460 lines
15 KiB
Plaintext
460 lines
15 KiB
Plaintext
Introduction Notes on Modular Sound Drivers and Soundcore
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Wade Hampton
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2/14/2001
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Purpose:
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========
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This document provides some general notes on the modular
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sound drivers and their configuration, along with the
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support modules sound.o and soundcore.o.
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Note, some of this probably should be added to the Sound-HOWTO!
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Note, soundlow.o was present with 2.2 kernels but is not
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required for 2.4.x kernels. References have been removed
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to this.
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Copying:
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========
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none
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History:
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========
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0.1.0 11/20/1998 First version, draft
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1.0.0 11/1998 Alan Cox changes, incorporation in 2.2.0
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as Documentation/sound/oss/Introduction
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1.1.0 6/30/1999 Second version, added notes on making the drivers,
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added info on multiple sound cards of similar types,]
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added more diagnostics info, added info about esd.
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added info on OSS and ALSA.
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1.1.1 19991031 Added notes on sound-slot- and sound-service.
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(Alan Cox)
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1.1.2 20000920 Modified for Kernel 2.4 (Christoph Hellwig)
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1.1.3 20010214 Minor notes and corrections (Wade Hampton)
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Added examples of sound-slot-0, etc.
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Modular Sound Drivers:
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======================
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Thanks to the GREAT work by Alan Cox (alan@lxorguk.ukuu.org.uk),
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[And Oleg Drokin, Thomas Sailer, Andrew Veliath and more than a few
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others - not to mention Hannu's original code being designed well
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enough to cope with that kind of chopping up](Alan)
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the standard Linux kernels support a modular sound driver. From
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Alan's comments in linux/drivers/sound/README.FIRST:
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The modular sound driver patches were funded by Red Hat Software
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(www.redhat.com). The sound driver here is thus a modified version of
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Hannu's code. Please bear that in mind when considering the appropriate
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forums for bug reporting.
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The modular sound drivers may be loaded via insmod or modprobe.
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To support all the various sound modules, there are two general
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support modules that must be loaded first:
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soundcore.o: Top level handler for the sound system, provides
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a set of functions for registration of devices
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by type.
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sound.o: Common sound functions required by all modules.
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For the specific sound modules (e.g., sb.o for the Soundblaster),
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read the documentation on that module to determine what options
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are available, for example IRQ, address, DMA.
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Warning, the options for different cards sometime use different names
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for the same or a similar feature (dma1= versus dma16=). As a last
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resort, inspect the code (search for module_param).
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Notes:
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1. There is a new OpenSource sound driver called ALSA which is
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currently under development: http://www.alsa-project.org/
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The ALSA drivers support some newer hardware that may not
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be supported by this sound driver and also provide some
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additional features.
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2. The commercial OSS driver may be obtained from the site:
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http://www.opensound.com. This may be used for cards that
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are unsupported by the kernel driver, or may be used
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by other operating systems.
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3. The enlightenment sound daemon may be used for playing
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multiple sounds at the same time via a single card, eliminating
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some of the requirements for multiple sound card systems. For
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more information, see: http://www.tux.org/~ricdude/EsounD.html
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The "esd" program may be used with the real-player and mpeg
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players like mpg123 and x11amp. The newer real-player
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and some games even include built-in support for ESD!
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Building the Modules:
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=====================
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This document does not provide full details on building the
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kernel, etc. The notes below apply only to making the kernel
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sound modules. If this conflicts with the kernel's README,
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the README takes precedence.
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1. To make the kernel sound modules, cd to your /usr/src/linux
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directory (typically) and type make config, make menuconfig,
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or make xconfig (to start the command line, dialog, or x-based
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configuration tool).
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2. Select the Sound option and a dialog will be displayed.
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3. Select M (module) for "Sound card support".
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4. Select your sound driver(s) as a module. For ProAudio, Sound
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Blaster, etc., select M (module) for OSS sound modules.
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[thanks to Marvin Stodolsky <stodolsk@erols.com>]A
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5. Make the kernel (e.g., make bzImage), and install the kernel.
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6. Make the modules and install them (make modules; make modules_install).
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Note, for 2.5.x kernels, make sure you have the newer module-init-tools
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installed or modules will not be loaded properly. 2.5.x requires an
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updated module-init-tools.
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Plug and Play (PnP:
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===================
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If the sound card is an ISA PnP card, isapnp may be used
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to configure the card. See the file isapnp.txt in the
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directory one level up (e.g., /usr/src/linux/Documentation).
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Also the 2.4.x kernels provide PnP capabilities, see the
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file NEWS in this directory.
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PCI sound cards are highly recommended, as they are far
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easier to configure and from what I have read, they use
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less resources and are more CPU efficient.
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INSMOD:
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=======
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If loading via insmod, the common modules must be loaded in the
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order below BEFORE loading the other sound modules. The card-specific
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modules may then be loaded (most require parameters). For example,
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I use the following via a shell script to load my SoundBlaster:
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SB_BASE=0x240
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SB_IRQ=9
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SB_DMA=3
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SB_DMA2=5
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SB_MPU=0x300
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#
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echo Starting sound
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/sbin/insmod soundcore
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/sbin/insmod sound
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#
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echo Starting sound blaster....
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/sbin/insmod uart401
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/sbin/insmod sb io=$SB_BASE irq=$SB_IRQ dma=$SB_DMA dma16=$SB_DMA2 mpu_io=$SB_MP
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When using sound as a module, I typically put these commands
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in a file such as /root/soundon.sh.
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MODPROBE:
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=========
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If loading via modprobe, these common files are automatically loaded
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when requested by modprobe. For example, my /etc/modprobe.conf contains:
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alias sound sb
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options sb io=0x240 irq=9 dma=3 dma16=5 mpu_io=0x300
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All you need to do to load the module is:
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/sbin/modprobe sb
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Sound Status:
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=============
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The status of sound may be read/checked by:
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cat (anyfile).au >/dev/audio
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[WWH: This may not work properly for SoundBlaster PCI 128 cards
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such as the es1370/1 (see the es1370/1 files in this directory)
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as they do not automatically support uLaw on /dev/audio.]
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The status of the modules and which modules depend on
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which other modules may be checked by:
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/sbin/lsmod
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/sbin/lsmod should show something like the following:
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sb 26280 0
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uart401 5640 0 [sb]
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sound 57112 0 [sb uart401]
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soundcore 1968 8 [sb sound]
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Removing Sound:
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===============
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Sound may be removed by using /sbin/rmmod in the reverse order
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in which you load the modules. Note, if a program has a sound device
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open (e.g., xmixer), that module (and the modules on which it
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depends) may not be unloaded.
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For example, I use the following to remove my Soundblaster (rmmod
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in the reverse order in which I loaded the modules):
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/sbin/rmmod sb
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/sbin/rmmod uart401
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/sbin/rmmod sound
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/sbin/rmmod soundcore
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When using sound as a module, I typically put these commands
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in a script such as /root/soundoff.sh.
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Removing Sound for use with OSS:
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================================
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If you get really stuck or have a card that the kernel modules
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will not support, you can get a commercial sound driver from
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http://www.opensound.com. Before loading the commercial sound
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driver, you should do the following:
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1. remove sound modules (detailed above)
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2. remove the sound modules from /etc/modprobe.conf
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3. move the sound modules from /lib/modules/<kernel>/misc
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(for example, I make a /lib/modules/<kernel>/misc/tmp
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directory and copy the sound module files to that
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directory).
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Multiple Sound Cards:
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=====================
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The sound drivers will support multiple sound cards and there
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are some great applications like multitrack that support them.
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Typically, you need two sound cards of different types. Note, this
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uses more precious interrupts and DMA channels and sometimes
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can be a configuration nightmare. I have heard reports of 3-4
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sound cards (typically I only use 2). You can sometimes use
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multiple PCI sound cards of the same type.
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On my machine I have two sound cards (cs4232 and Soundblaster Vibra
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16). By loading sound as modules, I can control which is the first
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sound device (/dev/dsp, /dev/audio, /dev/mixer) and which is
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the second. Normally, the cs4232 (Dell sound on the motherboard)
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would be the first sound device, but I prefer the Soundblaster.
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All you have to do is to load the one you want as /dev/dsp
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first (in my case "sb") and then load the other one
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(in my case "cs4232").
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If you have two cards of the same type that are jumpered
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cards or different PnP revisions, you may load the same
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module twice. For example, I have a SoundBlaster vibra 16
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and an older SoundBlaster 16 (jumpers). To load the module
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twice, you need to do the following:
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1. Copy the sound modules to a new name. For example
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sb.o could be copied (or symlinked) to sb1.o for the
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second SoundBlaster.
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2. Make a second entry in /etc/modprobe.conf, for example,
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sound1 or sb1. This second entry should refer to the
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new module names for example sb1, and should include
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the I/O, etc. for the second sound card.
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3. Update your soundon.sh script, etc.
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Warning: I have never been able to get two PnP sound cards of the
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same type to load at the same time. I have tried this several times
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with the Soundblaster Vibra 16 cards. OSS has indicated that this
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is a PnP problem.... If anyone has any luck doing this, please
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send me an E-MAIL. PCI sound cards should not have this problem.a
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Since this was originally release, I have received a couple of
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mails from people who have accomplished this!
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NOTE: In Linux 2.4 the Sound Blaster driver (and only this one yet)
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supports multiple cards with one module by default.
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Read the file 'Soundblaster' in this directory for details.
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Sound Problems:
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===============
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First RTFM (including the troubleshooting section
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in the Sound-HOWTO).
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1) If you are having problems loading the modules (for
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example, if you get device conflict errors) try the
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following:
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A) If you have Win95 or NT on the same computer,
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write down what addresses, IRQ, and DMA channels
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those were using for the same hardware. You probably
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can use these addresses, IRQs, and DMA channels.
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You should really do this BEFORE attempting to get
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sound working!
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B) Check (cat) /proc/interrupts, /proc/ioports,
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and /proc/dma. Are you trying to use an address,
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IRQ or DMA port that another device is using?
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C) Check (cat) /proc/isapnp
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D) Inspect your /var/log/messages file. Often that will
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indicate what IRQ or IO port could not be obtained.
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E) Try another port or IRQ. Note this may involve
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using the PnP tools to move the sound card to
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another location. Sometimes this is the only way
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and it is more or less trial and error.
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2) If you get motor-boating (the same sound or part of a
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sound clip repeated), you probably have either an IRQ
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or DMA conflict. Move the card to another IRQ or DMA
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port. This has happened to me when playing long files
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when I had an IRQ conflict.
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3. If you get dropouts or pauses when playing high sample
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rate files such as using mpg123 or x11amp/xmms, you may
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have too slow of a CPU and may have to use the options to
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play the files at 1/2 speed. For example, you may use
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the -2 or -4 option on mpg123. You may also get this
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when trying to play mpeg files stored on a CD-ROM
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(my Toshiba T8000 PII/366 sometimes has this problem).
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4. If you get "cannot access device" errors, your /dev/dsp
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files, etc. may be set to owner root, mode 600. You
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may have to use the command:
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chmod 666 /dev/dsp /dev/mixer /dev/audio
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5. If you get "device busy" errors, another program has the
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sound device open. For example, if using the Enlightenment
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sound daemon "esd", the "esd" program has the sound device.
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If using "esd", please RTFM the docs on ESD. For example,
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esddsp <program> may be used to play files via a non-esd
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aware program.
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6) Ask for help on the sound list or send E-MAIL to the
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sound driver author/maintainer.
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7) Turn on debug in drivers/sound/sound_config.h (DEB, DDB, MDB).
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8) If the system reports insufficient DMA memory then you may want to
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load sound with the "dmabufs=1" option. Or in /etc/conf.modules add
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preinstall sound dmabufs=1
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This makes the sound system allocate its buffers and hang onto them.
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You may also set persistent DMA when building a 2.4.x kernel.
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Configuring Sound:
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==================
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There are several ways of configuring your sound:
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1) On the kernel command line (when using the sound driver(s)
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compiled in the kernel). Check the driver source and
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documentation for details.
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2) On the command line when using insmod or in a bash script
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using command line calls to load sound.
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3) In /etc/modprobe.conf when using modprobe.
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4) Via Red Hat's GPL'd /usr/sbin/sndconfig program (text based).
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5) Via the OSS soundconf program (with the commercial version
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of the OSS driver.
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6) By just loading the module and let isapnp do everything relevant
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for you. This works only with a few drivers yet and - of course -
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only with isapnp hardware.
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And I am sure, several other ways.
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Anyone want to write a linuxconf module for configuring sound?
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Module Loading:
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===============
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When a sound card is first referenced and sound is modular, the sound system
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will ask for the sound devices to be loaded. Initially it requests that
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the driver for the sound system is loaded. It then will ask for
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sound-slot-0, where 0 is the first sound card. (sound-slot-1 the second and
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so on). Thus you can do
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alias sound-slot-0 sb
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To load a soundblaster at this point. If the slot loading does not provide
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the desired device - for example a soundblaster does not directly provide
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a midi synth in all cases then it will request "sound-service-0-n" where n
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is
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0 Mixer
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2 MIDI
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3, 4 DSP audio
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For example, I use the following to load my Soundblaster PCI 128
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(ES 1371) card first, followed by my SoundBlaster Vibra 16 card,
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then by my TV card:
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# Load the Soundblaster PCI 128 as /dev/dsp, /dev/dsp1, /dev/mixer
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alias sound-slot-0 es1371
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# Load the Soundblaster Vibra 16 as /dev/dsp2, /dev/mixer1
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alias sound-slot-1 sb
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options sb io=0x240 irq=5 dma=1 dma16=5 mpu_io=0x330
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# Load the BTTV (TV card) as /dev/mixer2
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alias sound-slot-2 bttv
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alias sound-service-2-0 tvmixer
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pre-install bttv modprobe tuner ; modprobe tvmixer
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pre-install tvmixer modprobe msp3400; modprobe tvaudio
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options tuner debug=0 type=8
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options bttv card=0 radio=0 pll=0
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For More Information (RTFM):
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============================
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1) Information on kernel modules: manual pages for insmod and modprobe.
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2) Information on PnP, RTFM manual pages for isapnp.
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3) Sound-HOWTO and Sound-Playing-HOWTO.
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4) OSS's WWW site at http://www.opensound.com.
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5) All the files in Documentation/sound.
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6) The comments and code in linux/drivers/sound.
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7) The sndconfig and rhsound documentation from Red Hat.
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8) The Linux-sound mailing list: sound-list@redhat.com.
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9) Enlightenment documentation (for info on esd)
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http://www.tux.org/~ricdude/EsounD.html.
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10) ALSA home page: http://www.alsa-project.org/
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Contact Information:
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====================
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Wade Hampton: (whampton@staffnet.com)
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