/[gentoo]/xml/htdocs/doc/en/alsa-guide.xml
Gentoo

Contents of /xml/htdocs/doc/en/alsa-guide.xml

Parent Directory Parent Directory | Revision Log Revision Log


Revision 1.76 - (show annotations) (download) (as text)
Mon Apr 16 05:39:54 2007 UTC (7 years, 5 months ago) by nightmorph
Branch: MAIN
Changes since 1.75: +4 -4 lines
File MIME type: application/xml
changed modules-update command to update-modules, per the runtime warning about modules-update being deprecated. weird. seems update-modules used to be the name anyway years ago, see lpi 101 part 2.

1 <?xml version='1.0' encoding="UTF-8"?>
2 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/alsa-guide.xml,v 1.75 2007/03/10 13:02:28 jkt 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>2.19</version>
28 <date>2007-04-15</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>Use ALSA provided by your kernel.</li>
86 <li>Use Gentoo's <c>media-sound/alsa-driver</c> package.</li>
87 </ol>
88
89 <p>
90 The in-kernel drivers and the <c>alsa-driver</c> package can vary a little; it's
91 possible that features and fixes found in one might not yet be incorporated into
92 the other. The upstream developers are aware of this, but the two drivers are
93 effectively separate branches of the ALSA project; they are not entirely
94 identical. You should be aware that they might function slightly differently, so
95 if one doesn't work for you, try the other! We shall take a peek into both
96 before finally deciding on one.
97 </p>
98
99 <p>
100 If you were to use ALSA provided by the kernel, the following are the pros and
101 cons :
102 </p>
103
104 <table>
105 <tr>
106 <th>Kernel ALSA</th>
107 <th>Pros and Cons</th>
108 </tr>
109 <tr>
110 <th>+</th>
111 <ti>
112 No need to emerge yet another package; drivers are integrated into kernel.
113 </ti>
114 </tr>
115 <tr>
116 <th>+</th>
117 <ti>One shot solution, no repeating emerges.</ti>
118 </tr>
119 <tr>
120 <th>-</th>
121 <ti>Might be a slightly different version than <c>alsa-driver</c>.</ti>
122 </tr>
123 </table>
124
125 <p>
126 And, if you were to use alsa-driver,
127 </p>
128
129 <table>
130 <tr>
131 <th>alsa-driver</th>
132 <th>Pros and Cons</th>
133 </tr>
134 <tr>
135 <th>+</th>
136 <ti>Possibly the latest drivers from the ALSA Project.</ti>
137 </tr>
138 <tr>
139 <th>+</th>
140 <ti>Useful if you intend to develop audio drivers.</ti>
141 </tr>
142 <tr>
143 <th>-</th>
144 <ti>Every kernel recompile requires a re-emerge of <c>alsa-driver</c>.</ti>
145 </tr>
146 <tr>
147 <th>-</th>
148 <ti>Needs certain kernel config options disabled to work correctly.</ti>
149 </tr>
150 </table>
151
152 </body>
153 </section>
154 <section>
155 <title>So...</title>
156 <body>
157
158 <p>
159 The differences between <c>alsa-driver</c> and the in-kernel ALSA drivers are
160 quite subtle, as mentioned earlier. Since there are not any huge differences,
161 this guide will go through the process of using the ALSA provided by the kernel
162 <e>first</e> for ease of use. However, if you run into problems, try switching
163 to <c>alsa-driver</c>. Before reporting any sound related issues to <uri
164 link="https://bugs.gentoo.org">Gentoo Bugzilla</uri>, please try to reproduce
165 them using <c>alsa-driver</c> and file the bug report no matter what the
166 result.
167 </p>
168
169 </body>
170 </section>
171 <section id="lspci">
172 <title>Before you proceed</title>
173 <body>
174
175 <p>
176 Whichever method of install you choose, you need to know what drivers your
177 sound card uses. In most cases, sound cards (onboard and otherwise) are PCI
178 based and <c>lspci</c> will help you in digging out the required information.
179 Please <c>emerge sys-apps/pciutils</c> to get <c>lspci</c>, if you don't have it
180 installed already. In case you have a USB sound card, <c>lsusb</c> from
181 <c>sys-apps/usbutils</c> <e>might</e> be of help. For ISA cards, try using
182 <c>sys-apps/isapnptools</c>. Also, the following pages <e>may</e> help users
183 with ISA based sound cards.
184 </p>
185
186 <ul>
187 <li>
188 <uri link="http://www.roestock.demon.co.uk/isapnptools/">The ISAPNPTOOLS
189 Page</uri>
190 </li>
191 <li>
192 <uri link="http://www2.linuxjournal.com/article/3269">LinuxJournal PnP
193 Article</uri>
194 </li>
195 <li>
196 <uri link="http://www.tldp.org/HOWTO/Sound-HOWTO/x320.html">TLDP Sound
197 HowTo</uri>
198 </li>
199 </ul>
200
201 <note>
202 For ease of use/explanation, we assume the user has a PCI based sound card for
203 the remainder of this guide.
204 </note>
205
206 <p>
207 We now proceed to find out details about the sound card.
208 </p>
209
210 <pre caption="Soundcard Details">
211 # <i>lspci -v | grep -i audio</i>
212 0000:00:0a.0 Multimedia audio controller: Creative Labs SB Live! EMU10k1 (rev 06)
213 </pre>
214
215 <p>
216 We now know that the sound card on the machine is a Sound Blaster Live! and
217 the card manufacturer is Creative Labs. Head over to the
218 <uri link="http://www.alsa-project.org/alsa-doc/"> ALSA Soundcard Matrix</uri>
219 page and select Creative Labs from the drop down menu. You will be taken to
220 the Creative Labs matrix page where you can see that the SB Live! uses the
221 <c>emu10k1</c> module. That is the information we need for now. If you are
222 interested in detailed information, you can click on the link next to the
223 "Details" and that will take you to the <c>emu10k1</c> specific page.
224 </p>
225
226 <p>
227 If you intend to use MIDI, then you should add <c>midi</c> to your USE flags in
228 <path>/etc/make.conf</path> before emerging any ALSA packages. Later in the
229 guide, we will show you how to set up <uri link="#midi">MIDI support</uri>.
230 </p>
231
232 </body>
233 </section>
234 <section id="kernel">
235 <title>Using ALSA provided by your Kernel</title>
236 <body>
237
238 <p>
239 If you're a person who likes to keep things simple like I do, then this is
240 the way to go.
241 </p>
242
243 <note>
244 Since the 2005.0 release, Gentoo Linux uses 2.6 as the default kernel. Unless
245 you are specifically using the 2.4 profile, <c>gentoo-sources</c> will be a
246 2.6 kernel on <e>most</e> architectures. Please check that your kernel is a
247 2.6 series kernel. This method will <e>not</e> work on a 2.4 kernel.
248 </note>
249
250 <p>
251 Let us now configure the kernel to enable ALSA.
252 </p>
253
254 <impo>
255 <c>genkernel</c> users should now run <c>genkernel --menuconfig all</c> and
256 then follow the instructions in <uri link="#doc_chap2_pre3">Kernel Options for
257 ALSA</uri>.
258 </impo>
259
260 <pre caption="Heading over to the source">
261 # <i>cd /usr/src/linux</i>
262 # <i>make menuconfig</i>
263 </pre>
264
265 <note>
266 The above example assumes that <path>/usr/src/linux</path> symlink points to
267 the kernel sources you want to use. Please ensure the same before proceeding.
268 </note>
269
270 <p>
271 Now we will look at some of the options we will have to enable in the 2.6
272 kernel to ensure proper ALSA support for our sound card.
273 </p>
274
275 <p>
276 Please note that for ease of use, all examples show ALSA built as modules. It
277 is advisable to follow the same as it then allows the use of <c>alsaconf</c>
278 which is a boon when you want to configure your card. Please do <e>not</e> skip
279 the <uri link="#alsa-config">Configuration</uri> section of this document. If
280 you still like to have options built-in, ensure that you make changes to your
281 config accordingly.
282 </p>
283
284 <pre caption="Kernel Options for ALSA">
285 Device Drivers ---&gt;
286 Sound ---&gt;
287
288 <comment>(This needs to be enabled)</comment>
289 &lt;M&gt; Sound card support
290
291 <comment>(Make sure OSS is disabled)</comment>
292 Open Sound System ---&gt;
293 &lt; &gt; Open Sound System (DEPRECATED)
294
295 <comment>(Move one step back and enter ALSA)</comment>
296 Advanced Linux Sound Architecture ---&gt;
297 &lt;M&gt; Advanced Linux Sound Architecture
298 <comment>(Select this if you want MIDI sequencing and routing)</comment>
299 &lt;M&gt; Sequencer support
300 <comment>(Old style /dev/mixer* and /dev/dsp* support. Recommended.)</comment>
301 &lt;M&gt; OSS Mixer API
302 &lt;M&gt; OSS PCM (digital audio) API
303
304 <comment>(You now have a choice of devices to enable support for. Generally,
305 you will have one type of device and not more. If you have more than one
306 sound card, please enable them all here.)</comment>
307
308 <comment>(Mostly for testing and development purposes, not needed for normal
309 users unless you know what you are doing.)</comment>
310 Generic devices ---&gt;
311
312 <comment>(For ISA Sound cards)</comment>
313 ISA devices ---&gt;
314 <comment>(IF you had the Gravis, you would select this option)</comment>
315 &lt;M&gt; Gravis UltraSound Extreme
316
317 <comment>(Move one level back and into PCI devices. Most sound cards today are
318 PCI devices)</comment>
319 PCI devices ---&gt;
320 <comment>(We now select the emu10k1 driver for our card)</comment>
321 &lt;M&gt; Emu10k1 (SB Live!, Audigy, E-mu APS)
322 <comment>(Or an Intel card would be)</comment>
323 &lt;M&gt; Intel/SiS/nVidia/AMD/ALi AC97 Controller
324 <comment>(Or if you have a VIA Card)</comment>
325 &lt;M&gt; VIA 82C686A/B, 8233/8235 AC97 Controller
326
327 <comment>(Move one level back and select in case you have an USB sound card)</comment>
328 USB Devices ---&gt;
329 </pre>
330
331 <p>
332 Now that your options are set, you can (re)compile the kernel and ALSA support
333 for your card should be functional once you reboot into the new kernel. Don't
334 forget to update your GRUB configuration to use the newly built kernel.
335 You can now proceed to <uri link="#alsa-utilities">ALSA Utilities</uri> and
336 see if everything is working as it should.
337 </p>
338
339 </body>
340 </section>
341 <section id="alsa-driver">
342 <title>Using the ALSA Driver package</title>
343 <body>
344
345 <p>
346 So you've decided to go the <c>alsa-driver</c> way. Let's get started then.
347 There are a few minor things to be done to ensure only the drivers for your
348 sound card are compiled. Although this is not really necessary, it cuts down
349 on the unnecessary drivers that will be compiled otherwise.
350 </p>
351
352 <p>
353 If you don't have an idea of what drivers your sound card might need, please
354 take a look at the <uri link="#lspci">lspci</uri> section of this guide. Once
355 you have your driver name (<c>emu10k1</c> in our example), edit
356 <path>/etc/make.conf</path> and add a variable, <c>ALSA_CARDS</c>.
357 </p>
358
359 <pre caption="Adding ALSA_CARDS to make.conf">
360 <comment>(For one sound card)</comment>
361 ALSA_CARDS="emu10k1"
362 <comment>(For more than one, separate names with spaces)</comment>
363 ALSA_CARDS="emu10k1 via82xx"
364 </pre>
365
366 <p>
367 If you have compiled your kernel and want to use <c>alsa-driver</c>, please
368 ensure the following before proceeding, else <c>alsa-driver</c> is likely to
369 fail. The next code listing gives you one way of performing the checks.
370 </p>
371
372 <note>
373 <c>genkernel</c> users can proceed with <uri link="#doc_chap2_pre6">Installing
374 alsa-driver</uri> as their configuration is in sync with the one shown below by
375 default.
376 </note>
377
378 <ol>
379 <li>
380 <c>CONFIG_SOUND</c> is set. (Basic Sound support enabled)
381 </li>
382 <li>
383 <c>CONFIG_SOUND_PRIME</c> is not set. (In-built OSS support disabled)
384 </li>
385 <li>
386 <c>CONFIG_SND</c> is not set. (In-built ALSA support disabled)
387 </li>
388 <li>
389 <path>/usr/src/linux</path> points to the kernel you want ALSA working on.
390 </li>
391 </ol>
392
393 <pre caption=".config checks">
394 <comment>(Assuming the linux symlink points to the correct kernel)</comment>
395 # <i>cd /usr/src/linux</i>
396 # <i>grep SOUND .config</i>
397 <comment>(1. is true)</comment>
398 CONFIG_SOUND=y
399 <comment>(2. is true)</comment>
400 CONFIG_SOUND_PRIME is not set
401 # <i>grep SND .config</i>
402 <comment>(and 3. is true)</comment>
403 CONFIG_SND is not set
404 </pre>
405
406 <p>
407 Now all you have to do is type the magic words... and no, it's not abracadabra.
408 </p>
409
410 <pre caption="Installing alsa-driver">
411 # <i>emerge alsa-driver</i>
412 </pre>
413
414 <impo>
415 Please note that you will have to run <c>emerge alsa-driver</c> after every
416 kernel (re)compile, as the earlier drivers are deleted. To make this task
417 easier, you may want to emerge the <c>module-rebuild</c> package, which will
418 keep track of module packages and rebuild them for you. First run
419 <c>module-rebuild populate</c> to create the list, and then after every kernel
420 (re)compile, you just run <c>module-rebuild rebuild</c>, and your external
421 modules will be rebuilt.
422 </impo>
423
424 </body>
425 </section>
426 </chapter>
427
428 <chapter>
429 <title>Configuring/Testing ALSA</title>
430 <section id="alsa-utilities">
431 <title>ALSA Utilities</title>
432 <body>
433
434 <p>
435 <c>alsa-utils</c> forms an integral part of ALSA as it has a truckload of
436 programs that are highly useful, including the ALSA Initscripts. Hence we
437 strongly recommend that you install <c>alsa-utils</c>
438 </p>
439
440 <pre caption="Install alsa-utils">
441 # <i>emerge alsa-utils</i>
442 </pre>
443
444 <note>
445 If you activated ALSA in your <uri link="#kernel">kernel</uri> <e>and</e> did
446 not compile ALSA as modules, please proceed to the
447 <uri link="#initscript">ALSA Initscript</uri> section. The rest of you need
448 to configure ALSA. This is made very easy by the existence of the
449 <c>alsaconf</c> tool provided by <c>alsa-utils</c>.
450 </note>
451
452 </body>
453 </section>
454 <section id="alsa-config">
455 <title>Configuration</title>
456 <body>
457
458 <p>
459 Recent versions of <c>udev</c> (<c>>=udev-103</c>) provide some degree of
460 kernel-level autoconfiguration of your sound card. If possible, try to rely on
461 just letting your kernel automatically setup your sound card for you. Otherwise,
462 use <c>alsaconf</c> to configure your card, as shown below.
463 </p>
464
465 <note>
466 Please shut down any programs that <e>might</e> access the sound card while
467 running <c>alsaconf</c>.
468 </note>
469
470 <p>
471 Another way to configure your sound card is to run <c>alsaconf</c>. Just type
472 <c>alsaconf</c> in a shell as root.
473 </p>
474
475 <pre caption="Invoking alsaconf">
476 # <i>alsaconf</i>
477 </pre>
478
479 <p>
480 You will now see a neat menu guided interface that will automatically probe
481 your devices and try to find out your sound card. You will be asked to pick
482 your sound card from a list. Once that's done, it will ask you permission to
483 automatically make required changes to <path>/etc/modules.d/alsa</path>.
484 It will then adjust your volume settings to optimum levels, run
485 <c>update-modules</c> and start the <path>/etc/init.d/alsasound</path> service.
486 Once <c>alsaconf</c> exits, you can proceed with setting up the ALSA
487 initscript.
488 </p>
489
490 </body>
491 </section>
492 <section id="initscript">
493 <title>ALSA Initscript</title>
494 <body>
495
496 <p>
497 We're now almost all setup. Whichever method you chose to install ALSA, you'll
498 need to have something load your modules or initialize ALSA and restore your
499 volume settings when your system comes up. The ALSA Initscript handles all of
500 this for you and is called <c>alsasound</c>. Add it to the boot runlevel.
501 </p>
502
503 <pre caption="Adding ALSA to the boot runlevel">
504 # <i>rc-update add alsasound boot</i>
505 * alsasound added to runlevel boot
506 * rc-update complete.
507 </pre>
508
509 <p>
510 Next, just check the <path>/etc/conf.d/alsasound</path> file and ensure that
511 SAVE_ON_STOP variable is set to yes. This saves your sound settings when you
512 shutdown your system.
513 </p>
514
515 </body>
516 </section>
517 <section>
518 <title>Audio Group</title>
519 <body>
520
521 <p>
522 Before we move on to testing, there's one last <e>important</e> thing that needs
523 to be setup. Rule of thumb in a *nix OS : Do not run as root unless needed.
524 This applies here as well ;) How? Well, most of the times you should be logged
525 in as a user and would like to listen to music or access your soundcard. For
526 that to happen, you need to be in the "audio" group. At this point, we'll add
527 users to the audio group, so that they won't have any issues when they want to
528 access sound devices. We'll use <c>gpasswd</c> here and you need to be logged in
529 as root for this to work.
530 </p>
531
532 <pre caption="Adding users to the audio group">
533 <comment>(Substitute &lt;username&gt; with your user)</comment>
534 # <i>gpasswd -a &lt;username&gt; audio </i>
535 Adding user &lt;username&gt; to group audio
536 </pre>
537
538 </body>
539 </section>
540 <section>
541 <title>Volume Check!</title>
542 <body>
543
544 <p>
545 We've completed all the setups and prerequisites, so let's fire up ALSA. If
546 you ran <c>alsaconf</c>, you can skip this step, since <c>alsaconf</c> already
547 does this for you.
548 </p>
549
550 <pre caption="Start the service">
551 # <i>/etc/init.d/alsasound start</i>
552 </pre>
553
554 <p>
555 Now that the required things have been taken care of, we need to check up on
556 the volume as in certain cases, it is muted. We use <c>alsamixer</c> for this
557 purpose.
558 </p>
559
560 <pre caption="Starting alsamixer">
561 <comment>(Opens up a console program. Only required settings are shown)</comment>
562 # <i>alsamixer</i>
563 </pre>
564
565 <impo>
566 If you have issues starting up <c>alsamixer</c> and get errors such as
567 alsamixer: function snd_ctl_open failed for default: No such file or directory,
568 this is usually an issue with udev setting up the devices. Run <c>killall
569 udevd; udevstart</c> to reload <path>/dev</path> entries and fire up
570 <c>alsamixer</c>. It should solve the issue.
571 </impo>
572
573 <p>
574 This is how the ALSA Mixer <e>might</e> look the first time you open it. Pay
575 attention to the Master and PCM channels which both have an MM below them.
576 That means they are muted. If you try to play anything with <c>alsamixer</c>
577 in this state, you will not hear anything on your speakers.
578 </p>
579
580 <figure link="/images/docs/alsa-mixermuted.png" short="AlsaMixer Muted" caption="The Alsa Mixer Main Window, Muted"/>
581
582 <p>
583 Now, we shall unmute the channels, and set volume levels as needed.
584 </p>
585
586 <warn>
587 Both Master <e>and</e> PCM need to be unmuted and set to audible volume levels
588 if you want to hear some output on your speakers.
589 </warn>
590
591 <ul>
592 <li>
593 To move between channels, use your left and right arrow keys. (&lt;-
594 &amp; -&gt;)
595 </li>
596 <li>
597 To toggle mute, move to the specific channel, for example Master and press
598 the <e>m</e> key on the keyboard.
599 </li>
600 <li>
601 To increase and decrease the volume levels, use the up and down arrow keys
602 respectively.
603 </li>
604 </ul>
605
606 <note>
607 Be careful when setting your Bass and Treble values. 50 is usually a good
608 number for both. Extremely high values of Bass may cause <e>jarring</e>
609 on speakers that are not designed to handle them.
610 </note>
611
612 <p>
613 After you're all done, your ALSA Mixer should look similar to the one below.
614 Note the 00 instead of the MM and also the volume levels for some optimum
615 settings.
616 </p>
617
618 <figure link="/images/docs/alsa-mixerunmuted.png" short="AlsaMixer Unmuted" caption="Alsa Mixer ready to roll"/>
619
620 </body>
621 </section>
622 <section>
623 <title>Sound Check!</title>
624 <body>
625
626 <p>
627 Finally. Some music. If everything above is perfect, you should now be able to
628 listen to some good music. A quick way to test is to use a command line tool
629 like <c>media-sound/madplay</c>. You could also use something more well known
630 like <c>mpg123</c>. If you are an ogg fan, you could use <c>ogg123</c> provided
631 by <c>media-sound/vorbis-tools</c>. Use any player you are comfortable with. As
632 always, <c>emerge</c> what you need.
633 </p>
634
635 <pre caption="Getting the software">
636 <comment>(Install the applications you want)</comment>
637 # <i>emerge madplay mpg123</i>
638 <comment>(To play .ogg files)</comment>
639 # <i>emerge vorbis-tools</i>
640 </pre>
641
642 <p>
643 And then play your favorite sound track...
644 </p>
645
646 <pre caption="Playing Music">
647 # <i>madplay -v /mnt/shyam/Music/Paul\ Oakenfold\ -\ Dread\ Rock.mp3</i>
648 MPEG Audio Decoder 0.15.2 (beta) - Copyright (C) 2000-2004 Robert Leslie et al.
649 Title: Dread Rock
650 Artist: Paul Oakenfold
651 Album: Matrix Reloaded
652 Year: 2003
653 Genre: Soundtrack
654 Soundtrack
655 00:04:19 Layer III, 160 kbps, 44100 Hz, joint stereo (MS), no CRC
656
657 # <i>ogg123 Paul\ Oakenfold\ -\ Dread\ Rock.ogg</i>
658 Audio Device: Advanced Linux Sound Architecture (ALSA) output
659
660 Playing: Paul Oakenfold - Dread Rock.ogg
661 Ogg Vorbis stream: 2 channel, 44100 Hz
662 Genre: Soundtrack
663 Transcoded: mp3;160
664 Title: Dread Rock
665 Artist: Paul Oakenfold
666 Date: 2003
667 Album: Matrix Reloaded
668 Time: 00:11.31 [04:28.75] of 04:40.06 (200.6 kbps) Output Buffer 96.9%
669 </pre>
670
671 </body>
672 </section>
673 <section>
674 <title>ALSA and USE</title>
675 <body>
676
677 <p>
678 You can now add the <c>alsa</c> use flag to <path>/etc/make.conf</path> to
679 ensure that your applications that support ALSA get built with it. Some
680 architectures like x86 and amd64 have the flag enabled by default.
681 </p>
682
683 </body>
684 </section>
685 <section>
686 <title>Issues?</title>
687 <body>
688
689 <p>
690 If for some reason you're unable to hear sound, the first thing to do would
691 be to check your <uri link="#doc_chap3_pre6">alsamixer</uri> settings. 80% of
692 the issues lie with muted channels or low volume. Also check your Window
693 Manager's sound applet and verify that volumes are set to audible levels.
694 </p>
695
696 <p>
697 <path>/proc</path> is your friend. And in this case, <path>/proc/asound</path>
698 is your best friend. We shall just take a short look at how much info is made
699 available to us there.
700 </p>
701
702 <pre caption="Fun with /proc/asound">
703 <comment>(First and foremost, if /proc/asound/cards shows your card, ALSA has
704 picked up your sound card fine.)</comment>
705 # <i>cat /proc/asound/cards</i>
706 0 [Live ]: EMU10K1 - Sound Blaster Live!
707 Sound Blaster Live! (rev.6, serial:0x80271102) at 0xb800, irq 11
708
709 <comment>(If you run ALSA off the kernel like I do and wonder how far behind
710 you are from alsa-driver, this displays current running ALSA version)</comment>
711 # <i>cat /proc/asound/version</i>
712 Advanced Linux Sound Architecture Driver Version 1.0.8 (Thu Jan 13 09:39:32 2005 UTC).
713
714 <comment>(ALSA OSS emulation details)</comment>
715 # <i>cat /proc/asound/oss/sndstat</i>
716 Sound Driver:3.8.1a-980706 (ALSA v1.0.8 emulation code)
717 Kernel: Linux airwolf.zion 2.6.11ac1 #2 Wed May 4 00:35:08 IST 2005 i686
718 Config options: 0
719
720 Installed drivers:
721 Type 10: ALSA emulation
722
723 Card config:
724 Sound Blaster Live! (rev.6, serial:0x80271102) at 0xb800, irq 11
725
726 Audio devices:
727 0: EMU10K1 (DUPLEX)
728
729 Synth devices: NOT ENABLED IN CONFIG
730
731 Midi devices:
732 0: EMU10K1 MPU-401 (UART)
733
734 Timers:
735 7: system timer
736
737 Mixers:
738 0: SigmaTel STAC9721/23
739 </pre>
740
741 <p>
742 The other most common issue users face is the dreaded "Unknown symbol in module"
743 error. An example of the same is shown below.
744 </p>
745
746 <pre caption="Unknown Symbol in module error">
747 # <i>/etc/init.d/alsasound start</i>
748 * Loading ALSA modules ...
749 * Loading: snd-card-0 ... [ ok ]
750 * Loading: snd-pcm-oss ...
751 WARNING: Error inserting snd_mixer_oss
752 (/lib/modules/2.6.12-gentoo-r6/kernel/sound/core/oss/snd-mixer-oss.ko): Unknown
753 symbol in module, or unknown parameter (see dmesg) FATAL: Error inserting
754 snd_pcm_oss
755 (/lib/modules/2.6.12-gentoo-r6/kernel/sound/core/oss/snd-pcm-oss.ko): Unknown
756 symbol in module, or unknown parameter (see dmesg)
757 [ !! ]
758 * Loading: snd-mixer-oss ...
759 FATAL: Error inserting snd_mixer_oss
760 (/lib/modules/2.6.12-gentoo-r6/kernel/sound/core/oss/snd-mixer-oss.ko): Unknown
761 symbol in module, or unknown parameter (see dmesg)
762 [ !! ]
763 * Loading: snd-seq ... [ ok ]
764 * Loading: snd-emu10k1-synth ... [ ok ]
765 * Loading: snd-seq-midi ... [ ok ]
766 * Restoring Mixer Levels ... [ ok ]
767 </pre>
768
769 <p>
770 And when you take a look at <c>dmesg</c> as suggested, you're quite likely to
771 see:
772 </p>
773
774 <pre caption="dmesg output">
775 <comment>(Only relevant portions are shown below)</comment>
776 # <i>dmesg | less</i>
777 ACPI: PCI Interrupt 0000:02:06.0[A] -> Link [APC3] -> GSI 18 (level, low) -> IRQ 209
778 snd_mixer_oss: Unknown symbol snd_unregister_oss_device
779 snd_mixer_oss: Unknown symbol snd_register_oss_device
780 snd_mixer_oss: Unknown symbol snd_mixer_oss_notify_callback
781 snd_mixer_oss: Unknown symbol snd_oss_info_register
782 snd_pcm_oss: Unknown symbol snd_unregister_oss_device
783 snd_pcm_oss: Unknown symbol snd_register_oss_device
784 snd_pcm_oss: Unknown symbol snd_mixer_oss_ioctl_card
785 snd_pcm_oss: Unknown symbol snd_oss_info_register
786 snd_mixer_oss: Unknown symbol snd_unregister_oss_device
787 snd_mixer_oss: Unknown symbol snd_register_oss_device
788 snd_mixer_oss: Unknown symbol snd_mixer_oss_notify_callback
789 snd_mixer_oss: Unknown symbol snd_oss_info_register
790 </pre>
791
792 <p>
793 The above issue is caused when you switch from <c>alsa-driver</c> to in-kernel
794 ALSA because when you unmerge <c>alsa-driver</c> the module files are config
795 protected and hence get left behind. So, when you switch to in-kernel
796 drivers, running <c>modprobe</c> gives you a mix of <c>alsa-driver</c> and
797 in-kernel modules thus causing the above errors.
798 </p>
799
800 <p>
801 The solution is quite easy. We just need to manually remove the problem causing
802 directory after you unmerge <c>alsa-driver</c>. Be sure to remove the correct
803 kernel version and not the current one!
804 </p>
805
806 <pre caption="Removing the alsa-driver modules">
807 # <i>rm -rf /lib/modules/$(uname -r)/alsa-driver</i>
808 </pre>
809
810 <p>
811 Another reason for error messages similar to the ones above could be a file in
812 <path>/etc/modules.d</path> supplying a <c>device_mode</c> parameter when it
813 isn't required. Confirm that this is indeed the issue and find out which file
814 is the culprit.
815 </p>
816
817 <pre caption="Confirming and searching for device_mode">
818 <comment>(Check dmesg to confirm)</comment>
819 # <i>dmesg | grep device_mode</i>
820 snd: Unknown parameter `device_mode'
821 <comment>(Now, to get to the source of the issue)</comment>
822 # <i>grep device_mode /etc/modules.d/*</i>
823 </pre>
824
825 <p>
826 Usually it is a file called <path>alsa</path> with the line <c>options snd
827 device_mode=0666</c>. Remove this line and restart the alsasound service and
828 that should take care of this issue.
829 </p>
830
831 </body>
832 </section>
833 </chapter>
834
835 <chapter>
836 <title>Other things ALSA</title>
837 <section id="midi">
838 <title>Setting up MIDI support</title>
839 <body>
840
841 <p>
842 First, check to make sure that you enabled the <c>midi</c> USE flag in
843 <path>/etc/make.conf</path>. If you didn't, go ahead and add it now. You will
844 also need to re-emerge any ALSA packages that use the <c>midi</c> flag, such as
845 <c>alsa-lib</c>, <c>alsa-utils</c>, and <c>alsa-driver</c>.
846 </p>
847
848 <p>
849 If your sound card is one of those that come with on-board MIDI synthesizers
850 and you would like to listen to some .mid files, you have to install
851 <c>awesfx</c> which is basically a set of utilities for controlling the AWE32
852 driver. We need to install it first. If you don't have a hardware synthesizer,
853 you can use a virtual one. Please see the section on
854 <uri link="#vsynth">Virtual Synthesizers</uri> for more information.
855 </p>
856
857 <pre caption="Installing awesfx">
858 # <i>emerge awesfx</i>
859 </pre>
860
861 <note>
862 You will need to copy over SoundFont (SF2) files from your sound card's driver
863 CD or a Windows installation into <path>/usr/share/sounds/sf2/</path>. For
864 example a sound font file for the Creative SBLive! card would be 8MBGMSFX.SF2.
865 </note>
866
867 <p>
868 After copying over the Soundfont files, we can then play a midi file as shown.
869 You can also add the <c>asfxload</c> command to
870 <path>/etc/conf.d/local.start</path>, so that the sound font is loaded
871 every time the system starts up.
872 </p>
873
874 <note>
875 <path>/mnt</path> paths mentioned in the code listing(s) below will <e>not</e>
876 be the same in your machine. They are just an example. Please be careful to
877 change the path to suit your machine.
878 </note>
879
880 <pre caption="Loading Soundfonts">
881 <comment>(First, copy the Soundfont)</comment>
882 # <i>cp /mnt/win2k/Program\ Files/CreativeSBLive2k/SFBank/8MBGMSFX.SF2 /usr/share/sounds/sf2/</i>
883 <comment>(Or get it from your SoundBlaster CD)</comment>
884 # <i>cp /mnt/cdrom/AUDIO/ENGLISH/SFBANK/8MBGMSFX.SF2 /usr/share/sounds/sf2/</i>
885 <comment>(We load the specific Soundfont)</comment>
886 # <i>asfxload /usr/share/sounds/sf2/8MBGMSFX.SF2</i>
887 </pre>
888
889 <p>
890 You can now play midi files using a program like <c>aplaymidi</c>. Run
891 <c>aplaymidi -l</c> to get a list of available ports and then pick one
892 to play the file on.
893 </p>
894
895 <pre caption="Playing MIDI">
896 <comment>(Check open ports)</comment>
897 # <i>aplaymidi -l</i>
898 Port Client name Port name
899 64:0 EMU10K1 MPU-401 (UART) EMU10K1 MPU-401 (UART)
900 65:0 Emu10k1 WaveTable Emu10k1 Port 0
901 65:1 Emu10k1 WaveTable Emu10k1 Port 1
902 65:2 Emu10k1 WaveTable Emu10k1 Port 2
903 65:3 Emu10k1 WaveTable Emu10k1 Port 3
904 <comment>(Pick a port, and play a mid file)</comment>
905 # <i> aplaymidi --port=65:0 /mnt/shyam/music/midi/mi2.mid</i>
906 </pre>
907
908 </body>
909 </section>
910 <section id="vsynth">
911 <title>Virtual Synthesizers</title>
912 <body>
913
914 <p>
915 If your sound card lacks a hardware synthesizer, you could use a virtual one
916 like <c>timidity++</c>. Installation is a breeze.
917 </p>
918
919 <pre caption="Installing timidity++">
920 # <i>emerge timidity++</i>
921 </pre>
922
923 <p>
924 For timidity to play sounds, it needs a sound font. Fortunately, the ebuild will
925 install some sound font packages for you. There are a few other font packages
926 available in Portage, such as <c>timidity-freepats</c> and
927 <c>timidity-eawpatches</c>. You can have multiple sound font configurations
928 installed, and you can place your own in <path>/usr/share/timidity/</path>. To
929 switch between different timidity configurations, you should use
930 <c>eselect</c>.
931 </p>
932
933 <pre caption="Changing configurations">
934 # <i>eselect timidity list</i>
935 # <i>eselect timidity set eawpatches</i>
936 </pre>
937
938 <p>
939 Don't forget to add <c>timidity</c> to the default runlevel.
940 </p>
941
942 <pre caption="Adding timidity to the default runlevel">
943 # <i>rc-update add timidity default</i>
944 # <i>/etc/init.d/timidity start</i>
945 </pre>
946
947 <p>
948 You can now try out <uri link="#doc_chap4_pre3">Playing MIDI</uri> files.
949 </p>
950
951 </body>
952 </section>
953 <section>
954 <title>Tools and Firmware</title>
955 <body>
956
957 <p>
958 Some specific sound cards can benefit from certain tools provided by the
959 <c>alsa-tools</c> and <c>alsa-firmware</c> packages. You may install either with
960 a simple <c>emerge</c>.
961 </p>
962
963 <pre caption="Installing ALSA Tools">
964 # <i>emerge alsa-tools</i>
965 </pre>
966
967 </body>
968 </section>
969 <section>
970 <title>Multiple sound cards</title>
971 <body>
972
973 <p>
974 You can have more than one sound card in your system simultaneously, provided
975 that you have built ALSA as modules in your kernel (or have installed
976 <c>alsa-driver</c> instead). You just need to specify which should be started
977 first in <path>/etc/modules.d/alsa</path>. Your cards are identified by their
978 driver names inside this file. 0 is the first card, 1 is the second, and so on.
979 Here's an example for a system with two sound cards.
980 </p>
981
982 <pre caption="Two sound cards in /etc/modules.d/alsa">
983 options snd-emu10k1 index=0
984 options snd-via82xx index=1
985 </pre>
986
987 <p>
988 Or, if you have two cards that use the same driver, you specify them on the same
989 line, using comma-separated numbers. Here's an example for a system with three
990 sound cards, two of which are the same Intel High Definition Audio card.
991 </p>
992
993 <pre caption="Multiple sound cards in /etc/modules.d/alsa">
994 options snd-ymfpci index=0
995 options snd-hda-intel index=1,2
996 </pre>
997
998 </body>
999 </section>
1000 <section>
1001 <title>Plugins</title>
1002 <body>
1003
1004 <p>
1005 You may want to install some plugins for extra functionality.
1006 <c>alsa-plugins</c> is a collection of useful plugins, which include: PulseAudio
1007 output, a sample rate converter, jack (a low-latency audio server), and an
1008 encoder that lets you output 6-channel audio through digital S/PDIF connections
1009 (both optical and coaxial). You can choose which of its plugins you want
1010 installed by adding their USE flags to <path>/etc/portage/package.use</path>.
1011 </p>
1012
1013 <pre caption="Installing alsa-plugins">
1014 # <i>emerge -avt alsa-plugins</i>
1015 </pre>
1016
1017 </body>
1018 </section>
1019 <section>
1020 <title>A big thank you to...</title>
1021 <body>
1022
1023 <p>
1024 Everyone who contributed to the earlier version of the Gentoo ALSA Guide:
1025 Vincent Verleye, Grant Goodyear, Arcady Genkin, Jeremy Huddleston,
1026 John P. Davis, Sven Vermeulen, Benny Chuang, Tiemo Kieft and Erwin.
1027 </p>
1028
1029 </body>
1030 </section>
1031 <section>
1032 <title>References</title>
1033 <body>
1034
1035 <ul>
1036 <li><uri link="http://www.alsa-project.org/">The ALSA Project</uri></li>
1037 <li><uri link="http://linux-sound.org">Linux Sound/MIDI Software</uri></li>
1038 </ul>
1039
1040 </body>
1041 </section>
1042 </chapter>
1043 </guide>

  ViewVC Help
Powered by ViewVC 1.1.20