snd-pcm-oss	694	# <i>cp /mnt/cdrom/AUDIO/ENGLISH/SFBANK/8MBGMSFX.SF2 /usr/share/sounds/sf2/</i>
280	alias /dev/midi snd-seq-oss	695	<comment>(We load the specific Soundfont)</comment>
281	</pre>	696	# <i>asfxload /usr/share/sounds/sf2/8MBGMSFX.SF2</i>
282	<p>
283	Now double-check the file <path>/etc/modules.d/alsa</path> and when you're sure everyting is ok, run <c>modules-update</c>.
284	<pre>	697	</pre>
285	# <i>modules-update</i>	698
286	</pre>
287	</p>	699	<p>
288	<note>	700	You can now play midi files using a program like <c>aplaymidi</c>. Run
289	Running <c>modules-update</c> here will insert the data from <path>/etc/modules.d/alsa</path> into <path>/etc/modules.conf</path>	701	<c>aplaymidi -l</c> to get a list of available ports and then pick one
290	</note>	702	to play the file on.
291	<p>	703	</p>
292	You should also verify that /etc/devfsd.conf has the alsa devices and permissions correctly registered.	704
		705	<pre caption="Playing MIDI">
		706	<comment>(Check open ports)</comment>
		707	# <i>aplaymidi -l</i>
		708	Port Client name Port name
		709	64:0 EMU10K1 MPU-401 (UART) EMU10K1 MPU-401 (UART)
		710	65:0 Emu10k1 WaveTable Emu10k1 Port 0
		711	65:1 Emu10k1 WaveTable Emu10k1 Port 1
		712	65:2 Emu10k1 WaveTable Emu10k1 Port 2
		713	65:3 Emu10k1 WaveTable Emu10k1 Port 3
		714	<comment>(Pick a port, and play a mid file)</comment>
		715	# <i> aplaymidi --port=65:0 /mnt/shyam/music/midi/mi2.mid</i>
293	</p>	716	</pre>
294	<pre caption="/etc/devfsd.conf">	717
295	# ALSA/OSS stuff
296	# Comment/change these if you want to change the permissions on
297	# the audio devices
298	LOOKUP snd MODLOAD ACTION snd
299	LOOKUP dsp MODLOAD
300	LOOKUP mixer MODLOAD
301	LOOKUP midi MODLOAD
302	REGISTER sound/.* PERMISSIONS root.audio 660
303	REGISTER snd/.* PERMISSIONS root.audio 660
304	</pre>
305	<note>
306	Notice that devfsd.conf sets /dev/sound permissions to be root.audio. Thus, for non-root users to use audio they will have to be part of the audio group.
307	</note>
308	</body>	718	</body>
309	</section>
310	</chapter>
311	<chapter>
312	<title>Starting ALSA</title>
313	<section>	719	</section>
314	<title>Adding alsasound to a runlevel</title>	720	<section id="vsynth">
315	<body>	721	<title>Virtual Synthesizers</title>
316	<p>
317	First thing to do now, is to make ALSA startup at boottime. Like this:
318	<pre>
319	# <i>rc-update add alsasound boot</i>
320	</pre>
321	</p>
322	<p>
323	<warn>Note that the alsasound script should be added to the "boot" runlevel, not the "default" runlevel.</warn>
324	</p>
325	</body>	722	<body>
326	</section>	723
		724	<p>
		725	If your sound card lacks a hardware synthesizer, you could use a virtual one
		726	like <c>timidity++</c>. Installation is a breeze.
		727	</p>
		728
		729	<pre caption="Installing timidity++">
		730	# <i>emerge timidity++</i>
		731	</pre>
		732
		733	<p>
		734	For timidity to play sounds, it needs a sound font. Fortunately, the ebuild will
		735	install some sound font packages for you. There are a few other font packages
		736	available in Portage, such as <c>timidity-freepats</c> and
		737	<c>timidity-eawpatches</c>. You can have multiple sound font configurations
		738	installed, and you can place your own in <path>/usr/share/timidity/</path>. To
		739	switch between different timidity configurations, you should use
		740	<c>eselect</c>.
		741	</p>
		742
		743	<pre caption="Changing configurations">
		744	# <i>eselect timidity list</i>
		745	# <i>eselect timidity set eawpatches</i>
		746	</pre>
		747
		748	<p>
		749	Don't forget to add <c>timidity</c> to the default runlevel.
		750	</p>
		751
		752	<pre caption="Adding timidity to the default runlevel">
		753	# <i>rc-update add timidity default</i>
		754	# <i>/etc/init.d/timidity start</i>
		755	</pre>
		756
		757	<p>
		758	You can now try out <uri link="#doc_chap4_pre3">Playing MIDI</uri> files.
		759	</p>
		760
		761	</body>
327	<section>	762	</section>
328	<title>Running and unmuting</title>
329	<body>
330	<p>
331	Since we're Linux users, we don't want to reboot. So we'll start the alsasound script manually.
332	</p>
333	<pre>
334	# <i>/etc/init.d/alsasound start</i>
335	</pre>
336	<p>
337	ALSA is running now. If everything is ok, you should be able to see the ALSA modules loaded when running <c>lsmod</c>.
338	However, sound won't work yet, because the channels are still muted. We need <c>amixer</c> for this.
339	</p>
340	<pre caption = "Running amixer">
341	# <i>amixer</i>
342	</pre>
343	<p>
344	<warn>
345	You shouldn't get this, but <e>if</e> you get an error about "amixer: Mixer attach default error: No such file or directory", you should manually modprobe
346	<c>snd-mixer-oss</c> and <c>snd-pcm-oss</c> once. After that run amixer again.
347	</warn>
348	</p>
349	<pre caption="only if you get an error when running amixer">
350	# <i>modprobe snd-mixer-oss</i>
351	# <i>modprobe snd-pcm-oss</i>
352	# <i>amixer</i>
353	</pre>
354	<p>
355	If you got this far, now unmute Master and PCM channels. Some hardware
356	even requires you to unmute the center channel or even the surround
357	channel.
358	</p>
359	<p>
360	<pre caption = "Unmuting channels">
361	# <i>amixer set Master 100 unmute</i>
362	# <i>amixer set PCM 100 unmute</i>
363	<comment>Only if the above doesn't succeed on its own:</comment>
364	# <i>amixer set Center 100 unmute</i>
365	# <i>amixer set Surround 100 unmute</i>
366	<comment>Test the sound:</comment>
367	# <i>aplay $KDEDIR/share/sounds/pop.wav</i> <codenote>(pop.wav is part of KDE)</codenote>
368	</pre>
369	</p>
370	We check to see if sound is working by using the aplay (alsa play) command. If you hear a pop, then sound is indeed working.
371	Then, adjust the volume settings to your liking; the ncurses-based <c>alsamixer</c> is a great way to get them "just so".
372	<p>
373	You may want to emerge <c>alsa-xmms</c> as that will provide ALSA support for XMMS.
374	</p>
375	When you reboot your system, the <e>alsasound</e> init script will properly save and restore your volume settings.
376	</body>
377	</section>	763	<section>
378	</chapter>	764	<title>Tools and Firmware</title>
379	<chapter>	765	<body>
380	<title>Final Notes</title>	766
		767	<p>
		768	Some specific sound cards can benefit from certain tools provided by the
		769	<c>alsa-tools</c> and <c>alsa-firmware</c> packages. You may install either with
		770	a simple <c>emerge</c>.
		771	</p>
		772
		773	<pre caption="Installing ALSA Tools">
		774	# <i>emerge alsa-tools</i>
		775	</pre>
		776
		777	</body>
381	<section>	778	</section>
382	<title>After kernel-upgrades..</title>
383	<body>
384	<p>When you ever rebuild your kernel, or upgrade to another kernel, you'll have to rebuild the ALSA modules.</p>
385	<p>Although you might have installed <c>alsa-driver</c>, <c>alsa-libs</c> and <c>alsa-utils</c>, only the first will
386	have to be installed again, since it will put the alsa modules in
387	<path>/lib/modules/*/kernel/sound/pci/</path>.</p>
388	<pre caption="needed after each kernel compile">
389	# <i>emerge alsa-driver</i>
390	</pre>
391	</body>
392	</section>	779	<section>
		780	<title>Multiple sound cards</title>
		781	<body>
		782
		783	<p>
		784	You can have more than one sound card in your system simultaneously, provided
		785	that you have built ALSA as modules in your kernel. You just need to specify
		786	which should be started first in <path>/etc/modprobe.d/alsa.conf</path>. Your cards
		787	are identified by their driver names inside this file. 0 is the first card, 1 is
		788	the second, and so on. Here's an example for a system with two sound cards.
		789	</p>
		790
		791	<pre caption="Two sound cards in /etc/modprobe.d/alsa.conf">
		792	options snd-emu10k1 index=0
		793	options snd-via82xx index=1
		794	</pre>
		795
		796	<p>
		797	Or, if you have two cards that use the same driver, you specify them on the same
		798	line, using comma-separated numbers. Here's an example for a system with three
		799	sound cards, two of which are the same Intel High Definition Audio card.
		800	</p>
		801
		802	<pre caption="Multiple sound cards in /etc/modprobe.d/alsa.conf">
		803	options snd-ymfpci index=0
		804	options snd-hda-intel index=1,2
		805	</pre>
		806
		807	</body>
393	<section>	808	</section>
394	<title>/etc/modules.autoload</title>
395	<body>
396	<p>You won't have to edit this file for use with ALSA. After our <c>rc-update add alsasound boot</c>, our system will
397	load the correct modules at startup.</p>
398	<p>It's not necessary to add <c>snd-pcm-oss</c> or <c>snd-mixer-oss</c> in this file.
399	Check the <uri link="http://www.djcj.org/LAU/guide/alsbook/faq1.html">this FAQ</uri> for more info.</p>
400	</body>
401	</section>	809	<section>
		810	<title>Plugins</title>
		811	<body>
402		812
		813	<p>
		814	You may want to install some plugins for extra functionality.
		815	<c>alsa-plugins</c> is a collection of useful plugins, which include: PulseAudio
		816	output, a sample rate converter, jack (a low-latency audio server), and an
		817	encoder that lets you output 6-channel audio through digital S/PDIF connections
		818	(both optical and coaxial). You can choose which of its plugins you want
		819	installed by adding their USE flags to <path>/etc/portage/package.use</path>.
		820	</p>
		821
		822	<pre caption="Installing alsa-plugins">
		823	# <i>emerge -avt alsa-plugins</i>
		824	</pre>
		825
		826	</body>
403	<section>	827	</section>
404	<title>Known bugs</title>	828	<section>
		829	<title>A big thank you to...</title>
		830	<body>
		831
		832	<p>
		833	Everyone who contributed to the earlier version of the Gentoo ALSA Guide:
		834	Vincent Verleye, Grant Goodyear, Arcady Genkin, Jeremy Huddleston,
		835	John P. Davis, Sven Vermeulen, Benny Chuang, Tiemo Kieft and Erwin.
		836	</p>
		837
405	<body>	838	</body>
406		839	</section>
407	<note>	840	<section>
408	This guide lags behind on the alsa-development. Chances are these bugs	841	<title>References</title>
409	are already fixed when you read this.	842	<body>
410	</note>
411		843
412	<ul>	844	<ul>
413	<li>	845	<li><uri link="http://www.alsa-project.org/">The ALSA Project</uri></li>
414	If you have <b>lots of noise</b> when using <b>oss</b> emulation, add	846	<li><uri link="http://linux-sound.org">Linux Sound/MIDI Software</uri></li>
415	<e>options snd-pcm-oss dsp_map=1</e> to
416	<path>/etc/modules.d/alsa</path>.
417	</li>
418	</ul>	847	</ul>
419		848
420	</body>
421	</section>
422
423	<section>
424	<title>More links..</title>
425	<body>
426	<p>
427	You could check these for additional info:
428	</p>
429	<p>
430	<ul>
431	<li><uri link="http://www.gentoo.org/doc/en/desktop.xml">The Gentoo Linux Desktop Configuration Guide</uri></li>
432	<li><uri link="http://www.alsa-project.org">ALSA Project Homepage</uri></li>
433	<li><uri link="http://www.alsa-project.org/documentation.php3">ALSA Users Documentation</uri></li>
434	<li><uri link="http://www.djcj.org">ALSA Howto's and FAQ's</uri></li>
435	<li><uri link="http://tldp.org/HOWTO/Sound-HOWTO/index.html">Linux Sound HOWTO</uri></li>
436	<li><uri link="http://linux-sound.org/">Sound and MIDI Software For Linux</uri></li>
437	</ul>
438	</p>
439	</body>	849	</body>
440	</section>	850	</section>
441	</chapter>	851	</chapter>
442	</guide>	852	</guide>

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