audio_support

- audio driver support routines and interface

Synopsis

#include <sys/audio.h>

Description

The audio support module supports audio drivers that use the new audio driver architecture. It also provides a limited number of ioctl(2) functions for application programmers.

DATA STRUCTURES

The following data structures are defined to manage the different audio device types and channels.

Device Types

The following enumeration lists a number of generic device types.

typedef enum {
    UNDEFINED, AUDIO, AUDIOCTL, USER1, USER2, USER3
} audio_device_type_e;

Currently, the Solaris audio mixer implements only the AUDIO and AUDIOCTL audio device types. See the mixer(7I) manual page for details. The USER1, USER2 and USER3 device types allow third parties to write audio personality modules of their own.

Channel Structure

This structure is used to get and set state information on individual channels.

struct audio_channel {
    pid_t            pid;            /* application's process ID */
    uint_t            ch_number;    /* device channel */
    audio_device_type_e    dev_type;        /* device type */
    uint_t            info_size;    /* size of channel's */
                                /* info structure */
    void                *info;        /* channel state information */
;
typedef struct audio_channel audio_channel_t;

The ch_number must specify the specific channel number to get or set. When the ioctl() returns, the pid contains the process ID of the process that has that channel open and dev_type will contain the device type. If pid is 0 (zero), then the channel is not open. The pointer *info must point to a buffer large enough to hold whatever audio device-related state structure that may be returned. Currently, only the audio_info_t structure is returned. See the audio(7I) and mixer(7I) man pages for more information.

ioctls

The audio support driver provides the following ioctls():

AUDIO_GET_CH_NUMBER

This ioctl() returns the channel number pointed to by the file descriptor. It is returned in the integer pointer of the ioctl() argument.

AUDIO_GET_CH_TYPE

This ioctl() returns the type of channel the process has open. It is returned in the audio_device_type_e enumeration pointer of the ioctl() argument.

AUDIO_GET_NUM_CHS

This ioctl() returns the number of channels the device supports. It is returned in the integer pointer of the ioctl() argument.

MACROS

The following macro can be used to initialize data structures. The established convention is that the state corresponding to a field set to -1 will not be modified.

AUDIO_INIT(I, S)

Where I is a pointer to an info structure and S is the size of that structure.

The following code segment demonstrates how to use this macro:

audio_info_t    info;

AUDIO_INIT(&info, sizeof(info));
info.play.port = AUDIO_HEADPHONE;
err = ioctl(audio_fd, AUDIO_SETINFO, &info);

Errors

EINVAL

The ioctl() is invalid for this file descriptor. The audio_channel_t structure's info pointer does not point to a buffer, or the ch_number is bad.

ENOMEM

The ioctl() failed due to lack of memory.

Files

/usr/share/audio/samples

Audio sample files

Attributes

See attributes(5) for a description of the following attributes:

See Also

ioctl(2), attributes(5), audio(7I), mixer(7I), streamio(7I)

FUTURE DIRECTIONS

Over time, additional audio personality modules will be added. Audio application programmers are encouraged to review this man page with each Solaris release for new audio personality modules.