The Linux Sound HOWTO

Table of Contents
1. Introduction
    1.1. Acknowledgments
    1.2. New versions of this document
    1.3. Feedback
    1.4. Distribution Policy
   
   
2. Sound Card Technology
3. Supported Hardware
    3.1. Platform Notes
    3.2. Sound Card Types
    3.3. Sound Cards
    3.4. Alternate Sound Drivers
   
   
4. Installation
    4.1. Installing the Sound Card
    4.2. Configuring ISA Plug and Play
    4.3. Configuring the Kernel
    4.4. Creating the Device Files
    4.5. Booting Linux and Testing the Installation
    4.6. Troubleshooting
   
   
5. Applications Supporting Sound
6. Answers To Frequently Asked Questions
    6.1. What are the various sound device files?
    6.2. How can I play a sound sample?
    6.3. How can I record a sample?
    6.4. Can I have more than one sound card?
    6.5. Error: No such file or directory for sound devices
    6.6. Error: No such device for sound devices
    6.7. Error: No space left on device for sound devices
    6.8. Error: Device busy for sound devices
    6.9. I still get device busy errors!
    6.10. Partial playback of digitized sound file
    6.11. There are pauses when playing MOD files
    6.12. Compile errors when compiling sound applications
    6.13. SEGV when running sound binaries that worked previously
    6.14. What known bugs or limitations are there in the sound driver?
    6.15. Where are the sound driver ioctls() etc. documented?
    6.16. What CPU resources are needed to play or record without pauses?
    6.17. Problems with a PAS16 and an Adaptec 1542 SCSI host adaptor
    6.18. Is it possible to read and write samples simultaneously?
    6.19. My SB16 is set to IRQ 2, but configure does not allow this value.
    6.20. If I run Linux, then boot DOS, I get errors and/or sound
        applications do not work properly.
    6.21. Problems running DOOM under Linux
    6.22. How can I reduce noise picked up by my sound card?
    6.23. I can play sounds, but not record.
    6.24. My "compatible" sound card only works if I first initialize under
        MS-DOS.
    6.25. My 16-bit SoundBlaster "compatible" sound card only works in 8-bit
        mode under Linux.
    6.26. Where can I find sound applications for Linux?
    6.27. Can the sound drivers be compiled as a loadable module?
    6.28. Can I use a sound card to replace the system console beep?
    6.29. What is VoxWare?
    6.30. Sox/Play/Vplay reports "invalid block size 1024"
    6.31. The mixer settings are reset whenever I load the sound driver
        module
    6.32. Only user root can record sound
    6.33. Is the sound hardware on the IBM ThinkPad supported?
    6.34. Applications fail because my sound card has no mixer
    6.35. Problems with a SB16 CT4170
    6.36. How to connect a MIDI keyboard to a soundcard
    6.37. Problems with IRQ 15 and Ensoniq PCI 128
    6.38. Where can I get freely available MIDI patches to run SoftOSS?
   
   
7. References

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 ([mailto:hannu@opensound.com]
hannu@opensound.com). Thanks go to Hannu, Alan Cox, and the many other people
who developed the Linux kernel sound drivers and utilities.

Thanks to the [http://www.docbook.org] DocBook tools, this HOWTO is available
in several formats, all generated from a common source file.
-----------------------------------------------------------------------------

1.2. New versions of this document

New versions of this document will be periodically posted to the [news:
comp.os.linux.answers] comp.os.linux.answers newsgroup. Hypertext versions of
this and other Linux HOWTOs are available on many world-wide web sites,
including [http://www.linuxdoc.org/] http://www.linuxdoc.org. 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.

Please note that, due to the dynamic nature of the Internet, all web and ftp
links listed in this document are subject to change.

Translations of this document are available in several languages:

Chinese: [http://www.linux.org.tw/CLDP/Sound-HOWTO.html] http://
www.linux.org.tw/CLDP/Sound-HOWTO.html

French: [http://www.freenix.org/unix/linux/HOWTO/] http://www.freenix.org/
unix/linux/HOWTO/

Italian: [http://www.pluto.linux.it/ildp/HOWTO/index.html] http://
www.pluto.linux.it/ildp/HOWTO/index.html

Japanese: [http://yebisu.ics.es.osaka-u.ac.jp/linux/] http://
yebisu.ics.es.osaka-u.ac.jp/linux/

Korean: [http://kldp.org/HOWTO/html/Sound/Sound-HOWTO.html] http://kldp.org/
HOWTO/html/Sound/Sound-HOWTO.html

Russian: [http://www.phtd.tpu.edu.ru/~ott/russian/linux/howto-rus/
Sound-HOWTO.html] http://www.phtd.tpu.edu.ru/~ott/russian/linux/howto-rus/
Sound-HOWTO.html

Spanish: [ftp://ftp.insflug.org/es] ftp://ftp.insflug.org/es

Most translations of this and other Linux HOWTOs can also be found at [http:/
/www.ibiblio.org/pub/Linux/docs/HOWTO/translations/] http://www.ibiblio.org/
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.
-----------------------------------------------------------------------------

1.3. 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, [mailto:
tranter@pobox.com] 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 LDP at [mailto:feedback@linuxdoc.org]
feedback@linuxdoc.org for more information.
-----------------------------------------------------------------------------

1.4. Distribution Policy

Copyright (c) 1995-2001 by Jeff Tranter. Permission is granted to copy,
distribute and/or modify this document under the terms of the GNU Free
Documentation License, Version 1.1 or any later version published by the Free
Software Foundation; with no Invariant Sections, with no Front-Cover Texts,
and with no Back-Cover Texts. A copy of the license is available at [http://
www.gnu.org/copyleft/fdl.html] http://www.gnu.org/copyleft/fdl.html
-----------------------------------------------------------------------------

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.

MP3 files are a popular format for distributing computer music and speech.
MP3 uses a sophisticated encoding scheme (MPEG layer 3) to compress audio by
roughly a factor of 10 with little reduction in quality as compared to CD
audio.
-----------------------------------------------------------------------------

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
kernel, which at time of writing was version 2.4.4. This document only
applies to the sound drivers included with the standard Linux kernel source
distribution. There are other sound drivers available for Linux (see the
later section entitled Alternate Sound Drivers).

For the latest information on supported sound cards and features see the
files included with the Linux kernel source code, usually installed in the
directory /usr/src/linux/Documentation/sound.
-----------------------------------------------------------------------------

3.1. Platform Notes

The information in this HOWTO is valid for Linux on the Intel x86 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.

Users have reported that 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 currently has sound support for some models of Sun
workstations. I've been told that the on-board sound hardware works but the
external DSP audio box is not supported because Sun has not released the
specifications for it.
-----------------------------------------------------------------------------

3.2. Sound Card Types

A number of different types of sound cards exist, reflecting the different
bus architectures available. Here is a brief overview of the more common
types and their distinguishing features.

ISA bus cards are among the oldest sound cards using the original (non Plug
and Play) ISA bus. These typically use jumpers to select hardware settings
for I/O addresses, IRQ, and DMA channel. You are unlikely to find any of this
type manufactured today.

ISA Plug and Play cards use the extended version of the ISA bus that supports
software identification and configuration of card settings. Few of these, if
any, are still being manufactured.

PCI bus cards use the higher bandwidth PCI bus which provides identification
and configuration of cards in software. The majority of sound cards
manufactured today now use PCI. Most motherboards that provide on-board sound
hardware also make use of the PCI bus.

USB is a newer bus architecture for external hot-pluggable devices. In theory
USB bus sound cards could be developed, but I am only aware of USB-bus
speakers being sold currently.
-----------------------------------------------------------------------------

3.3. Sound Cards

The following sound cards are supported by the Linux kernel sound driver.
Some of the items listed are audio chip sets rather than models of sound
cards. The list is incomplete because there are many sound cards compatible
with these that will work under Linux. To add further to the confusion, some
manufacturers periodically change the design of their cards causing
incompatibilities and continue to sell them as the same model.


+------------------+------------------+-------------------+-----------------+
|6850 UART MIDI    |AD1816/AD1816A    |AD1816/AD1816A     |AD1848 sound chip|
|Interface         |based cards       |sound chip         |                 |
+------------------+------------------+-------------------+-----------------+
|ADSP-2115         |ALS-007 based     |ALS-1x0 sound chip |ATARI onboard    |
|                  |cards (Avance     |                   |sound            |
|                  |Logic)            |                   |                 |
+------------------+------------------+-------------------+-----------------+
|ATI Stereo F/X    |Acer FX-3D        |AdLib              |Amiga onboard    |
|                  |                  |                   |sound            |
+------------------+------------------+-------------------+-----------------+
|Audio Excel DSP 16|AudioDrive        |Aztech Sound Galaxy|Aztech Sound     |
|                  |                  |Washington 16      |Galaxy WaveRider |
|                  |                  |                   |3D               |
+------------------+------------------+-------------------+-----------------+
|Aztech Sound      |Beethoven ADSP-16 |CMI8330 sound chip |CMI8338/8378     |
|Galaxy WaveRider  |                  |                   |sound chip       |
|Pro32             |                  |                   |                 |
+------------------+------------------+-------------------+-----------------+
|Cardinal DSP16    |Compaq Deskpro XL |Corel Netwinder    |Crystal CS423x   |
|                  |onboard sound     |WaveArtist         |                 |
+------------------+------------------+-------------------+-----------------+
|Crystal CS4280    |Crystal CS46xx    |ES1370 sound chip  |ES1371 sound chip|
+------------------+------------------+-------------------+-----------------+
|ESC614 sound chip |ESS Maestro 1/2/2E|ESS Solo1 sound    |ESS1688 sound    |
|                  |sound ship        |chip               |chip             |
+------------------+------------------+-------------------+-----------------+
|ESS1788 sound chip|ESS1868 sound chip|ESS1869 sound chip |ESS1887 sound    |
|                  |                  |                   |chip             |
+------------------+------------------+-------------------+-----------------+
|ESS1888 sound chip|ESS688 sound chip |Ensoniq AudioPCI   |Ensoniq AudioPCI |
|                  |                  |(ES1370)           |97 (ES1371)      |
+------------------+------------------+-------------------+-----------------+
|Ensoniq/Reveal/   |Gallant SC-6000   |Gallant SC-6600    |Gravis Ultrasound|
|Spea SoundScape   |                  |                   |                 |
+------------------+------------------+-------------------+-----------------+
|Gravis Ultrasound |Gravis Ultrasound |Gravis Ultrasound  |HP Kayak         |
|ACE               |Max               |with 16 bit option |                 |
+------------------+------------------+-------------------+-----------------+
|Highscreen        |IBM MWAVE         |Jazz 16            |Logitech Sound   |
|Sound-Booster32   |                  |                   |Man 16           |
|Wave3D            |                  |                   |                 |
+------------------+------------------+-------------------+-----------------+
|Logitech SoundMan |Logitech SoundMan |MAD16 Pro (OpTi    |Media Vision     |
|Games             |Wave              |82C9xx chipsets)   |Jazz16           |
+------------------+------------------+-------------------+-----------------+
|MediaTriX         |Microsoft Windows |MiroSOUND PCM12    |Mozart (OAK      |
|AudioTriX Pro     |Sound System      |                   |OTI-601)         |
+------------------+------------------+-------------------+-----------------+
|NeoMagic 256AV/   |OpTi 82C931       |Orchid SW32        |Personal Sound   |
|256ZX             |                  |                   |System (PSS)     |
+------------------+------------------+-------------------+-----------------+
|Pinnacle          |Power Mac onboard |Pro Audio Spectrum |Pro Audio Studio |
|MultiSound        |sound             |16                 |16               |
+------------------+------------------+-------------------+-----------------+
|Pro Sonic 16      |Q40 onboard sound |Roland MPU-401 MIDI|S3 SonicVibes    |
|                  |                  |interface          |                 |
+------------------+------------------+-------------------+-----------------+
|SGI Visual        |SM Games          |SY-1816            |SoundBlaster 1.0 |
|Workstation       |                  |                   |                 |
+------------------+------------------+-------------------+-----------------+
|SoundBlaster 16   |SoundBlaster 16ASP|SoundBlaster 2.0   |SoundBlaster 32  |
+------------------+------------------+-------------------+-----------------+
|SoundBlaster 64   |SoundBlaster AWE32|SoundBlaster AWE64 |SoundBlaster     |
|                  |                  |                   |Live!            |
+------------------+------------------+-------------------+-----------------+
|SoundBlaster PCI  |SoundBlaster PCI  |SoundBlaster Pro   |SoundBlaster     |
|128               |512               |                   |Vibra16          |
+------------------+------------------+-------------------+-----------------+
|SoundBlaster      |TI TM4000M        |Terratec Base 1    |Terratec Base 64 |
|Vibra16X          |notebook          |                   |                 |
+------------------+------------------+-------------------+-----------------+
|ThunderBoard      |Trident 4DWave DX/|Trident Ali 5451   |Trident SiS 7018 |
|                  |NX                |                   |                 |
+------------------+------------------+-------------------+-----------------+
|Turtle Beach Maui |Turtle Beach      |Turtle Beach       |Turtle Beach     |
|                  |MultiSound Classic|MultiSound Fiji    |MultiSound       |
|                  |                  |                   |Hurricane        |
+------------------+------------------+-------------------+-----------------+
|Turtle Beach      |Turtle Beach      |Turtle Beach       |Turtle Beach     |
|MultiSound        |MultiSound        |MultiSound Tahiti  |WaveFront Maui   |
|Monterey          |Pinnacle          |                   |                 |
+------------------+------------------+-------------------+-----------------+
|Turtle Beach      |Turtle Beach      |VIA 82Cxxx chip set|VIDC 16-bit sound|
|WaveFront Tropez  |WaveFront Tropez+ |                   |                 |
+------------------+------------------+-------------------+-----------------+
|Yamaha OPL2 sound |Yamaha OPL3 sound |Yamaha OPL3-SA1    |Yamaha OPL3-SA2  |
|chip              |chip              |sound chip         |sound chip       |
+------------------+------------------+-------------------+-----------------+
|Yamaha OPL3-SA3   |Yamaha OPL3-SAx   |Yamaha OPL4 sound  |Yamaha YM3812    |
|sound chip        |sound chip        |chip               |sound chip       |
+------------------+------------------+-------------------+-----------------+

 

A word about compatibility: 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 [ftp://www.ibiblio.org/pub/Linux/docs/
HOWTO/unmaintained/SCSI-HOWTO] SCSI HOWTO and [http://www.ibiblio.org/LDP/
HOWTO/CDROM-HOWTO.html] CDROM HOWTO documents for more information.

A kernel driver to support joystick ports, including those provided on some
sound cards, is included as part of the 2.2 and later kernels.

Note that the kernel SCSI, CD-ROM, joystick, and sound drivers are completely
independent of each other.
-----------------------------------------------------------------------------

3.4. Alternate Sound Drivers

3.4.1. OSS/4Front

Sound support in the Linux kernel was originally written by Hannu Savolainen.
Hannu then went on to develop the Open Sound system, a commercial set of
sound drivers sold by 4Front Technologies that is supported on a number of
Unix systems. Red Hat Software sponsored Alan Cox to enhance the kernel sound
drivers to make them fully modular. Various other people also contributed bug
fixes and developed additional drivers for new sound cards. These modified
drivers were shipped by Red Hat in their 5.0 through 5.2 releases. These
changes have now been integrated into the standard kernel as of version 2.0.
Alan Cox is now the maintainer of the standard kernel sound drivers, although
Hannu still periodically contributes code taken from the commercial driver.

The commercial Open Sound System driver from 4Front Technologies tends to be
easier to configure and support more sound cards, particularly the newer
models. It is also compatible with applications written for the standard
kernel sound drivers. The disadvantage is that you need to pay for it, and
you do not get source code. You can download a free evaluation copy of the
product before deciding whether to purchase it. For more information see the
4Front Technologies web page at [http://www.opensound.com] http://
www.opensound.com.
-----------------------------------------------------------------------------

3.4.2. ALSA

Jaroslav Kysela and others started writing an alternate sound driver for the
Gravis UltraSound Card. The project was renamed Advanced Linux Sound
Architecture (ALSA) and has resulted in what they believe is a more generally
usable sound driver that can be used as a replacement for the built-in kernel
drivers. The ALSA drivers support a number of popular sound cards, are full
duplex, fully modularized, and compatible with the sound architecture in the
kernel. The main web site of the ALSA project is [http://
www.alsa-project.org] http://www.alsa-project.org. A separate
"Alsa-sound-mini-HOWTO" is available which deals with compiling and
installing these drivers. The ALSA drivers may move into the standard Linux
kernel as part of the 2.5 kernel development.
-----------------------------------------------------------------------------

3.4.3. Turtle Beach

Markus Mummert ([mailto:mum@mmk.e-technik.tu-muenchen.de]
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 recording/playback without losing
sync even on a busy system. Other features such as wave synthesis, MIDI and
digital signal 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] http://
www.cs.colorado.edu/~mccreary/tbeach.
-----------------------------------------------------------------------------

3.4.4. Roland MPU-401

Kim Burgaard ([mailto:burgaard@daimi.aau.dk] 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 policy 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://www.ibiblio.org/pub/Linux/kernel/sound/
mpu401-0.2.tar.gz] ftp://www.ibiblio.org/pub/Linux/kernel/sound/
mpu401-0.2.tar.gz.
-----------------------------------------------------------------------------

3.4.5. SoundBlaster Live!

Creative Labs has Linux drivers for several cards, including the SoundBlaster
Live!, at [http://opensource.creative.com] http://opensource.creative.com.
-----------------------------------------------------------------------------

3.4.6. Packet Radio

Another novel use for a sound card under Linux is as a modem for amateur
packet radio. The 2.1 and later 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).
-----------------------------------------------------------------------------

3.4.7. PC Speaker

An alternate sound driver is available that requires no additional sound
hardware; it uses the internal PC speaker. It is 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 latest version of the PC speaker driver can be found at [ftp://
ftp.infradead.org/pub/pcsp/] ftp://ftp.infradead.org/pub/pcsp/.
-----------------------------------------------------------------------------

3.4.8. 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 Plug and Play (if applicable).
   
 3. Configuring and building the kernel for sound support.
   
 4. Creating the device files.
   
 5. Booting the Linux kernel and testing the installation.
   

 

Some Linux distributions provide a sound driver configuration utility that
will detect your sound card and set up all of the necessary configuration
files to load the appropriate sound drivers for your card. Red Hat Linux, for
example, provides the sndconfig utility. If your distribution provides such a
tool I suggest you try using it. If it works for you then you can skip the
rest of the instructions in this section.

If this fails or you want to follow the manual method in order to better
understand what you are doing, then 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 ISA Plug and Play

Some sound cards use the ISA Plug and Play protocol to configure settings for
i/o addresses, interrupts, and DMA channels. If you have a newer PCI-bus type
of sound card, or one of the very old ISA sound cards that uses fixed
settings or jumpers, then you can skip this section.

The preferred way to configure Plug and Play cards is to use the isapnp tools
which ship with most Linux distributions (or you can download them from Red
Hat's web site [http://www.redhat.com/] http://www.redhat.com/).

First check the documentation for your Linux distribution. It may already
have Plug and Play support set up for you or it may work slightly differently
than described here. If you need to configure it yourself,the details can be
found in the man pages for the isapnp tools. Briefly the process you would
normally follow is:

 

  * Use pnpdump to capture the possible settings for all your Plug and Play
    devices, saving the result to the file /etc/isapnp.conf. 
   
  * Choose settings for the sound card that do not conflict with any other
    devices in your system and uncomment the appropriate lines in /etc/
    isapnp.conf. Don't forget to uncomment the (ACT Y) command near the end. 
   
  * Make sure that isapnp is run when your system boots up, normally done by
    one of the startup scripts. Reboot your system or run isapnp manually. 
   

 

If for some reason you cannot or do not wish to use the isapnp tools, there
are a couple of other options. If you use the card under Microsoft Windows 95
or 98, you can use the device manager to set up the card, then soft boot into
Linux using the LOADLIN program. Make sure Windows 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.

True ISA PnP support is implemented in the 2.4 and later kernels. Some of the
sound card drivers now support automatically detecting and configuring the
cards without the isapnp tools. Check the documentation for the card's driver
for details.
-----------------------------------------------------------------------------

4.3. Configuring the Kernel

 You need the appropriate device drivers for your sound card to be present in
the kernel. The kernel running on your system may already include the drivers
for your sound card. In most cases the drivers would have been built as
kernel loadable modules. You can check which drivers are available as modules
by looking in the /lib/modules directories. For the 2.4.4 kernel, the sound
drivers would normally appear in /lib/modules/2.4.4/kernel/drivers/sound/. If
you see the driver(s) for your sound card, you can try using the module
directory and skip recompiling the kernel.

If the sound drivers are not already built, you will need to configure and
build a new kernel. You can either build the sound drivers into the kernel or
build them as kernel loadable modules. In most cases building as modules is
preferred, as it allows you to easily experiment with loading different
drivers if unsure which one to use and the drivers can be unloaded when not
needed, freeing up memory. Building the drivers into the kernel itself may be
desirable if you are unfamiliar with kernel modules and want a simpler
solution.

The [http://www.ibiblio.org/LDP/HOWTO/Kernel-HOWTO.html] Linux Kernel HOWTO
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 the relevant documentation included with the kernel sound
drivers, particularly information specific to your card type. The files can
be found in the kernel documentation directory, usually installed in /usr/src
/linux/Documentation/sound. If this directory is missing you likely either
have a very old kernel version or you have not installed the kernel source
code.

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.

When configuring the kernel there will be many choices for selecting the type
of sound card you have and the driver options to use. The on-line help within
the configuration tool should provide an explanation of what each option is
for. Select the appropriate options to the best of your knowledge.

After configuring the options you should compile and install the new kernel
as per the Kernel HOWTO.
-----------------------------------------------------------------------------

4.4. 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/dsp                                                           |
|crw-rw-rw-   1 root     root      14,   3 Apr 25  1995 /dev/dsp            |
+---------------------------------------------------------------------------+

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. Most Linux distributions have a /dev/MAKEDEV script which can be used
for this purpose.

Note that if you are using the devfs filesystem support in the 2.4 kernels,
the sound device files are actually found in /dev/sound, but there will be
symbolic links to the older devices, such as /dev/dsp.
-----------------------------------------------------------------------------

4.5. 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).

If you are using loadable kernel modules for sound, you will need to load
them using the modprobe command for the appropriate drivers, e.g. run the
command modprobe sb for a SoundBlaster card. 

After booting, or loading the kernel modules, check for a message such as the
following using the dmesg command:
+----------------------------------------------------------------------------+
|Soundblaster audio driver Copyright (C) by Hannu Savolainen 1993-1996       |
|sb: Creative SB AWE64  PnP detected                                         |
|sb: ISAPnP reports 'Creative SB AWE64  PnP' at i/o 0x220, irq 5, dma 1, 5   |
|SB 4.16 detected OK (220)                                                   |
|sb: 1 Soundblaster PnP card(s) found.                                       |
|                                                                            |
|Crystal 4280/46xx + AC97 Audio, version 1.22.32, 10:28:40 Apr 28 2001       |
|cs46xx: Card found at 0xf4100000 and 0xf4000000, IRQ 11                     |
|cs46xx: Thinkpad 600X/A20/T20 (1014:0153) at 0xf4100000/0xf4000000, IRQ 11  |
|ac97_codec: AC97 Audio codec, id: 0x4352:0x5914 (Cirrus Logic CS4297A rev B)|
+----------------------------------------------------------------------------+

The message should indicate that a sound card was found and match your sound
card type and jumper settings (if any). The driver may also display some
error messages and warnings if you have incorrectly configured the driver or
chosen the wrong one.

Previous versions of this HOWTO suggested checking the output of /dev/
sndstat. This is no longer supported in the 2.4 and later kernels.

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.

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] 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                                |
|% 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.
-----------------------------------------------------------------------------

4.6. 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.
-----------------------------------------------------------------------------

4.6.1. Step 1: Make sure you are really running the kernel you compiled.

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 2.2.4 #1 Tue Mar 23 11:23:21 EST 1999 i586 unknown           |
+---------------------------------------------------------------------------+

or by displaying the file /proc/version:
+----------------------------------------------------------------------------------------+
|% cat /proc/version                                                                     |
|Linux version 2.2.4 (root@fizzbin) (gcc version 2.7.2.3) #1 Tue Mar 23 11:23:21 EST 1999|
+----------------------------------------------------------------------------------------+

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 lilo)? If booting from floppy, did
you create a new boot floppy and use it when booting?

If you are using kernel loadable modules, use the lsmod command to make sure
the modules are loaded:
+---------------------------------------------------------------------------+
|% /sbin/lsmod                                                              |
|Module                  Size  Used by                                      |
|sb                      6320   0 (unused)                                  |
|sb_lib                 35040   0 [sb]                                      |
|uart401                 6544   0 [sb_lib]                                  |
|sound                  59888   0 [sb_lib uart401]                          |
|soundcore               4144   5 [sb_lib sound]                            |
|isa-pnp                28304   0 [sb]                                      |
|...                                                                        |
+---------------------------------------------------------------------------+
-----------------------------------------------------------------------------

4.6.2. 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.
-----------------------------------------------------------------------------

4.6.3. 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/log/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.
-----------------------------------------------------------------------------

4.6.4. 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.
-----------------------------------------------------------------------------

4.6.5. 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 and the relevant
    kernel source documentation 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.google.com] http://www.google.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.

If you are running a graphical desktop such as [http://www.kde.org] KDE or
[http://www.gnome.org] GNOME then it should already include a number of
multimedia applications that are integrated with your desktop.

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 (also available as /proc/sound,
    removed in 2.4 kernels)
   

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.

If you are running a graphical desktop such as [http://www.kde.org] KDE or
[http://www.gnome.org] GNOME then it should already include a graphical sound
file player program.

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 2.0 and newer 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. You can preallocate the DMA buffers when the driver is
loaded using the kernel option "dma_buf=1".
-----------------------------------------------------------------------------

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.

On some systems you may need to be root when running the fuser command in
order to see the processes of other users.

Under the KDE desktop, the artsd sound server usually take control of the
sound device. Applications should make requests to play sound through the
sound server, or the sound server should be paused. A similar situation
exists under GNOME with the esd sound server.
-----------------------------------------------------------------------------

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 files included with the sound driver kernel source.
-----------------------------------------------------------------------------

6.15. Where are the sound driver ioctls() etc. documented?

Currently the best documentation, other than the source code, is available at
the 4Front Technologies web site, [http://www.opensound.com] http://
www.opensound.com. 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 or better 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?

The drivers for some sound cards support full duplex mode. Check the
documentation available from 4Front Technologies for information on how to
use it.
-----------------------------------------------------------------------------

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. If I run Linux, then boot DOS, I get errors and/or sound applications
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 :-).
-----------------------------------------------------------------------------

6.21. 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://
www.ibiblio.org/pub/Linux/games/doom] ftp://www.ibiblio.org/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] ftp://pandora.st.hmc.edu/
pub/linux/musserver.tgz.
-----------------------------------------------------------------------------

6.22. 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.

Philipp Braunbeck reported that on his ESS-1868 sound card there was a jumper
to turn off the built-in amplifier which helped reduce noise when enabled.

On one 386 system I found that the kernel command line option no-hlt reduced
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.

Some sound cards are simply not designed with good shielding and grounding
and are prone to noise pickup.
-----------------------------------------------------------------------------

6.23. 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.
-----------------------------------------------------------------------------

6.24. 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.
-----------------------------------------------------------------------------

6.25. 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.
-----------------------------------------------------------------------------

6.26. Where can I find sound applications for Linux?

Here are some good archive sites to search for Linux specific sound
applications:

 

  * [ftp://www.ibiblio.org/pub/Linux/kernel/sound/] ftp://www.ibiblio.org/pub
    /Linux/kernel/sound/
   
  * [ftp://www.ibiblio.org/pub/Linux/apps/sound/] ftp://www.ibiblio.org/pub/
    Linux/apps/sound/
   
  * [ftp://tsx-11.mit.edu/pub/linux/packages/sound/] ftp://tsx-11.mit.edu/pub
    /linux/packages/sound/>
   
  * [ftp://nic.funet.fi/pub/Linux/util/sound/] ftp://nic.funet.fi/pub/Linux/
    util/sound/
   
  * [ftp://nic.funet.fi/pub/Linux/xtra/snd-kit/] ftp://nic.funet.fi/pub/Linux
    /xtra/snd-kit/
   
  * [ftp://nic.funet.fi/pub/Linux/ALPHA/sound/] ftp://nic.funet.fi/pub/Linux/
    ALPHA/sound/
   

 

Also see the References section of this document.
-----------------------------------------------------------------------------

6.27. Can the sound drivers be compiled as a loadable module?

With recent kernels the sound driver is supported as several kernel loadable
modules.

See the files in /usr/src/linux/Documentation/sound, especially the files
Introduction and README.modules.
-----------------------------------------------------------------------------

6.28. Can I use a sound card to replace the system console beep?

Try the oplbeep program, found at [ftp://www.ibiblio.org/pub/Linux/apps/sound
/oplbeep-2.3.tar.gz] ftp://www.ibiblio.org/pub/Linux/apps/sound/
oplbeep-2.3.tar.gz

Another variant is the beep program found at [ftp://www.ibiblio.org/pub/Linux
/kernel/patches/misc/modreq_beep.tgz] ftp://www.ibiblio.org/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.

Version 2.0 and later of KDE allows playing a sound file for the console beep
in KDE applications such as konsole.

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.
-----------------------------------------------------------------------------

6.29. What is VoxWare?

The commercial version of the sound drivers sold by 4Front Technologies was
previously known by other names such as VoxWare, USS (Unix Sound System), and
even TASD (Temporarily Anonymous Sound Driver). It is now marketed as OSS
(Open Sound System). The version included in the Linux kernel is sometimes
referred to as OSS/Free.

For more information see the 4Front Technologies web page at [http://
www.opensound.com/] http://www.opensound.com/. I wrote a review of OSS/Linux
in the June 1997 issue of [http://www.ssc.com/lj/] Linux Journal.
-----------------------------------------------------------------------------

6.30. 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 latest sound driver
versions have been fixed to avoid allocating fragments shorter than 4096
bytes which solves this problem with old utilities.
-----------------------------------------------------------------------------

6.31. 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                                           |
|post-install sound /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.
-----------------------------------------------------------------------------

6.32. 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.
-----------------------------------------------------------------------------

6.33. Is the sound hardware on the IBM ThinkPad supported?

Information on how to use the mwave sound card on an IBM ThinkPad laptop
computer can be found in the file /usr/src/linux/Documentation/sound/mwave,
which is part of the kernel source distribution (note that not all IBM
ThinkPads use the MWAVE sound chip).
-----------------------------------------------------------------------------

6.34. Applications fail because my sound card has no mixer

Some old 8-bit SoundBlaster cards have no mixer circuitry. Some sound
applications insist on being able to open the mixer device, and fail with
these cards. Jens Werner ([mailto:werner@bert.emv.ing.tu-bs.de]
werner@bert.emv.ing.tu-bs.de) reports a workaround for this is to link /dev/
mixer to /dev/null and everything should work fine.
-----------------------------------------------------------------------------

6.35. Problems with a SB16 CT4170

From Scott Manley ([mailto:spm@star.arm.ac.uk] spm@star.arm.ac.uk):

There seems to be a new type of Soundblaster - it was sold to us as a SB16 -
the Model no. on the Card is CT4170. These Beasties only have one DMA channel
so when you try to set them up then the kernel will have trouble accessing
the 16 bit DMA. The solution is to set the second DMA to 1 so that the card
will behave as advertised.
-----------------------------------------------------------------------------

6.36. How to connect a MIDI keyboard to a soundcard

From Kim G. S. OEyhus ([mailto:kim@pvv.ntnu.no] kim@pvv.ntnu.no):

I looked all around the internet and in sound documentation on how to do
something as simple as connecting the MIDI output from a master keyboard to
the MIDI input on a sound card. I found nothing. The problem is that they
both use the same device, /dev/midi, at least when using the OSS sound
system. So I found a way to do it, which I want to share. This makes for a
very simple synthesizer, with full MIDI support:

CONNECTING A MIDI MASTER-KEYBOARD DIRECTLY TO A SOUNDCARD WITH MIDI

A MIDI master-keyboard is a keyboard without any synthesizer, and with only a
MIDI-out plug. This can be connected to the 15-pin D-SUB port on most
sound-cards with a suitable cable.

Such a keyboard can be used to control the MIDI synthesizer device for the
card, thus making a simple keyboard controlled synthesizer.

Compile the following program, say with 'gcc -o prog prog.c' and run it:
+---------------------------------------------------------------------------+
|#include <fcntl.h>                                                         |
|                                                                           |
|main()                                                                     |
|{                                                                          |
|  int fil, a;                                                              |
|  char b[256];                                                             |
|                                                                           |
|  fil=open("/dev/midi", O_RDWR);                                           |
|  for(;;)                                                                  |
|    {                                                                      |
|      a=read(fil, b, 256);                                                 |
|      write(fil, b, a);                                                    |
|    }                                                                      |
|}                                                                          |
+---------------------------------------------------------------------------+
 
-----------------------------------------------------------------------------

6.37. Problems with IRQ 15 and Ensoniq PCI 128

From Matthew Inger ([mailto:mattinger@mindless.com] mattinger@mindless.com):

Information on getting an Ensoniq PCI 128 card to work.

The problem that it was exhibiting was that it was trying to use interrupt 15
by default (Plug and Pray was responsible for this one). This interrupt is
used by the secondary ide controller, and cannot be shared by other devices.
You need to somehow force the es1370 to use another interrupt (should use
interrupt 11 like it does under windows).

I figured this one out for myself believe it or not.

What I had to do was:

a) in the BIOS, you have to tell the computer that you don't have a Plug and
Play OS. I believe this is under advanced options in my BIOS.

b) in the PCI settings in the BIOS, tell the computer to reserve interrupt 15
for legacy ISA devices. In my bios, under advanced options, there is a
section for PCI settings. Under there, there is a Resource Exclusion area,
and that's where to do this.

When you reboot into linux you will be able to use sound. (I don't remember
if it shows up in the boot messages or not like it used to). To be safe, I
ran sndconfig again so that it would play the test message, which sounded not
great, but it was there. When I played a CD however, it sounded perfect.

Don't worry about windows, I tried both my cards: ISA Modem, and the Sound
Card out, and they work without any hitches.

The odds are your BIOS will be different from mine, but you just have to
figure out where the settings are for the above two items. Good luck.
-----------------------------------------------------------------------------

6.38. Where can I get freely available MIDI patches to run SoftOSS?

SoftOSS is a software-based wavetable synthesizer included with the kernel
sound driver that is compatible with the Gravis Utrasound card. To operate
the driver needs GUS compatible MIDI patch files. The documentation mentions
the "public domain MIDIA patchset available from several ftp sites". Note
that SoftOSS is no longer included as of the 2.4 kernels.

As explained on the 4Front Technologies web page [http://www.opensound.com/
softoss.html] http://www.opensound.com/softoss.html they can be downloaded
from [ftp://archive.cs.umbc.edu/pub/midia/instruments.tar.gz] ftp://
archive.cs.umbc.edu/pub/midia/instruments.tar.gz.
-----------------------------------------------------------------------------

7. References

If you have a sound card that supports a CD-ROM or SCSI interface, the Linux
[ftp://www.ibiblio.org/pub/Linux/docs/HOWTO/unmaintained/SCSI-HOWTO] SCSI
HOWTO and the Linux [http://www.ibiblio.org/LDP/HOWTO/CDROM-HOWTO.html]
CD-ROM HOWTO have additional information that may be useful to you.

The [http://www.ibiblio.org/LDP/HOWTO/Sound-Playing-HOWTO.html] Sound Playing
HOWTO describes how to play various types of sound and music files under
Linux.

The [http://www.ibiblio.org/LDP/HOWTO/mini/Soundblaster-AWE.html] Linux
SoundBlaster AWE32/64 Mini-HOWTO describes how to get a SoundBlaster 32 or 64
card working under Linux.

Programming information is available from the 4Front Technologies web site at
[http://www.opensound.com/pguide] http://www.opensound.com/pguide.

The following FAQs are regularly posted to the Usenet newsgroup [news:
news.announce] news.announce as well as being archived at [ftp://rtfm.mit.edu
/pub/usenet/news.answers] 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:

 

  * [news:alt.binaries.sounds] alt.binaries.sounds.* (various groups for
    posting sound files)
   
  * [news:alt.binaries.multimedia] alt.binaries.multimedia (for posting
    Multimedia files)
   
  * [news:alt.sb.programmer] alt.sb.programmer (Soundblaster programming
    topics)
   
  * [news:comp.multimedia] comp.multimedia (Multimedia topics)
   
  * [news:comp.music] comp.music (Computer music theory and research)
   
  * [news:comp.sys.ibm.pc.soundcard] comp.sys.ibm.pc.soundcard.* (various IBM
    PC sound card groups)
   

 

A web site dedicated to multimedia can be found at [http://www.scala.com/
multimedia/] http://www.scala.com/multimedia/. Another good site for Linux
MIDI and sound applications is [http://sound.condorow.net/] http://
sound.condorow.net/. Creative Labs has a web site at [http://www.creaf.com/]
http://www.creaf.com/.

The Linux mailing list has a number of "channels" dedicated to different
topics. To find out how to join, send a mail message with the word "help" as
the message body to [mailto:majordomo@vger.kernel.org]
majordomo@vger.kernel.org.

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.

Information on OSS, the commercial sound driver for Linux and other Unix
compatible operating systems, can be found at the 4Front Technologies web
page at [http://www.opensound.com/] http://www.opensound.com/.

The Linux Software Map (LSM) is an invaluable reference for locating Linux
software. The LSM home page is at [http://www.ExecPC.com/lsm/] http://
www.ExecPC.com/lsm/. and there is an on-line browsable version at [http://
www.boutell.com/lsm/] http://www.boutell.com/lsm/.

Another great site for finding Linux applications is [http://
www.freshmeat.net/] http://www.freshmeat.net/.

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] http://www.ora.com/catalog/multilinux/noframes.html.