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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>
10 <author title="Editor"><mail link="zhen@gentoo.org">
11 John P. Davis</mail>
12 </author>
14 <abstract>
15 This guide will show you how to set up the Advanced Linux Sound Architecture (ALSA) on Gentoo Linux.
16 In addition to the Gentoo Linux Desktop Configuration Guide, this guide is supposed to give you more information on this subject. </abstract>
18 <version>1.2</version>
19 <date>18 February 2003</date>
21 <chapter>
22 <title>Introduction</title>
23 <section>
24 <title>What is ALSA?</title>
25 <body>
26 <p>
27 The Advanced Linux Sound Architecture (ALSA) is a project to improve the Linux sound subsystem by rewriting
28 large chunks of it.
29 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.
30 </p>
32 <p>
33 ALSA provides audio and MIDI functionality for Linux.
34 </p>
36 <p>
37 Quoted from <uri>http://www.alsa-project.org</uri>, ALSA has the following features:
38 <ul><li> Efficient support for all types of audio interfaces, from consumer soundcards to professional multichannel audio interfaces.</li>
39 <li> Fully modularized sound drivers.</li>
40 <li> SMP and thread-safe design.</li>
41 <li> User space library (alsa-lib) to simplify application programming and provide higher level functionality.</li>
42 <li> Support for the older OSS API, providing binary compatibility for most OSS programs.</li>
43 </ul>
44 There's lots more to ALSA however, like support for Full Duplex playback and recording, multiple soundcard support,
45 hardware mixing of streams, extensive mixer capabilities (to support advanced features of new soundcards), ...
46 </p>
47 </body>
48 </section>
49 <section>
50 <title>Why use ALSA?</title>
51 <body>
52 <p>
53 If your soundcard is supported by the Linux kernel sound system or the commercial OSS/4Front sound driver system,
54 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.
55 If you want this, just read through the <uri link="http://www.tldp.org/HOWTO/Sound-HOWTO/index.html">Linux Sound HOWTO</uri>.
56 </p>
57 <p>
58 However, those OSS/4Front drivers have some limitations -- being commercial is one.
59 ALSA is an attempt to go beyond these limitations and to do so in an open source fashion.
60 ALSA is a fully GPL and LGPL'ed sound driver system, that provides a professional quality system for recording, playback,
61 and MIDI sequencing.
62 </p>
63 </body>
64 </section>
65 <section>
66 <title>What cards does ALSA support?</title>
67 <body>
68 <p>
69 ALSA tries to support as many (new) cards as possible by providing open-source drivers.
70 However, some vendors may provide binary-only packages.
71 </p>
72 <p>To know if your card is supported, you can find a Soundcard Matrix of supported and not-supported cards here:
73 <uri>http://www.alsa-project.org/alsa-doc/</uri>.
74 </p>
75 </body>
76 </section>
77 </chapter>
79 <chapter>
80 <title>Installation</title>
81 <section>
82 <title>Kernel modules</title>
83 <body>
84 <p>
85 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.
86 </p>
87 <p>
88 First we'll make sure that our kernel configuration is ready for use with ALSA.
89 All you need in your kernel configuration is having Sound Card Support set to be built as a module (M).
90 This will build <c>soundcore.o</c>.
91 </p>
92 <p>
93 <note>
94 Possibly, this will also work when you built Sound Card Support in the kernel (Y) instead of building it as a module (M).
95 However, the official ALSA documentation suggests building it as a module, since ALSA will try loading it.
96 </note>
97 </p>
98 <p>If you already have a working kernel configuration, make sure you remove all sound drivers (except for Sound Card Support).
99 If you wish to do this without having to reboot, you could do like this:
100 </p>
101 <pre>
102 # <c>cd /usr/src/linux</c>
103 # <c>cp .config ~/</c>
104 # <c>make mrproper</c>
105 # <c>cp ~/.config .</c>
106 # <c>make menuconfig</c>
107 </pre>
108 <p>
109 Now select <e>Sound Card Support</e> as Module (M) and deselect all other sound drivers.
110 Exit and say Y to save your kernel configuration.
111 After that, build the modules:
112 </p>
113 <pre>
114 # <c>make dep clean</c>
115 # <c>make modules modules_install</c>
116 </pre>
117 <p>
118 Before installing your new modules, this last line will delete all your previous modules,
119 even the ones from a previous ALSA installation.
120 </p>
121 <p>
122 <impo>
123 This means, whenever you recompile your kernel later on, you MUST recompile <c>alsa-driver</c>.
124 </impo>
125 </p>
126 <p>
127 <note>However, there's no need to reinstall <c>nvidia-kernel</c>, the Nvidia drivers are in a separate directory
128 in <path>/lib/modules/*/video</path> and won't get deleted by a <c>make modules modules_install</c>
129 </note>
130 </p>
131 </body>
132 </section>
134 <section>
135 <title>ALSA modules</title>
136 <body>
138 <p>
139 Now it's time to install the ALSA drivers for your soundcard(s). If your soundcard is PCI, you can find out the name
140 and type of your soundcard by looking at the output of /proc/pci
141 <pre># <c>grep audio /proc/pci</c></pre>
142 </p>
144 <p>
145 <warn>
146 If you had a previous sound setup and there are still non-ALSA sound modules loaded, unload them <e>now</e>.
147 Check with <c>lsmod</c> and use <c>rmmod</c> to unload all sound-related modules on your system.
148 </warn>
149 </p>
151 <p>
152 We could simply do an <c>emerge alsa-driver</c> now, this would compile and install <e>all</e> ALSA sound drivers.
153 </p>
154 <p>
155 However, to save some time, lookup the <e>Module Name</e> of your soundcard(s) on the
156 <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.
157 Mine is <c>snd-emu10k1</c>, since I have an SBlive! soundcard, with the <e>EMU10K1</e> chipset.
158 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.
159 </p>
161 <p>
162 <pre>
163 # <c>env ALSA_CARDS='emu10k1' emerge alsa-driver</c>
164 </pre>
165 </p>
166 <p>
167 <note>
168 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>.
169 For example, like this: <c>echo 'ALSA_CARDS="emu10k1"' >> /etc/make.conf</c>
170 </note>
172 <note>
173 When you want to install ALSA drivers for more than one soundcard, you could set ALSA_CARDS to a space-separated list
174 of drivers; like this: <c>env ALSA_CARDS='emu10k1 intel8x0 ens1370' emerge alsa-driver</c>
175 </note>
177 <note>If you want to have OSS compatibility, make sure to emerge <i>alsa-oss</i>, it is the ALSA/OSS compatibility
178 wrapper. </note>
180 </p>
181 <p>
182 After this, the ALSA modules should be installed on your system.
183 </p>
184 </body>
185 </section>
186 <section>
187 <title>Configuration of ALSA</title>
188 <body>
189 <p>
190 Let's start configuring now to get ALSA working properly.
191 We'll need to edit some files, to let our system know about the freshly installed ALSA modules.
192 </p>
193 <p>
194 First file to edit is <path>/etc/modules.d/alsa</path>.
195 </p>
196 <warn>
197 There is no need to edit <path>/etc/modules.conf</path>. Instead, always edit files in <path>/etc/modules.d</path>.
198 </warn>
199 <p>
200 Check the ALSA portion <e>at the bottom of the file</e>.
201 By tweaking this line you can specify the max number of soundcards you have (generally, just one).
202 </p>
203 <p>
204 <pre caption="At the bottom of /etc/modules.d/alsa">
205 alias /dev/mixer snd-mixer-oss
206 alias /dev/dsp snd-pcm-oss
207 alias /dev/midi snd-seq-oss
209 # Set this to the correct number of cards.
210 <c>options snd cards_limit=1</c>
211 </pre>
212 </p>
213 <p>
214 Now we'll specify the sounddriver(s) ALSA should use. In the same file, edit like this:
215 <pre caption="In /etc/modules.d/alsa">
216 ## and then run `update-modules' command.
217 ## Read alsa-driver's INSTALL file in /usr/share/doc for more info.
218 ##
219 ## ALSA portion
220 <c>alias snd-card-0 snd-emu10k1</c>
221 <c>## If you have more than one, add:
222 ## alias snd-card-1 snd-intel8x0
223 ## alias snd-card-2 snd-ens1370</c>
224 ## OSS/Free portion
225 ## alias sound-slot-0 snd-card-0
226 ## alias sound-slot-1 snd-card-1
227 ##
228 </pre>
229 </p>
230 <p>
231 <note>
232 If you have more than one soundcard, adjust the <c>cards_limit</c> value and add more snd-card aliases to the file.
233 I don't have experience with this, but you can find examples for configurations with two or more soundcards in
234 <uri link="http://www.alsa-project.org/alsa-doc/alsa-howto/c1660.htm">Chapter 6</uri>
235 of the <uri link="http://www.alsa-project.org/alsa-doc/alsa-howto/alsa-howto.html">ALSA Howto</uri>.
236 </note>
237 </p>
238 <p>
239 Last thing to do in this file, almost at the end, check if these lines are there and uncommented:
240 <pre caption="Near the end of /etc/modules.d/alsa">
241 alias /dev/mixer snd-mixer-oss
242 alias /dev/dsp snd-pcm-oss
243 alias /dev/midi snd-seq-oss
244 </pre>
245 </p>
246 <p>
247 Now double-check the file <path>/etc/modules.d/alsa</path> and when you're sure everyting is ok, run <c>update-modules</c>.
248 <pre>
249 # <c>update-modules</c>
250 </pre>
251 </p>
252 <note>
253 Running <c>update-modules</c> here will insert the data from <path>/etc/modules.d/alsa</path> into <path>/etc/modules.conf</path>
254 </note>
255 <p>
256 You should also verify that /etc/devfsd.conf has the alsa devices and permissions correctly registered.
257 </p>
258 <pre caption="/etc/devfsd.conf">
259 # ALSA/OSS stuff
260 # Comment/change these if you want to change the permissions on
261 # the audio devices
266 REGISTER sound/.* PERMISSIONS root.audio 660
267 REGISTER snd/.* PERMISSIONS root.audio 660
268 </pre>
269 <note>
270 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.
271 </note>
272 </body>
273 </section>
274 </chapter>
275 <chapter>
276 <title>Starting ALSA</title>
277 <section>
278 <title>Adding alsasound to a runlevel</title>
279 <body>
280 <p>
281 First thing to do now, is to make ALSA startup at boottime. Like this:
282 <pre>
283 # <c>rc-update add alsasound boot</c>
284 </pre>
285 </p>
286 <p>
287 <warn>Note that the alsasound script should be added to the "boot" runlevel, not the "default" runlevel.</warn>
288 </p>
289 </body>
290 </section>
291 <section>
292 <title>Running and unmuting</title>
293 <body>
294 <p>
295 Since we're Linux users, we don't want to reboot. So we'll start the alsasound script manually.
296 </p>
297 <pre>
298 # <c>/etc/init.d/alsasound start</c>
299 </pre>
300 <p>
301 ALSA is running now. If everything is ok, you should be able to see the ALSA modules loaded when running <c>lsmod</c>.
302 However, sound won't work yet, because the channels are still muted. We need <c>alsa-utils</c> for this.
303 </p>
304 <pre>
305 # <c>emerge alsa-utils</c>
306 # <c>amixer</c>
307 </pre>
308 <p>
309 <warn>
310 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
311 <c>snd-mixer-oss</c> and <c>snd-pcm-oss</c> once. After that run amixer again.
312 </warn>
313 </p>
314 <pre caption="only if you get an error when running amixer">
315 # <c>insmod snd-mixer-oss</c>
316 # <c>insmod snd-pcm-oss</c>
317 # <c>amixer</c>
318 </pre>
319 <p>
320 If you got this far, now unmute both Master and PCM channels.
321 </p>
322 <p>
323 <pre>
324 # <c>amixer set Master 100 unmute</c>
325 # <c>amixer set PCM 100 unmute</c>
326 # <c>aplay /usr/kde/3/share/sounds/pop.wav</c> <codenote>(pop.wav is part of KDE)</codenote>
327 </pre>
328 </p>
329 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.
330 Then, adjust the volume settings to your liking; the ncurses-based <c>alsamixer</c> is a great way to get them "just so".
331 <p>
332 You may want to emerge <c>alsa-xmms</c> as that will provide ALSA support for XMMS.
333 </p>
334 When you reboot your system, the <e>alsasound</e> init script will properly save and restore your volume settings.
335 </body>
336 </section>
337 </chapter>
338 <chapter>
339 <title>Final Notes</title>
340 <section>
341 <title>After kernel-upgrades..</title>
342 <body>
343 <p>When you ever rebuild your kernel, or upgrade to another kernel, you'll have to rebuild the ALSA modules.</p>
344 <p>Although you might have installed <c>alsa-driver</c>, <c>alsa-libs</c> and <c>alsa-utils</c>, only the first will
345 have to be installed again, since it will put the alsa modules in
346 <path>/lib/modules/*/kernel/sound/pci/</path>.</p>
347 <pre caption="needed after each kernel compile">
348 # <c>emerge alsa-driver</c>
349 </pre>
350 </body>
351 </section>
352 <section>
353 <title>/etc/modules.autoload</title>
354 <body>
355 <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
356 load the correct modules at startup.</p>
357 <p>It's not necessary to add <c>snd-pcm-oss</c> or <c>snd-mixer-oss</c> in this file.
358 Check the <uri link="http://www.djcj.org/LAU/guide/alsbook/faq1.html">this FAQ</uri> for more info.</p>
359 </body>
360 </section>
361 <section>
362 <title>More links..</title>
363 <body>
364 <p>
365 You could check these for additional info:
366 </p>
367 <p>
368 <ul>
369 <li><uri link="http://www.gentoo.org/doc/en/desktop.xml">The Gentoo Linux Desktop Configuration Guide</uri></li>
370 <li><uri link="http://www.alsa-project.org">ALSA Project Homepage</uri></li>
371 <li><uri link="http://www.alsa-project.org/documentation.php3">ALSA Users Documentation</uri></li>
372 <li><uri link="http://www.djcj.org">ALSA Howto's and FAQ's</uri></li>
373 <li><uri link="http://tldp.org/HOWTO/Sound-HOWTO/index.html">Linux Sound HOWTO</uri></li>
374 <li><uri link="http://linux-sound.org/">Sound and MIDI Software For Linux</uri></li>
375 </ul>
376 </p>
377 </body>
378 </section>
379 </chapter>
380 </guide>

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