1.\" Copyright (c) 2009 Sun Microsystems, Inc. All rights reserved. 2.\" Copyright 2019, Joyent, Inc. 3.\" The contents of this file are subject to the terms of the 4.\" Common Development and Distribution License (the "License"). 5.\" You may not use this file except in compliance with the License. 6.\" 7.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 8.\" or http://www.opensolaris.org/os/licensing. 9.\" See the License for the specific language governing permissions 10.\" and limitations under the License. 11.\" 12.\" When distributing Covered Code, include this CDDL HEADER in each 13.\" file and include the License file at usr/src/OPENSOLARIS.LICENSE. 14.\" If applicable, add the following below this CDDL HEADER, with the 15.\" fields enclosed by brackets "[]" replaced with your own identifying 16.\" information: Portions Copyright [yyyy] [name of copyright owner] 17.Dd March 13, 2022 18.Dt MIXER 4I 19.Os 20.Sh NAME 21.Nm mixer 22.Nd generic mixer device interface 23.Sh SYNOPSIS 24.In sys/soundcard.h 25.Sh DESCRIPTION 26.Ss "Mixer Pseudo-Device" 27The 28.Pa /dev/mixer 29pseudo-device is provided for two purposes: 30.Bl -bullet -offset indent 31.It 32The first purpose is for applications that wish to learn about the list of 33audio devices on the system, so that they can select (or provide for users to 34select) an appropriate audio device. 35The 36.Pa /dev/mixer 37pseudo-device 38provides interfaces to enumerate all of the audio devices on the system. 39.It 40The second purpose is for mixer panel type applications which need to control 41master settings for the audio hardware in the system, such as gain levels, 42balance, port functionality, and other device features. 43.El 44.Pp 45Ordinary audio applications should 46.Em not 47attempt to adjust their playback 48or record volumes or other device settings using this device. 49Instead, they 50should use the 51.Dv SNDCTL_DSP_SETPLAYVOL 52and 53.Dv SNDCTL_DSP_SETRECVOL 54ioctls that are documented in 55.Xr dsp 4I . 56.Ss "Sndstat Device" 57The 58.Pa /dev/sndstat 59device supports 60.Xr read 2 , 61and can be read to 62retrieve human-readable information about the audio devices on the system. 63Software should not attempt to interpret the contents of this device. 64.Sh IOCTLS 65.Ss "Information IOCTLs" 66The following ioctls are intended to aid applications in identifying the audio 67devices available on the system. 68These ioctls can be issued against either the 69pseudo-device 70.Pa /dev/mixer , 71or a against a file descriptor open to any 72other audio device in the system. 73.Pp 74Applications should issue 75.Dv SNDCTL_SYSINFO 76first to learn what audio 77devices and mixers are available on the system, and then use 78.Dv SNDCTL_AUDIOINFO 79or 80.Dv SNDCTL_MIXERINFO 81to obtain more information 82about the audio devices or mixers, respectively. 83.Bl -tag -width SNDCTL_AUDIOINFO 84.It Dv OSS_GETVERSION 85The argument is a pointer to an integer, which retrieves the version of the 86.Sy OSS API 87used. 88The value is encoded with the major version (currently 4) 89encoded in the most significant 16 bits, and a minor version encoded in the 90lower 16 bits. 91.It Dv SNDCTL_SYSINFO 92The argument is a pointer to an 93.Vt oss_sysinfo 94structure, which has the following definition: 95.Bd -literal -offset 2n 96typedef struct oss_sysinfo { 97 char product[32]; /* E.g. SunOS Audio */ 98 char version[32]; /* E.g. 4.0a */ 99 int versionnum; /* See OSS_GETVERSION */ 100 char options[128]; /* NOT SUPPORTED */ 101 102 int numaudios; /* # of audio/dsp devices */ 103 int openedaudio[8]; /* Reserved, always 0 */ 104 105 int numsynths; /* NOT SUPPORTED, always 0 */ 106 int nummidis; /* NOT SUPPORTED, always 0 */ 107 int numtimers; /* NOT SUPPORTED, always 0 */ 108 int nummixers; /* # of mixer devices */ 109 110 /* Mask of midi devices are busy */ 111 int openedmidi[8]; 112 113 /* Number of sound cards in the system */ 114 int numcards; 115 116 /* Number of audio engines in the system */ 117 int numaudioengines; 118 char license[16]; /* E.g. "GPL" or "CDDL" */ 119 char revision_info[256]; /* Reserved */ 120 int filler[172]; /* Reserved */ 121} oss_sysinfo; 122.Ed 123.Pp 124The important fields here are 125.Fa numaudios , 126which is used to determine the 127number of audio devices that can be queried with 128.Dv SNDCTL_AUDIOINFO , 129.Fa nummixers 130which provides a count of mixers on the system, and 131.Fa numcards 132which counts to total number of aggregate devices. 133A 134.Sy card 135can consist of one or more audio devices and one or more mixers, although more 136typically there is exactly one audio device and one mixer for each card. 137.It Dv SNDCTL_AUDIOINFO 138The argument is a pointer to an 139.Vt oss_audioinfo 140structure, which has the following structure: 141.Bd -literal -offset 2n 142typedef struct oss_audioinfo { 143 int dev; /* Device to query */ 144 char name[64]; /* Human readable name */ 145 int busy; /* reserved */ 146 int pid; /* reserved */ 147 148 /* PCM_CAP_INPUT, PCM_CAP_OUTPUT */ 149 int caps; 150 int iformats; /* Supported input formats */ 151 int oformats; /* Supported output formats */ 152 int magic; /* reserved */ 153 char cmd[64]; /* reserved */ 154 int card_number; 155 int port_number; /* reserved */ 156 int mixer_dev; 157 158 /* Obsolete field. Replaced by devnode */ 159 int legacy_device; 160 int enabled; /* reserved */ 161 int flags; /* reserved */ 162 int min_rate; /* Minimum sample rate */ 163 int max_rate; /* Maximum sample rate */ 164 int min_channels; /* Minimum number of channels */ 165 int max_channels; /* Maximum number of channels */ 166 int binding; /* reserved */ 167 int rate_source; /* reserved */ 168 char handle[32]; /* reserved */ 169 unsigned int nrates; /* reserved */ 170 unsigned int rates[20]; /* reserved */ 171 char song_name[64]; /* reserved */ 172 char label[16]; /* reserved */ 173 int latency; /* reserved */ 174 175 /* Device special file name (absolute path) */ 176 char devnode[32]; 177 int next_play_engine; /* reserved */ 178 int next_rec_engine; /* reserved */ 179 int filler[184]; /* reserved */ 180} oss_audioinfo; 181.Ed 182.Pp 183In the above structure, all of the fields are reserved except the following: 184.Fa dev , 185.Fa name , 186.Fa card_number , 187.Fa mixer_dev , 188.Fa caps , 189.Fa min_rate , 190.Fa max_rate , 191.Fa min_channels , 192.Fa max_channels , 193and 194.Fa devnode . 195The reserved fields are provided for compatibility with other OSS 196implementations, and available for legacy applications. 197New applications should not attempt to use these fields. 198.Pp 199The 200.Fa dev 201field should be initialized by the application to the number of 202the device to query. 203This is a number between zero (inclusive) and value of 204.Fa numaudios 205(exclusive) returned by 206.Dv SNDCTL_SYSINFO . 207Alternatively, 208when issuing the ioctl against a real mixer or 209.Sy dsp 210device, the special 211value 212.Sy -1 213can be used to indicate that the query is being made against the device opened. 214If 215.Sy -1 216is used, the field is overwritten with the device 217number for the current device on successful return. 218.Pp 219No other fields are significant upon entry, but a successful return contains 220details of the device. 221.Pp 222The 223.Fa name 224field is a human readable name representing the device. 225Applications should not try to interpret it. 226.Pp 227The 228.Fa card_number 229field indicates the number assigned to the aggregate device. 230This can be used with the 231.Dv SNDCTL_CARDINFO 232ioctl. 233.Pp 234The 235.Fa mixer_dev 236is the mixer device number for the mixing device associated 237with the audio device. 238This can be used with the 239.Dv SNDCTL_MIXERINFO 240ioctl. 241.Pp 242The 243.Fa caps 244field contains any of the bits 245.Dv PCM_CAP_INPUT , 246.Dv PCM_CAP_OUTPUT , 247and 248.Dv PCM_CAP_DUPLEX . 249Indicating whether the device 250support input, output, and whether input and output can be used simultaneously. 251All other bits are reserved. 252.Pp 253The 254.Fa min_rate 255and 256.Fa max_rate 257fields indicate the minimum and maximum sample rates supported by the device. 258Most applications should try to use the maximum supported rate for the best 259audio quality and lowest system resource consumption. 260.Pp 261The 262.Fa min_channels 263and 264.Fa max_channels 265provide an indication of the number of channels (1 for mono, 2 for stereo, 2666 for 5\&.1, etc\&.) supported by the device. 267.Pp 268The 269.Fa devnode 270field contains the actual full path to the device node for this device, such as 271.Pa /dev/sound/audio810:0dsp . 272Applications should open this file to access the device. 273.It Dv SNDCTL_CARDINFO 274The argument is a pointer to a 275.Vt struct oss_card_info , 276which has the following definition: 277.Bd -literal -offset 2n 278typedef struct oss_card_info { 279 int card; 280 char shortname[16]; 281 char longname[128]; 282 int flags; /* reserved */ 283 char hw_info[400]; 284 int intr_count; /* reserved */ 285 int ack_count; /* reserved */ 286 int filler[154]; 287} oss_card_info; 288.Ed 289.Pp 290This ioctl is used to query for information about the aggregate audio device. 291.Pp 292The 293.Fa card 294field should be initialized by the application to the number of 295the card to query. 296This is a number between zero 297.Pq inclusive 298and value of 299.Fa numcards 300.Pq exclusive 301returned by 302.Dv SNDCTL_SYSINFO . 303Alternatively, 304when issuing the ioctl against a real mixer or 305.Sy dsp 306device, the special value 307.Sy -1 308can be used to indicate that the query is being made against the device opened. 309If 310.Sy -1 311is used, the field is overwritten with the number 312for the current hardware device on successful return. 313.Pp 314The 315.Fa shortname , 316.Fa longname , 317and 318.Fa hw_info 319contain 320.Sy ASCIIZ 321strings describing the device in more detail. 322The 323.Fa hw_info 324member can contain multiple lines of detail, each line ending in a NEWLINE. 325.Pp 326The 327.Fa flag , 328.Fa intr_count , 329and 330.Fa ack_count 331fields are not used by this implementation. 332.It Dv SNDCTL_MIXERINFO 333The argument is a pointer to a 334.Vt struct oss_mixer_info , 335which has the following definition: 336.Bd -literal -offset 2n 337typedef struct oss_mixerinfo { 338 int dev; 339 char id[16]; /* Reserved */ 340 char name[32]; 341 int modify_counter; 342 int card_number; 343 int port_number; /* Reserved */ 344 char handle[32]; /* Reserved */ 345 int magic; /* Reserved */ 346 int enabled; /* Reserved */ 347 int caps; /* Reserved */ 348 int flags; /* Reserved */ 349 int nrext; 350 int priority; 351 352 /* Deice special file name (absolute path) */ 353 char devnode[32]; 354 int legacy_device; /* Reserved */ 355 int filler[245]; /* Reserved */ 356} oss_mixerinfo; 357.Ed 358.Pp 359In the above structure, all of the fields are reserved except the following: 360.Fa dev , 361.Fa name , 362.Fa modify_counter , 363.Fa card_number , 364.Fa nrext , 365.Fa priority , 366and 367.Fa devnode . 368The reserved fields are provided for compatibility with other 369OSS implementations, and available for legacy applications. 370New applications should not attempt to use these fields. 371.Pp 372The 373.Fa dev 374field should be initialized by the application to the number of 375the device to query. 376This is a number between zero inclusive and value of 377.Fa nummixers 378(exclusive) returned by 379.Dv SNDCTL_SYSINFO , 380or by 381.Dv SNDCTL_MIX_NRMIX . 382Alternatively, when issuing the ioctl against a real mixer or 383.Sy dsp 384device, the special value 385.Sy -1 386can be used to indicate 387that the query is being made against the device opened. 388If 389.Sy -1 390is used, 391the field is overwritten with the mixer number for the current open file on 392successful return. 393.Pp 394No other fields are significant upon entry, but on successful return contains 395details of the device. 396.Pp 397The 398.Fa name 399field is a human readable name representing the device. 400Applications should not try to interpret it. 401.Pp 402The 403.Fa modify_counter 404is changed by the mixer framework each time the 405settings for the various controls or extensions of the device are changed. 406Applications can poll this value to learn if any other changes need to be 407searched for. 408.Pp 409The 410.Fa card_number 411field is the number of the aggregate audio device this 412mixer is located on. 413It can be used with the 414.Dv SNDCTL_CARDINFO 415ioctl. 416.Pp 417The 418.Fa nrext 419field is the number of mixer extensions available on this mixer. 420See the 421.Dv SNDCTL_MIX_NREXT 422description. 423.Pp 424The priority is used by the framework to assign a preference that applications 425can use in choosing a device. 426Higher values are preferable. 427Mixers with priorities less than -1 should never be selected by default. 428.Pp 429The 430.Fa devnode 431field contains the actual full path to the device node for 432the physical mixer, such as 433.Pa /dev/sound/audio810:0mixer . 434Applications 435should open this file to access the mixer settings. 436.El 437.Ss "Mixer Extension IOCTLs" 438The pseudo 439.Pa /dev/mixer 440device supports ioctls that can change the 441various settings for the audio hardware in the system. 442.Pp 443Those ioctls should only be used by dedicated mixer applications or desktop 444volume controls, and not by typical ordinary audio applications such as media 445players. 446Ordinary applications that wish to adjust their own volume settings 447should use the 448.Dv SNDCTL_DSP_SETPLAYVOL 449or 450.Dv SNDCTL_DSP_SETRECVOL 451ioctls for that purpose. 452See 453.Xr dsp 4I 454for more information. 455Ordinary 456applications should never attempt to change master port selection or hardware 457settings such as monitor gain settings. 458.Pp 459The ioctls in this section can only be used to access the mixer device that is 460associated with the current file descriptor. 461.Pp 462Applications should not assume that a single 463.Pa /dev/mixer 464node is able to access any physical settings. 465Instead, they should use the ioctl 466.Dv SNDCTL_MIXERINFO 467to determine the device path for the real mixer device, 468and issue ioctls on a file descriptor opened against the corresponding 469.Fa devnode 470field. 471.Pp 472When a 473.Fa dev 474member is specified in each of the following ioctls, the 475application should specify 476.Sy -1 , 477although for compatibility the mixer 478allows the application to specify the mixer device number. 479.Pp 480.Bl -tag -width SNDCTL_MIX_ENUMINFO -compact 481.It Dv SNDCTL_MIX_NRMIX 482The argument is a pointer to an integer, which receives the number of mixer 483devices in the system. 484Each can be queried by using its number with the 485.Dv SNDCTL_MIXERINFO 486ioctl. 487The same information is available using the 488.Fa SNDCTL_SYSINFO 489ioctl. 490.Pp 491.It Dv SNDCTL_MIX_NREXT 492The argument is a pointer to an integer. 493On entry, the integer should contain 494the special value 495.Sy -1 . 496On return the argument receives the number of mixer 497extensions (or mixer controls) supported by the mixer device. 498More details 499about each extension can be obtained by 500.Fa SNDCTL_MIX_EXTINFO 501ioctl. 502.Pp 503.It Dv SNDCTL_MIX_EXTINFO 504The argument is a pointer to an 505.Vt oss_mixext 506structure which is defined as follows: 507.Bd -literal -offset 2n 508typedef struct oss_mixext { 509 int dev; /* Mixer device number */ 510 int ctrl; /* Extension number */ 511 int type; /* Entry type */ 512 int maxvalue; 513 int minvalue; 514 int flags; 515 char id[16]; /* Mnemonic ID (internal use) */ 516 int parent; /* Entry# of parent (-1 if root) */ 517 int dummy; /* NOT SUPPORTED */ 518 int timestamp; 519 char data[64]; /* Reserved */ 520 521 /* Mask of allowed enum values */ 522 unsigned char enum_present[32]; 523 int control_no; /* Reserved */ 524 unsigned int desc; /* NOT SUPPORTED */ 525 char extname[32]; 526 int update_counter; 527 int filler[7]; /* Reserved */ 528} oss_mixext; 529.Ed 530.Pp 531On entry, the 532.Fa dev 533field should be initialized to the value 534.Sy -1 , 535and 536the 537.Fa ctrl 538field should be initialized with the number of the extension 539being accessed. 540Between 0, inclusive, and the value returned by 541.Dv SNDCTL_MIX_NREXT , 542exclusive. 543.Pp 544Mixer extensions are organized as a logical tree, starting with a root node. 545The root node always has a 546.Fa ctrl 547value of zero. 548The structure of the tree can be determined by looking at the parent field, 549which contains the extension number of the parent extension, or 550.Sy -1 551if the extension is the root extension. 552.Pp 553The type indicates the type of extension used. 554This implementation supports the following values: 555.Bl -column -offset 2n "MIXT_STEREOSLIDER" "Enumerated value, 0 to maxvalue" 556.It Dv MIXT_DEVROOT Ta Root node for extension tree 557.It Dv MIXT_GROUP Ta Logical grouping of controls 558.It Dv MXIT_ONOFF Ta Boolean value, 0 = off, 1 = on. 559.It Dv MIXT_ENUM Ta Enumerated value, 0 to maxvalue. 560.It Dv MIXT_MONOSLIDER Ta Monophonic slider, 0 to 255. 561.It Dv MIXT_STEREOSLIDER Ta Stereophonic slider, 0 to 255 (encoded as lower two bytes in value.) 562.It Dv MIXT_MARKER Ta Place holder, can ignore. 563.El 564.Pp 565The flags field is a bit array. 566This implementation makes use of the following 567possible bits: 568.Bl -column -offset 2n "MIXF_WRITEABLE" "Extensions value is modifiable" 569.It Dv MIXF_READABLE Ta Extension's value is readable. 570.It Dv MIXF_WRITEABLE Ta Extension's value is modifiable. 571.It Dv MIXF_POLL Ta Extension can self-update. 572.It Dv MIXF_PCMVOL Ta Extension is for master PCM playback volume. 573.It Dv MIXF_MAINVOL Ta Extension is for a typical analog volume 574.It Dv MIXF_RECVOL Ta Extension is for master record gain. 575.It Dv MIXF_MONVOL Ta Extension is for a monitor source's gain. 576.El 577.Pp 578The 579.Fa id 580field contains an 581.Sy ASCIIZ 582identifier for the extension. 583.Pp 584The timestamp field is set when the extension tree is first initialized. 585Applications must use the same timestamp value when attempting to change the 586values. 587A change in the timestamp indicates a change a in the structure of the 588extension tree. 589.Pp 590The 591.Fa enum_present 592field is a bit mask of possible enumeration values. 593If a 594bit is present in the 595.Fa enum_present 596mask, then the corresponding enumeration value is legal. 597The mask is in little endian order. 598.Pp 599The 600.Fa desc 601field provides information about scoping, which can be useful as 602layout hints to applications. 603The following hints are available: 604.Bl -column -offset 2n "MIXEXT_SCOPE_MONITOR" "No scoping hint provided." 605.It Dv MIXEXT_SCOPE_MASK Ta Mask of possible scope values. 606.It Dv MIXEXT_SCOPE_INPUT Ta Extension is an input control. 607.It Dv MIXEXT_SCOPE_OUTPUT Ta Extension is an output control. 608.It Dv MIXEXT_SCOPE_MONITOR Ta Extension relates to input monitoring. 609.It Dv MIXEXT_SCOPE_OTHER Ta No scoping hint provided. 610.El 611.Pp 612The 613.Fa extname 614is the full name of the extension. 615.Pp 616The 617.Fa update_counter 618is incremented each time the control's value is changed. 619.Pp 620.It Dv SNDCTL_MIX_ENUMINFO 621The argument is a pointer to an 622.Vt oss_mixer_enuminfo 623structure, which is defined as follows: 624.Bd -literal -offset 2n 625typedef struct oss_mixer_enuminfo { 626 int dev; 627 int ctrl; 628 int nvalues; 629 int version; 630 short strindex[255]; 631 char strings[3000]; 632} oss_mixer_enuminfo; 633.Ed 634.Pp 635On entry, the 636.Fa dev 637field should be initialized to the value 638.Sy -1 , 639and 640the 641.Fa ctrl 642field should be initialized with the number of the extension being accessed. 643Between 0, inclusive, and the value returned by 644.Dv SNDCTL_MIX_NREXT , 645exclusive. 646.Pp 647On return the 648.Fa nvalues 649field contains the number of values, and 650.Fa strindex 651contains an array of indices into the strings member, each index 652pointing to an 653.Sy ASCIIZ 654describing the enumeration value. 655.Pp 656.It Dv SNDCTL_MIX_READ 657.It Dv SNDCTL_MIX_WRITE 658The argument is a pointer to an 659.Vt oss_mixer_value 660structure, defined as follows: 661.Bd -literal -offset 2n 662typedef struct oss_mixer_value { 663 int dev; 664 int ctrl; 665 int value; 666 667 /* Reserved for future use. Initialize to 0 */ 668 int flags; 669 670 /* Must be set to oss_mixext.timestamp */ 671 int timestamp; 672 673 /* Reserved for future use. Initialize to 0 */ 674 int filler[8]; 675} oss_mixer_value; 676.Pp 677.Ed 678On entry, the 679.Fa dev 680field should be initialized to the value 681.Sy -1 , 682and the 683.Fa ctrl 684field should be initialized with the number of the extension 685being accessed. 686Between 0, inclusive, and the value returned by 687.Dv SNDCTL_MIX_NREXT , 688exclusive. 689Additionally, the timestamp member must be 690initialized to the same value as was supplied in the 691.Vt oss_mixext 692structure 693used with 694.Dv SNDCTL_MIX_EXTINFO . 695.Pp 696For 697.Dv SNDCTL_MIX_WRITE , 698the application should supply the new value for the extension. 699For 700.Dv SNDCTL_MIX_READ , 701the mixer returns the extensions current value in value. 702.El 703.Ss "Compatibility IOCTLs" 704The following ioctls are for compatibility use only: 705.Pp 706.Bl -tag -offset 2n -width SNDCTL_MIX_ENUMINFO -compact 707.It Dv SOUND_MIXER_READ_VOLUME 708.It Dv SOUND_MIXER_READ_PCM 709.It Dv SOUND_MIXER_READ_OGAIN 710.It Dv SOUND_MIXER_READ_RECGAIN 711.It Dv SOUND_MIXER_READ_RECLEV 712.It Dv SOUND_MIXER_READ_IGAIN 713.It Dv SOUND_MIXER_READ_RECSRC 714.It Dv SOUND_MIXER_READ_RECMASK 715.It Dv SOUND_MIXER_READ_DEVMASK 716.It Dv SOUND_MIXER_READ_STEREODEVS 717.It Dv SOUND_MIXER_WRITE_VOLUME 718.It Dv SOUND_MIXER_WRITE_PCM 719.It Dv SOUND_MIXER_WRITE_OGAIN 720.It Dv SOUND_MIXER_WRITE_RECGAIN 721.It Dv SOUND_MIXER_WRITE_RECLEV 722.It Dv SOUND_MIXER_WRITE_IGAIN 723.It Dv SOUND_MIXER_WRITE_RECSRC 724.It Dv SOUND_MIXER_WRITE_RECMASK 725.It Dv SOUND_MIXER_INFO 726.It Dv SNDCTL_AUDIOINFO_EX 727.It Dv SNDCTL_ENGINEINFO 728.El 729.Pp 730These ioctls can affect the software volume levels associated with the calling 731process. 732They have no effect on the physical hardware levels or settings. 733They should not be used in new applications. 734.Sh FILES 735.Bl -tag -width /dev/sndstat 736.It Pa /dev/mixer 737Symbolic link to the pseudo mixer device for the system 738.It Pa /dev/sndstat 739Sound status device 740.El 741.Sh ERRORS 742An 743.Xr ioctl 2 744fails if: 745.Bl -tag -width EINVAL 746.It Er EINVAL 747The parameter changes requested in the ioctl are invalid or are not supported 748by the device. 749.It Er ENXIO 750The device or extension referenced does not exist. 751.El 752.Sh ARCHITECTURE 753SPARC 754x86 755.Sh INTERFACE STABILITY 756The information and mixer extension IOCTLs are Uncommitted. 757The Compatibility IOCTLs are Obsolete Uncommitted. 758The extension names are Uncommitted. 759.Sh SEE ALSO 760.Xr close 2 , 761.Xr ioctl 2 , 762.Xr open 2 , 763.Xr read 2 , 764.Xr dsp 4I , 765.Xr attributes 7 766.Sh BUGS 767The names of mixer extensions are not guaranteed to be predictable. 768