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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>
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>
28 <license/>
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>
34 <version>1.3.3</version>
35 <date>October 9, 2003</date>
37 <chapter>
38 <title>Introduction</title>
39 <section>
40 <title>What is ALSA?</title>
41 <body>
42 <p>
43 The Advanced Linux Sound Architecture (ALSA) is a project to improve the Linux sound subsystem by rewriting
44 large chunks of it.
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.
46 </p>
48 <p>
49 ALSA provides audio and MIDI functionality for Linux.
50 </p>
52 <p>
53 Quoted from <uri>http://www.alsa-project.org</uri>, ALSA has the following features:
54 <ul><li> Efficient support for all types of audio interfaces, from consumer soundcards to professional multichannel audio interfaces.</li>
55 <li> Fully modularized sound drivers.</li>
56 <li> SMP and thread-safe design.</li>
57 <li> User space library (alsa-lib) to simplify application programming and provide higher level functionality.</li>
58 <li> Support for the older OSS API, providing binary compatibility for most OSS programs.</li>
59 </ul>
60 There's lots more to ALSA however, like support for Full Duplex playback and recording, multiple soundcard support,
61 hardware mixing of streams, extensive mixer capabilities (to support advanced features of new soundcards), ...
62 </p>
63 </body>
64 </section>
65 <section>
66 <title>Why use ALSA?</title>
67 <body>
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>
80 </section>
81 <section>
82 <title>What cards does ALSA support?</title>
83 <body>
84 <p>
85 ALSA tries to support as many (new) cards as possible by providing open-source drivers.
86 However, some vendors may provide binary-only packages.
87 </p>
88 <p>To know if your card is supported, you can find a Soundcard Matrix of supported and not-supported cards here:
89 <uri>http://www.alsa-project.org/alsa-doc/</uri>.
90 </p>
91 </body>
92 </section>
93 </chapter>
95 <chapter>
96 <title>Installation</title>
97 <section>
98 <title>Gentoo USE flags</title>
99 <body>
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>
108 </body>
109 </section>
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>
117 <p>
118 First we'll make sure that our kernel configuration is ready for use with ALSA.
119 All you need in your kernel configuration is having Sound Card Support set to be built as a module (M).
120 This will build <c>soundcore.o</c>.
121 </p>
122 <p>
123 <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).
125 However, the official ALSA documentation suggests building it as a module, since ALSA will try loading it.
126 </note>
127 </p>
128 <p>If you already have a working kernel configuration, make sure you remove all sound drivers (except for Sound Card Support).
129 If you wish to do this without having to reboot, you could do like this:
130 </p>
131 <pre>
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>
139 Now select <e>Sound Card Support</e> as Module (M) and deselect all other sound drivers.
140 Exit and say Y to save your kernel configuration.
141 After that, build the modules:
142 </p>
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>
160 </p>
161 </body>
162 </section>
164 <section>
165 <title>ALSA modules</title>
166 <body>
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>
172 <pre>
173 # <i>grep audio /proc/pci</i>
174 </pre>
177 <p>
178 <warn>
179 If you had a previous sound setup and there are still non-ALSA sound modules loaded, unload them <e>now</e>.
180 Check with <c>lsmod</c> and use <c>rmmod</c> to unload all sound-related modules on your system.
181 </warn>
182 </p>
184 <p>
185 We could simply do an <c>emerge alsa-driver</c> now, this would compile and install <e>all</e> ALSA sound drivers.
186 </p>
187 <p>
188 However, to save some time, lookup the <e>Module Name</e> of your soundcard(s) on the
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.
190 Mine is <c>snd-emu10k1</c>, since I have an SBlive! soundcard, with the <e>EMU10K1</e> chipset.
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.
192 </p>
194 <pre>
195 # <i>env ALSA_CARDS='emu10k1' emerge alsa-driver</i>
196 </pre>
197 <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>.
199 For example, like this: <c>echo 'ALSA_CARDS="emu10k1"' >> /etc/make.conf</c>
200 </note>
202 <note>
203 When you want to install ALSA drivers for more than one soundcard, you could set ALSA_CARDS to a space-separated list
204 of drivers; like this: <c>env ALSA_CARDS='emu10k1 intel8x0 ens1370' emerge alsa-driver</c>
205 </note>
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>
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>
216 <p>
217 After this, the ALSA modules should be installed on your system.
218 </p>
219 </body>
220 </section>
221 <section>
222 <title>Configuration of ALSA</title>
223 <body>
224 <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>
229 <p>
230 First, install <c>alsa-utils</c> on your system:
231 </p>
233 <pre caption = "Emerging alsa-utils">
234 # <i>emerge alsa-utils</i>
235 </pre>
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>
269 If you have more than one soundcard, adjust the <c>cards_limit</c> value and add more snd-card aliases to the file.
270 I don't have experience with this, but you can find examples for configurations with two or more soundcards in
271 <uri link="http://www.alsa-project.org/alsa-doc/alsa-howto/c1660.htm">Chapter 6</uri>
272 of the <uri link="http://www.alsa-project.org/alsa-doc/alsa-howto/alsa-howto.html">ALSA Howto</uri>.
273 </note>
274 <p>
275 Last thing to do in this file, almost at the end, check if these lines are there and uncommented:
276 </p>
277 <pre caption="Near the end of /etc/modules.d/alsa">
278 alias /dev/mixer snd-mixer-oss
279 alias /dev/dsp snd-pcm-oss
280 alias /dev/midi snd-seq-oss
281 </pre>
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>
285 # <i>modules-update</i>
286 </pre>
287 </p>
288 <note>
289 Running <c>modules-update</c> here will insert the data from <path>/etc/modules.d/alsa</path> into <path>/etc/modules.conf</path>
290 </note>
291 <p>
292 You should also verify that /etc/devfsd.conf has the alsa devices and permissions correctly registered.
293 </p>
294 <pre caption="/etc/devfsd.conf">
295 # ALSA/OSS stuff
296 # Comment/change these if you want to change the permissions on
297 # the audio devices
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>
309 </section>
310 </chapter>
311 <chapter>
312 <title>Starting ALSA</title>
313 <section>
314 <title>Adding alsasound to a runlevel</title>
315 <body>
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>
326 </section>
327 <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>
378 </chapter>
379 <chapter>
380 <title>Final Notes</title>
381 <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>
393 <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>
403 <section>
404 <title>Known bugs</title>
405 <body>
407 <note>
408 This guide lags behind on the alsa-development. Chances are these bugs
409 are already fixed when you read this.
410 </note>
412 <ul>
413 <li>
414 If you have <b>lots of noise</b> when using <b>oss</b> emulation, add
415 <e>options snd-pcm-oss dsp_map=1</e> to
416 <path>/etc/modules.d/alsa</path>.
417 </li>
418 </ul>
420 </body>
421 </section>
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>
440 </section>
441 </chapter>
442 </guide>

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