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The Linux Sound HOWTO Jeff Tranter, jeff_tranter@pobox.com v1.18, 1 November 1997 This document describes sound support for Linux. It lists the sup¡ ported sound hardware, describes how to configure the kernel drivers, and answers frequently asked questions. The intent is to bring new users up to speed more quickly and reduce the amount of traffic in the Usenet news groups and mailing lists. 1. Introduction This is the Linux Sound HOWTO. It is intended as a quick reference covering everything you need to know to install and configure sound support under Linux. Frequently asked questions about sound under Linux are answered, and references are given to some other sources of information on a variety of topics related to computer generated sound and music. The scope is limited to the aspects of sound cards pertaining to Linux. See the other documents listed in the References section for more general information on sound cards and computer sound and music generation. 1.1. Acknowledgments Much of this information came from the documentation provided with the sound driver source code, by Hannu Savolainen (hannu@voxware.pp.fi). Thanks go to Hannu and the many other people who developed the Linux kernel sound drivers and utilities. Thanks to the SGML Tools package, this HOWTO is available in several formats, all generated from a common source file. 1.2. Revision History Version 1.1 first version; posted to SOUND channel of Linux activists mailing list only Version 1.2 minor updates; first version available on archive sites Version 1.3 converted to SGML; now available in several formats using Matt Welsh's Linuxdoc-SGML tools; appearance changed due to new format, only minor changes to content Version 1.4 minor tweaking of SGML; added answer on PAS16 and Adaptec1542A SCSI adaptor incompatibilities Version 1.5 2.5a sound driver is now in 1.1 kernel distribution; note on GUS-MAX support; other minor updates Version 1.6 added info on "no space on device" error; added note that Hacker's Guide is in a "hidden" directory; added question on bidirectional mode; info on "device busy" errors; other minor changes Version 1.7 added info on ASP and AWE32; VoxWare 2.9 is available; answer to question on using IRQ2; references to Sound and SCSI HOWTOs Version 1.8 added question on errors under DOS; many minor things updated to match the version 2.90 sound driver; info on DOOM; answer on reducing noise Version 1.9 questions on recording and clone cards Version 1.10 mentioned that HOWTO is available on WWW, as printed copies, and translations; info on DMA conflict with QIC tape driver; info on Sound Galaxy NX Pro and Logitech BusMouse Version 1.11 A long overdue update (I've been busy); document placed under GPL; brought up to date with version 3.0 sound driver; info on many new supported sound card drivers; more info on configuration and troubleshooting; lots of HTML links added; brought in line with format of CD-ROM HOWTO Version 1.12 new sound drivers in 1.3.34 kernel; new sound device names; 1542 address is 334 not 333; clarify status of Creative Labs Emu and ASP; pointer to Creative Labs and MediaTrix Web sites Version 1.13 note on the name VoxWare; updated to reflect latest supported sound cards and configuration options; question on Plug and Play support; question on block size problem; new xconfig and menuconfig options; modutils has sound device support; vger mailing list going away; emphasize author's Web site; other miscellaneous minor changes Version 1.14 Audio Excell DSP16 is not currently supported (should be working again in a few months); changes to configure program; Italian version of HOWTO available; trick for setting mixer gains when loading sound module; latest stable kernel is now 2.0; new name for sound driver; question on root permissions on sound device files Version 1.15 removed some questions that were very old and now obsolete; new e-mail address for author; fixed some links to point to latest software packages; more information on multimedia book; minor spelling and grammatical changes Version 1.16 many updates and corrections from Hannu Savolainen; added six month "best before" date; new URL to web page for book; added link to Spanish translation; minor spelling and grammatical changes Version 1.17 Chinese version available; alternate GUS driver; packet radio modem; Linux Multimedia guide is now available in French and Japanese; references to a couple of relevant mini-HOWTOs; pointer for IBM ThinkPad Version 1.18 Korean translation available; more information on status of sound on MIPS; updated info on multiple sound card support; should be root when running fuser 1.3. New versions of this document New versions of this document will be periodically posted to the comp.os.linux.answers newsgroup. They will also be uploaded to various anonymous ftp sites that archive such information including <ftp://sunsite.unc.edu/pub/Linux/docs/HOWTO/>. Hypertext versions of this and other Linux HOWTOs are available on many World-Wide-Web sites, including <http://sunsite.unc.edu/LDP/>. Most Linux CD-ROM distributions include the HOWTOs, often under the /usr/doc directory, and you can also buy printed copies from several vendors. Sometimes the HOWTOs available from CD-ROM vendors, ftp sites, and printed format are out of date. If the date on this HOWTO is more than six months in the past, then a newer copy is probably available on the Internet. A French translation of this document is available at <ftp://ftp.ibp.fr/pub2/linux/french/docs/HOWTO/>. A Japanese translation is available from <http://yebisu.ics.es.osaka- u.ac.jp/linux/>. An Italian translation is available from <http://www.psy.unipd.it/ildp/docs/HOWTO/Sound-HOWTO.html>. A Spanish translation is available from <http://www.insflug.nova.es/howtos/online/sonido/sonido-COMO.html>. A Chinese translation is available from <http://linux.ntcic.edu.tw/~yorkwu/linux/howto/sound/>. A Hangul (Korean) translation is available from <http://members.iWorld.net/mangchi/HOWTO/Sound-HOWTO.html>. Most translations of this and other Linux HOWTOs can also be found at <http://sunsite.unc.edu/pub/Linux/docs/HOWTO/translations/> and <ftp://sunsite.unc.edu/pub/Linux/docs/HOWTO/translations/>. If you make a translation of this document into another language, let me know and I'll include a reference to it here. 1.4. Feedback I rely on you, the reader, to make this HOWTO useful. If you have any suggestions, corrections, or comments, please send them to me, jeff_tranter@pobox.com, and I will try to incorporate them in the next revision. I am also willing to answer general questions on sound cards under Linux, as best I can. Before doing so, please read all of the information in this HOWTO, and send me detailed information about the problem. Please do not ask me about using sound cards under operating systems other than Linux. If you publish this document on a CD-ROM or in hardcopy form, a complimentary copy would be appreciated. Mail me for my postal address. Also consider making a donation to the Linux Documentation Project to help support free documentation for Linux. Contact the Linux HOWTO coordinator, Greg Hankins <mailto:gregh@sunsite.unc.edu>, for more information. 1.5. Distribution Policy Copyright 1995-1997 Jeff Tranter. This HOWTO is free documentation; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This document is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose. See the GNU General Public License for more details. You can obtain a copy of the GNU General Public License by writing to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 2. Sound Card Technology This section gives a very cursory overview of computer audio technology, in order to help you understand the concepts used later in the document. You should consult a book on digital audio or digital signal processing in order to learn more. Sound is an analog property; it can take on any value over a continuous range. Computers are digital; they like to work with discrete values. Sound cards use a device known as an Analog to Digital Converter (A/D or ADC) to convert voltages corresponding to analog sound waves into digital or numeric values which can be stored in memory. Similarly, a Digital to Analog Converter (D/A or DAC) converts numeric values back to an analog voltage which can in turn drive a loudspeaker, producing sound. The process of analog to digital conversion, known as sampling, introduces some error. Two factors are key in determining how well the sampled signal represents the original. Sampling rate is the number of samples made per unit of time (usually expresses as samples per second or Hertz). A low sampling rate will provide a less accurate representation of the analog signal. Sample size is the range of values used to represent each sample, usually expressed in bits. The larger the sample size, the more accurate the digitized signal will be. Sound cards commonly use 8 or 16 bit samples at sampling rates from about 4000 to 44,000 samples per second. The samples may also be contain one channel (mono) or two (stereo). FM Synthesis is an older technique for producing sound. It is based on combining different waveforms (e.g. sine, triangle, square). FM synthesis is simpler to implement in hardware that D/A conversion, but is more difficult to program and less flexible. Many sound cards provide FM synthesis for backward compatibility with older cards and software. Several independent sound generators or voices are usually provided. Wavetable Synthesis combines the flexibility of D/A conversion with the multiple channel capability of FM synthesis. With this scheme digitized voices can be downloaded into dedicated memory, and then played, combined, and modified with little CPU overhead. State of the art sound cards all support wavetable synthesis. Most sound cards provide the capability of mixing, combining signals from different input sources and controlling gain levels. MIDI stands for Musical Instrument Digital Interface, and is a standard hardware and software protocol for allowing musical instruments to communicate with each other. The events sent over a MIDI bus can also be stored as MIDI files for later editing and playback. Many sound cards provide a MIDI interface. Those that do not can still play MIDI files using the on-board capabilities of the sound card. MOD files are a common format for computer generated songs. As well as information about the musical notes to be played, the files contain digitized samples for the instruments (or voices). MOD files originated on the Amiga computer, but can be played on other systems, including Linux, with suitable software. 3. Supported Hardware This section lists the sound cards and interfaces that are currently supported under Linux. The information here is based on the latest Linux kernels, at time of writing. The sound driver has its own version numbering. The latest stable Linux kernel release was version 2.0.31, using sound driver version 3.5.4-960630. The author of the sound driver, Hannu Savolainen, typically also makes available newer beta releases of the sound driver before they are included as part of the standard Linux kernel distribution. The most up to date list of supported cards is available at <http://www.4front- tech.com/ossfree/new_cards.html> (USA) or <http://personal.eunet.fi/pp/voxware/new_cards.html> (Europe). These pages indicate which sound driver version is required for a given type of sound card or if support for it is still under development. The file /usr/src/linux/drivers/sound/Readme.cards distributed with the kernel sound driver contains information on supported cards but it is not always up to date. The information in this HOWTO is valid for Linux on the Intel platform. The sound driver should also work with most sound cards on the Alpha platform. However, some cards may conflict with I/O ports of other devices on Alpha systems even though they work perfectly on i386 machines, so in general it's not possible to tell if a given card will work or not without actually trying it. At the time of writing the sound driver was not yet working on the PowerPC version of Linux, but it should be supported in future. Sound can be configured into the kernel under the MIPs port of Linux, and some MIPs machines have EISA slots and/or built in sound hardware. I'm told the Linux-MIPs group is interested in adding sound support in the future. The Linux kernel includes a separate driver for the Atari and Amiga versions of Linux that implements a compatible subset of the sound driver on the Intel platform using the built-in sound hardware on these machines. The SPARC port of Linux does not currently have sound support. Like the Amiga and Atari, SPARC machines have built in sound hardware, so it could be done with a new driver (this is somewhat ironic, as under Linux /dev/dsp emulates the SunOS sound device). 3.1. Sound Cards The following sound cards are supported by the Linux kernel sound driver: ╖ ATI Stereo F/X (no longer manufactured) ╖ AdLib (no longer manufactured) ╖ Ensoniq SoundScape (and compatibles made by Reveal and Spea) ╖ Gravis Ultrasound ╖ Gravis Ultrasound ACE ╖ Gravis Ultrasound Max ╖ Gravis Ultrasound with 16 bit sampling option ╖ Logitech Sound Man 16 ╖ Logitech SoundMan Games ╖ Logitech SoundMan Wave ╖ MAD16 Pro (OPTi 82C928, 82C929, 82C930, 82C924 chipsets) ╖ Media Vision Jazz16 ╖ MediaTriX AudioTriX Pro ╖ Microsoft Windows Sound System (MSS/WSS) ╖ Mozart (OAK OTI-601) ╖ Orchid SW32 ╖ Personal Sound System (PSS) ╖ Pro Audio Spectrum 16 ╖ Pro Audio Studio 16 ╖ Pro Sonic 16 ╖ Roland MPU-401 MIDI interface ╖ Sound Blaster 1.0 ╖ Sound Blaster 16 ╖ Sound Blaster 16ASP ╖ Sound Blaster 2.0 ╖ Sound Blaster AWE32 ╖ Sound Blaster Pro ╖ TI TM4000M notebook ╖ ThunderBoard ╖ Turtle Beach Tropez ("classic" but not Plus) ╖ Turtle Beach Maui ╖ Yamaha FM synthesizers (OPL2, OPL3 and OPL4) ╖ 6850 UART MIDI Interface It should be noted that Plug and Play (PnP) sound cards are not fully compatible with the older non-PnP models of the same device. For example, the SoundBlaster16 PnP is not fully compatible with the original SoundBlaster16. The same is true for the Soundscape PnP and GUS PnP cards. More information related to Plug and Play is found later in this document. The following cards are not supported, either because they are obsolete or because the vendor will not release the programming information needed to write a driver: ╖ Pro Audio Spectrum (original) ╖ Pro Audio Spectrum+ ╖ older (Sierra Aria based) sound cards made by Diamond Other sound cards that are claimed to be compatible with one of the supported sound cards may work if they are hardware (i.e. register level) compatible. Even though most sound cards are claimed to be "SoundBlaster compatible", very few currently sold cards are compatible enough to work with the Linux SoundBlaster driver. These cards usually work better using the MSS/WSS or MAD16 driver. Only real SoundBlaster cards made by Creative Labs, which use Creative's custom chips (e.g. SoundBlaster16 Vibra), MV Jazz16 and ESS688/1688 based cards generally work with the SoundBlaster driver. Trying to use a "SoundBlaster Pro compatible 16 bit sound card" with the SoundBlaster driver is usually just a waste of time. The Linux kernel supports the SCSI port provided on some sound cards (e.g. ProAudioSpectrum 16) and the proprietary interface for some CD- ROM drives (e.g. Soundblaster Pro). See the Linux SCSI HOWTO and CDROM HOWTO documents for more information. A loadable kernel module to support joystick ports, including those provided on some sound cards, is also available. Note that the kernel SCSI, CD-ROM, joystick, and sound drivers are completely independent of each other. For the latest information on the sound card driver check Hannu Savolainen's World-Wide Web site listed in the References section. 3.2. Alternate Sound Drivers There are some "unofficial" sound drivers available, not included in the standard Linux kernel distribution, and used in place of the standard sound driver. A commercial version of the Linux sound driver is sold by 4Front Technologies. It offers a number of additional features over the free version included in the Linux kernel. For more information see the 4Front Technologies Web page at <http://www.4front-tech.com/>. Markus Mummert (mum@mmk.e-technik.tu-muenchen.de) has written a driver package for the Turtle Beach MultiSound (classic), Tahiti, and Monterey sound cards. The documentation states: "It is designed for high quality hard disk record¡ ing/playback without losing sync even on a busy system. Other features such as wave synthesis, MIDI and digital sig¡ nal processor (DSP) cannot be used. Also, recording and playback at the same time is not possible. It currently replaces VoxWare and was tested on several kernel versions ranging from 1.0.9 to 1.2.1. Also, it is installable on UN*X SysV386R3.2 systems." It can be found at <http://www.cs.colorado.edu/~mccreary/tbeach>. Kim Burgaard (burgaard@daimi.aau.dk) has written a device driver and utilities for the Roland MPU-401 MIDI interface. The Linux software map entry gives this description: "A device driver for true Roland MPU-401 compatible MIDI interfaces (including Roland SCC-1 and RAP-10/ATW-10). Comes with a useful collection of utilities including a Standard MIDI File player and recorder. Numerous improvements have been made since version 0.11a. Among other things, the driver now features IRQ sharing pol¡ icy and complies with the new kernel module interface. Metronome functionality, possibility for synchronizing e.g. graphics on a per beat basis without losing precision, advanced replay/record/overdub interface and much, much more." It can be found at <ftp://sunsite.unc.edu/pub/Linux/kernel/sound/mpu401-0.2.tar.gz>. Jaroslav Kysela and others have written an alternate sound driver for the Gravis UltraSound Card. Information can be found at <http://romeo.pf.jcu.cz/~perex/ultra>, the home page of the Linux UltraSound Project. Another novel use for a sound card under Linux is as a modem for amateur packet radio. The recent 2.1.x kernels include a driver that works with SoundBlaster and Windows Sound System compatible sound cards to implement 1200 bps AFSK and 9600 bps FSK packet protocols. See the Linux AX25 HOWTO for details (I'm a ham myself, by the way -- callsign VE3ICH). 3.3. PC Speaker An alternate sound driver is available that requires no additional sound hardware; it uses the internal PC speaker. It is mostly software compatible with the sound card driver, but, as might be expected, provides much lower quality output and has much more CPU overhead. The results seem to vary, being dependent on the characteristics of the individual loudspeaker. For more information, see the documentation provided with the release. The current version is 1.1, and can be found at <ftp://ftp.informatik.hu-berlin.de/pub/os/linux/hu-sound/> 3.4. Parallel Port Another option is to build a digital to analog converter using a parallel printer port and some additional components. This provides better sound quality than the PC speaker but still has a lot of CPU overhead. The PC sound driver package mentioned above supports this, and includes instructions for building the necessary hardware. 4. Installation Configuring Linux to support sound involves the following steps: 1. Installing the sound card. 2. Configuring and building the kernel for sound support. 3. Creating the device files. 4. Booting the Linux kernel and testing the installation. The next sections will cover each of these steps in detail. 4.1. Installing the Sound Card Follow the manufacturer's instructions for installing the hardware or have your dealer perform the installation. Older sound cards usually have switch or jumper settings for IRQ, DMA channel, etc; note down the values used. If you are unsure, use the factory defaults. Try to avoid conflicts with other devices (e.g. ethernet cards, SCSI host adaptors, serial and parallel ports) if possible. Usually you should use the same I/O port, IRQ, and DMA settings that work under DOS. In some cases though (particularly with PnP cards) you may need to use different settings to get things to work under Linux. Some experimentation may be needed. 4.2. Configuring the Kernel When initially installing Linux you likely used a precompiled kernel. These kernels usually do not provide sound support. It is best to recompile the kernel yourself with the drivers you need. You may also want to recompile the kernel in order to upgrade to a newer version or to free up memory resources by minimizing the size of the kernel. The Linux Kernel HOWTO <http://sunsite.unc.edu/LDP/HOWTO/Kernel- HOWTO.html> should be consulted for the details of building a kernel. I will just mention here some issues that are specific to sound cards. If you have never configured the kernel for sound support before it is a good idea to read all of the Readme files included with the kernel sound drivers, particularly information specific to your card type. The following documentation files can be found in the kernel sound driver directory, usually installed in /usr/src/linux/drivers/sound: CHANGELOG - description of changes in each release COPYING - copying and copyright restrictions Readme - latest and most important news Readme.aedsp16 - information about Audio Excel DSP 16 sound card Readme.cards - notes on configuring specific cards Readme.linux - notes on installing separately release sound drivers Readme.modules - how to build driver as a loadable kernel module Readme.v30 - new features in version 3.0 sound driver experimental.txt - notes on experimental features Follow the usual procedure for building the kernel. There are currently three interfaces to the configuration process. A graphical user interface that runs under X11 can be invoked using "make xconfig". A menu-based system that only requires text displays is available as "make menuconfig". The original method, using "make config", offers a simple text-based interface. Special care must be taken when using "make xconfig" or "make menuconfig". All Yes/No questions must be examined carefully. The default answer provided by these commands is always No which is not the proper one in all cases. In particular the "/dev/dsp and /dev/audio support" (CONFIG_AUDIO) option should usually be enabled. In this document I will assume that you use the traditional command line configuration process invoked using "make config", although the process is similar in each case. There are also two different ways to configure sound. The first is the "old" way (the only one offered prior to the 2.0.0 kernels). It uses a standalone configuration program that is part of the sound driver. This method works with most sound cards except the rare few that require additional "low level" drivers (miroSOUND, AWE32, and AEDSP16 cards). The second is the "new" method which is better integrated with the menu-based configuration used for the rest of the kernel. This one doesn't work with sound cards that require a firmware download file. This includes the PSS, SM Wave, AudioTrix Pro and TurtleBeach Tropez/Maui cards. With these cards the old method has to be used. The "new" method is always used by "make xconfig". When using "make menuconfig" you can select between the "old" and "new" methods in the sound subscreen. When using "make config" you get the "old" method by default. However if you have used the "new" method once, it will be used by "make config" too. You can switch back to the "old" method by running "make menuconfig" and by selecting the "old" one. The recommended method is to use "make menuconfig" together with the "old" sound config method. Many sound configuration problems are caused (at least partly) by incorrect use of the "new" method. It is also possible to build the sound driver as a kernel loadable module. I recommend initially building the driver into the kernel. Once it is tested and working you can explore using the kernel module option. When you run make config, enable sound support by answering "y" to the question Sound card support (CONFIG_SOUND) [M/n/y/?] At the end of the configuration questions a sound configuration program will be compiled, run, and will then ask you what sound card options you want. Be careful when answering these questions since answering a question incorrectly may prevent some later ones from being asked. For example, don't answer "yes" to the first question (PAS16) if you don't really have a PAS16. Don't enable more cards than you really need, since they just consume memory. Also some drivers (like MPU-401) may conflict with your SCSI controller and prevent the kernel from booting. I list here a brief description of each of the configuration dialog options. Answer "y" (yes) or "n" (no) to each question. The default answer is shown so that "Y/n/?" means "y" by default and "N/y/?" means the default is "n". To use the default value, just hit Enter, but remember that the default value isn't necessarily correct. Entering a question mark ("?") will produce a short descriptive message describing that configuration option. Note also that all questions may not be asked. The configuration program may disable some questions depending on the earlier choices. It may also select some options automatically as well. Old configuration exists in /etc/soundconf. Use it Y/n/? If you have previously compiled the kernel for sound support, then the previous configuration can be saved. If you want to use the previous setup, answer "y". If you are trying a different configuration or have upgraded to a newer kernel, you should answer "n" and go through the configuration process. ProAudioSpectrum 16 support Y/n/? Answer "y" only if you have a Pro Audio Spectrum 16, ProAudio Studio 16 or Logitech SoundMan 16. Don't answer 'y' if you have some other card made by Media Vision or Logitech since they are not PAS16 compatible. SoundBlaster support Y/n/? Answer "y" if you have an original SoundBlaster card made by Creative Labs or a 100% hardware compatible clone (like the Thunderboard or SM Games). If your card was in the list of supported cards look at the card specific instructions in the Readme.cards file before answering this question. For an unknown card you may answer "y'"if the card claims to be SoundBlaster compatible. Gravis Ultrasound support Y/n/? Answer "y" if you have a GUS or GUS MAX. Answer "n" if you don't have a GUS since the driver consumes a lot of memory. MPU-401 support (NOT for SB16) Y/n/? Be careful with this question. The MPU-401 interface is supported by almost all sound cards. However, some natively supported cards have their own driver for MPU-401. Enabling the MPU-401 option with these cards will cause a conflict. Also enabling MPU-401 on a system that doesn't really have a MPU-401 could cause some trouble. If your card was in the list of supported cards, look at the card specific instructions in the Readme.cards file. It's safe to answer "y" if you have a true MPU-401 MIDI interface card. 6850 UART Midi support Y/n/? It's safe to answer "n" to this question in all cases. The 6850 UART interface is very rarely used. PSS (ECHO-ADI2111) support Y/n/? Answer "y" only if you have Orchid SW32, Cardinal DSP16 or some other card based on the PSS chipset (AD1848 codec + ADSP-2115 DSP chip + Echo ESC614 ASIC CHIP). 16 bit sampling option of GUS (not GUS MAX) Y/n/? Answer "y" if you have installed the 16 bit sampling daughtercard on your GUS. Answer "n" if you have a GUS MAX. Enabling this option disables GUS MAX support. GUS MAX support Y/n/? Answer "y" only if you have a GUS MAX. Microsoft Sound System support Y/n/? Again think carefully before answering "y" to this question. It's safe to answer "y" if you have the original Windows Sound System card made by Microsoft or Aztech SG 16 Pro (or NX16 Pro). Also you may answer "y" in case your card was not listed earlier in this file. For cards having native support in VoxWare, consult the card specific instructions in Readme.cards. Some drivers have their own MSS support and enabling this option will cause a conflict. Ensoniq Soundscape support Y/n/? Answer "y" if you have a sound card based on the Ensoniq SoundScape chipset. Such cards are being manufactured at least by Ensoniq, Spea and Reveal (Reveal makes other cards also). MediaTriX AudioTriX Pro support Y/n/? Answer "y" if you have the AudioTriX Pro. Support for MAD16 and/or Mozart based cards? Answer "y" if your card has a Mozart (OAK OTI-601) or MAD16 (OPTi 82C928 or 82C929) audio interface chip. These chips are currently quite common so it's possible that many no-name cards have one of them. In addition the MAD16 chip is used in some cards made by known manufacturers such as Turtle Beach (Tropez), Reveal (some models) and Diamond (latest ones). Support for Crystal CS4232 based (PnP) cards Y/n/? Answer "y" if you have a card based on the Crystal CS4232 chip set. Support for Turtle Beach Wave Front (Maui, Tropez) synthesizers Y/n/?" Answer "y" if you have any of these cards. SoundBlaster Pro support Y/n/? Enable this option if your card is a SoundBlaster Pro or SoundBlaster 16. Enable it also with any SoundBlaster Pro clones. Answering "n" saves some memory but "y" is the safe alternative. SoundBlaster 16 support Y/n/? Enable if you have a SoundBlaster 16 (including the AWE32). Audio Excel DSP 16 initialization support Y/n/? Enable this if you have an Audio Excel DSP16 card. See the file Readme.aedsp16 for more information. The configuration program then asks some questions about the higher level services. It's recommended to answer "y" to each of these questions. Answer "n" only if you know you will not need the option. /dev/dsp and /dev/audio support (usually required) Y/n/? Answering "n" disables /dev/dsp and /dev/audio, the A/D and D/A converter devices. Answer "y". MIDI interface support Y/n/? Answering "n" disables /dev/midixx devices and access to any MIDI ports using /dev/sequencer and /dev/music. This option also affects any MPU-401 and/or General MIDI compatible devices. FM synthesizer (YM3812/OPL-3) support Y/n/? Answer "y" here. /dev/sequencer support Y/n/? Answering "n" disables /dev/sequencer and /dev/music Do you want support for the mixer of SG NX Pro ? Answer "y" if you have a Sound Galaxy NX Pro sound card and want support for its extended mixer functions. Do you want support for the MV Jazz16 (ProSonic etc.) ? Answer "y" if you have an MV Jazz16 sound card. Do you have a Logitech SoundMan Games Y/n/? Answer "y" if you have a Logitech SoundMan Games sound card. After the above questions the configuration program prompts for the card specific configuration information. Usually just a set of I/O address, IRQ and DMA numbers are asked. With some cards the program asks for some files to be used during initialization of the card. These are used by cards which have a DSP chip or microprocessor which must be initialized by downloading a program (microcode) file to the card. In some cases this file is written to a .h file by the config program and then included to the driver during compile. Again, read the information in the file Readme.cards pertaining to your card type. At the end you will be prompted: The sound driver is now configured. Save copy of this configuration to /etc/soundconf [Y/n/?] Normally you would enter "y" so that if you later need to recompile the kernel you have the option of using the same sound driver configuration. If you are upgrading from an older sound driver, make sure that the files /usr/include/sys/soundcard.h and /usr/include/sys/ultrasound.h are symbolic links to the corresponding files in /usr/include/linux, or that they simply contain the lines #include <linux/soundcard.h> and #include <linux/ultrasound.h>, respectively. You are now ready to compile and install the new kernel. 4.3. Creating the Device Files For proper operation, device file entries must be created for the sound devices. These are normally created for you during installation of your Linux system. A quick check can be made using the command listed below. If the output is as shown (the date stamp will vary) then the device files are almost certainly okay. % ls -l /dev/sndstat crw-rw-rw- 1 root root 14, 6 Apr 25 1995 /dev/sndstat Note that having the right device files there doesn't guarantee anything on its own. The kernel driver must also be loaded or compiled in before the devices will work (more on that later). In rare cases, if you believe the device files are wrong, you can recreate them using the short shell script from the end of the file Readme.linux in the directory /usr/src/linux/drivers/sound, running it as user root. Alternatively, most Linux distributions have a /dev/MAKEDEV script which can be used for this purpose. If you are using the PC speaker sound driver, read the documentation that came with the package to determine if any device files need to be created. 4.4. Booting Linux and Testing the Installation You should now be ready to boot the new kernel and test the sound drivers. Follow your usual procedure for installing and rebooting the new kernel (keep the old kernel around in case of problems, of course). During booting, check for a message such as the following on powerup (if they scroll by too quickly to read, you may be able to retrieve them with the dmesg command): Sound initialization started <Sound Blaster 16 (4.13)> at 0x220 irq 5 dma 1,5 <Sound Blaster 16> at 0x330 irq 5 dma 0 <Yamaha OPL3 FM> at 0x388 Sound initialization complete This should match your sound card type and jumper settings (if any). Note that the above messages are not displayed when using loadable sound driver module (unless you enable it, e.g. using "insmod sound trace_init=1). When the sound driver is linked into the kernel, the "Sound initialization started" and "Sound initialization complete" messages should be displayed. If they are not printed, it means that there is no sound driver present in the kernel. In this case you should check that you actually installed the kernel you compiled when enabling the sound driver. If nothing is printed between the "Sound initialization started" and the "Sound initialization complete" lines, it means that no sound devices were detected. Most probably it means that you don't have the correct driver enabled, the card is not supported, the I/O port is bad or that you have a PnP card that has not been configured. The driver may also display some error messages and warnings during boot. Watch for these when booting the first time after configuring the sound driver. Next you should check the device file /dev/sndstat. Reading the sound driver status device file should provide additional information on whether the sound card driver initialized properly. Sample output should look something like this: % cat /dev/sndstat Sound Driver:3.5.4-960630 (Sat Jan 4 23:56:57 EST 1997 root, Linux fizzbin 2.0.27 #48 Thu Dec 5 18:24:45 EST 1996 i586) Kernel: Linux fizzbin 2.0.27 #48 Thu Dec 5 18:24:45 EST 1996 i586 Config options: 0 Installed drivers: Type 1: OPL-2/OPL-3 FM Type 2: Sound Blaster Type 7: SB MPU-401 Card config: Sound Blaster at 0x220 irq 5 drq 1,5 SB MPU-401 at 0x330 irq 5 drq 0 OPL-2/OPL-3 FM at 0x388 drq 0 Audio devices: 0: Sound Blaster 16 (4.13) Synth devices: 0: Yamaha OPL-3 Midi devices: 0: Sound Blaster 16 Timers: 0: System clock Mixers: 0: Sound Blaster The command above can report some error messages. "No such file or directory" indicates that you need to create the device files (see section 4.3). "No such device" means that sound driver is not loaded or linked into kernel. Go back to section 4.2 to correct this. If lines in the "Card config:" section of /dev/sndstat are listed inside parentheses (such as "(SoundBlaster at 0x220 irq 5 drq 1,5)"), it means that this device was configured but not detected. Now you should be ready to play a simple sound file. Get hold of a sound sample file, and send it to the sound device as a basic check of sound output, e.g. % cat endoftheworld >/dev/dsp % cat crash.au >/dev/audio (Make sure you don't omit the ">" in the commands above). Note that, in general, using cat is not the proper way to play audio files, it's just a quick check. You'll want to get a proper sound player program (described later) that will do a better job. This command will work only if there is at least one device listed in the audio devices section of /dev/sndstat. If the audio devices section is empty you should check why the device was not detected. If the above commands return "I/O error", you should look at the end of the kernel messages listed using the "dmesg" command. It's likely that an error message is printed there. Very often the message is "Sound: DMA (output) timed out - IRQ/DRQ config error?". The above message means that the driver didn't get the expected interrupt from the sound card. In most cases it means that the IRQ or the DMA channel configured to the driver doesn't work. The best way to get it working is to try with all possible DMAs and IRQs supported by the device. Another possible reason is that the device is not compatible with the device the driver is configured for. This is almost certainly the case when a supposedly "SoundBlaster (Pro/16) compatible" sound card doesn't work with the SoundBlaster driver. In this case you should try to find out the device your sound card is compatible with (by posting to the comp.os.linux.hardware newsgroup, for example). Some sample sound files can be obtained from <ftp://tsx-11.mit.edu/pub/linux/packages/sound/snd-data-0.1.tar.Z> Now you can verify sound recording. If you have sound input capability, you can do a quick test of this using commands such as the following: # record 4 seconds of audio from microphone EDT% dd bs=8k count=4 </dev/audio >sample.au 4+0 records in 4+0 records out # play back sound % cat sample.au >/dev/audio Obviously for this to work you need a microphone connected to the sound card and you should speak into it. You may also need to obtain a mixer program to set the microphone as the input device and adjust the recording gain level. If these tests pass, you can be reasonably confident that the sound D/A and A/D hardware and software are working. If you experience problems, refer to the next section of this document. 4.5. Troubleshooting If you still encounter problems after following the instructions in the HOWTO, here are some things to check. The checks are listed in increasing order of complexity. If a check fails, solve the problem before moving to the next stage. 4.5.1. Step 1: Make sure you are really running the kernel you com¡ piled. You can check the date stamp on the kernel to see if you are running the one that you compiled with sound support. You can do this with the uname command: % uname -a Linux fizzbin 2.0.0 #1 Tue Jun 4 16:57:55 EDT 1996 i386 or by displaying the file /proc/version: % cat /proc/version Linux version 2.0.0 (root@fizzbin) (gcc version 2.7.0) #1 Tue Jun 4 16:57:55 EDT 1996 If the date stamp doesn't seem to match when you compiled the kernel, then you are running an old kernel. Did you really reboot? If you use LILO, did you re-install it (typically by running /etc/lilo/install)? If booting from floppy, did you create a new boot floppy and use it when booting? 4.5.2. Step 2: Make sure the kernel sound drivers are compiled in. The easiest way to do this is to check the output of "dev/sndstat" as described earlier. If the output is not as expected then something went wrong with the kernel configuration or build. Start the installation process again, beginning with configuration and building of the kernel. 4.5.3. Step 3: Did the kernel detect your sound card during booting? Make sure that the sound card was detected when the kernel booted. You should have seen a message on bootup. If the messages scrolled off the screen, you can usually recall them using the dmesg command: % dmesg or % tail /var/adm/messages If your sound card was not found then something is wrong. Make sure it really is installed. If the sound card works under DOS then you can be reasonably confident that the hardware is working, so it is likely a problem with the kernel configuration. Either you configured your sound card as the wrong type or wrong parameters, or your sound card is not compatible with any of the Linux kernel sound card drivers. One possibility is that your sound card is one of the "compatible" type that requires initialization by the DOS driver. Try booting DOS and loading the vendor supplied sound card driver. Then soft boot Linux using Control-Alt-Delete. Make sure that card I/O address, DMA, and IRQ settings for Linux are the same as used under DOS. Read the Readme.cards file from the sound driver source distribution for hints on configuring your card type. If your sound card is not listed in this document, it is possible that the Linux drivers do not support it. You can check with some of the references listed at the end of this document for assistance. 4.5.4. Step 4: Can you read data from the dsp device? Try reading from the /dev/audio device using the dd command listed earlier in this document. The command should run without errors. If it doesn't work, then chances are that the problem is an IRQ or DMA conflict or some kind of hardware incompatibility (the device is not supported by Linux or the driver is configured for a wrong device). A remote possibility is broken hardware. Try testing the sound card under DOS, if possible, to eliminate that as a possibility. 4.5.5. When All Else Fails If you still have problems, here are some final suggestions for things to try: ╖ carefully re-read this HOWTO document ╖ read the references listed at the end of this document, especially Hannu Savolainen's web pages and the relevant kernel source Readme files ╖ post a question to one of the comp.os.linux or other Usenet newsgroups (comp.os.linux.hardware is a good choice; because of the high level of traffic in these groups it helps to put the string "sound" in the subject header for the article so the right experts will see it) ╖ Using a Web/Usenet search engine with an intelligently selected search criteria can give very good results quickly. One such choice is <http://www.altavista.digital.com> ╖ try using the latest Linux kernel (but only as a last resort, the latest development kernels can be unstable) ╖ send mail to the author of the sound driver ╖ send mail to the author of the Sound HOWTO ╖ fire up emacs and type Esc-x doctor :-) 5. Applications Supporting Sound I give here a sample of the types of applications that you likely want if you have a sound card under Linux. You can check the Linux Software Map, Internet archive sites, and/or files on your Linux CD-ROM for more up to date information. As a minimum, you will likely want to obtain the following sound applications: ╖ audio file format conversion utility (e.g. Sox) ╖ mixer utility (e.g. aumix or xmix) ╖ digitized file player/recorder (e.g. play or wavplay) ╖ MOD file player (e.g. tracker) ╖ MIDI file player (e.g. playmidi) There are text-based as well as GUI-based versions of most of these tools. There are also some more esoteric applications (e.g. speech synthesis and recognition) that you may wish to try. 6. Answers To Frequently Asked Questions This section answers some of the questions that have been commonly asked on the Usenet news groups and mailing lists. Answers to more questions can also be found at the OSS sound driver web page. 6.1. What are the various sound device files? These are the most "standard" device file names, some Linux distributions may use slightly different names. /dev/audio normally a link to /dev/audio0 /dev/audio0 Sun workstation compatible audio device (only a partial implementation, does not support Sun ioctl interface, just u-law encoding) /dev/audio1 second audio device (if supported by sound card or if more than one sound card installed) /dev/dsp normally a link to /dev/dsp0 /dev/dsp0 first digital sampling device /dev/dsp1 second digital sampling device /dev/mixer normally a link to /dev/mixer0 /dev/mixer0 first sound mixer /dev/mixer1 second sound mixer /dev/music high-level sequencer interface /dev/sequencer low level MIDI, FM, and GUS access /dev/sequencer2 normally a link to /dev/music /dev/midi00 1st raw MIDI port /dev/midi01 2nd raw MIDI port /dev/midi02 3rd raw MIDI port /dev/midi03 4th raw MIDI port /dev/sndstat displays sound driver status when read The PC speaker driver provides the following devices: /dev/pcaudio equivalent to /dev/audio /dev/pcsp equivalent to /dev/dsp /dev/pcmixer equivalent to /dev/mixer 6.2. How can I play a sound sample? Sun workstation (.au) sound files can be played by sending them to the /dev/audio device. Raw samples can be sent to /dev/dsp. This will generally give poor results though, and using a program such as play is preferable, as it will recognize most file types and set the sound card to the correct sampling rate, etc. Programs like wavplay or vplay (in the snd-util package) will give best results with WAV files. However they don't recognize Microsoft ADPCM compressed WAV files. Also older versions of play (from the Lsox package) doesn't work well with 16 bit WAV files. The splay command included in the snd-util package can be used to play most sound files if proper parameters are entered manually in the command line. 6.3. How can I record a sample? Reading /dev/audio or /dev/dsp will return sampled data that can be redirected to a file. A program such as vrec makes it easier to control the sampling rate, duration, etc. You may also need a mixer program to select the appropriate input device. 6.4. Can I have more than one sound card? With the current sound driver it's possible to have several SoundBlaster, SoundBlaster/Pro, SoundBlaster16, MPU-401 or MSS cards at the same time on the system. Installing two SoundBlasters is possible but requires defining the macros SB2_BASE, SB2_IRQ, SB2_DMA and (in some cases) SB2_DMA2 by editing local.h manually. It's also possible to have a SoundBlaster at the same time as a PAS16. With the newer 2.0.x kernels that configure sound using make config, instead of local.h, you need to edit the file /usr/include/linux/autoconf.h. After the section containing the lines: #define SBC_BASE 0x220 #define SBC_IRQ (5) #define SBC_DMA (1) #define SB_DMA2 (5) #define SB_MPU_BASE 0x0 #define SB_MPU_IRQ (-1) add these lines (with values appropriate for your system): #define SB2_BASE 0x330 #define SB2_IRQ (7) #define SB2_DMA (2) #define SB2_DMA2 (2) The following drivers don't permit multiple instances: ╖ GUS (driver limitation) ╖ MAD16 (hardware limitation) ╖ AudioTrix Pro (hardware limitation) ╖ CS4232 (hardware limitation) 6.5. Error: No such file or directory for sound devices You need to create the sound driver device files. See the section on creating device files. If you do have the device files, ensure that they have the correct major and minor device numbers (some older CD- ROM distributions of Linux may not create the correct device files during installation). 6.6. Error: No such device for sound devices You have not booted with a kernel containing the sound driver or the I/O address configuration doesn't match your hardware. Check that you are running the newly compiled kernel and verify that the settings entered when configuring the sound driver match your hardware setup. 6.7. Error: No space left on device for sound devices This can happen if you tried to record data to /dev/audio or /dev/dsp without creating the necessary device file. The sound device is now a regular file, and has filled up your disk partition. You need to run the script described in the Creating the Device Files section of this document. This may also happen with Linux 2.0 and later if there is not enough free RAM on the system when the device is opened. The audio driver requires at least two pages (8k) of contiguous physical RAM for each DMA channel. This happens sometimes in machines with less than 16M of RAM or which have been running for very long time. It may be possible to free some RAM by compiling and running the following C program before trying to open the device again: main() { int i; char mem[500000]; for (i = 0; i < 500000; i++) mem[i] = 0; exit(0); } 6.8. Error: Device busy for sound devices Only one process can open a given sound device at one time. Most likely some other process is using the device in question. One way to determine this is to use the fuser command: % fuser -v /dev/dsp /dev/dsp: USER PID ACCESS COMMAND tranter 265 f.... tracker In the above example, the fuser command showed that process 265 had the device open. Waiting for the process to complete or killing it will allow the sound device to be accessed once again. You should run the fuser command as root in order to report usage by users other than yourself. 6.9. I still get device busy errors! According to Brian Gough, for the SoundBlaster cards which use DMA channel 1 there is a potential conflict with the QIC-02 tape driver, which also uses DMA 1, causing "device busy" errors. If you are using FTAPE, you may have this driver enabled. According to the FTAPE-HOWTO the QIC-02 driver is not essential for the use of FTAPE; only the QIC-117 driver is required. Reconfiguring the kernel to use QIC-117 but not QIC-02 allows FTAPE and the sound-driver to coexist. 6.10. Partial playback of digitized sound file The symptom is usually that a sound sample plays for about a second and then stops completely or reports an error message about "missing IRQ" or "DMA timeout". Most likely you have incorrect IRQ or DMA channel settings. Verify that the kernel configuration matches the sound card jumper settings and that they do not conflict with some other card. Another symptom is sound samples that "loop". This is usually caused by an IRQ conflict. 6.11. There are pauses when playing MOD files Playing MOD files requires considerable CPU power. You may have too many processes running or your computer may be too slow to play in real time. Your options are to: ╖ try playing with a lower sampling rate or in mono mode ╖ eliminate other processes ╖ buy a faster computer ╖ buy a more powerful sound card (e.g. Gravis UltraSound) If you have a Gravis UltraSound card, you should use one of the mod file players written specifically for the GUS (e.g. gmod). 6.12. Compile errors when compiling sound applications The version 1.0c and earlier sound driver used a different and incompatible ioctl() scheme. Obtain newer source code or make the necessary changes to adapt it to the new sound driver. See the sound driver Readme file for details. Also ensure that you have used the latest version of soundcard.h and ultrasound.h when compiling the application. See the installation instructions at beginning of this text. 6.13. SEGV when running sound binaries that worked previously This is probably the same problem described in the previous question. 6.14. What known bugs or limitations are there in the sound driver? See the Readme and CHANGELOG files included with the sound driver kernel source. 6.15. Where are the sound driver ioctls() etc. documented? These are partially documented in the Hacker's Guide to VoxWare, currently available in draft form. The latest version is draft 2, and can be found on <ftp://nic.funet.fi/pub/Linux/ALPHA/sound/>. Note that this directory is "hidden" and will not appear in directory listings. If you "cd" to the directory and use the FTP "dir" command, the files are there. At time of writing new documentation was becoming available on the 4Front Technologies Web site. Another source of information is the Linux Multimedia Guide, described in the references section. 6.16. What CPU resources are needed to play or record without pauses? There is no easy answer to this question, as it depends on: ╖ whether using PCM sampling or FM synthesis ╖ sampling rate and sample size ╖ which application is used to play or record ╖ Sound Card hardware ╖ disk I/O rate, CPU clock speed, cache size, etc. In general, any 386 machine should be able to play samples or FM synthesized music on an 8 bit sound card with ease. Playing MOD files, however, requires considerable CPU resources. Some experimental measurements have shown that playing at 44kHz requires more than 40% of the speed of a 486/50 and a 386/25 can hardly play faster than 22 kHz (these are with an 8 bit card sound such as a SoundBlaster). A card such as the Gravis UltraSound card performs more functions in hardware, and will require less CPU resources. These statements assume the computer is not performing any other CPU intensive tasks. Converting sound files or adding effects using a utility such as sox is also much faster if you have a math coprocessor (or CPU with on board FPU). The kernel driver itself does not do any floating point calculations, though. 6.17. Problems with a PAS16 and an Adaptec 1542 SCSI host adaptor (the following explanation was supplied by seeker@indirect.com) Linux only recognizes the 1542 at address 330 (default) or 334, and the PAS only allows the MPU-401 emulation at 330. Even when you disable the MPU-401 under software, something still wants to conflict with the 1542 if it's at its preferred default address. Moving the 1542 to 334 makes everyone happy. Additionally, both the 1542 and the PAS-16 do 16-bit DMA, so if you sample at 16-bit 44 KHz stereo and save the file to a SCSI drive hung on the 1542, you're about to have trouble. The DMAs overlap and there isn't enough time for RAM refresh, so you get the dread ``PARITY ERROR - SYSTEM HALTED'' message, with no clue to what caused it. It's made worse because a few second-party vendors with QIC-117 tape drives recommend setting the bus on/off times such that the 1542 is on even longer than normal. Get the SCSISEL.EXE program from Adaptec's BBS or several places on the internet, and reduce the BUS ON time or increase the BUS OFF time until the problem goes away, then move it one notch or more further. SCSISEL changes the EEPROM settings, so it's more permanent than a patch to the DOS driver line in CONFIG.SYS, and will work if you boot right into Linux (unlike the DOS patch). Next problem solved. Last problem - the older Symphony chipsets drastically reduced the timing of the I/O cycles to speed up bus accesses. None of various boards I've played with had any problem with the reduced timing except for the PAS-16. Media Vision's BBS has SYMPFIX.EXE that's supposed to cure the problem by twiddling a diagnostic bit in Symphony's bus controller, but it's not a hard guarantee. You may need to: ╖ get the motherboard distributor to replace the older version bus chip, ╖ replace the motherboard, or ╖ buy a different brand of sound card. Young Microsystems will upgrade the boards they import for around $30 (US); other vendors may be similar if you can figure out who made or imported the motherboard (good luck). The problem is in ProAudio's bus interface chip as far as I'm concerned; nobody buys a $120 sound card and sticks it in a 6MHz AT. Most of them wind up in 25-40MHz 386/486 boxes, and should be able to handle at least 12MHz bus rates if the chips are designed right. Exit soapbox (stage left). The first problem depends on the chipset used on your motherboard, what bus speed and other BIOS settings, and the phase of the moon. The second problem depends on your refresh option setting (hidden or synchronous), the 1542 DMA rate and (possibly) the bus I/O rate. The third can be determined by calling Media Vision and asking which flavor of Symphony chip is incompatible with their slow design. Be warned, though - 3 of 4 techs I talked to were brain damaged. I would be very leery of trusting anything they said about someone else's hardware, since they didn't even know their own very well. 6.18. Is it possible to read and write samples simultaneously? Due to hardware limitations, this is not possible with most sound cards. Some newer cards do support it. See the section on "bidirectional mode" in the Hacker's Guide to Voxware for more information. 6.19. My SB16 is set to IRQ 2, but configure does not allow this value. On '286 and later machines, the IRQ 2 interrupt is cascaded to the second interrupt controller. It is equivalent to IRQ 9. 6.20. Are the SoundBlaster AWE32 or SoundBlaster16 ASP supported? In the past, Creative Labs was not willing to release programming information for these cards. They have since changed their policy and an AWE driver is now included in the Linux 2.1.x kernels. 6.21. If I run Linux, then boot DOS, I get errors and/or sound appli¡ cations do not work properly. This happens after a soft reboot to DOS. Sometimes the error message misleadingly refers to a bad CONFIG.SYS file. Most of the current sound cards have software programmable IRQ and DMA settings. If you use different settings between Linux and MS- DOS/Windows, this may cause problems. Some sound cards don't accept new parameters without a complete reset (i.e. cycle the power or use the hardware reset button). The quick solution to this problem it to perform a full reboot using the reset button or power cycle rather than a soft reboot (e.g. Ctrl- Alt-Del). The correct solution is to ensure that you use the same IRQ and DMA settings with MS-DOS and Linux (or not to use DOS :-). 6.22. Problems running DOOM under Linux Users of the port of ID software's game DOOM for Linux may be interested in these notes. For correct sound output you need version 2.90 or later of the sound driver; it has support for the real-time "DOOM mode". The sound samples are 16-bit. If you have an 8-bit sound card you can still get sound to work using one of several programs available in <ftp://sunsite.unc.edu/pub/Linux/games/doom>. If performance of DOOM is poor on your system, disabling sound (by renaming the file sndserver) may improve it. By default DOOM does not support music (as in the DOS version). The program musserver will add support for music to DOOM under Linux. It can be found at <ftp://pandora.st.hmc.edu/pub/linux/musserver.tgz>. 6.23. How can I reduce noise picked up by my sound card? Using good quality shielded cables and trying the sound card in different slots may help reduce noise. If the sound card has a volume control, you can try different settings (maximum is probably best). Using a mixer program you can make sure that undesired inputs (e.g. microphone) are set to zero gain. Some sound cards are simply not designed with good shielding and grounding and are prone to noise pickup. Finally, on my system I found that the kernel command line option no- hlt reduces the noise level. This tells the kernel not to use the halt instruction when running the idle process loop. You can try this manually when booting, or set it up using the command append="no-hlt" in your LILO configuration file. 6.24. I can play sounds, but not record. If you can play sound but not record, try these steps: ╖ use a mixer program to select the appropriate device (e.g. microphone) ╖ use the mixer to set the input gains to maximum ╖ If you can, try to test sound card recording under MS-DOS to determine if there is a hardware problem Sometimes a different DMA channel is used for recording than for playback. In this case the most probable reason is that the recording DMA is set up incorrectly. 6.25. My "compatible" sound card only works if I first initialize under MS-DOS. In most cases a "SoundBlaster compatible" card will work better under Linux if configured with a driver other than the SoundBlaster one. Most sound cards claim to be compatible (e.g. "16 bit SB Pro compatible" or "SB compatible 16 bit") but usually this SoundBlaster mode is just a "hack" provided for DOS games compatibility. Most cards have a 16 bit native mode which is likely to be supported by recent Linux versions (2.0.1 and later). Only with some (usually rather old) cards is it necessary to try to get them to work in the SoundBlaster mode. The only newer cards that are the exception to this rule are the Mwave-based cards. 6.26. My 16-bit SoundBlaster "compatible" sound card only works in 8-bit mode under Linux. 16-bit sound cards described as SoundBlaster compatible are really only compatible with the 8-bit SoundBlaster Pro. They typically have a 16-bit mode which is not compatible with the SoundBlaster 16 and not compatible with the Linux sound driver. You may be able to get the card to work in 16-bit mode by using the MAD16 or MSS/WSS driver. 6.27. Where can I find sound applications for Linux? Here are some good archive sites to search for Linux specific sound applications: ╖ <ftp://sunsite.unc.edu:/pub/Linux/kernel/sound/> ╖ <ftp://sunsite.unc.edu:/pub/Linux/apps/sound/> ╖ <ftp://tsx-11.mit.edu:/pub/linux/packages/sound/> ╖ <ftp://nic.funet.fi:/pub/Linux/util/sound/> ╖ <ftp://nic.funet.fi:/pub/Linux/xtra/snd-kit/> ╖ <ftp://nic.funet.fi:/pub/Linux/ALPHA/sound/> 6.28. Can the sound driver be compiled as a loadable module? With recent kernels the sound driver is supported as a kernel loadable module. See the files /usr/src/linux/drivers/sound/Readme.modules and /usr/src/linux/Documentation/modules.txt (or /usr/src/linux/README) for details. 6.29. Can I use a sound card to replace the system console beep? Try the oplbeep program, found at <ftp://sunsite.unc.edu/pub/Linux/apps/sound/oplbeep-alpha.tar.gz> Another variant is the beep program found at <ftp://sunsite.unc.edu/pub/Linux/kernel/patches/misc/modreq_beep.tgz> The modutils package has an example program and kernel patch that supports calling an arbitrary external program to generate sounds when requested by the kernel. Alternatively, with some sound cards you can connect the PC speaker output to the sound card so that all sounds come from the sound card speakers. 6.30. What is VoxWare? The kernel sound drivers support several different Intel-based Unix compatible operating systems, and can be obtained as a package separate from the Linux kernel. Up until February 1996 the author had called the software "VoxWare". Unfortunately this name has been registered by VoxWare Incorporated, and can not be used. The new name of the driver is OSS/Free. The Open Sound System (OSS) is a commercially available kernel sound driver for various Unix systems, sold by 4Front Technologies. The free version, known as OSS/Free will continue to be made freely available for Linux systems. Other names you may come across that have been used in the past to refer to the same sound driver are TASD (Temporarily Anonymous Sound Driver) and USS (Unix Sound System). For more information see the 4Front Technologies Web page at <http://www.4front-tech.com/>. I wrote a review of OSS/Linux in the June 1997 issue of Linux Journal. 6.31. Are Plug and Play sound card supported? Full Plug and Play support should be coming in Linux version 2.1. In the mean time there are a number of workarounds for getting Plug and Play sound cards to work. If you have a newer Pentium system with a Plug and Play BIOS, it should take care of configuring the cards for you. Make sure that you configure the Linux sound driver to use the same I/O address, IRQ, and DMA channel parameters as the BIOS. There is a package of Plug and Play tools for Linux that can be used to set up the card. It can be found at Red Hat's Web site <http://www.redhat.com/> (it may also be included in your Linux distribution). If you use the card under Windows95, you can use the device manager to set up the card, then soft boot into Linux using the LOADLIN program. Make sure Windows95 and Linux use the same card setup parameters. If you use the card under DOS, you can use the icu utility that comes with SoundBlaster16 PnP cards to configure it under DOS, then soft boot into Linux using the LOADLIN program. Again, make sure DOS and Linux use the same card setup parameters. The commercial OSS sound driver has support for the SoundBlaster16 PnP sound card. You can purchase this driver from 4Front Technologies. 6.32. Sox/Play/Vplay reports "invalid block size 1024" A change to the sound driver in version 1.3.67 broke some sound player programs which (incorrectly) checked that the result from the SNDCTL_DSP_GETBLKSIZE ioctl was greater than 4096. The utilities included in the latest snd-util-3.x.tar.gz package (at <ftp://ftp.4front-tech.com/ossfree>.) now handle this properly. The latest sound driver versions have also been fixed to avoid allocating fragments shorter than 4096 bytes which solves this problem with old utilities. 6.33. Why does the sound driver have its own configuration program? The sound driver supports many different configuration parameters. The configure program included with the sound driver checks for many dependencies between parameters. The tools used to configure the kernel don't support this level of functionality. That said, the latest kernels do optionally allow using the standard kernel configuration tools with the sound driver (see the earlier section on "Configuring the Kernel". 6.34. The mixer settings are reset whenever I load the sound driver module You can build the sound driver as a loadable module and use kerneld to automatically load and unload it. This can present one problem - whenever the module is reloaded the mixer settings go back to their default values. For some sound cards this can be too loud (e.g. SoundBlaster16) or too quiet. Markus Gutschke (gutschk@uni- muenster.de) found this solution. Use a line in your /etc/conf.modules file such as the following: options sound dma_buffsize=65536 && /usr/bin/setmixer igain 0 ogain 0 vol 75 This causes your mixer program (in this case setmixer) to be run immediately after the sound driver is loaded. The dma_buffsize parameter is just a dummy value needed because the option command requires a command line option. Change the line as needed to match your mixer program and gain settings. If you have compiled the sound driver into your kernel and you want to set the mixer gains at boot time you can put a call to your mixer program in a system startup file such as /etc/rc.d/rc.local. 6.35. Only user root can record sound By default the script in Readme.linux that creates the sound device files only allows the devices to be read by user root. This is to plug a potential security hole. In a networked environment, external users could conceivably log in remotely to a Linux PC with a sound card and microphone and eavesdrop. If you are not worried about this, you can change the permissions used in the script. With the default setup, users can still play sound files. This is not a security risk but is a potential for nuisance. 6.36. Is the sound hardware on the IBM ThinkPad supported? Information on how to use the mwave sound card on an IBM ThinkPad laptop computer under Linux can be found at <http://www.screamin.demon.co.uk/>. 7. References If you have a sound card that supports a CD-ROM or SCSI interface, the Linux SCSI HOWTO and the Linux CD-ROM HOWTO have additional information that may be useful to you. The Sound Playing HOWTO describes how to play various types of sound and music files under Linux. The Ultrasound Plug'n'play Mini-HOWTO describes how to get a plug and play Gravis Ultrasound card working under Linux. The Linux SoundBlaster 16 PnP Mini-HOWTO describes how to get a plug and play SoundBlaster 16 card working under Linux. The Linux SoundBlaster AWE64 PnP Mini-HOWTO describes how to get a plug and play SoundBlaster AWE64 card working under Linux. There is an old document called the Hacker's Guide to VoxWare, available from <ftp://nic.funet.fi/pub/Linux/ALPHA/sound/>. Most of the information in there has been superseded by the documents at <http://www.4front-tech.com/pguide>, but the section on /dev/sequencer may still be useful. The following FAQs are regularly posted to the Usenet newsgroup news.announce as well as being archived at <ftp://rtfm.mit.edu/pub/usenet/news.answers>: ╖ PCsoundcards/generic-faq (Generic PC Soundcard FAQ) ╖ PCsoundcards/soundcard-faq (comp.sys.ibm.pc.soundcard FAQ) ╖ PCsoundcards/gravis-ultrasound/faq (Gravis UltraSound FAQ) ╖ audio-fmts/part1 (Audio file format descriptions) ╖ audio-fmts/part2 (Audio file format descriptions) The FAQs also list several product specific mailing lists and archive sites. The following Usenet news groups discuss sound and/or music related issues: ╖ alt.binaries.sounds.* (various groups for posting sound files) ╖ alt.binaries.multimedia (for posting Multimedia files) ╖ alt.sb.programmer (Soundblaster programming topics) ╖ comp.multimedia (Multimedia topics) ╖ comp.music (Computer music theory and research) ╖ comp.sys.ibm.pc.soundcard.* (various IBM PC sound card groups) A Web site dedicated to multimedia can be found at <http://viswiz.gmd.de/MultimediaInfo/>. Creative Labs has a Web site at <http://www.creaf.com/>. MediaTrix has a Web site at <http://www.mediatrix.com/>. The Linux mailing list has a number of "channels" dedicated to different topics, including sound. To find out how to join, send a mail message with the word "help" as the message body to majordomo@vger.rutgers.edu. These mailing lists are not recommended for questions on sound card setup etc., they are intended for development related discussion. As mentioned several times before, the kernel sound driver includes a number of Readme files containing useful information about the sound card driver. These can typically be found in the directory /usr/src/linux/drivers/sound. The author of the kernel sound driver, Hannu Savolainen, can be contacted by email at hannu@voxware.pp.fi. He also has a World-Wide Web site at <http://personal.eunet.fi/pp/voxware>. The Web site is the best source for finding out the latest status of supported sound cards, known problems, and bug fixes. Information on OSS, the commercial sound driver for Linux and other Unix compatible operating systems, can be found on the 4Front Technologies Web page at <http://www.4front-tech.com/>. The Linux Software Map (LSM) is an invaluable reference for locating Linux software. Searching the LSM for keywords such as sound is a good way to identify applications related to sound hardware. The LSM can be found on various anonymous FTP sites, including <ftp://sunsite.unc.edu/pub/Linux/docs/LSM/>. The Linux Documentation Project has produced several books on Linux, including Linux Installation and Getting Started. These are freely available by anonymous FTP from major Linux archive sites or can be purchased in hardcopy format. Finally, a shameless plug: If you want to learn a lot more about multimedia under Linux (especially CD-ROM and sound card applications and programming), check out my book Linux Multimedia Guide, ISBN 1-56592-219-0, published by O'Reilly and Associates. As well as the original English version, French and Japanese translations are now in print. For details, call 800-998-9938 in North America or check the Web page <http://www.ora.com/catalog/multilinux/noframes.html> or my home page <http://www.pobox.com/~tranter>.