1.\" 2.\" Copyright (c) 1998, Luigi Rizzo 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.Dd November 14, 2003 29.Dt PCM 4 30.Os 31.Sh NAME 32.Nm pcm , 33.Nm snd 34.Nd FreeBSD PCM audio device infrastructure 35.Sh SYNOPSIS 36For a card with bridge driver support, and a PnP card: 37.Cd "device pcm" 38.Pp 39For a card without bridge driver support, and a non-PnP card, 40the following lines may be required in 41.Pa /boot/device.hints : 42.Cd hint.pcm.0.at="isa" 43.Cd hint.pcm.0.irq="5" 44.Cd hint.pcm.0.drq="1" 45.Cd hint.pcm.0.flags="0x0" 46.Sh DESCRIPTION 47The 48.Nm 49driver provides support for 50.Tn PCM 51audio play and capture. 52This driver also supports various 53.Tn PCI , 54.Tn WSS/MSS 55compatible, 56.Tn ISA 57sound cards, and AC97 mixer. 58Once the 59.Nm 60driver attaches, supported devices provide audio record and 61playback channels. 62The 63.Fx 64sound system provides dynamic mixing 65.Dq VCHAN 66and rate conversion 67.Dq soft formats . 68True full duplex operation is available on most cards. 69.Pp 70If the sound card is supported by a bridge driver, the 71.Nm 72driver works in conjunction with the bridge driver. 73.Pp 74Apart from the usual parameters, the flags field is used to specify 75the secondary 76.Tn DMA 77channel (generally used for capture in full duplex cards). 78Flags are set to 0 for cards not using a secondary 79.Tn DMA 80channel, or to 0x10 + C to specify channel C. 81.Pp 82The driver works best with 83.Tn WSS/MSS 84cards, which have a very clean 85architecture and an orthogonal set of features. 86They also happen to be 87among the cheapest audio cards on the market. 88.Pp 89The driver does its best to recognize the installed hardware and drive 90it correctly so the user is not required to add several lines in 91.Pa /boot/device.hints . 92For 93.Tn PCI 94and 95.Tn ISA 96.Tn PnP 97cards this is actually easy 98since they identify themselves. 99For legacy 100.Tn ISA 101cards, the driver looks for 102.Tn MSS 103cards at addresses 0x530 and 0x604 (unless overridden 104in 105.Pa /boot/device.hints ) . 106.Ss Boot Variables 107In general, the module 108.Pa snd_foo 109corresponds to device foo and can be 110loaded by the boot loader via 111.Pa boot/loader.conf 112or from the command line using the 113.Xr kldload 8 114utility. 115Options which can be specified in 116.Pa /boot/loader.conf 117include: 118.Bl -tag -width snd_emu10k1_load -offset indent 119.It Va snd_driver_load 120.Pq Dq NO 121If set to 122.Dq YES , 123this option loads all available drivers. 124.It Va snd_emu10k1_load 125.Pq Dq NO 126If set to 127.Dq YES , 128Only the SoundBlaster 5.1 driver and dependent modules will be loaded. 129.It Va snd_foo_load 130.Pq Dq NO 131If set to 132.Dq YES , 133load driver for card/chipset foo. 134.El 135.Ss VCHANS 136Each device can optionally support more playback channels 137that physical hardware provides by using 138.Dq virtual channels 139or 140.Tn VCHANs . 141.Tn VCHAN 142options can be configured via the 143.Xr sysctl 8 144interface but can only be manipulated while the device is inactive. 145.Ss Runtime Configuration 146The following 147.Xr sysctl 8 148tunables are available: 149.Bl -tag -width ".It Va hw.snd.report_soft_formats" -offset indent 150.It Va hw.snd.pcm%d.buffersize 151Configure the amount of 152.Tn DMA 153bufferspace available for a device. 154.It Va hw.snd.targetirqrate 155Set the default block size such that continuous 156playback will achieve this 157.Tn IRQ 158rate. 159This value can be tuned to improve application performance. 160Increase this value when the sound lags and decrease 161it if sound stutters or breaks up. 162.It Va hw.snd.unit 163When using 164.Xr devfs 5 , 165the default device for 166.Pa /dev/dsp . 167Equivalent to a symlink from 168.Pa /dev/dsp 169to 170.Pa /dev/dsp${hw.snd.unit} . 171.It Va hw.snd.report_soft_formats 172Controls the internal format conversion if it is 173available transparently to the application software. 174When disabled or not available, the application will 175only be able to select formats the device natively supports. 176.It Va hw.snd.verbose 177Level of verbosity for the 178.Pa /dev/sndstat 179device. 180Higher values include more output and the highest level, 181three, should be used when reported problems. 182Other options include: 1830 - Installed devices and their allocated bus resources. 1841 - The number of playback, record, virtual channels, and 185flags per device. 1862 - Channel information per device including the channel's 187current format, speed, and pseudo device statistics such as 188buffer overruns and buffer underruns. 1893 - File names and versions of the currently sound loaded modules. 190.It Va hw.snd.maxautovchans 191Global 192.Tn VCHAN 193setting that only affects devices that have only one playback channel. 194The sound system will dynamically create up this many 195.Tn VCHANs . 196Set to 197.Dq 0 198if no 199.Tn VCHANS 200are desired. 201.It Va hw.snd.pcm%d.vchans 202The current number of 203.Tn VCHANs 204allocated per device. 205This can be set to preallocate a certain number of 206.Tn VCHANs . 207Setting this value to 208.Dq 0 209will disable 210.Tn VCHANs 211for this device. 212.El 213.Ss Recording Channels 214On devices that have more than one recording source (ie: mic and line), 215there is a corresponding 216.Pa /dev/dspr%d.%d 217device. 218.Ss Statistics 219Channel statistics are only kept while the device is open. 220So with situations involving overruns and underruns, consider the output 221while the errant application is open and running. 222.Ss IOCTL Support 223The driver supports most of the 224.Tn OSS 225.Fn ioctl 226functions, and most applications work unmodified. 227A few differences exist, while memory mapped playback is 228supported natively and in Linux emulation, memory mapped recording is 229not due to 230.Tn VM 231system design. 232As a consequence, some applications may need to be recompiled 233with a slightly modified audio module. 234See 235.In sys/soundcard.h 236for a complete list of the supported 237.Fn ioctl 238functions. 239.Ss SUPPORTED CARDS 240Below we include a list of supported codecs/cards. 241If your sound card 242is not listed here, it may be supported by a bridge driver. 243.Bl -tag -width 2m 244.It CS4237, CS4236, CS4232, CS4231 (ISA) 245All these cards work perfectly in full duplex using the MSS mode. 246This chipset is used, among others, on the A/Open AW35 and AW32, on 247some Intel motherboards, and (the CS4231) on some non-PnP cards. 248.Pp 249The CS4232 is reported as buggy in the Voxware documentation but 250I am not sure if this is true. 251On one of my Intel motherboards, 252capture does not work simply because the capture DMA channel is 253not wired to the ISA DMA controller. 254.It Yamaha OPL-SAx (ISA) 255Works perfectly in all modes. 256This chip is used in several PnP cards, 257but also (in non-PnP mode) on motherboards and laptops (e.g. the 258Toshiba Libretto). 259.It OPTi931 (ISA) 260The chip is buggy, but the driver has many workarounds to make it work 261in full duplex because for some time these were the only full duplex 262cards I could find. u-law formats uses U8 format internally because of 263a bug in the chip. 264.It Trident 4DWave DX/NX (PCI) 265.It ENSONIQ AudioPCI ES1370/1371 (PCI) 266Creative Labs SoundBlaster PCI is supported as well. 267.It ESS Solo-1/1E (PCI) 268.It NeoMagic 256AV/ZX (PCI) 269.El 270.Sh FILES 271The 272.Nm 273drivers may create the following 274device nodes: 275.Pp 276.Bl -tag -width "/dev/dspr%d.%dXXX" -compact 277.It Pa /dev/audio%d.%d 278Sparc-compatible audio device. 279.It Pa /dev/dsp%d.%d 280Digitized voice device. 281.It Pa /dev/dspW%d.%d 282Like 283.Pa /dev/dsp , 284but 16 bits per sample. 285.It Pa /dev/dspr%d.%d 286Should be connected to a record codec. 287.It Pa /dev/sndstat 288Current 289.Nm 290status, including all channels and drivers. 291.El 292.Pp 293The first number in the device node 294represents the unit number of the 295.Nm PCM 296device. 297All 298.Nm 299PCM 300devices are listed 301in 302.Pa /dev/sndstat. 303Additional messages are sometimes recorded when the 304device is probed and attached, these messages can be viewed with the 305.Xr dmesg 8 306utility. 307.Sh DIAGNOSTICS 308.Bl -tag -width 2m 309.It ac97: dac not ready 310AC97 codec is not likely to be accompanied with the sound card. 311.It unsupported subdevice XX 312A device node is not created properly. 313.El 314.Sh BUGS 315Some features of your cards (e.g. global volume control) might not 316be supported on all devices. 317.Sh HISTORY 318The 319.Nm 320device driver first appeared in 321.Fx 2.2.6 written by Luigi Rizzo. 322It was later 323rewritten in 324.Fx 4.0 by Cameron Grant. 325The API evolved from the VOXWARE 326standard which later became OSS standard. 327.Sh SEE ALSO 328.Xr csa 4 , 329.Xr gusc 4 , 330.Xr sbc 4 , 331.Xr devfs 5 , 332.Xr loader.conf 5 , 333.Xr dmesg 8 , 334.Xr kldload 8 , 335.Xr sysctl 8 336.Rs 337.%T "The OSS API" 338.%O "http://www.opensound.com/pguide/oss.pdf" 339.Re 340.Sh AUTHORS 341.An -nosplit 342.An Luigi Rizzo Aq luigi@iet.unipi.it 343initially wrote the 344.Nm 345device driver and this manual page. 346.An Cameron Grant Aq gandalf@vilnya.demon.co.uk 347later revised the device driver for 348.Fx 4.0 . 349.An Seigo Tanimura Aq tanimura@r.dl.itc.u-tokyo.ac.jp 350revised this manual page. 351It was then rewritten for 352.Fx 5.2 .