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1 <?xml version='1.0' encoding="UTF-8"?>
2 <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
4 <guide link = "/doc/en/alsa-guide.xml">
5 <title>Gentoo Linux ALSA Guide</title>
6 <author title="Author"><mail link="zu@pandora.be">
7 Vincent Verleye</mail>
8 </author>
9 <author title="Author"><mail link="g2boojum@gentoo.org">
10 Grant Goodyear</mail>
11 </author>
12 <author title="Author"><mail link="agenkin@gentoo.org">
13 Arcady Genkin</mail>
14 </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>
22 <license/>
24 <abstract>
25 This guide will show you how to set up the Advanced Linux Sound Architecture (ALSA) on Gentoo Linux.
26 In addition to the Gentoo Linux Desktop Configuration Guide, this guide is supposed to give you more information on this subject. </abstract>
28 <version>1.3</version>
29 <date>September 7, 2003</date>
31 <chapter>
32 <title>Introduction</title>
33 <section>
34 <title>What is ALSA?</title>
35 <body>
36 <p>
37 The Advanced Linux Sound Architecture (ALSA) is a project to improve the Linux sound subsystem by rewriting
38 large chunks of it.
39 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.
40 </p>
42 <p>
43 ALSA provides audio and MIDI functionality for Linux.
44 </p>
46 <p>
47 Quoted from <uri>http://www.alsa-project.org</uri>, ALSA has the following features:
48 <ul><li> Efficient support for all types of audio interfaces, from consumer soundcards to professional multichannel audio interfaces.</li>
49 <li> Fully modularized sound drivers.</li>
50 <li> SMP and thread-safe design.</li>
51 <li> User space library (alsa-lib) to simplify application programming and provide higher level functionality.</li>
52 <li> Support for the older OSS API, providing binary compatibility for most OSS programs.</li>
53 </ul>
54 There's lots more to ALSA however, like support for Full Duplex playback and recording, multiple soundcard support,
55 hardware mixing of streams, extensive mixer capabilities (to support advanced features of new soundcards), ...
56 </p>
57 </body>
58 </section>
59 <section>
60 <title>Why use ALSA?</title>
61 <body>
62 <p>
63 If your soundcard is supported by the Linux kernel sound system or the commercial OSS/4Front sound driver system,
64 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.
65 If you want this, just read through the <uri link="http://www.tldp.org/HOWTO/Sound-HOWTO/index.html">Linux Sound HOWTO</uri>.
66 </p>
67 <p>
68 However, those OSS/4Front drivers have some limitations -- being commercial is one.
69 ALSA is an attempt to go beyond these limitations and to do so in an open source fashion.
70 ALSA is a fully GPL and LGPL'ed sound driver system, that provides a professional quality system for recording, playback,
71 and MIDI sequencing.
72 </p>
73 </body>
74 </section>
75 <section>
76 <title>What cards does ALSA support?</title>
77 <body>
78 <p>
79 ALSA tries to support as many (new) cards as possible by providing open-source drivers.
80 However, some vendors may provide binary-only packages.
81 </p>
82 <p>To know if your card is supported, you can find a Soundcard Matrix of supported and not-supported cards here:
83 <uri>http://www.alsa-project.org/alsa-doc/</uri>.
84 </p>
85 </body>
86 </section>
87 </chapter>
89 <chapter>
90 <title>Installation</title>
91 <section>
92 <title>Kernel modules</title>
93 <body>
94 <p>
95 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.
96 </p>
97 <p>
98 First we'll make sure that our kernel configuration is ready for use with ALSA.
99 All you need in your kernel configuration is having Sound Card Support set to be built as a module (M).
100 This will build <c>soundcore.o</c>.
101 </p>
102 <p>
103 <note>
104 Possibly, this will also work when you built Sound Card Support in the kernel (Y) instead of building it as a module (M).
105 However, the official ALSA documentation suggests building it as a module, since ALSA will try loading it.
106 </note>
107 </p>
108 <p>If you already have a working kernel configuration, make sure you remove all sound drivers (except for Sound Card Support).
109 If you wish to do this without having to reboot, you could do like this:
110 </p>
111 <pre>
112 # <c>cd /usr/src/linux</c>
113 # <c>cp .config ~/</c>
114 # <c>make mrproper</c>
115 # <c>cp ~/.config .</c>
116 # <c>make menuconfig</c>
117 </pre>
118 <p>
119 Now select <e>Sound Card Support</e> as Module (M) and deselect all other sound drivers.
120 Exit and say Y to save your kernel configuration.
121 After that, build the modules:
122 </p>
123 <pre>
124 # <c>make dep clean</c>
125 # <c>make modules modules_install</c>
126 </pre>
127 <p>
128 Before installing your new modules, this last line will delete all your previous modules,
129 even the ones from a previous ALSA installation.
130 </p>
131 <p>
132 <impo>
133 This means, whenever you recompile your kernel later on, you MUST recompile <c>alsa-driver</c>.
134 </impo>
135 </p>
136 <p>
137 <note>However, there's no need to reinstall <c>nvidia-kernel</c>, the Nvidia drivers are in a separate directory
138 in <path>/lib/modules/*/video</path> and won't get deleted by a <c>make modules modules_install</c>
139 </note>
140 </p>
141 </body>
142 </section>
144 <section>
145 <title>ALSA modules</title>
146 <body>
148 <p>
149 Now it's time to install the ALSA drivers for your soundcard(s). If your soundcard is PCI, you can find out the name
150 and type of your soundcard by looking at the output of /proc/pci
151 <pre># <c>grep audio /proc/pci</c></pre>
152 </p>
154 <p>
155 <warn>
156 If you had a previous sound setup and there are still non-ALSA sound modules loaded, unload them <e>now</e>.
157 Check with <c>lsmod</c> and use <c>rmmod</c> to unload all sound-related modules on your system.
158 </warn>
159 </p>
161 <p>
162 We could simply do an <c>emerge alsa-driver</c> now, this would compile and install <e>all</e> ALSA sound drivers.
163 </p>
164 <p>
165 However, to save some time, lookup the <e>Module Name</e> of your soundcard(s) on the
166 <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.
167 Mine is <c>snd-emu10k1</c>, since I have an SBlive! soundcard, with the <e>EMU10K1</e> chipset.
168 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.
169 </p>
171 <pre>
172 # <c>env ALSA_CARDS='emu10k1' emerge alsa-driver</c>
173 </pre>
174 <note>
175 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>.
176 For example, like this: <c>echo 'ALSA_CARDS="emu10k1"' >> /etc/make.conf</c>
177 </note>
179 <note>
180 When you want to install ALSA drivers for more than one soundcard, you could set ALSA_CARDS to a space-separated list
181 of drivers; like this: <c>env ALSA_CARDS='emu10k1 intel8x0 ens1370' emerge alsa-driver</c>
182 </note>
184 <note>If you want to have OSS compatibility, make sure to emerge <i>alsa-oss</i>, it is the ALSA/OSS compatibility
185 wrapper. </note>
187 <note>If you plan on recompiling your kernels numerous times, it might
188 be adviseable to emerge <c>alsa-driver</c> with <c>--buildpkg</c>. This
189 will create a binary package for it. Later, after recompiling your kernel,
190 you can just do <c>emerge --usepkg alsa-driver</c> which will install the
191 binary package instead of recompiling it completely.</note>
193 <p>
194 After this, the ALSA modules should be installed on your system.
195 </p>
196 </body>
197 </section>
198 <section>
199 <title>Configuration of ALSA</title>
200 <body>
201 <p>
202 Let's start configuring now to get ALSA working properly.
203 We'll need to edit some files, to let our system know about the freshly installed ALSA modules.
204 </p>
206 <p>
207 First, install <c>alsa-utils</c> on your system:
208 </p>
210 <pre caption = "Emerging alsa-utils">
211 # <i>emerge alsa-utils</i>
212 </pre>
214 <p>
215 Hereafter, we need to edit <path>/etc/modules.d/alsa</path>.
216 </p>
217 <warn>
218 There is no need to edit <path>/etc/modules.conf</path>. Instead, always edit files in <path>/etc/modules.d</path>.
219 </warn>
220 <p>
221 Check the ALSA portion <e>at the bottom of the file</e>.
222 By tweaking this line you can specify the max number of soundcards you have (generally, just one).
223 </p>
224 <p>
225 <pre caption="At the bottom of /etc/modules.d/alsa">
226 # Set this to the correct number of cards.
227 <c>options snd cards_limit=1</c>
228 </pre>
229 </p>
230 <p>
231 Now we'll specify the sounddriver(s) ALSA should use. In the same file, edit like this:
232 <pre caption="In /etc/modules.d/alsa">
233 ## and then run `update-modules' command.
234 ## Read alsa-driver's INSTALL file in /usr/share/doc for more info.
235 ##
236 ## ALSA portion
237 <c>alias snd-card-0 snd-emu10k1</c>
238 <c>## If you have more than one, add:
239 ## alias snd-card-1 snd-intel8x0
240 ## alias snd-card-2 snd-ens1370</c>
241 ## OSS/Free portion
242 ## alias sound-slot-0 snd-card-0
243 ## alias sound-slot-1 snd-card-1
244 ##
245 </pre>
246 </p>
247 <p>
248 <note>
249 If you have more than one soundcard, adjust the <c>cards_limit</c> value and add more snd-card aliases to the file.
250 I don't have experience with this, but you can find examples for configurations with two or more soundcards in
251 <uri link="http://www.alsa-project.org/alsa-doc/alsa-howto/c1660.htm">Chapter 6</uri>
252 of the <uri link="http://www.alsa-project.org/alsa-doc/alsa-howto/alsa-howto.html">ALSA Howto</uri>.
253 </note>
254 </p>
255 <p>
256 Last thing to do in this file, almost at the end, check if these lines are there and uncommented:
257 <pre caption="Near the end of /etc/modules.d/alsa">
258 alias /dev/mixer snd-mixer-oss
259 alias /dev/dsp snd-pcm-oss
260 alias /dev/midi snd-seq-oss
261 </pre>
262 </p>
263 <p>
264 Now double-check the file <path>/etc/modules.d/alsa</path> and when you're sure everyting is ok, run <c>update-modules</c>.
265 <pre>
266 # <c>update-modules</c>
267 </pre>
268 </p>
269 <note>
270 Running <c>update-modules</c> here will insert the data from <path>/etc/modules.d/alsa</path> into <path>/etc/modules.conf</path>
271 </note>
272 <p>
273 You should also verify that /etc/devfsd.conf has the alsa devices and permissions correctly registered.
274 </p>
275 <pre caption="/etc/devfsd.conf">
276 # ALSA/OSS stuff
277 # Comment/change these if you want to change the permissions on
278 # the audio devices
283 REGISTER sound/.* PERMISSIONS root.audio 660
284 REGISTER snd/.* PERMISSIONS root.audio 660
285 </pre>
286 <note>
287 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.
288 </note>
289 </body>
290 </section>
291 </chapter>
292 <chapter>
293 <title>Starting ALSA</title>
294 <section>
295 <title>Adding alsasound to a runlevel</title>
296 <body>
297 <p>
298 First thing to do now, is to make ALSA startup at boottime. Like this:
299 <pre>
300 # <c>rc-update add alsasound boot</c>
301 </pre>
302 </p>
303 <p>
304 <warn>Note that the alsasound script should be added to the "boot" runlevel, not the "default" runlevel.</warn>
305 </p>
306 </body>
307 </section>
308 <section>
309 <title>Running and unmuting</title>
310 <body>
311 <p>
312 Since we're Linux users, we don't want to reboot. So we'll start the alsasound script manually.
313 </p>
314 <pre>
315 # <c>/etc/init.d/alsasound start</c>
316 </pre>
317 <p>
318 ALSA is running now. If everything is ok, you should be able to see the ALSA modules loaded when running <c>lsmod</c>.
319 However, sound won't work yet, because the channels are still muted. We need <c>amixer</c> for this.
320 </p>
321 <pre caption = "Running amixer">
322 # <i>amixer</i>
323 </pre>
324 <p>
325 <warn>
326 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 insmod
327 <c>snd-mixer-oss</c> and <c>snd-pcm-oss</c> once. After that run amixer again.
328 </warn>
329 </p>
330 <pre caption="only if you get an error when running amixer">
331 # <c>insmod snd-mixer-oss</c>
332 # <c>insmod snd-pcm-oss</c>
333 # <c>amixer</c>
334 </pre>
335 <p>
336 If you got this far, now unmute Master and PCM channels. Some hardware
337 even requires you to unmute the center channel or even the surround
338 channel.
339 </p>
340 <p>
341 <pre caption = "Unmuting channels">
342 # <i>amixer set Master 100 unmute</i>
343 # <i>amixer set PCM 100 unmute</i>
344 <comment>Only if the above doesn't succeed on its own:</comment>
345 # <i>amixer set Center 100 unmute</i>
346 # <i>amixer set Surround 100 unmute</i>
347 <comment>Test the sound:</comment>
348 # <i>aplay $KDEDIR/share/sounds/pop.wav</i> <codenote>(pop.wav is part of KDE)</codenote>
349 </pre>
350 </p>
351 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.
352 Then, adjust the volume settings to your liking; the ncurses-based <c>alsamixer</c> is a great way to get them "just so".
353 <p>
354 You may want to emerge <c>alsa-xmms</c> as that will provide ALSA support for XMMS.
355 </p>
356 When you reboot your system, the <e>alsasound</e> init script will properly save and restore your volume settings.
357 </body>
358 </section>
359 </chapter>
360 <chapter>
361 <title>Final Notes</title>
362 <section>
363 <title>After kernel-upgrades..</title>
364 <body>
365 <p>When you ever rebuild your kernel, or upgrade to another kernel, you'll have to rebuild the ALSA modules.</p>
366 <p>Although you might have installed <c>alsa-driver</c>, <c>alsa-libs</c> and <c>alsa-utils</c>, only the first will
367 have to be installed again, since it will put the alsa modules in
368 <path>/lib/modules/*/kernel/sound/pci/</path>.</p>
369 <pre caption="needed after each kernel compile">
370 # <c>emerge alsa-driver</c>
371 </pre>
372 </body>
373 </section>
374 <section>
375 <title>/etc/modules.autoload</title>
376 <body>
377 <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
378 load the correct modules at startup.</p>
379 <p>It's not necessary to add <c>snd-pcm-oss</c> or <c>snd-mixer-oss</c> in this file.
380 Check the <uri link="http://www.djcj.org/LAU/guide/alsbook/faq1.html">this FAQ</uri> for more info.</p>
381 </body>
382 </section>
383 <section>
384 <title>More links..</title>
385 <body>
386 <p>
387 You could check these for additional info:
388 </p>
389 <p>
390 <ul>
391 <li><uri link="http://www.gentoo.org/doc/en/desktop.xml">The Gentoo Linux Desktop Configuration Guide</uri></li>
392 <li><uri link="http://www.alsa-project.org">ALSA Project Homepage</uri></li>
393 <li><uri link="http://www.alsa-project.org/documentation.php3">ALSA Users Documentation</uri></li>
394 <li><uri link="http://www.djcj.org">ALSA Howto's and FAQ's</uri></li>
395 <li><uri link="http://tldp.org/HOWTO/Sound-HOWTO/index.html">Linux Sound HOWTO</uri></li>
396 <li><uri link="http://linux-sound.org/">Sound and MIDI Software For Linux</uri></li>
397 </ul>
398 </p>
399 </body>
400 </section>
401 </chapter>
402 </guide>

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