This system call opens a named audio device (e.g. /dev/dvb/adapter0/audio0) for subsequent use. When an open() call has succeeded, the device will be ready for use. The significance of blocking or non-blocking mode is described in the documentation for functions where there is a difference. It does not affect the semantics of the open() call itself. A device opened in blocking mode can later be put into non-blocking mode (and vice versa) using the F_SETFL command of the fcntl system call. This is a standard system call, documented in the Linux manual page for fcntl. Only one user can open the Audio Device in O_RDWR mode. All other attempts to open the device in this mode will fail, and an error code will be returned. If the Audio Device is opened in O_RDONLY mode, the only ioctl call that can be used is AUDIO_GET_STATUS. All other call will return with an error code.

int open(const char ⋆deviceName, int flags);

const char *deviceName

Name of specific audio device.

int flags

A bit-wise OR of the following flags:

O_RDONLY read-only access

O_RDWR read/write access

O_NONBLOCK open in non-blocking mode

(blocking mode is the default)

ENODEV

Device driver not loaded/available.

EBUSY

Device or resource busy.

EINVAL

Invalid argument.

This system call closes a previously opened audio device.

int close(int fd);

int fd

File descriptor returned by a previous call to open().

EBADF

fd is not a valid open file descriptor.

This system call can only be used if AUDIO_SOURCE_MEMORY is selected in the ioctl call AUDIO_SELECT_SOURCE. The data provided shall be in PES format. If O_NONBLOCK is not specified the function will block until buffer space is available. The amount of data to be transferred is implied by count.

size_t write(int fd, const void ⋆buf, size_t count);

int fd

File descriptor returned by a previous call to open().

void *buf

Pointer to the buffer containing the PES data.

size_t count

Size of buf.

EPERM

Mode AUDIO_SOURCE_MEMORY not selected.

ENOMEM

Attempted to write more data than the internal buffer can hold.

EBADF

fd is not a valid open file descriptor.

This ioctl call asks the Audio Device to stop playing the current stream.

int ioctl(int fd, int request = AUDIO_STOP);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_STOP for this command.

This ioctl call asks the Audio Device to start playing an audio stream from the selected source.

int ioctl(int fd, int request = AUDIO_PLAY);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_PLAY for this command.

This ioctl call suspends the audio stream being played. Decoding and playing are paused. It is then possible to restart again decoding and playing process of the audio stream using AUDIO_CONTINUE command.

If AUDIO_SOURCE_MEMORY is selected in the ioctl call AUDIO_SELECT_SOURCE, the DVB-subsystem will not decode (consume) any more data until the ioctl call AUDIO_CONTINUE or AUDIO_PLAY is performed.

int ioctl(int fd, int request = AUDIO_PAUSE);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_PAUSE for this command.

This ioctl restarts the decoding and playing process previously paused with AUDIO_PAUSE command.

It only works if the stream were previously stopped with AUDIO_PAUSE

int ioctl(int fd, int request = AUDIO_CONTINUE);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_CONTINUE for this command.

This ioctl call informs the audio device which source shall be used for the input data. The possible sources are demux or memory. If AUDIO_SOURCE_MEMORY is selected, the data is fed to the Audio Device through the write command.

int ioctl(int fd, int request = AUDIO_SELECT_SOURCE, audio_stream_source_t source);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_SELECT_SOURCE for this command.

audio_stream_source_t source

Indicates the source that shall be used for the Audio stream.

This ioctl call asks the audio device to mute the stream that is currently being played.

int ioctl(int fd, int request = AUDIO_SET_MUTE, boolean state);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_SET_MUTE for this command.

boolean state

Indicates if audio device shall mute or not.

TRUE Audio Mute

FALSE Audio Un-mute

This ioctl call asks the Audio Device to turn ON or OFF A/V synchronization.

int ioctl(int fd, int request = AUDIO_SET_AV_SYNC, boolean state);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_AV_SYNC for this command.

boolean state

Tells the DVB subsystem if A/V synchronization shall be ON or OFF.

TRUE AV-sync ON

FALSE AV-sync OFF

This ioctl call asks the Audio Device to bypass the Audio decoder and forward the stream without decoding. This mode shall be used if streams that can’t be handled by the DVB system shall be decoded. Dolby DigitalTM streams are automatically forwarded by the DVB subsystem if the hardware can handle it.

int ioctl(int fd, int request = AUDIO_SET_BYPASS_MODE, boolean mode);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_SET_BYPASS_MODE for this command.

boolean mode

Enables or disables the decoding of the current Audio stream in the DVB subsystem.

TRUE Bypass is disabled

FALSE Bypass is enabled

This ioctl call asks the Audio Device to select the requested channel if possible.

int ioctl(int fd, int request = AUDIO_CHANNEL_SELECT, audio_channel_select_t);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_CHANNEL_SELECT for this command.

audio_channel_select_t ch

Select the output format of the audio (mono left/right, stereo).

This ioctl call asks the Audio Device to select the requested channel for bilingual streams if possible.

int ioctl(int fd, int request = AUDIO_BILINGUAL_CHANNEL_SELECT, audio_channel_select_t);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_BILINGUAL_CHANNEL_SELECT for this command.

audio_channel_select_t ch

Select the output format of the audio (mono left/right, stereo).

This ioctl call asks the Audio Device to return the current PTS timestamp.

int ioctl(int fd, int request = AUDIO_GET_PTS, __u64 *pts);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_GET_PTS for this command.

__u64 *pts

Returns the 33-bit timestamp as defined in ITU T-REC-H.222.0 / ISO/IEC 13818-1.

The PTS should belong to the currently played frame if possible, but may also be a value close to it like the PTS of the last decoded frame or the last PTS extracted by the PES parser.

This ioctl call asks the Audio Device to return the current state of the Audio Device.

int ioctl(int fd, int request = AUDIO_GET_STATUS, struct audio_status ⋆status);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_GET_STATUS for this command.

struct audio_status *status

Returns the current state of Audio Device.

This ioctl call asks the Audio Device to tell us about the decoding capabilities of the audio hardware.

int ioctl(int fd, int request = AUDIO_GET_CAPABILITIES, unsigned int ⋆cap);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_GET_CAPABILITIES for this command.

unsigned int *cap

Returns a bit array of supported sound formats.

This ioctl call asks the Audio Device to clear all software and hardware buffers of the audio decoder device.

int ioctl(int fd, int request = AUDIO_CLEAR_BUFFER);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_CLEAR_BUFFER for this command.

This ioctl selects which sub-stream is to be decoded if a program or system stream is sent to the video device. If no audio stream type is set the id has to be in [0xC0,0xDF] for MPEG sound, in [0x80,0x87] for AC3 and in [0xA0,0xA7] for LPCM. More specifications may follow for other stream types. If the stream type is set the id just specifies the substream id of the audio stream and only the first 5 bits are recognized.

int ioctl(int fd, int request = AUDIO_SET_ID, int id);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_SET_ID for this command.

int id

audio sub-stream id

This ioctl lets you adjust the mixer settings of the audio decoder.

int ioctl(int fd, int request = AUDIO_SET_MIXER, audio_mixer_t ⋆mix);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_SET_ID for this command.

audio_mixer_t *mix

mixer settings.

This ioctl tells the driver which kind of audio stream to expect. This is useful if the stream offers several audio sub-streams like LPCM and AC3.

int ioctl(fd, int request = AUDIO_SET_STREAMTYPE, int type);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_SET_STREAMTYPE for this command.

int type

stream type

EINVAL

type is not a valid or supported stream type.

This ioctl can be used to set the extension id for MPEG streams in DVD playback. Only the first 3 bits are recognized.

int ioctl(fd, int request = AUDIO_SET_EXT_ID, int id);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_SET_EXT_ID for this command.

int id

audio sub_stream_id

EINVAL

id is not a valid id.

This ioctl is intended for DVD playback and allows you to set certain information about the audio stream.

int ioctl(fd, int request = AUDIO_SET_ATTRIBUTES, audio_attributes_t attr );

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_SET_ATTRIBUTES for this command.

audio_attributes_t attr

audio attributes according to section ??

EINVAL

attr is not a valid or supported attribute setting.

This ioctl allows one to set the mixer settings for a karaoke DVD.

int ioctl(fd, int request = AUDIO_SET_KARAOKE, audio_karaoke_t ⋆karaoke);

int fd

File descriptor returned by a previous call to open().

int request

Equals AUDIO_SET_KARAOKE for this command.

audio_karaoke_t *karaoke

karaoke settings according to section ??.

EINVAL

karaoke is not a valid or supported karaoke setting.