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1 <?xml version='1.0' encoding="UTF-8"?>
2 <!-- $Header$ -->
3 <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
5 <guide link = "/doc/en/alsa-guide.xml">
6 <title>Gentoo Linux ALSA Guide</title>
7 <author title="Author"><mail link="zu@pandora.be">
8 Vincent Verleye</mail>
9 </author>
10 <author title="Author"><mail link="g2boojum@gentoo.org">
11 Grant Goodyear</mail>
12 </author>
13 <author title="Author"><mail link="agenkin@gentoo.org">
14 Arcady Genkin</mail>
15 </author>
16 <author title="Editor"><!-- zhen@gentoo.org -->
17 John P. Davis
18 </author>
19 <author title="Editor"><mail link="swift@gentoo.org">
20 Sven Vermeulen</mail>
21 </author>
22 <author title="Editor"><mail link="bennyc@gentoo.org">
23 Benny Chuang</mail>
24 </author>
25 <author title="Editor"><mail link="blubber@gentoo.org">
26 Tiemo Kieft</mail>
27 </author>
29 <license/>
31 <abstract>
32 This guide will show you how to set up the Advanced Linux Sound Architecture (ALSA) on Gentoo Linux.
33 In addition to the Gentoo Linux Desktop Configuration Guide, this guide is supposed to give you more information on this subject. </abstract>
35 <version>1.3.3</version>
36 <date>October 9, 2003</date>
38 <chapter>
39 <title>Introduction</title>
40 <section>
41 <title>What is ALSA?</title>
42 <body>
43 <p>
44 The Advanced Linux Sound Architecture (ALSA) is a project to improve the Linux sound subsystem by rewriting
45 large chunks of it.
46 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.
47 </p>
49 <p>
50 ALSA provides audio and MIDI functionality for Linux.
51 </p>
53 <p>
54 Quoted from <uri>http://www.alsa-project.org</uri>, ALSA has the following features:
55 <ul><li> Efficient support for all types of audio interfaces, from consumer soundcards to professional multichannel audio interfaces.</li>
56 <li> Fully modularized sound drivers.</li>
57 <li> SMP and thread-safe design.</li>
58 <li> User space library (alsa-lib) to simplify application programming and provide higher level functionality.</li>
59 <li> Support for the older OSS API, providing binary compatibility for most OSS programs.</li>
60 </ul>
61 There's lots more to ALSA however, like support for Full Duplex playback and recording, multiple soundcard support,
62 hardware mixing of streams, extensive mixer capabilities (to support advanced features of new soundcards), ...
63 </p>
64 </body>
65 </section>
66 <section>
67 <title>Why use ALSA?</title>
68 <body>
69 <p>
70 If your soundcard is supported by the Linux kernel sound system or the commercial OSS/4Front sound driver system,
71 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.
72 If you want this, just read through the <uri link="http://www.tldp.org/HOWTO/Sound-HOWTO/index.html">Linux Sound HOWTO</uri>.
73 </p>
74 <p>
75 However, those OSS/4Front drivers have some limitations -- being commercial is one.
76 ALSA is an attempt to go beyond these limitations and to do so in an open source fashion.
77 ALSA is a fully GPL and LGPL'ed sound driver system, that provides a professional quality system for recording, playback,
78 and MIDI sequencing.
79 </p>
80 </body>
81 </section>
82 <section>
83 <title>What cards does ALSA support?</title>
84 <body>
85 <p>
86 ALSA tries to support as many (new) cards as possible by providing open-source drivers.
87 However, some vendors may provide binary-only packages.
88 </p>
89 <p>To know if your card is supported, you can find a Soundcard Matrix of supported and not-supported cards here:
90 <uri>http://www.alsa-project.org/alsa-doc/</uri>.
91 </p>
92 </body>
93 </section>
94 </chapter>
96 <chapter>
97 <title>Installation</title>
98 <section>
99 <title>Gentoo USE flags</title>
100 <body>
102 <p>
103 To compile programs with ALSA-support, be sure to add <e>alsa</e> to
104 your USE-variable. However, several tools don't support alsa yet, and
105 require OSS. ALSA provides OSS-emulation if you define <e>oss</e> in your
106 USE-variable before you start.
107 </p>
109 </body>
110 </section>
112 <section>
113 <title>Kernel modules</title>
114 <body>
115 <p>
116 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.
117 </p>
118 <p>
119 First we'll make sure that our kernel configuration is ready for use with ALSA.
120 All you need in your kernel configuration is having Sound Card Support set to be built as a module (M).
121 This will build <c>soundcore.o</c>.
122 </p>
123 <p>
124 <note>
125 Possibly, this will also work when you built Sound Card Support in the kernel (Y) instead of building it as a module (M).
126 However, the official ALSA documentation suggests building it as a module, since ALSA will try loading it.
127 </note>
128 </p>
129 <p>If you already have a working kernel configuration, make sure you remove all sound drivers (except for Sound Card Support).
130 If you wish to do this without having to reboot, you could do like this:
131 </p>
132 <pre>
133 # <i>cd /usr/src/linux</i>
134 # <i>cp .config ~/</i>
135 # <i>make mrproper</i>
136 # <i>cp ~/.config .</i>
137 # <i>make menuconfig</i>
138 </pre>
139 <p>
140 Now select <e>Sound Card Support</e> as Module (M) and deselect all other sound drivers.
141 Exit and say Y to save your kernel configuration.
142 After that, build the modules:
143 </p>
144 <pre>
145 # <i>make dep clean</i>
146 # <i>make modules modules_install</i>
147 </pre>
148 <p>
149 Before installing your new modules, this last line will delete all your previous modules,
150 even the ones from a previous ALSA installation.
151 </p>
152 <p>
153 <impo>
154 This means, whenever you recompile your kernel later on, you MUST recompile <c>alsa-driver</c>.
155 </impo>
156 </p>
157 </body>
158 </section>
160 <section>
161 <title>ALSA modules</title>
162 <body>
164 <p>
165 Now it's time to install the ALSA drivers for your soundcard(s). If your soundcard is PCI, you can find out the name
166 and type of your soundcard by looking at the output of /proc/pci.
167 </p>
168 <pre>
169 # <i>grep audio /proc/pci</i>
170 </pre>
173 <p>
174 <warn>
175 If you had a previous sound setup and there are still non-ALSA sound modules loaded, unload them <e>now</e>.
176 Check with <c>lsmod</c> and use <c>rmmod</c> to unload all sound-related modules on your system.
177 </warn>
178 </p>
180 <p>
181 We could simply do an <c>emerge alsa-driver</c> now, this would compile and install <e>all</e> ALSA sound drivers.
182 </p>
183 <p>
184 However, to save some time, lookup the <e>Module Name</e> of your soundcard(s) on the
185 <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.
186 Mine is <c>snd-emu10k1</c>, since I have an SBlive! soundcard, with the <e>EMU10K1</e> chipset.
187 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.
188 </p>
190 <pre>
191 # <i>env ALSA_CARDS='emu10k1' emerge alsa-driver</i>
192 </pre>
193 <note>
194 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>.
195 For example, like this: <c>echo 'ALSA_CARDS="emu10k1"' >> /etc/make.conf</c>
196 </note>
198 <note>
199 When you want to install ALSA drivers for more than one soundcard, you could set ALSA_CARDS to a space-separated list
200 of drivers; like this: <c>env ALSA_CARDS='emu10k1 intel8x0 ens1370' emerge alsa-driver</c>
201 </note>
203 <note>If you want to have OSS compatibility, make sure to emerge <i>alsa-oss</i>, it is the ALSA/OSS compatibility
204 wrapper. </note>
206 <note>If you plan on recompiling your kernels numerous times, it might
207 be adviseable to emerge <c>alsa-driver</c> with <c>--buildpkg</c>. This
208 will create a binary package for it. Later, after recompiling your kernel,
209 you can just do <c>emerge --usepkg alsa-driver</c> which will install the
210 binary package instead of recompiling it completely.</note>
212 <p>
213 After this, the ALSA modules should be installed on your system.
214 </p>
215 </body>
216 </section>
217 <section>
218 <title>Configuration of ALSA</title>
219 <body>
220 <p>
221 Let's start configuring now to get ALSA working properly.
222 We'll need to edit some files, to let our system know about the freshly installed ALSA modules.
223 </p>
225 <p>
226 First, install <c>alsa-utils</c> on your system:
227 </p>
229 <pre caption = "Emerging alsa-utils">
230 # <i>emerge alsa-utils</i>
231 </pre>
233 <p>
234 Hereafter, we need to edit <path>/etc/modules.d/alsa</path>.
235 </p>
236 <warn>
237 There is no need to edit <path>/etc/modules.conf</path>. Instead, always edit files in <path>/etc/modules.d</path>.
238 </warn>
239 <p>
240 Check the ALSA portion <e>at the bottom of the file</e>.
241 By tweaking this line you can specify the max number of soundcards you have (generally, just one).
242 </p>
243 <pre caption="At the bottom of /etc/modules.d/alsa">
244 <comment>Set this to the correct number of cards.</comment>
245 options snd cards_limit=1
246 </pre>
247 <p>
248 Now we'll specify the sounddriver(s) ALSA should use. In the same file, edit like this:
249 </p>
250 <pre caption="In /etc/modules.d/alsa">
251 ## and then run `modules-update' command.
252 ## Read alsa-driver's INSTALL file in /usr/share/doc for more info.
253 ##
254 ## ALSA portion
255 alias snd-card-0 snd-emu10k1
256 <comment>## If you have more than one, add:</comment>
257 ## alias snd-card-1 snd-intel8x0
258 ## alias snd-card-2 snd-ens1370
259 ## OSS/Free portion
260 ## alias sound-slot-0 snd-card-0
261 ## alias sound-slot-1 snd-card-1
262 ##
263 </pre>
264 <note>
265 If you have more than one soundcard, adjust the <c>cards_limit</c> value and add more snd-card aliases to the file.
266 I don't have experience with this, but you can find examples for configurations with two or more soundcards in
267 <uri link="http://www.alsa-project.org/alsa-doc/alsa-howto/c1660.htm">Chapter 6</uri>
268 of the <uri link="http://www.alsa-project.org/alsa-doc/alsa-howto/alsa-howto.html">ALSA Howto</uri>.
269 </note>
270 <p>
271 Last thing to do in this file, almost at the end, check if these lines are there and uncommented:
272 </p>
273 <pre caption="Near the end of /etc/modules.d/alsa">
274 alias /dev/mixer snd-mixer-oss
275 alias /dev/dsp snd-pcm-oss
276 alias /dev/midi snd-seq-oss
277 </pre>
278 <p>
279 Now double-check the file <path>/etc/modules.d/alsa</path> and when you're sure everyting is ok, run <c>modules-update</c>.
280 <pre>
281 # <i>modules-update</i>
282 </pre>
283 </p>
284 <note>
285 Running <c>modules-update</c> here will insert the data from <path>/etc/modules.d/alsa</path> into <path>/etc/modules.conf</path>
286 </note>
287 <p>
288 You should also verify that /etc/devfsd.conf has the alsa devices and permissions correctly registered.
289 </p>
290 <pre caption="/etc/devfsd.conf">
291 # ALSA/OSS stuff
292 # Comment/change these if you want to change the permissions on
293 # the audio devices
298 REGISTER sound/.* PERMISSIONS root.audio 660
299 REGISTER snd/.* PERMISSIONS root.audio 660
300 </pre>
301 <note>
302 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.
303 </note>
304 </body>
305 </section>
306 </chapter>
307 <chapter>
308 <title>Starting ALSA</title>
309 <section>
310 <title>Adding alsasound to a runlevel</title>
311 <body>
312 <p>
313 First thing to do now, is to make ALSA startup at boottime. Like this:
314 <pre>
315 # <i>rc-update add alsasound boot</i>
316 </pre>
317 </p>
318 <p>
319 <warn>Note that the alsasound script should be added to the "boot" runlevel, not the "default" runlevel.</warn>
320 </p>
321 </body>
322 </section>
323 <section>
324 <title>Running and unmuting</title>
325 <body>
326 <p>
327 Since we're Linux users, we don't want to reboot. So we'll start the alsasound script manually.
328 </p>
329 <pre>
330 # <i>/etc/init.d/alsasound start</i>
331 </pre>
332 <p>
333 ALSA is running now. If everything is ok, you should be able to see the ALSA modules loaded when running <c>lsmod</c>.
334 However, sound won't work yet, because the channels are still muted. We need <c>amixer</c> for this.
335 </p>
336 <pre caption = "Running amixer">
337 # <i>amixer</i>
338 </pre>
339 <p>
340 <warn>
341 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
342 <c>snd-mixer-oss</c> and <c>snd-pcm-oss</c> once. After that run amixer again.
343 </warn>
344 </p>
345 <pre caption="only if you get an error when running amixer">
346 # <i>modprobe snd-mixer-oss</i>
347 # <i>modprobe snd-pcm-oss</i>
348 # <i>amixer</i>
349 </pre>
350 <p>
351 If you got this far, now unmute Master and PCM channels. Some hardware
352 even requires you to unmute the center channel or even the surround
353 channel.
354 </p>
355 <p>
356 <pre caption = "Unmuting channels">
357 # <i>amixer set Master 100 unmute</i>
358 # <i>amixer set PCM 100 unmute</i>
359 <comment>Only if the above doesn't succeed on its own:</comment>
360 # <i>amixer set Center 100 unmute</i>
361 # <i>amixer set Surround 100 unmute</i>
362 <comment>Test the sound:</comment>
363 # <i>aplay $KDEDIR/share/sounds/pop.wav</i> <codenote>(pop.wav is part of KDE)</codenote>
364 </pre>
365 </p>
366 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.
367 Then, adjust the volume settings to your liking; the ncurses-based <c>alsamixer</c> is a great way to get them "just so".
368 <p>
369 You may want to emerge <c>alsa-xmms</c> as that will provide ALSA support for XMMS.
370 </p>
371 When you reboot your system, the <e>alsasound</e> init script will properly save and restore your volume settings.
372 </body>
373 </section>
374 </chapter>
375 <chapter>
376 <title>Final Notes</title>
377 <section>
378 <title>After kernel-upgrades..</title>
379 <body>
380 <p>When you ever rebuild your kernel, or upgrade to another kernel, you'll have to rebuild the ALSA modules.</p>
381 <p>Although you might have installed <c>alsa-driver</c>, <c>alsa-libs</c> and <c>alsa-utils</c>, only the first will
382 have to be installed again, since it will put the alsa modules in
383 <path>/lib/modules/*/kernel/sound/pci/</path>.</p>
384 <pre caption="needed after each kernel compile">
385 # <i>emerge alsa-driver</i>
386 </pre>
387 </body>
388 </section>
389 <section>
390 <title>/etc/modules.autoload</title>
391 <body>
392 <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
393 load the correct modules at startup.</p>
394 <p>It's not necessary to add <c>snd-pcm-oss</c> or <c>snd-mixer-oss</c> in this file.
395 Check the <uri link="http://www.djcj.org/LAU/guide/alsbook/faq1.html">this FAQ</uri> for more info.</p>
396 </body>
397 </section>
399 <section>
400 <title>Known bugs</title>
401 <body>
403 <note>
404 This guide lags behind on the alsa-development. Chances are these bugs
405 are already fixed when you read this.
406 </note>
408 <ul>
409 <li>
410 If you have <b>lots of noise</b> when using <b>oss</b> emulation, add
411 <e>options snd-pcm-oss dsp_map=1</e> to
412 <path>/etc/modules.d/alsa</path>.
413 </li>
414 </ul>
416 </body>
417 </section>
419 <section>
420 <title>More links..</title>
421 <body>
422 <p>
423 You could check these for additional info:
424 </p>
425 <p>
426 <ul>
427 <li><uri link="http://www.gentoo.org/doc/en/desktop.xml">The Gentoo Linux Desktop Configuration Guide</uri></li>
428 <li><uri link="http://www.alsa-project.org">ALSA Project Homepage</uri></li>
429 <li><uri link="http://www.alsa-project.org/documentation.php3">ALSA Users Documentation</uri></li>
430 <li><uri link="http://www.djcj.org">ALSA Howto's and FAQ's</uri></li>
431 <li><uri link="http://tldp.org/HOWTO/Sound-HOWTO/index.html">Linux Sound HOWTO</uri></li>
432 <li><uri link="http://linux-sound.org/">Sound and MIDI Software For Linux</uri></li>
433 </ul>
434 </p>
435 </body>
436 </section>
437 </chapter>
438 </guide>

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