The Linux Sound HOWTO

The Linux Sound HOWTO
Jeff Tranter, [email protected]
v1.20, 24 March 1999

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.
______________________________________________________________________

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 Sound Cards
3.2 Alternate Sound Drivers
3.3 PC Speaker
3.4 Parallel Port

4. Installation

4.1 Installing the Sound Card
4.2 Configuring 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
4.6.1 Step 1: Make sure you are really running the kernel you compiled.
4.6.2 Step 2: Make sure the kernel sound drivers are compiled in.
4.6.3 Step 3: Did the kernel detect your sound card during booting?
4.6.4 Step 4: Can you read data from the dsp device?
4.6.5 When All Else Fails

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 driver 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 ([email protected]).
Thanks go to Hannu, Alan Cox, 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. 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://metalab.unc.edu/pub/Linux/docs/HOWTO/>.

Hypertext versions of this and other Linux HOWTOs are available on
many world-wide web sites, including <http://metalab.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.

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>

French: <http://www.freenix.org/unix/linux/HOWTO/>

Japanese: <http://yebisu.ics.es.osaka-u.ac.jp/linux/>

Korean: <http://kldp.linux-kr.org/HOWTO/html/Sound/Sound-HOWTO.html>

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

Spanish: <ftp://ftp.insflug.org/es>

Most translations of this and other Linux HOWTOs can also be found at
<http://metalab.unc.edu/pub/Linux/docs/HOWTO/translations/> and
<ftp://metalab.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.

1.3. 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,
[email protected], 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, Tim Bynum <mailto:linux-
[email protected]>, for more information.

1.4. Distribution Policy

Copyright (c) 1995-1999 by Jeff Tranter. This document may be
distributed under the terms set forth in the LDP license at
<http://metalab.unc.edu/LDP/COPYRIGHT.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.

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 2.2.4. 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.

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.

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.

3.1. 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.

o 6850 UART MIDI Interface

o AD1816/AD1816A based cards

o ADSP-2115

o ALS-007 based cards (Avance Logic)

o ATI Stereo F/X (no longer manufactured)

o Acer FX-3D

o AdLib (no longer manufactured)

o Audio Excel DSP 16

o AudioDrive

o CMI8330 sound chip

o Compaq Deskpro XL onboard sound

o Corel Netwinder WaveArtist

o Crystal CS423x

o ESC614

o ESS1688 sound chip

o ESS1788 sound chip

o ESS1868 sound chip

o ESS1869 sound chip

o ESS1887 sound chip

o ESS1888 sound chip

o ESS688 sound chip

o ES1370 sound chip

o ES1371 sound chip

o Ensoniq AudioPCI (ES1370)

o Ensoniq AudioPCI 97 (ES1371)

o Ensoniq SoundScape (and compatibles made by Reveal and Spea)

o Gallant SC-6000

o Gallant SC-6600

o Gravis Ultrasound

o Gravis Ultrasound ACE

o Gravis Ultrasound Max

o Gravis Ultrasound with 16 bit sampling option

o HP Kayak

o Highscreen Sound-Booster 32 Wave 3D

o IBM MWAVE

o Logitech Sound Man 16

o Logitech SoundMan Games

o Logitech SoundMan Wave

o MAD16 Pro (OPTi 82C928, 82C929, 82C930, 82C924 chipsets)

o Media Vision Jazz16

o MediaTriX AudioTriX Pro

o Microsoft Windows Sound System (MSS/WSS)

o MiroSOUND PCM12

o Mozart (OAK OTI-601)

o OPTi 82C931

o Orchid SW32

o Personal Sound System (PSS)

o Pinnacle MultiSound

o Pro Audio Spectrum 16

o Pro Audio Studio 16

o Pro Sonic 16

o Roland MPU-401 MIDI interface

o S3 SonicVibes

o SY-1816

o Sound Blaster 1.0

o Sound Blaster 2.0

o Sound Blaster 16

o Sound Blaster 16ASP

o Sound Blaster 32

o Sound Blaster 64

o Sound Blaster AWE32

o Sound Blaster AWE64

o Sound Blaster PCI 128

o Sound Blaster Pro

o Sound Blaster Vibra16

o Sound Blaster Vibra16X

o TI TM4000M notebook

o Terratec Base 1

o Terratec Base 64

o ThunderBoard

o Turtle Beach Maui

o Turtle Beach MultiSound Classic

o Turtle Beach MultiSound Fiji

o Turtle Beach MultiSound Hurricane

o Turtle Beach MultiSound Monterey

o Turtle Beach MultiSound Pinnacle

o Turtle Beach MultiSound Tahiti

o Turtle Beach WaveFront Maui

o Turtle Beach WaveFront Tropez

o Turtle Beach WaveFront Tropez+

o VIA chip set

o VIDC 16-bit sound

o Yamaha OPL2 sound chip

o Yamaha OPL3 sound chip

o Yamaha OPL3-SA1 sound chip

o Yamaha OPL3-SA2 sound chip

o Yamaha OPL3-SA3 sound chip

o Yamaha OPL3-SAx sound chip

o Yamaha OPL4 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 SCSI HOWTO and 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 kernels.

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

3.2. Alternate Sound Drivers

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>.

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>. A separate
"Alsa-sound-mini-HOWTO" is available which deals with compiling and
installing these drivers.

Markus Mummert ([email protected]) 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>.

Kim Burgaard ([email protected]) 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://metalab.unc.edu/pub/Linux/kernel/sound/mpu401-0.2.tar.gz>.

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).

3.3. 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 software, which has not been updated for some time, can be found
at <ftp://ftp.informatik.hu-berlin.de/pub/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 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.

If you are running Red Hat Linux there is a utility called sndconfig
that in most cases will detect your sound card and set up all of the
necessary configuration files to load the appropriate sound drivers
for your card. If you are running Red Hat I suggest you try using it.
If it works for you then you can skip the rest of the instructions in
this section.

If sndconfig fails, you are using another Linux distribution, 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 Plug and Play

Most sound cards now use the Plug and Play protocol to configure
settings for i/o addresses, interrupts, and DMA channels. If you have
one of the older sound cards that uses fixed settings or jumpers, then
you can skip this section.

As of version 2.2 Linux does not yet have full Plug and Play support
in the kernel. The preferred solution 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/>).

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:

o Use pnpdump to capture the possible settings for all your Plug and
Play devices, saving the result to the file /etc/isapnp.conf.

o 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.

o 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.

A few of the sound card drivers include the necessary software to
initialize Plug and Play for the card. Check the documentation for
that card's driver for details.

4.3. Configuring the Kernel

When initially installing Linux you likely used a precompiled kernel.
These kernels often 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.
Later, when your sound card is working, you may wish to rebuild the
kernel sound drivers as modules.

The Linux Kernel HOWTO <http://metalab.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 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/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. Most Linux distributions have a /dev/MAKEDEV script
which can be used for this purpose.

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).

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.

4.6. 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 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 2.2.4 #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?

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:

o carefully re-read this HOWTO document

o read the references listed at the end of this document and the
relevant kernel source documentation files

o 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)

o 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>

o try using the latest Linux kernel (but only as a last resort, the
latest development kernels can be unstable)

o send mail to the author of the sound driver

o send mail to the author of the Sound HOWTO

o 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:

o audio file format conversion utility (e.g. sox)

o mixer utility (e.g. aumix or xmix)

o digitized file player/recorder (e.g. play or wavplay)

o MOD file player (e.g. tracker)

o 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)

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 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:

o GUS (driver limitation)

o MAD16 (hardware limitation)

o AudioTrix Pro (hardware limitation)

o 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.

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

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:

o try playing with a lower sampling rate or in mono mode

o eliminate other processes

o buy a faster computer

o 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>. 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:

o whether using PCM sampling or FM synthesis

o sampling rate and sample size

o which application is used to play or record

o Sound Card hardware

o 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 [email protected])

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:

o get the motherboard distributor to replace the older version bus
chip,

o replace the motherboard, or

o 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 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 :-).

6.21. 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://metalab.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>.

6.22. 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:

o use a mixer program to select the appropriate device (e.g.
microphone)

o use the mixer to set the input gains to maximum

o 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:

o <ftp://metalab.unc.edu/pub/Linux/kernel/sound/>

o <ftp://metalab.unc.edu/pub/Linux/apps/sound/>

o <ftp://tsx-11.mit.edu/pub/linux/packages/sound/>

o <ftp://nic.funet.fi/pub/Linux/util/sound/>

o <ftp://nic.funet.fi/pub/Linux/xtra/snd-kit/>

o <ftp://nic.funet.fi/pub/Linux/ALPHA/sound/>

Also see the References section of this document.

6.27. Can the sound driver 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://metalab.unc.edu/pub/Linux/apps/sound/oplbeep-2.3.tar.gz>

Another variant is the beep program found at
<ftp://metalab.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.

6.29. 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/>. I wrote a review of OSS/Linux in the June
1997 issue of 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 && /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.

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 ([email protected]) 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 ([email protected]):

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 ([email protected]):

I looked all around the internet and in sound documentation
on how to do something as simple as connecting the MIDI out-
put 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 synthe-
sizer, 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 con-
trolled 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 ([email protected]):

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 per-
fect.
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".

As explained on the 4Front Technologies web page
<http://www.opensound.com/softoss.html> they can be downloaded from
<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 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 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>.

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>:

o PCsoundcards/generic-faq (Generic PC Soundcard FAQ)

o PCsoundcards/soundcard-faq (comp.sys.ibm.pc.soundcard FAQ)

o PCsoundcards/gravis-ultrasound/faq (Gravis UltraSound FAQ)

o audio-fmts/part1 (Audio file format descriptions)

o 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:

o alt.binaries.sounds.* (various groups for posting sound files)

o alt.binaries.multimedia (for posting Multimedia files)

o alt.sb.programmer (Soundblaster programming topics)

o comp.multimedia (Multimedia topics)

o comp.music (Computer music theory and research)

o 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/>. Another good site for Linux
MIDI and sound applications is <http://sound.condorow.net/>. 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
[email protected]. 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.

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/>.

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://metalab.unc.edu/pub/Linux/docs/LSM/> (formerly known as
sunsite). There are also various web sites that maintain databases of
Linux applications. One such site is <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> or my
home page <http://www.pobox.com/~tranter>.