Annotation of src/usr.bin/aucat/aucat.1, Revision 1.66
1.66 ! ratchov 1: .\" $OpenBSD: aucat.1,v 1.65 2010/04/03 17:59:17 ratchov Exp $
1.1 kstailey 2: .\"
1.16 ratchov 3: .\" Copyright (c) 2006 Alexandre Ratchov <alex@caoua.org>
1.1 kstailey 4: .\"
1.16 ratchov 5: .\" Permission to use, copy, modify, and distribute this software for any
6: .\" purpose with or without fee is hereby granted, provided that the above
7: .\" copyright notice and this permission notice appear in all copies.
1.1 kstailey 8: .\"
1.16 ratchov 9: .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10: .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11: .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12: .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13: .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14: .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15: .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
1.1 kstailey 16: .\"
1.66 ! ratchov 17: .Dd $Mdocdate: April 3 2010 $
1.1 kstailey 18: .Dt AUCAT 1
1.5 aaron 19: .Os
1.1 kstailey 20: .Sh NAME
21: .Nm aucat
1.47 ratchov 22: .Nd audio server and stream manipulation tool
1.1 kstailey 23: .Sh SYNOPSIS
24: .Nm aucat
1.16 ratchov 25: .Bk -words
1.59 ratchov 26: .Op Fl dlnu
1.49 jmc 27: .Op Fl b Ar nframes
1.16 ratchov 28: .Op Fl C Ar min : Ns Ar max
29: .Op Fl c Ar min : Ns Ar max
30: .Op Fl e Ar enc
1.9 millert 31: .Op Fl f Ar device
1.16 ratchov 32: .Op Fl h Ar fmt
33: .Op Fl i Ar file
1.37 ratchov 34: .Op Fl m Ar mode
1.16 ratchov 35: .Op Fl o Ar file
1.66 ! ratchov 36: .Op Fl q Ar device
1.16 ratchov 37: .Op Fl r Ar rate
1.57 ratchov 38: .Op Fl s Ar name
1.62 ratchov 39: .Op Fl t Ar mode
1.54 ratchov 40: .Op Fl U Ar unit
1.30 ratchov 41: .Op Fl v Ar volume
1.22 ratchov 42: .Op Fl x Ar policy
1.62 ratchov 43: .Op Fl z Ar nframes
1.16 ratchov 44: .Ek
1.1 kstailey 45: .Sh DESCRIPTION
46: The
1.7 aaron 47: .Nm
1.16 ratchov 48: utility can record one input stream
49: and store it on multiple destination files,
50: doing the necessary conversions on the fly.
1.48 ratchov 51: It can play, convert, and mix multiple input files simultaneously,
52: and can also act as an audio server.
1.9 millert 53: .Nm
1.16 ratchov 54: also has a legacy mode that works like previous versions of
55: .Nm ,
56: which does not convert on the fly and supports playback of .au files.
1.17 jmc 57: .Pp
1.16 ratchov 58: The options are as follows:
1.26 ratchov 59: .Bl -tag -width Ds
1.49 jmc 60: .It Fl b Ar nframes
1.66 ! ratchov 61: The buffer size of the audio device in frames.
1.49 jmc 62: A frame consists of one sample for each channel in the stream.
63: This is the number of frames that will be buffered before being played
64: and thus controls the playback latency.
1.25 jmc 65: .It Xo
66: .Fl C Ar min : Ns Ar max ,
67: .Fl c Ar min : Ns Ar max
68: .Xc
1.26 ratchov 69: The range of channel numbers on the record or playback stream, respectively.
1.17 jmc 70: The default is 0:1, i.e. stereo.
1.59 ratchov 71: .It Fl d
72: Do not daemonize.
73: If this option is specified,
74: .Nm
75: will run in the foreground and log to
76: .Em stderr .
1.26 ratchov 77: .It Fl e Ar enc
78: Encoding of the playback or recording stream (see below).
1.17 jmc 79: The default is signed, 16-bit, native byte order.
80: .It Fl f Ar device
81: The
1.57 ratchov 82: .Xr sndio 7
83: audio device to use for playing and/or recording.
1.26 ratchov 84: .It Fl h Ar fmt
85: File format of the playback or record stream (see below).
1.17 jmc 86: The default is auto.
1.16 ratchov 87: .It Fl i Ar file
88: Add this file to the list of files to play.
89: If the option argument is
90: .Sq -
91: then standard input will be used.
1.26 ratchov 92: .It Fl l
1.60 sobrado 93: Listen for incoming connections on a
1.61 sobrado 94: .Ux Ns -domain
95: socket.
1.39 jmc 96: This allows clients to use
1.26 ratchov 97: .Nm
1.57 ratchov 98: instead of the physical audio device for audio input and output
1.26 ratchov 99: in order to share the physical device with other clients.
1.57 ratchov 100: The default
101: .Xr sndio 7
102: device exposed is
103: .Pa aucat:0
104: .Pq "also known as" Pa aucat:0.default
1.45 ratchov 105: but other names can be used with the
1.35 ratchov 106: .Fl s
107: option.
1.37 ratchov 108: .It Fl m Ar mode
1.66 ! ratchov 109: Set the stream mode.
1.37 ratchov 110: Valid modes are
1.39 jmc 111: .Ar play ,
112: .Ar rec ,
1.37 ratchov 113: and
1.66 ! ratchov 114: .Ar mon ,
! 115: corresponding to playback, recording and monitoring.
! 116: A monitoring stream is a fake recording stream corresponding to
! 117: the mix of all playback streams.
! 118: Multiple modes can be specified, separated by commas,
! 119: but the same stream cannot be used for both recording and monitoring.
1.37 ratchov 120: The default is
1.66 ! ratchov 121: .Ar play , rec
! 122: (i.e. full-duplex).
1.42 ratchov 123: .It Fl n
124: Loopback mode.
125: Instead of using an audio device, send input streams
126: to the output, processing them on the fly.
127: This mode is useful to mix, demultiplex, resample or reencode
1.43 jmc 128: audio files offline.
1.16 ratchov 129: .It Fl o Ar file
130: Add this file to the list of files in which to store recorded samples.
131: If the option argument is
132: .Sq -
133: then standard output will be used.
1.66 ! ratchov 134: .It Fl q Ar device
! 135: The
! 136: .Xr sndio 7
! 137: MIDI device to use for controlling stream volumes or
! 138: to start multiple streams synchronously.
1.26 ratchov 139: .It Fl r Ar rate
140: Sample rate in Hertz of the playback or record stream.
1.17 jmc 141: The default is 44100Hz.
1.57 ratchov 142: .It Fl s Ar name
143: Add
144: .Ar name
145: to the list of sub-devices to expose in server mode.
146: Defining multiple sub-devices allows splitting a physical audio device
1.63 jmc 147: into logical devices having different properties (e.g. channel ranges).
1.57 ratchov 148: The given
149: .Ar name
1.62 ratchov 150: corresponds to the
1.57 ratchov 151: .Dq option
152: part of the
153: .Xr sndio 7
154: device name string.
1.62 ratchov 155: .It Fl t Ar mode
156: Select the way sub-devices are controlled by MMC (MIDI Machine Control) messages.
157: If the mode is
158: .Va off
159: (the default), then streams are not affected by MMC messages.
160: If the mode is
161: .Va slave ,
162: then streams are started synchronously by MMC start messages;
163: additionally, the server clock is exposed as MTC (MIDI Time Code)
164: messages allowing MTC-capable software or hardware to be synchronized
165: to audio streams.
1.54 ratchov 166: .It Fl U Ar unit
167: Unit number to use when running in server mode.
168: Each
169: .Nm
170: server instance has an unique unit number,
171: used in
172: .Xr sndio 7
173: device names.
174: The default is 0.
1.16 ratchov 175: .It Fl u
1.21 jmc 176: Normally
177: .Nm
178: tries to automatically determine the optimal parameters for the audio device;
179: if this option is specified,
180: it will instead use the parameters specified by the
1.26 ratchov 181: .Fl Ccer
1.21 jmc 182: options.
1.30 ratchov 183: .It Fl v Ar volume
184: Software volume attenuation of the playback stream.
185: The value must be between 1 and 127,
1.31 jmc 186: corresponding to \-42dB and \-0dB attenuation.
1.33 ratchov 187: In server mode, clients inherit this parameter.
1.34 jmc 188: Reducing the volume in advance reduces a client's dynamic range,
189: but allows client volume to stay independent from the number
1.33 ratchov 190: of clients as long as their number is small enough.
1.34 jmc 191: A good compromise is to use \-4dB attenuation (12 volume units)
192: for each additional client expected
193: (115 if 2 clients are expected, 103 for 3 clients, and so on).
1.26 ratchov 194: .It Fl x Ar policy
1.22 ratchov 195: Action when the output stream cannot accept
1.26 ratchov 196: recorded data fast enough or the input stream
197: cannot provide data to play fast enough.
1.22 ratchov 198: If the policy
199: is
1.23 jmc 200: .Dq ignore
1.26 ratchov 201: (the default) then samples that cannot be written are discarded
202: and samples that cannot be read are replaced by silence.
1.22 ratchov 203: If the policy is
1.23 jmc 204: .Dq sync
1.26 ratchov 205: then recorded samples are discarded, but the same amount of silence will be written
1.22 ratchov 206: once the stream is unblocked, in order to reach the right position in time.
1.26 ratchov 207: Similarly silence is played, but the same amount of samples will be discarded
208: once the stream is unblocked.
1.22 ratchov 209: If the policy is
1.23 jmc 210: .Dq error
211: then the stream is closed permanently.
1.62 ratchov 212: .Pp
213: If a sub-device is created with
1.63 jmc 214: .Fl t ,
215: the
1.62 ratchov 216: .Dq ignore
1.63 jmc 217: action is disabled for any stream connected to it
218: to ensure proper synchronization.
1.62 ratchov 219: .It Fl z Ar nframes
220: The audio block size in frames.
1.63 jmc 221: This is the number of frames between audio clock ticks,
222: i.e. the clock resolution.
1.62 ratchov 223: If a sub-device is created with
1.63 jmc 224: .Fl t ,
1.62 ratchov 225: and MTC (Midi Time Code) is used for synchronization, the clock
226: resolution must be 96, 100 or 120 ticks per second for maximum
1.63 jmc 227: accuracy.
228: For instance, 120 ticks per second at 48000Hz corresponds
229: to a 400 frame block size.
1.21 jmc 230: .El
231: .Pp
1.32 ratchov 232: If
233: .Nm
234: is sent
1.44 ratchov 235: .Dv SIGHUP ,
236: .Dv SIGINT
237: or
238: .Dv SIGTERM ,
1.32 ratchov 239: it terminates recording to files.
240: .Pp
1.35 ratchov 241: Settings for input files
242: .Pq Fl i ,
243: output files
1.39 jmc 244: .Pq Fl o ,
1.57 ratchov 245: and sub-devices
1.35 ratchov 246: .Pq Fl s
247: can be changed using the
248: .Fl Ccehrvx
1.16 ratchov 249: options.
1.21 jmc 250: The last
1.35 ratchov 251: .Fl Ccehrvx
1.23 jmc 252: options specified before an
1.35 ratchov 253: .Fl i ,
1.39 jmc 254: .Fl o ,
255: or
1.35 ratchov 256: .Fl s
1.41 jmc 257: are applied to the corresponding file.
1.21 jmc 258: .Pp
259: Settings for the audio device
260: can be changed using the
1.26 ratchov 261: .Fl Ccer
1.21 jmc 262: options.
263: They apply to the audio device only if the
264: .Fl u
265: option is given as well.
266: The last
1.26 ratchov 267: .Fl Ccer
1.21 jmc 268: option specified before an
1.16 ratchov 269: .Fl f
1.21 jmc 270: is applied to
271: .Ar device .
272: .Pp
273: If no audio device
274: .Pq Fl f
1.53 ratchov 275: is specified,
276: settings are applied as if
277: the default device is specified as the last argument.
1.57 ratchov 278: If no sub-devices
1.53 ratchov 279: .Pq Fl s
280: are specified
281: settings are applied as if
1.57 ratchov 282: .Ar default
283: is specified as the last argument.
1.14 jmc 284: .Pp
1.20 jmc 285: File formats are specified using the
286: .Fl h
1.26 ratchov 287: option.
1.16 ratchov 288: The following file formats are supported:
1.66 ! ratchov 289: .Bl -tag -width s32lexxx -offset indent
1.16 ratchov 290: .It raw
291: Headerless file.
1.17 jmc 292: This format is recommended since it has no limitations.
1.16 ratchov 293: .It wav
294: Microsoft WAVE file format.
295: There are limitations inherent to the file format itself:
296: not all encodings are supported,
297: file sizes are limited to 2GB,
1.17 jmc 298: and the file must support the
1.16 ratchov 299: .Xr lseek 2
1.17 jmc 300: operation (e.g. pipes do not support it).
1.16 ratchov 301: .It auto
302: Try to guess, depending on the file name.
1.9 millert 303: .El
304: .Pp
1.20 jmc 305: Encodings are specified using the
306: .Fl e
1.26 ratchov 307: option.
1.16 ratchov 308: The following encodings are supported:
309: .Pp
1.66 ! ratchov 310: .Bl -tag -width s32lexxx -offset indent -compact
1.16 ratchov 311: .It s8
312: signed 8-bit
313: .It u8
314: unsigned 8-bit
315: .It s16le
316: signed 16-bit, little endian
317: .It u16le
318: unsigned 16-bit, little endian
319: .It s16be
320: signed 16-bit, big endian
321: .It u16be
322: unsigned 16-bit, big endian
323: .It s24le
324: signed 24-bit, stored in 4 bytes, little endian
325: .It u24le
326: unsigned 24-bit, stored in 4 bytes, little endian
327: .It s24be
328: signed 24-bit, stored in 4 bytes, big endian
329: .It u24be
330: unsigned 24-bit, stored in 4 bytes, big endian
331: .It s32le
332: signed 32-bit, little endian
333: .It u32le
334: unsigned 32-bit, little endian
335: .It s32be
336: signed 32-bit, big endian
337: .It u32be
338: unsigned 32-bit, big endian
339: .It s24le3
340: signed 24-bit, packed in 3 bytes, little endian
341: .It u24le3
342: unsigned 24-bit, packed in 3 bytes, big endian
343: .It s24be3
344: signed 24-bit, packed in 3 bytes, little endian
345: .It u24be3
346: unsigned 24-bit, packed in 3 bytes, big endian
347: .It s20le3
348: signed 20-bit, packed in 3 bytes, little endian
349: .It u20le3
350: unsigned 20-bit, packed in 3 bytes, big endian
351: .It s20be3
352: signed 20-bit, packed in 3 bytes, little endian
353: .It u20be3
354: unsigned 20-bit, packed in 3 bytes, big endian
355: .It s18le3
356: signed 18-bit, packed in 3 bytes, little endian
357: .It u18le3
358: unsigned 18-bit, packed in 3 bytes, big endian
359: .It s18be3
360: signed 18-bit, packed in 3 bytes, little endian
361: .It u18be3
362: unsigned 18-bit, packed in 3 bytes, big endian
363: .El
1.46 ratchov 364: .Sh SERVER MODE
365: .Nm
366: can be used in server mode
367: .Pq Fl l
368: to overcome hardware limitations and allow applications
369: to run on fixed sample rate devices or on devices
370: supporting only unusual encodings.
371: It is generally not desirable to have multiple
372: instances of
373: .Nm
374: running in server mode,
375: so it is good practice to start it thus:
376: .Bd -literal -offset indent
377: $ pgrep -x aucat || aucat -l
378: .Ed
379: .Pp
380: This also ensures privacy by preventing
381: other users from accessing the audio system.
382: On multi-user machines
383: .Nm
384: should be killed when no longer in use to make audio resources
385: available again to others:
386: .Bd -literal -offset indent
387: $ pkill -x aucat
388: .Ed
389: .Pp
390: Certain applications, such as synthesis software,
391: require a low latency audio setup.
392: To reduce the probability of buffer underruns or overruns,
393: the
394: .Xr renice 8
1.49 jmc 395: command can be used to give a higher priority to the
1.46 ratchov 396: .Nm
1.49 jmc 397: process.
1.46 ratchov 398: Superuser privileges are required.
399: For example:
400: .Bd -literal -offset indent
401: $ aucat -b 3500 -l
402: $ sudo renice -n -20 -p `pgrep -x aucat`
403: .Ed
1.55 ratchov 404: .Sh MIDI CONTROL
405: While running in server mode
406: .Pq Fl l
407: .Nm
408: exposes a MIDI device with the same name as the default audio
409: device.
1.62 ratchov 410: It allows MIDI hardware or software to control programs
411: using
412: .Nm
413: or to synchronize to them.
414: .Pp
1.56 jmc 415: A MIDI channel is assigned to each stream, and the volume
1.55 ratchov 416: is changed using the standard volume controller (number 7).
417: Similarly, when the audio application changes its volume,
418: the same MIDI controller message is sent out; it can be used
1.56 jmc 419: for instance for monitoring or as feedback for motorized
1.55 ratchov 420: faders.
1.62 ratchov 421: .Pp
422: Clients connected to sub-devices created with
1.63 jmc 423: .Fl t
1.62 ratchov 424: are controlled by the following MMC (MIDI Machine Control) messages:
1.66 ! ratchov 425: .Bl -tag -width relocateXXX -offset indent
1.62 ratchov 426: .It stop
427: Put the sub-device in stopped mode (the default).
428: In this mode, any stream attempting to start playback or recording
429: is paused.
430: Streams that are already started are not affected until they stop
431: and try to start again.
432: .It relocate
433: Gives
434: .Nm
435: the time, relative to the beginning of the stream, at which playback
436: and recording must start.
437: It is not interpreted by
438: .Nm
439: itself.
1.63 jmc 440: The given time position is sent to MIDI clients as an MTC
1.62 ratchov 441: .Dq "full frame"
442: message forcing all MTC-slaves to relocate to the given
443: position (see below).
444: .It start
445: Put the sub-device in starting mode.
446: In this mode, the sub-device waits for all streams to become ready
447: to start, and then starts them synchronously.
448: Once started, new streams can be created, but they will be blocked
449: until the next stop-to-start transition.
450: .El
451: .Pp
452: Sub-devices created with
1.63 jmc 453: .Fl t
1.62 ratchov 454: will export the server clock using MTC (MIDI Time Code), allowing non-audio
455: software or hardware to be synchronized to the audio stream.
456: The following sample rates
457: .Pq Fl r
458: and block sizes
459: .Pq Fl z
460: are recommended for maximum accuracy:
461: .Pp
1.66 ! ratchov 462: .Bl -bullet -offset indent -compact
1.62 ratchov 463: .It
464: 44100Hz, 441 frames
465: .It
466: 48000Hz, 400 frames
467: .It
468: 48000Hz, 480 frames
469: .It
470: 48000Hz, 500 frames
471: .El
472: .Pp
473: For instance, the following command will create two devices:
474: the default
475: .Va aucat:0
1.63 jmc 476: and a MIDI-controlled
477: .Va aucat:0.mmc :
1.62 ratchov 478: .Bd -literal -offset indent
479: $ aucat -l -r 48000 -z 400 -s default -t slave -s mmc
480: .Ed
481: .Pp
482: Streams connected to
483: .Va aucat:0
484: behave normally, while streams connected to
485: .Va aucat:0.mmc
486: wait for the MMC start signal and start synchronously.
1.63 jmc 487: Regardless of which device a stream is connected to,
488: its playback volume knob is exposed.
1.66 ! ratchov 489: .Pp
! 490: If
! 491: .Nm
! 492: is used to play and record audio files, it offers
! 493: similar MIDI control.
! 494: .Nm
! 495: can open a
! 496: .Xr sndio 7
! 497: MIDI device allowing MIDI hardware or software
! 498: to control playback and recording in real time.
! 499: .Pp
! 500: A MIDI channel is assigned to each stream, and the volume
! 501: is changed using the standard volume controller (number 7).
! 502: Streams created with
! 503: .Fl t
! 504: option are controlled by the following MIDI Machine Control (MMC) messages:
! 505: .Bl -tag -width relocateXXX -offset indent
! 506: .It start
! 507: Start all streams synchronously.
! 508: By default, streams are created in a stopped state.
! 509: .It stop
! 510: Playback or recording is stopped, and
! 511: the stream is rewound back to the starting position.
! 512: .It relocate
! 513: Streams are relocated to the requested time postion
! 514: relative to the beginning of the stream, at which playback
! 515: and recording must start.
! 516: If the requested position is beyond the end of file,
! 517: the stream is temporarly disabled until a valid postion is requested.
! 518: .El
! 519: .Pp
! 520: For instance, the following command will play a file on the
! 521: .Va aucat:0.mmc
! 522: audio device, and give full control to MIDI software or hardware
! 523: connected to the
! 524: .Va midithru:0
! 525: MIDI device:
! 526: .Bd -literal -offset indent
! 527: $ aucat -f aucat:0.mmc -t slave -q midithru:0 -i file.wav
! 528: .Ed
! 529: .Pp
! 530: At this stage,
! 531: .Nm
! 532: will start, stop and relocate automatically following all user
! 533: actions in the MIDI sequencer.
! 534: Note that the sequencer must use
! 535: .Va aucat:0
! 536: as the MTC source, i.e. the audio server, not the audio player.
1.16 ratchov 537: .Sh LEGACY MODE
538: If neither
539: .Fl i
540: nor
541: .Fl o
1.17 jmc 542: are specified,
1.16 ratchov 543: .Nm
1.17 jmc 544: will run in legacy mode, and won't convert sample formats or sampling rates.
1.16 ratchov 545: In legacy mode, all options except
1.17 jmc 546: .Fl f
547: are ignored, and all other arguments are assumed to be names of files.
1.16 ratchov 548: In legacy mode
549: .Nm
550: reads files sequentially, and writes them to the specified device.
551: If a Sun .au header is detected it is skipped over and not copied to
552: the audio device.
553: .Nm
1.52 jakemsr 554: will attempt to parse the format, number of channels and sample rate
555: from Sun .au file headers.
556: However, only alaw and ulaw formats are supported for .au files.
557: Other formats will be interpreted as ulaw.
1.16 ratchov 558: If a Microsoft .wav header (RIFF) is detected it is interpreted
559: to select the right audio encoding for playback and the data chunk of the
560: file is copied to the audio device.
561: If the device does not support the encoding,
562: .Nm
563: will exit with an error.
1.9 millert 564: .Sh ENVIRONMENT
1.35 ratchov 565: .Bl -tag -width "AUDIODEVICE" -compact
1.24 jmc 566: .It Ev AUDIODEVICE
1.57 ratchov 567: .Xr sndio 7
568: audio device to use if the
1.50 ratchov 569: .Fl f
570: option is not specified.
1.9 millert 571: .El
1.16 ratchov 572: .Sh EXAMPLES
573: The following will mix and play two stereo streams,
574: the first at 48kHz and the second at 44.1kHz:
575: .Bd -literal -offset indent
576: $ aucat -r 48000 -i file1.raw -r 44100 -i file2.raw
577: .Ed
578: .Pp
579: The following will record channels 2 and 3 into one stereo file and
580: channels 6 and 7 into another stereo file using a 96kHz sampling rate for
581: both:
582: .Bd -literal -offset indent
1.26 ratchov 583: $ aucat -r 96000 -C 2:3 -o file1.raw -C 6:7 -o file2.raw
1.42 ratchov 584: .Ed
585: .Pp
1.43 jmc 586: The following will split a stereo file into two mono files:
1.42 ratchov 587: .Bd -literal -offset indent
588: $ aucat -n -i stereo.wav -C 0:0 -o left.wav -C 1:1 -o right.wav
1.16 ratchov 589: .Ed
590: .Pp
1.35 ratchov 591: The following will start
592: .Nm
1.40 jmc 593: in server mode using default parameters, but will create an
1.57 ratchov 594: additional sub-device for output to channels 2:3 only (rear speakers
595: on most cards), exposing the
596: .Pa aucat:0
597: and
598: .Pa aucat:0.rear
599: devices:
1.35 ratchov 600: .Bd -literal -offset indent
1.45 ratchov 601: $ aucat -l -s default -c 2:3 -s rear
1.35 ratchov 602: .Ed
603: .Pp
604: The following will start
605: .Nm
1.57 ratchov 606: in server mode creating the default sub-device with low volume and
607: an additional sub-device for high volume output, exposing the
608: .Pa aucat:0
609: and
610: .Pa aucat:0.max
611: devices:
1.35 ratchov 612: .Bd -literal -offset indent
1.45 ratchov 613: $ aucat -l -v 65 -s default -v 127 -s max
1.16 ratchov 614: .Ed
1.2 kstailey 615: .Sh SEE ALSO
1.12 jmc 616: .Xr audioctl 1 ,
1.17 jmc 617: .Xr cdio 1 ,
1.9 millert 618: .Xr mixerctl 1 ,
1.54 ratchov 619: .Xr audio 4 ,
620: .Xr sndio 7
1.16 ratchov 621: .Sh BUGS
622: The
1.1 kstailey 623: .Nm
1.16 ratchov 624: utility assumes non-blocking I/O for input and output streams.
625: It will not work reliably on files that may block
626: (ordinary files block, pipes don't).
627: .Pp
628: Resampling is low quality; down-sampling especially should be avoided
629: when recording.
630: .Pp
631: Processing is done using 16-bit arithmetic,
632: thus samples with more than 16 bits are rounded.
1.17 jmc 633: 16 bits (i.e. 97dB dynamic) are largely enough for most applications though.
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