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Manual Pages for UNIX Operating System command usage for man mixer

Ioctl Requests mixer(7I)

NAME

mixer - generic mixer device interface

SYNOPSIS

#include

DESCRIPTION

Mixer Pseudo-Device

The /dev/mixer pseudo-device is provided for two purposes:

o The first purpose is for applications that wish to

learn about the list of audio devices on the sys-

tem, so that they can select (or provide for users to select) an appropriate audio device. The

/dev/mixer pseudo-device provides interfaces to

enumerate all of the audio devices on the system.

o The second purpose is for mixer panel type applica-

tions which need to control master settings for the audio hardware in the system, such as gain levels, balance, port functionality, and other device features. Ordinary audio applications should not attempt to adjust their playback or record volumes or other device settings using this device. Instead, they should use the

SNDCTL_DSP_SETPLAYVOL and SNDCTL_DSP_SETRECVOL ioctls that

are documented in dsp(7I). Sndstat Device The /dev/sndstat device supports read(2), and can be read to

retrieve human-readable information about the audio devices

on the system. Software should not attempt to interpret the contents of this device. IOCTLS Information IOCTLs The following ioctls are intended to aid applications in identifying the audio devices available on the system. These

ioctls can be issued against either the pseudo-device

/dev/mixer, or a against a file descriptor open to any other

audio device in the system.

Applications should issue SNDCTL_SYSINFO first to learn what

audio devices and mixers are available on the system, and

then use SNDCTL_AUDIOINFO or SNDCTL_MIXERINFO to obtain more

information about the audio devices or mixers, respectively.

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Ioctl Requests mixer(7I)

OSS_GETVERSION The argument is a pointer to an integer,

which retrieves the version of the OSS API used. The value is encoded with the major version (currently 4) encoded in the most significant 16 bits, and a minor version encoded in the lower 16 bits.

SNDCTL_SYSINFO The argument is a pointer to an

oss_sysinfo structure, which has the

following definition:

typedef struct oss_sysinfo {

char product[32]; /* E.g. SunOS Audio */ char version[32]; /* E.g. 4.0a */

int versionnum; /* See OSS_GETVERSION */

char options[128]; /* NOT SUPPORTED */

int numaudios; /* # of audio/dsp devices */

int openedaudio[8]; /* Reserved, always 0 */ int numsynths; /* NOT SUPPORTED, always 0 */ int nummidis; /* NOT SUPPORTED, always 0 */ int numtimers; /* NOT SUPPORTED, always 0 */

int nummixers; /* # of mixer devices */

int openedmidi[8]; /* Mask of midi devices are busy */ int numcards; /* Number of sound cards in the system */ int numaudioengines; /* Number of audio engines in the system */ char license[16]; /* E.g. "GPL" or "CDDL" */

char revision_info[256]; /* Reserved */

int filler[172]; /* Reserved */

} oss_sysinfo;

The important fields here are numaudios, which is used to determine the number of audio devices that can be queried with

SNDCTL_AUDIOINFO, nummixers which pro-

vides a count of mixers on the system,

and numcards which counts to total number of aggregate devices. A card can consist of one or more audio devices and

one or more mixers, although more typi-

cally there is exactly one audio device

and one mixer for each card.

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Ioctl Requests mixer(7I)

SNDCTL_AUDIOINFO The argument is a pointer to an

oss_audioinfo structure, which has the

following structure:

typedef struct oss_audioinfo {

int dev; /* Device to query */ char name[64]; /* Human readable name */ int busy; /* reserved */ int pid; /* reserved */

int caps; /* PCM_CAP_INPUT, PCM_CAP_OUTPUT */

int iformats; /* Supported input formats */ int oformats; /* Supported output formats */ int magic; /* reserved */ char cmd[64]; /* reserved */

int card_number;

int port_number; /* reserved */

int mixer_dev;

int legacy_device; /* Obsolete field.

Replaced by devnode */ int enabled; /* reserved */ int flags; /* reserved */

int min_rate; /* Minimum sample rate */

int max_rate; /* Maximum sample rate */

int min_channels; /* Minimum number

of channels */

int max_channels; /* Maximum number

of channels */ int binding; /* reserved */

int rate_source; /* reserved */

char handle[32]; /* reserved */ unsigned int nrates; /* reserved */ unsigned int rates[20]; /* reserved */

char song_name[64]; /* reserved */

char label[16]; /* reserved */ int latency; /* reserved */ char devnode[32]; /* Device special file name (absolute path) */

int next_play_engine; /* reserved */

int next_rec_engine; /* reserved */

int filler[184]; /* reserved */

} oss_audioinfo;

In the above structure, all of the

fields are reserved except the follow-

ing: dev, name, card_number, mixer_dev,

caps, min_rate, max_rate, min_channels,

max_channels, and devnode. The reserved

fields are provided for compatibility with other OSS implementations, and available for legacy applications. New applications should not attempt to use

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Ioctl Requests mixer(7I)

these fields. The dev field should be initialized by the application to the number of the device to query. This is a number between zero (inclusive) and value of numaudios (exclusive) returned by

SNDCTL_SYSINFO. Alternatively, when

issuing the ioctl against a real mixer

or dsp device, the special value -1 can

be used to indicate that the query is being made against the device opened. If

-1 is used, the field is overwritten

with the device number for the current device on successful return. No other fields are significant upon entry, but a successful return contains details of the device. The name field is a human readable name representing the device. Applications should not try to interpret it.

The card_number field indicates the

number assigned to the aggregate device. This can be used with the

SNDCTL_CARDINFO ioctl.

The mixer_dev is the mixer device number

for the mixing device associated with the audio device. This can be used with

the SNDCTL_MIXERINFO ioctl.

The caps field contains any of the bits

PCM_CAP_INPUT, PCM_CAP_OUTPUT, and

PCM_CAP_DUPLEX. Indicating whether the

device support input, output, and whether input and output can be used simultaneously. All other bits are reserved.

The min_rate and max_rate fields indi-

cate the minimum and maximum sample rates supported by the device. Most

applications should try to use the max-

imum supported rate for the best audio

quality and lowest system resource con-

sumption.

The min_channels and max_channels pro-

vide an indication of the number of

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Ioctl Requests mixer(7I)

channels (1 for mono, 2 for stereo, 6 for 5.1, etc.) supported by the device. The devnode field contains the actual full path to the device node for this device, such as /dev/sound/audio810:0dsp. Applications

should open this file to access the dev-

ice.

SNDCTL_CARDINFO The argument is a pointer to a struct

oss_card_info, which has the following

definition:

typedef struct oss_card_info {

int card; char shortname[16]; char longname[128]; int flags;/* reserved */

char hw_info[400];

int intr_count;/* reserved */

int ack_count;/* reserved */

int filler[154];

} oss_card_info;

This ioctl is used to query for informa-

tion about the aggregate audio device. The card field should be initialized by the application to the number of the card to query. This is a number between zero inclusive and value of numcards

(exclusive) returned by SNDCTL_SYSINFO.)

Alternatively, when issuing the ioctl

against a real mixer or dsp device, the

special value -1 can be used to indicate

that the query is being made against the

device opened. If -1 is used, the field

is overwritten with the number for the current hardware device on successful return.

The shortname, longname, and hw_info

contain ASCIIZ strings describing the

device in more detail. The hw_info

member can contain multiple lines of detail, each line ending in a NEWLINE.

The flag, intr_count, and ack_count

fields are not used by this

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Ioctl Requests mixer(7I)

implementation.

SNDCTL_MIXERINFO The argument is a pointer to a struct

oss_mixer_info, which has the following

definition:

typedef struct oss_mixerinfo {

int dev; char id[16];/* Reserved */ char name[32];

int modify_counter;

int card_number;

int port_number;/* Reserved */

char handle[32];/* Reserved */ int magic;/* Reserved */ int enabled;/* Reserved */ int caps;/* Reserved */ int flags;/* Reserved */ int nrext; int priority; char devnode[32];/* Device special file name (absolute path) */

int legacy_device;/* Reserved */

int filler[245];/* Reserved */

} oss_mixerinfo;

In the above structure, all of the

fields are reserved except the follow-

ing: dev, name, modify_counter,

card_number, nrext, priority, and dev-

node. The reserved fields are provided

for compatibility with other OSS imple-

mentations, and available for legacy applications. New applications should not attempt to use these fields. The dev field should be initialized by the application to the number of the device to query. This is a number

between zero inclusive and value of num-

mixers (exclusive) returned by

SNDCTL_SYSINFO, or by SNDCTL_MIX_NRMIX.

Alternatively, when issuing the ioctl

against a real mixer or dsp device, the

special value -1 can be used to indicate

that the query is being made against the

device opened. If -1 is used, the field

is overwritten with the mixer number for

the current open file on successful return.

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Ioctl Requests mixer(7I)

No other fields are significant upon entry, but on successful return contains details of the device. The name field is a human readable name representing the device. Applications should not try to interpret it.

The modify_counter is changed by the

mixer framework each time the settings

for the various controls or extensions of the device are changed. Applications can poll this value to learn if any other changes need to be searched for.

The card_number field is the number of

the aggregate audio device this mixer is

located on. It can be used with the

SNDCTL_CARDINFO ioctl.

The nrext field is the number of mixer

extensions available on this mixer. See

the SNDCTL_MIX_NREXT description.

The priority is used by the framework to assign a preference that applications can use in choosing a device. Higher values are preferable. Mixers with

priorities less than -1 should never be

selected by default. The devnode field contains the actual full path to the device node for the

physical mixer, such as

/dev/sound/audio810:0mixer. Applications

should open this file to access the

mixer settings.

Mixer Extension IOCTLs

The pseudo /dev/mixer device supports ioctls that can change

the various settings for the audio hardware in the system.

Those ioctls should only be used by dedicated mixer applica-

tions or desktop volume controls, and not by typical ordi-

nary audio applications such as media players. Ordinary applications that wish to adjust their own volume settings

should use the SNDCTL_DSP_SETPLAYVOL or SNDCTL_DSP_SETRECVOL

ioctls for that purpose. See dsp(7I) for more information. Ordinary applications should never attempt to change master port selection or hardware settings such as monitor gain

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Ioctl Requests mixer(7I)

settings. The ioctls in this section can only be used to access the

mixer device that is associated with the current file

descriptor.

Applications should not assume that a single /dev/mixer node

is able to access any physical settings. Instead, they

should use the ioctl SNDCTL_MIXERINFO to determine the dev-

ice path for the real mixer device, and issue ioctls on a

file descriptor opened against the corresponding devnode field. When a dev member is specified in each of the following

ioctls, the application should specify -1, although for com-

patibility the mixer allows the application to specify the

mixer device number.

SNDCTL_MIX_NRMIX The argument is a pointer to an

integer, which receives the number of

mixer devices in the system. Each can

be queried by using its number with

the SNDCTL_MIXERINFO ioctl. The same

information is available using the

SNDCTL_SYSINFO ioctl.

SNDCTL_MIX_NREXT The argument is a pointer to an

integer. On entry, the integer should

contain the special value -1. On

return the argument receives the

number of mixer extensions (or mixer

controls) supported by the mixer dev-

ice. More details about each exten-

sion can be obtained by

SNDCTL_MIX_EXTINFO ioctl.

SNDCTL_MIX_EXTINFO The argument is a pointer to an

oss_mixext structure which is defined

as follows:

typedef struct oss_mixext {

int dev; /* Mixer device number */ int ctrl; /* Extension number */ int type; /* Entry type */ int maxvalue; int minvalue; int flags;

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Ioctl Requests mixer(7I)

char id[16]; /* Mnemonic ID (internal use) */

int parent; /* Entry# of parent

(-1 if root) */

int dummy; /* NOT SUPPORTED */ int timestamp; char data[64]; /* Reserved */

unsigned char enum_present[32]; /* Mask

of allowed enum values */

int control_no; /* Reserved */

unsigned int desc; /* NOT SUPPORTED */ char extname[32];

int update_counter;

int filler[7]; /* Reserved */

} oss_mixext;

On entry, the dev field should be

initialized to the value -1, and the

ctrl field should be initialized with the number of the extension being accessed. Between 0, inclusive, and the value returned by

SNDCTL_MIX_NREXT, exclusive.

Mixer extensions are organized as a logical tree, starting with a root node. The root node always has a ctrl value of zero. The structure of the tree can be determined by looking at the parent field, which contains the

extension number of the parent exten-

sion, or -1 if the extension is the

root extension.

The type indicates the type of exten-

sion used. This implementation sup-

ports the following values:

MIXT_DEVROOT Root node for extension tree

MIXT_GROUP Logical grouping of controls

MXIT_ONOFF Boolean value, 0 = off, 1 = on.

MIXT_ENUM Enumerated value, 0 to maxvalue.

MIXT_MONOSLIDER Monophonic slider, 0 to 255.

MIXT_STEREOSLIDER Stereophonic slider, 0 to 255

(encoded as lower two bytes in value.)

MIXT_MARKER Place holder, can ignore.

The flags field is a bit array. This

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Ioctl Requests mixer(7I)

implementation makes use of the fol-

lowing possible bits:

MIXF_READABLE Extension's value is readable.

MIXF_WRITEABLE Extension's value is modifiable.

MIXF_POLL Extension can self-update.

MIXF_PCMVOL Extension is for master

PCM playback volume.

MIXF_MAINVOL Extension is for a typical

analog volume

MIXF_RECVOL Extension is for master

record gain.

MIXF_MONVOL Extension is for a monitor

source's gain.

The id field contains an ASCIIZ iden-

tifier for the extension. The timestamp field is set when the extension tree is first initialized.

Applications must use the same times-

tamp value when attempting to change the values. A change in the timestamp indicates a change a in the structure of the extension tree.

The enum_present field is a bit mask

of possible enumeration values. If a

bit is present in the enum_present

mask, then the corresponding enumera-

tion value is legal. The mask is in little endian order. The desc field provides information about scoping, which can be useful as layout hints to applications. The following hints are available:

MIXEXT_SCOPE_MASK Mask of possible scope

values.

MIXEXT_SCOPE_INPUT Extension is an input

control.

MIXEXT_SCOPE_OUTPUT Extension is an

output control.

MIXEXT_SCOPE_MONITOR Extension relates to

input monitoring.

MIXEXT_SCOPE_OTHER No scoping hint provided.

The extname is the full name of the extension.

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Ioctl Requests mixer(7I)

The update_counter is incremented

each time the control's value is changed.

SNDCTL_MIX_ENUMINFO The argument is a pointer to an

oss_mixer_enuminfo structure, which

is defined as follows:

typedef struct oss_mixer_enuminfo {

int dev; int ctrl; int nvalues; int version; short strindex[255]; char strings[3000];

} oss_mixer_enuminfo;

On entry, the dev field should be

initialized to the value -1, and the

ctrl field should be initialized with the number of the extension being accessed. Between 0, inclusive, and the value returned by

SNDCTL_MIX_NREXT, exclusive.

On return the nvalues field contains the number of values, and strindex contains an array of indices into the strings member, each index pointing

to an ASCIIZ describing the enumera-

tion value.

SNDCTL_MIX_READ The argument is a pointer to an

SNDCTL_MIX_WRITE oss_mixer_value structure, defined as

follows:

typedef struct oss_mixer_value {

int dev; int ctrl; int value; int flags; /* Reserved for future use. Initialize to 0 */ int timestamp; /* Must be set to

oss_mixext.timestamp */

int filler[8]; /* Reserved for future use. Initialize to 0 */

} oss_mixer_value;

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Ioctl Requests mixer(7I)

On entry, the dev field should be

initialized to the value -1, and the

ctrl field should be initialized with the number of the extension being accessed. Between 0, inclusive, and the value returned by

SNDCTL_MIX_NREXT, exclusive. Addi-

tionally, the timestamp member must be initialized to the same value as

was supplied in the oss_mixext struc-

ture used with SNDCTL_MIX_EXTINFO.

For SNDCTL_MIX_WRITE, the application

should supply the new value for the

extension. For SNDCTL_MIX_READ, the

mixer returns the extensions current

value in value. Compatibility IOCTLs The following ioctls are for compatibility use only:

SOUND_MIXER_READ_VOLUME

SOUND_MIXER_READ_PCM

SOUND_MIXER_READ_OGAIN

SOUND_MIXER_READ_RECGAIN

SOUND_MIXER_READ_RECLEV

SOUND_MIXER_READ_IGAIN

SOUND_MIXER_READ_RECSRC

SOUND_MIXER_READ_RECMASK

SOUND_MIXER_READ_DEVMASK

SOUND_MIXER_READ_STEREODEVS

SOUND_MIXER_WRITE_VOLUME

SOUND_MIXER_WRITE_PCM

SOUND_MIXER_WRITE_OGAIN

SOUND_MIXER_WRITE_RECGAIN

SOUND_MIXER_WRITE_RECLEV

SOUND_MIXER_WRITE_IGAIN

SOUND_MIXER_WRITE_RECSRC

SOUND_MIXER_WRITE_RECMASK

SOUND_MIXER_INFO

SNDCTL_AUDIOINFO_EX

SNDCTL_ENGINEINFO

These ioctls can affect the software volume levels associ-

ated with the calling process. They have no effect on the physical hardware levels or settings. They should not be used in new applications.

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Ioctl Requests mixer(7I)

ERRORS

An ioctl() fails if: EINVAL The parameter changes requested in the ioctl are invalid or are not supported by the device. ENXIO The device or extension referenced does not exist. FILES

/dev/mixer Symbolic link to the pseudo mixer device for

the system /dev/sndstat Sound status device

ATTRIBUTES

See attributes(5) for a description of the following attri-

butes:

_____________________________________________________________

| ATTRIBUTE TYPE | ATTRIBUTE VALUE |

|____________________|_______________________________________|

| Architecture | SPARC, x86 |

|____________________|_______________________________________|

| Availability | SUNWcs, driver/audio,|

| | system/header/header-audio |

|____________________|_______________________________________|

| Interface Stability| See below. |

|____________________|_______________________________________|

The information and mixer extension IOCTLs are Uncommitted.

The Compatibility IOCTLs are Obsolete Uncommitted. The extension names are Uncommitted.

BUGS

The names of mixer extensions are not guaranteed to be

predictable.

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Manual Pages for UNIX Operating System command usage for man mixer

Ioctl Requests mixer(7I)

NAME

mixer - generic mixer device interface

SYNOPSIS

DESCRIPTION

The /dev/mixer pseudo-device is provided for two purposes:

/dev/mixer pseudo-device provides interfaces to

o The second purpose is for mixer panel type applica-

/dev/mixer, or a against a file descriptor open to any other

audio devices and mixers are available on the system, and

information about the audio devices or mixers, respectively.

Ioctl Requests mixer(7I)

int nummixers; /* # of mixer devices */

SNDCTL_AUDIOINFO, nummixers which pro-

vides a count of mixers on the system,

one or more mixers, although more typi-

and one mixer for each card.

Ioctl Requests mixer(7I)

int caps; /* PCM_CAP_INPUT, PCM_CAP_OUTPUT */

int mixer_dev;

ing: dev, name, card_number, mixer_dev,

Ioctl Requests mixer(7I)

issuing the ioctl against a real mixer

The mixer_dev is the mixer device number

PCM_CAP_INPUT, PCM_CAP_OUTPUT, and

Ioctl Requests mixer(7I)

against a real mixer or dsp device, the

Ioctl Requests mixer(7I)

oss_mixer_info, which has the following

typedef struct oss_mixerinfo {

} oss_mixerinfo;

mixers (exclusive) returned by

against a real mixer or dsp device, the

is overwritten with the mixer number for

Ioctl Requests mixer(7I)

mixer framework each time the settings

the aggregate audio device this mixer is

The nrext field is the number of mixer

extensions available on this mixer. See

physical mixer, such as

/dev/sound/audio810:0mixer. Applications

mixer settings.

The pseudo /dev/mixer device supports ioctls that can change

Those ioctls should only be used by dedicated mixer applica-

Ioctl Requests mixer(7I)

mixer device that is associated with the current file

Applications should not assume that a single /dev/mixer node

ice path for the real mixer device, and issue ioctls on a

patibility the mixer allows the application to specify the

mixer device number.

mixer devices in the system. Each can

number of mixer extensions (or mixer

controls) supported by the mixer dev-

Ioctl Requests mixer(7I)

Ioctl Requests mixer(7I)

MIXEXT_SCOPE_INPUT Extension is an input

MIXEXT_SCOPE_OUTPUT Extension is an

Ioctl Requests mixer(7I)

oss_mixer_enuminfo structure, which

typedef struct oss_mixer_enuminfo {

} oss_mixer_enuminfo;

SNDCTL_MIX_WRITE oss_mixer_value structure, defined as

typedef struct oss_mixer_value {

} oss_mixer_value;

Ioctl Requests mixer(7I)

mixer returns the extensions current

Ioctl Requests mixer(7I)

ERRORS

/dev/mixer Symbolic link to the pseudo mixer device for

ATTRIBUTES

| ATTRIBUTE TYPE | ATTRIBUTE VALUE |

The information and mixer extension IOCTLs are Uncommitted.

SEE ALSO

BUGS

The names of mixer extensions are not guaranteed to be