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37 PCM audio device infrastructure
39 For a card with bridge driver support, and a PnP card:
42 For a card without bridge driver support, and a non-PnP card,
43 the following lines may be required in
44 .Pa /boot/device.hints :
45 .Cd hint.pcm.0.at="isa"
46 .Cd hint.pcm.0.irq="5"
47 .Cd hint.pcm.0.drq="1"
48 .Cd hint.pcm.0.flags="0x0"
51 Note: There exists some ambiguity in the naming at the moment
52 .Pq Nm sound , pcm , snd .
53 It will be resolved soon by renaming
57 and doing associated changes.
62 driver provides support for
64 audio play and capture.
65 This driver also supports various
70 sound cards, and AC97 mixer.
73 driver attaches, supported devices provide audio record and
77 sound system provides dynamic mixing
81 True full duplex operation is available on most cards.
83 If the sound card is supported by a bridge driver, the
85 driver works in conjunction with the bridge driver.
87 Apart from the usual parameters, the flags field is used to specify
90 channel (generally used for capture in full duplex cards).
91 Flags are set to 0 for cards not using a secondary
93 channel, or to 0x10 + C to specify channel C.
95 The driver does its best to recognize the installed hardware and drive
96 it correctly so the user is not required to add several lines in
97 .Pa /boot/device.hints .
103 cards this is actually easy
104 since they identify themselves.
107 cards, the driver looks for
109 cards at addresses 0x530 and 0x604 (unless overridden
111 .Pa /boot/device.hints ) .
113 In general, the module
122 or from the command line using the
125 Options which can be specified in
126 .Pa /boot/loader.conf
128 .Bl -tag -width ".Va snd_emu10k1_load" -offset indent
129 .It Va snd_driver_load
133 this option loads all available drivers.
134 .It Va snd_emu10k1_load
138 only the SoundBlaster 5.1 driver and dependent modules will be loaded.
143 load driver for card/chipset foo.
146 To define default values for the different mixer channels,
147 set the channel to the preferred value using hints, e.g.:
148 .Va hint.pcm.0.line Ns = Ns Qq Li 0 .
149 This will mute the input channel per default.
151 Each device can optionally support more playback channels
152 than physical hardware provides by using
157 options can be configured via the
159 interface but can only be manipulated while the device is inactive.
160 .Ss Runtime Configuration
163 variables are available:
164 .Bl -tag -width ".Va hw.snd.report_soft_formats" -offset indent
165 .It Va hw.snd.pcm%d.buffersize
166 Configure the amount of
168 bufferspace available for a device.
169 .It Va hw.snd.targetirqrate
170 Set the default block size such that continuous
171 playback will achieve this
174 This value can be tuned to improve application performance.
175 Increase this value when the sound lags and decrease
176 it if sound stutters or breaks up.
180 the default device for
182 Equivalent to a symlink from
185 .Pa /dev/dsp Ns Va ${hw.snd.unit} .
186 .It Va hw.snd.report_soft_formats
187 Controls the internal format conversion if it is
188 available transparently to the application software.
189 When disabled or not available, the application will
190 only be able to select formats the device natively supports.
191 .It Va hw.snd.verbose
192 Level of verbosity for the
195 Higher values include more output and the highest level,
196 three, should be used when reporting problems.
197 Other options include:
200 Installed devices and their allocated bus resources.
202 The number of playback, record, virtual channels, and
205 Channel information per device including the channel's
206 current format, speed, and pseudo device statistics such as
207 buffer overruns and buffer underruns.
209 File names and versions of the currently sound loaded modules.
211 .It Va hw.snd.maxautovchans
214 setting that only affects devices that have only one playback channel.
215 The sound system will dynamically create up this many
222 .It Va hw.snd.pcm%d.vchans
223 The current number of
225 allocated per device.
226 This can be set to preallocate a certain number of
228 Setting this value to
234 .Ss Recording Channels
235 On devices that have more than one recording source (ie: mic and line),
236 there is a corresponding
240 Channel statistics are only kept while the device is open.
241 So with situations involving overruns and underruns, consider the output
242 while the errant application is open and running.
244 The driver supports most of the
247 functions, and most applications work unmodified.
248 A few differences exist, while memory mapped playback is
249 supported natively and in
251 emulation, memory mapped recording is
255 As a consequence, some applications may need to be recompiled
256 with a slightly modified audio module.
259 for a complete list of the supported
265 drivers may create the following
268 .Bl -tag -width ".Pa /dev/audio%d.%d" -compact
269 .It Pa /dev/audio%d.%d
270 Sparc-compatible audio device.
272 Digitized voice device.
273 .It Pa /dev/dspW%d.%d
276 but 16 bits per sample.
277 .It Pa /dev/dspr%d.%d
278 Should be connected to a record codec.
282 status, including all channels and drivers.
285 The first number in the device node
286 represents the unit number of the
294 Additional messages are sometimes recorded when the
295 device is probed and attached, these messages can be viewed with the
300 .It ac97: dac not ready
301 AC97 codec is not likely to be accompanied with the sound card.
302 .It unsupported subdevice XX
303 A device node is not created properly.
329 .Xr snd_via82c686 4 ,
338 .%O "http://www.opensound.com/pguide/oss.pdf"
343 device driver first appeared in
354 The API evolved from the VOXWARE
355 standard which later became OSS standard.
358 .An Luigi Rizzo Aq luigi@iet.unipi.it
361 device driver and this manual page.
362 .An Cameron Grant Aq gandalf@vilnya.demon.co.uk
363 later revised the device driver for
365 .An Seigo Tanimura Aq tanimura@r.dl.itc.u-tokyo.ac.jp
366 revised this manual page.
367 It was then rewritten for
370 Some features of your cards (e.g., global volume control) might not
371 be supported on all devices.