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1 <?xml version='1.0' encoding="UTF-8"?>
2 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/alsa-guide.xml,v 1.78 2007/05/06 23:27:46 nightmorph Exp $ -->
3
4 <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
5
6 <guide link="/doc/en/alsa-guide.xml">
7 <title>Gentoo Linux ALSA Guide</title>
8
9 <author title="Author">
10 <mail link="fox2mike@gentoo.org">Shyam Mani</mail>
11 </author>
12 <author title="Author">
13 <mail link="nightmorph@gentoo.org">Joshua Saddler</mail>
14 </author>
15 <author title="Contributor">
16 <mail link="flameeyes@gentoo.org">Diego Pettenò</mail>
17 </author>
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 -->
25 <license/>
26
27 <version>2.22</version>
28 <date>2007-05-07</date>
29
30 <chapter>
31 <title>Introduction</title>
32 <section>
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
52 </body>
53 </section>
54 <section>
55 <title>ALSA on Gentoo</title>
56 <body>
57
58 <p>
59 One of Gentoo's main strengths lies in giving the user maximum control over
60 how a system is installed/configured. ALSA on Gentoo follows the same
61 principle. There are two ways you can get ALSA support up and running on your
62 system. We shall look at them in detail in the next chapter.
63 </p>
64
65 </body>
66 </section>
67 </chapter>
68
69 <chapter>
70 <title>Installing ALSA</title>
71 <section>
72 <title>Options</title>
73 <body>
74
75 <warn>
76 The methods shown below are mutually exclusive. You cannot have ALSA compiled
77 in your kernel and use <c>media-sound/alsa-driver</c>. It <e>will</e> fail.
78 </warn>
79
80 <p>
81 The two options are:
82 </p>
83
84 <ol>
85 <li>
86 Use ALSA provided by your kernel. This is the preferred/recommended method.
87 </li>
88 <li>Use Gentoo's <c>media-sound/alsa-driver</c> package.</li>
89 </ol>
90
91 <p>
92 The in-kernel drivers and the <c>alsa-driver</c> package can vary a little; it's
93 possible that features and fixes found in one might not yet be incorporated into
94 the other. The upstream developers are aware of this, but the two drivers are
95 effectively separate branches of the ALSA project; they are not entirely
96 identical. You should be aware that they might function slightly differently, so
97 if one doesn't work for you, try the other! We shall take a peek into both
98 before finally deciding on one.
99 </p>
100
101 <p>
102 If you were to use ALSA provided by the kernel, the following are the pros and
103 cons:
104 </p>
105
106 <table>
107 <tr>
108 <th>Kernel ALSA</th>
109 <th>Pros and Cons</th>
110 </tr>
111 <tr>
112 <th>+</th>
113 <ti>
114 No need to emerge yet another package; drivers are integrated into kernel.
115 </ti>
116 </tr>
117 <tr>
118 <th>+</th>
119 <ti>One shot solution, no repeating emerges.</ti>
120 </tr>
121 <tr>
122 <th>-</th>
123 <ti>Might be a slightly different version than <c>alsa-driver</c>.</ti>
124 </tr>
125 </table>
126
127 <p>
128 And, if you were to use <c>alsa-driver</c>,
129 </p>
130
131 <table>
132 <tr>
133 <th>alsa-driver</th>
134 <th>Pros and Cons</th>
135 </tr>
136 <tr>
137 <th>+</th>
138 <ti>Possibly the latest drivers from the ALSA Project.</ti>
139 </tr>
140 <tr>
141 <th>+</th>
142 <ti>Useful if you intend to develop audio drivers.</ti>
143 </tr>
144 <tr>
145 <th>-</th>
146 <ti>Every kernel recompile requires a re-emerge of <c>alsa-driver</c>.</ti>
147 </tr>
148 <tr>
149 <th>-</th>
150 <ti>Needs certain kernel config options disabled to work correctly.</ti>
151 </tr>
152 </table>
153
154 </body>
155 </section>
156 <section>
157 <title>So...</title>
158 <body>
159
160 <p>
161 The differences between <c>alsa-driver</c> and the in-kernel ALSA drivers are
162 quite subtle, as mentioned earlier. Since there are not any huge differences,
163 you are encouraged to go through the process of using the ALSA provided by the
164 kernel <e>first</e> for ease of use. Before reporting any sound related issues
165 to <uri link="https://bugs.gentoo.org">Gentoo Bugzilla</uri>, please try to
166 reproduce them using <c>alsa-driver</c> and file the bug report no matter what
167 the result.
168 </p>
169
170 </body>
171 </section>
172 <section id="lspci">
173 <title>Before you proceed</title>
174 <body>
175
176 <p>
177 Whichever method of install you choose, you need to know what drivers your
178 sound card uses. In most cases, sound cards (onboard and otherwise) are PCI
179 based and <c>lspci</c> will help you in digging out the required information.
180 Please <c>emerge sys-apps/pciutils</c> to get <c>lspci</c>, if you don't have it
181 installed already. In case you have a USB sound card, <c>lsusb</c> from
182 <c>sys-apps/usbutils</c> <e>might</e> be of help. For ISA cards, try using
183 <c>sys-apps/isapnptools</c>. Also, the following pages <e>may</e> help users
184 with ISA based sound cards.
185 </p>
186
187 <ul>
188 <li>
189 <uri link="http://www.roestock.demon.co.uk/isapnptools/">The ISAPNPTOOLS
190 Page</uri>
191 </li>
192 <li>
193 <uri link="http://www2.linuxjournal.com/article/3269">LinuxJournal PnP
194 Article</uri>
195 </li>
196 <li>
197 <uri link="http://www.tldp.org/HOWTO/Sound-HOWTO/x320.html">TLDP Sound
198 HowTo</uri>
199 </li>
200 </ul>
201
202 <note>
203 For ease of use/explanation, we assume the user has a PCI based sound card for
204 the remainder of this guide.
205 </note>
206
207 <p>
208 We now proceed to find out details about the sound card.
209 </p>
210
211 <pre caption="Soundcard Details">
212 # <i>lspci -v | grep -i audio</i>
213 0000:00:0a.0 Multimedia audio controller: Creative Labs SB Live! EMU10k1 (rev 06)
214 </pre>
215
216 <p>
217 We now know that the sound card on the machine is a Sound Blaster Live! and the
218 card manufacturer is Creative Labs. Head over to the <uri
219 link="http://bugtrack.alsa-project.org/main/index.php/Matrix:Main">ALSA
220 Soundcard Matrix</uri> page and select Creative Labs from the drop down menu.
221 You will be taken to the Creative Labs matrix page where you can see that the SB
222 Live! uses the <c>emu10k1</c> module. That is the information we need for now.
223 If you are interested in detailed information, you can click on the link next to
224 the "Details" and that will take you to the <c>emu10k1</c> specific page.
225 </p>
226
227 <p>
228 If you intend to use MIDI, then you should add <c>midi</c> to your USE flags in
229 <path>/etc/make.conf</path> before emerging any ALSA packages. Later in the
230 guide, we will show you how to set up <uri link="#midi">MIDI support</uri>.
231 </p>
232
233 </body>
234 </section>
235 <section id="kernel">
236 <title>Using ALSA provided by your Kernel</title>
237 <body>
238
239 <p>
240 If you're a person who likes to keep things simple, then this is the way to go.
241 </p>
242
243 <note>
244 Since the 2005.0 release, Gentoo Linux uses 2.6 as the default kernel. Please
245 check that your kernel is a 2.6 series kernel. This method will <e>not</e> work
246 on a 2.4 kernel.
247 </note>
248
249 <p>
250 Let us now configure the kernel to enable ALSA.
251 </p>
252
253 <impo>
254 <c>genkernel</c> users should now run <c>genkernel --menuconfig all</c> and
255 then follow the instructions in <uri link="#doc_chap2_pre3">Kernel Options for
256 ALSA</uri>.
257 </impo>
258
259 <pre caption="Heading over to the source">
260 # <i>cd /usr/src/linux</i>
261 # <i>make menuconfig</i>
262 </pre>
263
264 <note>
265 The above example assumes that <path>/usr/src/linux</path> symlink points to
266 the kernel sources you want to use. Please ensure the same before proceeding.
267 </note>
268
269 <p>
270 Now we will look at some of the options we will have to enable in the 2.6
271 kernel to ensure proper ALSA support for our sound card.
272 </p>
273
274 <p>
275 Please note that for ease of use, all examples show ALSA built as modules. It
276 is advisable to follow the same as it then allows the use of <c>alsaconf</c>
277 which is a boon when you want to configure your card. Please do <e>not</e> skip
278 the <uri link="#alsa-config">Configuration</uri> section of this document. If
279 you still like to have options built-in, ensure that you make changes to your
280 config accordingly.
281 </p>
282
283 <pre caption="Kernel Options for ALSA">
284 Device Drivers ---&gt;
285 Sound ---&gt;
286
287 <comment>(This needs to be enabled)</comment>
288 &lt;M&gt; Sound card support
289
290 <comment>(Make sure OSS is disabled)</comment>
291 Open Sound System ---&gt;
292 &lt; &gt; Open Sound System (DEPRECATED)
293
294 <comment>(Move one step back and enter ALSA)</comment>
295 Advanced Linux Sound Architecture ---&gt;
296 &lt;M&gt; Advanced Linux Sound Architecture
297 <comment>(Select this if you want MIDI sequencing and routing)</comment>
298 &lt;M&gt; Sequencer support
299 <comment>(Old style /dev/mixer* and /dev/dsp* support. Recommended.)</comment>
300 &lt;M&gt; OSS Mixer API
301 &lt;M&gt; OSS PCM (digital audio) API
302
303 <comment>(You now have a choice of devices to enable support for. Generally,
304 you will have one type of device and not more. If you have more than one
305 sound card, please enable them all here.)</comment>
306
307 <comment>(Mostly for testing and development purposes, not needed for normal
308 users unless you know what you are doing.)</comment>
309 Generic devices ---&gt;
310
311 <comment>(For ISA Sound cards)</comment>
312 ISA devices ---&gt;
313 <comment>(IF you had the Gravis, you would select this option)</comment>
314 &lt;M&gt; Gravis UltraSound Extreme
315
316 <comment>(Move one level back and into PCI devices. Most sound cards today are
317 PCI devices)</comment>
318 PCI devices ---&gt;
319 <comment>(We now select the emu10k1 driver for our card)</comment>
320 &lt;M&gt; Emu10k1 (SB Live!, Audigy, E-mu APS)
321 <comment>(Or an Intel card would be)</comment>
322 &lt;M&gt; Intel/SiS/nVidia/AMD/ALi AC97 Controller
323 <comment>(Or if you have a VIA Card)</comment>
324 &lt;M&gt; VIA 82C686A/B, 8233/8235 AC97 Controller
325
326 <comment>(Move one level back and select in case you have an USB sound card)</comment>
327 USB Devices ---&gt;
328 </pre>
329
330 <p>
331 Now that your options are set, you can (re)compile the kernel and ALSA support
332 for your card should be functional once you reboot into the new kernel. Don't
333 forget to update your GRUB configuration to use the newly built kernel.
334 You can now proceed to <uri link="#alsa-utilities">ALSA Utilities</uri> and
335 see if everything is working as it should.
336 </p>
337
338 </body>
339 </section>
340 <section id="alsa-driver">
341 <title>Using the ALSA Driver package</title>
342 <body>
343
344 <p>
345 So you've decided to go the <c>alsa-driver</c> way. Let's get started then.
346 There are a few minor things to be done to ensure only the drivers for your
347 sound card are compiled. Although this is not really necessary, it cuts down
348 on the unnecessary drivers that will be compiled otherwise.
349 </p>
350
351 <p>
352 If you don't have an idea of what drivers your sound card might need, please
353 take a look at the <uri link="#lspci">lspci</uri> section of this guide. Once
354 you have your driver name (<c>emu10k1</c> in our example), edit
355 <path>/etc/make.conf</path> and add a variable, <c>ALSA_CARDS</c>.
356 </p>
357
358 <pre caption="Adding ALSA_CARDS to make.conf">
359 <comment>(For one sound card)</comment>
360 ALSA_CARDS="emu10k1"
361 <comment>(For more than one, separate names with spaces)</comment>
362 ALSA_CARDS="emu10k1 via82xx"
363 </pre>
364
365 <p>
366 If you have compiled your kernel and want to use <c>alsa-driver</c>, please
367 ensure the following before proceeding, else <c>alsa-driver</c> is likely to
368 fail. The next code listing gives you one way of performing the checks.
369 </p>
370
371 <note>
372 <c>genkernel</c> users can proceed with <uri link="#doc_chap2_pre6">Installing
373 alsa-driver</uri> as their configuration is in sync with the one shown below by
374 default.
375 </note>
376
377 <ol>
378 <li>
379 <c>CONFIG_SOUND</c> is set. (Basic Sound support enabled)
380 </li>
381 <li>
382 <c>CONFIG_SOUND_PRIME</c> is not set. (In-built OSS support disabled)
383 </li>
384 <li>
385 <c>CONFIG_SND</c> is not set. (In-built ALSA support disabled)
386 </li>
387 <li>
388 <path>/usr/src/linux</path> points to the kernel you want ALSA working on.
389 </li>
390 </ol>
391
392 <pre caption=".config checks">
393 <comment>(Assuming the linux symlink points to the correct kernel)</comment>
394 # <i>cd /usr/src/linux</i>
395 # <i>grep SOUND .config</i>
396 <comment>(1. is true)</comment>
397 CONFIG_SOUND=y
398 <comment>(2. is true)</comment>
399 CONFIG_SOUND_PRIME is not set
400 # <i>grep SND .config</i>
401 <comment>(and 3. is true)</comment>
402 CONFIG_SND is not set
403 </pre>
404
405 <p>
406 Now all you have to do is type the magic words... and no, it's not abracadabra.
407 </p>
408
409 <pre caption="Installing alsa-driver">
410 # <i>emerge alsa-driver</i>
411 </pre>
412
413 <impo>
414 Please note that you will have to run <c>emerge alsa-driver</c> after every
415 kernel (re)compile, as the earlier drivers are deleted. To make this task
416 easier, you may want to emerge the <c>module-rebuild</c> package, which will
417 keep track of module packages and rebuild them for you. First run
418 <c>module-rebuild populate</c> to create the list, and then after every kernel
419 (re)compile, you just run <c>module-rebuild rebuild</c>, and your external
420 modules will be rebuilt.
421 </impo>
422
423 </body>
424 </section>
425 </chapter>
426
427 <chapter>
428 <title>Configuring/Testing ALSA</title>
429 <section id="alsa-utilities">
430 <title>ALSA Utilities</title>
431 <body>
432
433 <p>
434 <c>alsa-utils</c> forms an integral part of ALSA as it has a truckload of
435 programs that are highly useful, including the ALSA Initscripts. Hence we
436 strongly recommend that you install <c>alsa-utils</c>
437 </p>
438
439 <pre caption="Install alsa-utils">
440 # <i>emerge alsa-utils</i>
441 </pre>
442
443 <note>
444 If you activated ALSA in your <uri link="#kernel">kernel</uri> <e>and</e> did
445 not compile ALSA as modules, please proceed to the
446 <uri link="#initscript">ALSA Initscript</uri> section. The rest of you need
447 to configure ALSA. This is made very easy by the existence of the
448 <c>alsaconf</c> tool provided by <c>alsa-utils</c>.
449 </note>
450
451 </body>
452 </section>
453 <section id="alsa-config">
454 <title>Configuration</title>
455 <body>
456
457 <p>
458 Recent versions of <c>udev</c> (<c>>=udev-103</c>) provide some degree of
459 kernel-level autoconfiguration of your sound card. If possible, try to rely on
460 just letting your kernel automatically setup your sound card for you. Otherwise,
461 use <c>alsaconf</c> to configure your card, as shown below.
462 </p>
463
464 <note>
465 Please shut down any programs that <e>might</e> access the sound card while
466 running <c>alsaconf</c>.
467 </note>
468
469 <p>
470 Another way to configure your sound card is to run <c>alsaconf</c>. Just type
471 <c>alsaconf</c> in a shell as root.
472 </p>
473
474 <pre caption="Invoking alsaconf">
475 # <i>alsaconf</i>
476 </pre>
477
478 <p>
479 You will now see a neat menu guided interface that will automatically probe
480 your devices and try to find out your sound card. You will be asked to pick
481 your sound card from a list. Once that's done, it will ask you permission to
482 automatically make required changes to <path>/etc/modules.d/alsa</path>.
483 It will then adjust your volume settings to optimum levels, run
484 <c>update-modules</c> and start the <path>/etc/init.d/alsasound</path> service.
485 Once <c>alsaconf</c> exits, you can proceed with setting up the ALSA
486 initscript.
487 </p>
488
489 </body>
490 </section>
491 <section id="initscript">
492 <title>ALSA Initscript</title>
493 <body>
494
495 <p>
496 We're now almost all setup. Whichever method you chose to install ALSA, you'll
497 need to have something load your modules or initialize ALSA and restore your
498 volume settings when your system comes up. The ALSA Initscript handles all of
499 this for you and is called <c>alsasound</c>. Add it to the boot runlevel.
500 </p>
501
502 <pre caption="Adding ALSA to the boot runlevel">
503 # <i>rc-update add alsasound boot</i>
504 * alsasound added to runlevel boot
505 * rc-update complete.
506 </pre>
507
508 <p>
509 Next, just check the <path>/etc/conf.d/alsasound</path> file and ensure that
510 SAVE_ON_STOP variable is set to yes. This saves your sound settings when you
511 shutdown your system.
512 </p>
513
514 </body>
515 </section>
516 <section>
517 <title>Audio Group</title>
518 <body>
519
520 <p>
521 Before we move on to testing, there's one last <e>important</e> thing that needs
522 to be setup. Rule of thumb in a *nix OS: Do not run as root unless needed.
523 This applies here as well ;) How? Well, most of the times you should be logged
524 in as a user and would like to listen to music or access your soundcard. For
525 that to happen, you need to be in the "audio" group. At this point, we'll add
526 users to the audio group, so that they won't have any issues when they want to
527 access sound devices. We'll use <c>gpasswd</c> here and you need to be logged in
528 as root for this to work.
529 </p>
530
531 <pre caption="Adding users to the audio group">
532 <comment>(Substitute &lt;username&gt; with your user)</comment>
533 # <i>gpasswd -a &lt;username&gt; audio </i>
534 Adding user &lt;username&gt; to group audio
535 </pre>
536
537 </body>
538 </section>
539 <section>
540 <title>Volume Check!</title>
541 <body>
542
543 <p>
544 We've completed all the setups and prerequisites, so let's fire up ALSA. If
545 you ran <c>alsaconf</c>, you can skip this step, since <c>alsaconf</c> already
546 does this for you.
547 </p>
548
549 <pre caption="Start the service">
550 # <i>/etc/init.d/alsasound start</i>
551 </pre>
552
553 <p>
554 Now that the required things have been taken care of, we need to check up on
555 the volume as in certain cases, it is muted. We use <c>alsamixer</c> for this
556 purpose.
557 </p>
558
559 <pre caption="Starting alsamixer">
560 <comment>(Opens up a console program. Only required settings are shown)</comment>
561 # <i>alsamixer</i>
562 </pre>
563
564 <impo>
565 If you have issues starting up <c>alsamixer</c> and get errors such as
566 alsamixer: function snd_ctl_open failed for default: No such file or directory,
567 this is usually an issue with udev setting up the devices. Run <c>killall
568 udevd; udevstart</c> to reload <path>/dev</path> entries and fire up
569 <c>alsamixer</c>. It should solve the issue.
570 </impo>
571
572 <p>
573 This is how the ALSA Mixer <e>might</e> look the first time you open it. Pay
574 attention to the Master and PCM channels which both have an MM below them.
575 That means they are muted. If you try to play anything with <c>alsamixer</c>
576 in this state, you will not hear anything on your speakers.
577 </p>
578
579 <figure link="/images/docs/alsa-mixermuted.png" short="AlsaMixer Muted" caption="The Alsa Mixer Main Window, Muted"/>
580
581 <p>
582 Now, we shall unmute the channels, and set volume levels as needed.
583 </p>
584
585 <warn>
586 Both Master <e>and</e> PCM need to be unmuted and set to audible volume levels
587 if you want to hear some output on your speakers.
588 </warn>
589
590 <ul>
591 <li>
592 To move between channels, use your left and right arrow keys. (&lt;-
593 &amp; -&gt;)
594 </li>
595 <li>
596 To toggle mute, move to the specific channel, for example Master and press
597 the <e>m</e> key on the keyboard.
598 </li>
599 <li>
600 To increase and decrease the volume levels, use the up and down arrow keys
601 respectively.
602 </li>
603 </ul>
604
605 <note>
606 Be careful when setting your Bass and Treble values. 50 is usually a good
607 number for both. Extremely high values of Bass may cause <e>jarring</e>
608 on speakers that are not designed to handle them.
609 </note>
610
611 <p>
612 After you're all done, your ALSA Mixer should look similar to the one below.
613 Note the 00 instead of the MM and also the volume levels for some optimum
614 settings.
615 </p>
616
617 <figure link="/images/docs/alsa-mixerunmuted.png" short="AlsaMixer Unmuted" caption="Alsa Mixer ready to roll"/>
618
619 </body>
620 </section>
621 <section>
622 <title>Sound Check!</title>
623 <body>
624
625 <p>
626 Finally. Some music. If everything above is perfect, you should now be able to
627 listen to some good music. A quick way to test is to use a command line tool
628 like <c>media-sound/madplay</c>. You could also use something more well known
629 like <c>mpg123</c>. If you are an ogg fan, you could use <c>ogg123</c> provided
630 by <c>media-sound/vorbis-tools</c>. Use any player you are comfortable with. As
631 always, <c>emerge</c> what you need.
632 </p>
633
634 <pre caption="Getting the software">
635 <comment>(Install the applications you want)</comment>
636 # <i>emerge madplay mpg123</i>
637 <comment>(To play .ogg files)</comment>
638 # <i>emerge vorbis-tools</i>
639 </pre>
640
641 <p>
642 And then play your favorite sound track...
643 </p>
644
645 <pre caption="Playing Music">
646 # <i>madplay -v /mnt/shyam/Music/Paul\ Oakenfold\ -\ Dread\ Rock.mp3</i>
647 MPEG Audio Decoder 0.15.2 (beta) - Copyright (C) 2000-2004 Robert Leslie et al.
648 Title: Dread Rock
649 Artist: Paul Oakenfold
650 Album: Matrix Reloaded
651 Year: 2003
652 Genre: Soundtrack
653 Soundtrack
654 00:04:19 Layer III, 160 kbps, 44100 Hz, joint stereo (MS), no CRC
655
656 # <i>ogg123 Paul\ Oakenfold\ -\ Dread\ Rock.ogg</i>
657 Audio Device: Advanced Linux Sound Architecture (ALSA) output
658
659 Playing: Paul Oakenfold - Dread Rock.ogg
660 Ogg Vorbis stream: 2 channel, 44100 Hz
661 Genre: Soundtrack
662 Transcoded: mp3;160
663 Title: Dread Rock
664 Artist: Paul Oakenfold
665 Date: 2003
666 Album: Matrix Reloaded
667 Time: 00:11.31 [04:28.75] of 04:40.06 (200.6 kbps) Output Buffer 96.9%
668 </pre>
669
670 </body>
671 </section>
672 <section>
673 <title>ALSA and USE</title>
674 <body>
675
676 <p>
677 You can now add the <c>alsa</c> use flag to <path>/etc/make.conf</path> to
678 ensure that your applications that support ALSA get built with it. Some
679 architectures like x86 and amd64 have the flag enabled by default.
680 </p>
681
682 </body>
683 </section>
684 <section>
685 <title>Issues?</title>
686 <body>
687
688 <p>
689 If for some reason you're unable to hear sound, the first thing to do would
690 be to check your <uri link="#doc_chap3_pre6">alsamixer</uri> settings. 80% of
691 the issues lie with muted channels or low volume. Also check your Window
692 Manager's sound applet and verify that volumes are set to audible levels.
693 </p>
694
695 <p>
696 <path>/proc</path> is your friend. And in this case, <path>/proc/asound</path>
697 is your best friend. We shall just take a short look at how much info is made
698 available to us there.
699 </p>
700
701 <pre caption="Fun with /proc/asound">
702 <comment>(First and foremost, if /proc/asound/cards shows your card, ALSA has
703 picked up your sound card fine.)</comment>
704 # <i>cat /proc/asound/cards</i>
705 0 [Live ]: EMU10K1 - Sound Blaster Live!
706 Sound Blaster Live! (rev.6, serial:0x80271102) at 0xb800, irq 11
707
708 <comment>(This displays the current running ALSA version)</comment>
709 # <i>cat /proc/asound/version</i>
710 Advanced Linux Sound Architecture Driver Version 1.0.8 (Thu Jan 13 09:39:32 2005 UTC).
711
712 <comment>(ALSA OSS emulation details)</comment>
713 # <i>cat /proc/asound/oss/sndstat</i>
714 Sound Driver:3.8.1a-980706 (ALSA v1.0.8 emulation code)
715 Kernel: Linux airwolf.zion 2.6.11ac1 #2 Wed May 4 00:35:08 IST 2005 i686
716 Config options: 0
717
718 Installed drivers:
719 Type 10: ALSA emulation
720
721 Card config:
722 Sound Blaster Live! (rev.6, serial:0x80271102) at 0xb800, irq 11
723
724 Audio devices:
725 0: EMU10K1 (DUPLEX)
726
727 Synth devices: NOT ENABLED IN CONFIG
728
729 Midi devices:
730 0: EMU10K1 MPU-401 (UART)
731
732 Timers:
733 7: system timer
734
735 Mixers:
736 0: SigmaTel STAC9721/23
737 </pre>
738
739 <p>
740 The other most common issue users face is the dreaded "Unknown symbol in module"
741 error. An example of the same is shown below.
742 </p>
743
744 <pre caption="Unknown Symbol in module error">
745 # <i>/etc/init.d/alsasound start</i>
746 * Loading ALSA modules ...
747 * Loading: snd-card-0 ... [ ok ]
748 * Loading: snd-pcm-oss ...
749 WARNING: Error inserting snd_mixer_oss
750 (/lib/modules/2.6.12-gentoo-r6/kernel/sound/core/oss/snd-mixer-oss.ko): Unknown
751 symbol in module, or unknown parameter (see dmesg) FATAL: Error inserting
752 snd_pcm_oss
753 (/lib/modules/2.6.12-gentoo-r6/kernel/sound/core/oss/snd-pcm-oss.ko): Unknown
754 symbol in module, or unknown parameter (see dmesg)
755 [ !! ]
756 * Loading: snd-mixer-oss ...
757 FATAL: Error inserting snd_mixer_oss
758 (/lib/modules/2.6.12-gentoo-r6/kernel/sound/core/oss/snd-mixer-oss.ko): Unknown
759 symbol in module, or unknown parameter (see dmesg)
760 [ !! ]
761 * Loading: snd-seq ... [ ok ]
762 * Loading: snd-emu10k1-synth ... [ ok ]
763 * Loading: snd-seq-midi ... [ ok ]
764 * Restoring Mixer Levels ... [ ok ]
765 </pre>
766
767 <p>
768 And when you take a look at <c>dmesg</c> as suggested, you're quite likely to
769 see:
770 </p>
771
772 <pre caption="dmesg output">
773 <comment>(Only relevant portions are shown below)</comment>
774 # <i>dmesg | less</i>
775 ACPI: PCI Interrupt 0000:02:06.0[A] -> Link [APC3] -> GSI 18 (level, low) -> IRQ 209
776 snd_mixer_oss: Unknown symbol snd_unregister_oss_device
777 snd_mixer_oss: Unknown symbol snd_register_oss_device
778 snd_mixer_oss: Unknown symbol snd_mixer_oss_notify_callback
779 snd_mixer_oss: Unknown symbol snd_oss_info_register
780 snd_pcm_oss: Unknown symbol snd_unregister_oss_device
781 snd_pcm_oss: Unknown symbol snd_register_oss_device
782 snd_pcm_oss: Unknown symbol snd_mixer_oss_ioctl_card
783 snd_pcm_oss: Unknown symbol snd_oss_info_register
784 snd_mixer_oss: Unknown symbol snd_unregister_oss_device
785 snd_mixer_oss: Unknown symbol snd_register_oss_device
786 snd_mixer_oss: Unknown symbol snd_mixer_oss_notify_callback
787 snd_mixer_oss: Unknown symbol snd_oss_info_register
788 </pre>
789
790 <p>
791 The above issue is caused when you switch from <c>alsa-driver</c> to in-kernel
792 ALSA because when you unmerge <c>alsa-driver</c> the module files are config
793 protected and hence get left behind. So, when you switch to in-kernel
794 drivers, running <c>modprobe</c> gives you a mix of <c>alsa-driver</c> and
795 in-kernel modules thus causing the above errors.
796 </p>
797
798 <p>
799 The solution is quite easy. We just need to manually remove the problem causing
800 directory after you unmerge <c>alsa-driver</c>. Be sure to remove the correct
801 kernel version and not the current one!
802 </p>
803
804 <pre caption="Removing the alsa-driver modules">
805 # <i>rm -rf /lib/modules/$(uname -r)/alsa-driver</i>
806 </pre>
807
808 <p>
809 Another reason for error messages similar to the ones above could be a file in
810 <path>/etc/modules.d</path> supplying a <c>device_mode</c> parameter when it
811 isn't required. Confirm that this is indeed the issue and find out which file
812 is the culprit.
813 </p>
814
815 <pre caption="Confirming and searching for device_mode">
816 <comment>(Check dmesg to confirm)</comment>
817 # <i>dmesg | grep device_mode</i>
818 snd: Unknown parameter `device_mode'
819 <comment>(Now, to get to the source of the issue)</comment>
820 # <i>grep device_mode /etc/modules.d/*</i>
821 </pre>
822
823 <p>
824 Usually it is a file called <path>alsa</path> with the line <c>options snd
825 device_mode=0666</c>. Remove this line and restart the alsasound service and
826 that should take care of this issue.
827 </p>
828
829 </body>
830 </section>
831 </chapter>
832
833 <chapter>
834 <title>Other things ALSA</title>
835 <section id="midi">
836 <title>Setting up MIDI support</title>
837 <body>
838
839 <p>
840 First, check to make sure that you enabled the <c>midi</c> USE flag in
841 <path>/etc/make.conf</path>. If you didn't, go ahead and add it now. You will
842 also need to re-emerge any ALSA packages that use the <c>midi</c> flag, such as
843 <c>alsa-lib</c>, <c>alsa-utils</c>, and <c>alsa-driver</c>.
844 </p>
845
846 <p>
847 If your sound card is one of those that come with on-board MIDI synthesizers
848 and you would like to listen to some .mid files, you have to install
849 <c>awesfx</c> which is basically a set of utilities for controlling the AWE32
850 driver. We need to install it first. If you don't have a hardware synthesizer,
851 you can use a virtual one. Please see the section on
852 <uri link="#vsynth">Virtual Synthesizers</uri> for more information.
853 </p>
854
855 <pre caption="Installing awesfx">
856 # <i>emerge awesfx</i>
857 </pre>
858
859 <note>
860 You will need to copy over SoundFont (SF2) files from your sound card's driver
861 CD or a Windows installation into <path>/usr/share/sounds/sf2/</path>. For
862 example a sound font file for the Creative SBLive! card would be 8MBGMSFX.SF2.
863 </note>
864
865 <p>
866 After copying over the Soundfont files, we can then play a midi file as shown.
867 You can also add the <c>asfxload</c> command to
868 <path>/etc/conf.d/local.start</path>, so that the sound font is loaded
869 every time the system starts up.
870 </p>
871
872 <note>
873 <path>/mnt</path> paths mentioned in the code listing(s) below will <e>not</e>
874 be the same in your machine. They are just an example. Please be careful to
875 change the path to suit your machine.
876 </note>
877
878 <pre caption="Loading Soundfonts">
879 <comment>(First, copy the Soundfont)</comment>
880 # <i>cp /mnt/win2k/Program\ Files/CreativeSBLive2k/SFBank/8MBGMSFX.SF2 /usr/share/sounds/sf2/</i>
881 <comment>(Or get it from your SoundBlaster CD)</comment>
882 # <i>cp /mnt/cdrom/AUDIO/ENGLISH/SFBANK/8MBGMSFX.SF2 /usr/share/sounds/sf2/</i>
883 <comment>(We load the specific Soundfont)</comment>
884 # <i>asfxload /usr/share/sounds/sf2/8MBGMSFX.SF2</i>
885 </pre>
886
887 <p>
888 You can now play midi files using a program like <c>aplaymidi</c>. Run
889 <c>aplaymidi -l</c> to get a list of available ports and then pick one
890 to play the file on.
891 </p>
892
893 <pre caption="Playing MIDI">
894 <comment>(Check open ports)</comment>
895 # <i>aplaymidi -l</i>
896 Port Client name Port name
897 64:0 EMU10K1 MPU-401 (UART) EMU10K1 MPU-401 (UART)
898 65:0 Emu10k1 WaveTable Emu10k1 Port 0
899 65:1 Emu10k1 WaveTable Emu10k1 Port 1
900 65:2 Emu10k1 WaveTable Emu10k1 Port 2
901 65:3 Emu10k1 WaveTable Emu10k1 Port 3
902 <comment>(Pick a port, and play a mid file)</comment>
903 # <i> aplaymidi --port=65:0 /mnt/shyam/music/midi/mi2.mid</i>
904 </pre>
905
906 </body>
907 </section>
908 <section id="vsynth">
909 <title>Virtual Synthesizers</title>
910 <body>
911
912 <p>
913 If your sound card lacks a hardware synthesizer, you could use a virtual one
914 like <c>timidity++</c>. Installation is a breeze.
915 </p>
916
917 <pre caption="Installing timidity++">
918 # <i>emerge timidity++</i>
919 </pre>
920
921 <p>
922 For timidity to play sounds, it needs a sound font. Fortunately, the ebuild will
923 install some sound font packages for you. There are a few other font packages
924 available in Portage, such as <c>timidity-freepats</c> and
925 <c>timidity-eawpatches</c>. You can have multiple sound font configurations
926 installed, and you can place your own in <path>/usr/share/timidity/</path>. To
927 switch between different timidity configurations, you should use
928 <c>eselect</c>.
929 </p>
930
931 <pre caption="Changing configurations">
932 # <i>eselect timidity list</i>
933 # <i>eselect timidity set eawpatches</i>
934 </pre>
935
936 <p>
937 Don't forget to add <c>timidity</c> to the default runlevel.
938 </p>
939
940 <pre caption="Adding timidity to the default runlevel">
941 # <i>rc-update add timidity default</i>
942 # <i>/etc/init.d/timidity start</i>
943 </pre>
944
945 <p>
946 You can now try out <uri link="#doc_chap4_pre3">Playing MIDI</uri> files.
947 </p>
948
949 </body>
950 </section>
951 <section>
952 <title>Tools and Firmware</title>
953 <body>
954
955 <p>
956 Some specific sound cards can benefit from certain tools provided by the
957 <c>alsa-tools</c> and <c>alsa-firmware</c> packages. You may install either with
958 a simple <c>emerge</c>.
959 </p>
960
961 <pre caption="Installing ALSA Tools">
962 # <i>emerge alsa-tools</i>
963 </pre>
964
965 </body>
966 </section>
967 <section>
968 <title>Multiple sound cards</title>
969 <body>
970
971 <p>
972 You can have more than one sound card in your system simultaneously, provided
973 that you have built ALSA as modules in your kernel (or have installed
974 <c>alsa-driver</c> instead). You just need to specify which should be started
975 first in <path>/etc/modules.d/alsa</path>. Your cards are identified by their
976 driver names inside this file. 0 is the first card, 1 is the second, and so on.
977 Here's an example for a system with two sound cards.
978 </p>
979
980 <pre caption="Two sound cards in /etc/modules.d/alsa">
981 options snd-emu10k1 index=0
982 options snd-via82xx index=1
983 </pre>
984
985 <p>
986 Or, if you have two cards that use the same driver, you specify them on the same
987 line, using comma-separated numbers. Here's an example for a system with three
988 sound cards, two of which are the same Intel High Definition Audio card.
989 </p>
990
991 <pre caption="Multiple sound cards in /etc/modules.d/alsa">
992 options snd-ymfpci index=0
993 options snd-hda-intel index=1,2
994 </pre>
995
996 </body>
997 </section>
998 <section>
999 <title>Plugins</title>
1000 <body>
1001
1002 <p>
1003 You may want to install some plugins for extra functionality.
1004 <c>alsa-plugins</c> is a collection of useful plugins, which include: PulseAudio
1005 output, a sample rate converter, jack (a low-latency audio server), and an
1006 encoder that lets you output 6-channel audio through digital S/PDIF connections
1007 (both optical and coaxial). You can choose which of its plugins you want
1008 installed by adding their USE flags to <path>/etc/portage/package.use</path>.
1009 </p>
1010
1011 <pre caption="Installing alsa-plugins">
1012 # <i>emerge -avt alsa-plugins</i>
1013 </pre>
1014
1015 </body>
1016 </section>
1017 <section>
1018 <title>A big thank you to...</title>
1019 <body>
1020
1021 <p>
1022 Everyone who contributed to the earlier version of the Gentoo ALSA Guide:
1023 Vincent Verleye, Grant Goodyear, Arcady Genkin, Jeremy Huddleston,
1024 John P. Davis, Sven Vermeulen, Benny Chuang, Tiemo Kieft and Erwin.
1025 </p>
1026
1027 </body>
1028 </section>
1029 <section>
1030 <title>References</title>
1031 <body>
1032
1033 <ul>
1034 <li><uri link="http://www.alsa-project.org/">The ALSA Project</uri></li>
1035 <li><uri link="http://linux-sound.org">Linux Sound/MIDI Software</uri></li>
1036 </ul>
1037
1038 </body>
1039 </section>
1040 </chapter>
1041 </guide>

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