The Audio I/O API provides functions for controlling audio devices.

Required Header

#include <audio_io.h>

Overview

The Audio I/O API provides a set of functions to directly manage the system audio devices. It gives easy access to the hardware layer of the sound card with a professional multichannel audio interface. It should be used for activities requiring raw audio data buffers(PCM format).

Programming the interface requires first obtaining a handle to the device, via the audio_in_create() or audio_out_create_new() function.

The input and output devices both have an available set of queries, to find the suggested buffer size, sampling rate, channel type, and sample type. For output, there is an additional query, to get the sound type (these types are defined in the Sound Manager API).

Reading from input device is done by audio_in_read() with allocated buffer after audio_in_prepare(). Similarly, writing to output device is done by audio_out_write() with allocated buffer after audio_out_prepare().

Enumeration Type Documentation

enum audio_channel_e

Enumeration for audio channel.

Since :: 2.3.1

Enumerator:

AUDIO_CHANNEL_MONO	1 channel, mono
AUDIO_CHANNEL_STEREO	2 channel, stereo

enum audio_io_error_e

Enumeration for audio input and output error.

Since :: 2.3.1

Enumerator:

AUDIO_IO_ERROR_NONE	Successful
AUDIO_IO_ERROR_OUT_OF_MEMORY	Out of memory
AUDIO_IO_ERROR_INVALID_PARAMETER	Invalid parameter
AUDIO_IO_ERROR_INVALID_OPERATION	Invalid operation
AUDIO_IO_ERROR_PERMISSION_DENIED	Device open error by security
AUDIO_IO_ERROR_NOT_SUPPORTED	Not supported
AUDIO_IO_ERROR_DEVICE_POLICY_RESTRICTION	Device policy restriction (Since 3.0)
AUDIO_IO_ERROR_DEVICE_NOT_OPENED	Device open error
AUDIO_IO_ERROR_DEVICE_NOT_CLOSED	Device close error
AUDIO_IO_ERROR_INVALID_BUFFER	Invalid buffer pointer
AUDIO_IO_ERROR_SOUND_POLICY	Sound policy error
AUDIO_IO_ERROR_INVALID_STATE	Invalid state (Since 3.0)
AUDIO_IO_ERROR_NOT_SUPPORTED_TYPE	Not supported stream type (Since 3.0)

enum audio_io_state_e

Enumeration for audio input and output state.

Since :: 3.0

Enumerator:

AUDIO_IO_STATE_IDLE	Audio-io handle is created, but not prepared
AUDIO_IO_STATE_RUNNING	Audio-io handle is ready and the stream is running
AUDIO_IO_STATE_PAUSED	Audio-io handle is ready and the stream is paused

enum audio_sample_type_e

Enumeration for audio sample type with bit depth.

Since :: 2.3.1

Enumerator:

AUDIO_SAMPLE_TYPE_U8	Unsigned 8-bit audio samples
AUDIO_SAMPLE_TYPE_S16_LE	Signed 16-bit audio samples
AUDIO_SAMPLE_TYPE_S24_LE	Signed 24-bit audio samples (Since 5.0)
AUDIO_SAMPLE_TYPE_S24_32_LE	Signed 24-bit (packed in 32-bit) audio samples (Since 5.0)