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.. -*- coding: utf-8; mode: rst -*-
.. _audio_data_types:
Audio Data Types
This section describes the structures, data types and defines used when
talking to the audio device.
.. c:type:: audio_stream_source
The audio stream source is set through the AUDIO_SELECT_SOURCE call
and can take the following values, depending on whether we are replaying
from an internal (demux) or external (user write) source.
.. code-block:: c
typedef enum {
} audio_stream_source_t;
AUDIO_SOURCE_DEMUX selects the demultiplexer (fed either by the
frontend or the DVR device) as the source of the video stream. If
AUDIO_SOURCE_MEMORY is selected the stream comes from the application
through the ``write()`` system call.
.. c:type:: audio_play_state
The following values can be returned by the AUDIO_GET_STATUS call
representing the state of audio playback.
.. code-block:: c
typedef enum {
} audio_play_state_t;
.. c:type:: audio_channel_select
The audio channel selected via AUDIO_CHANNEL_SELECT is determined by
the following values.
.. code-block:: c
typedef enum {
} audio_channel_select_t;
.. c:type:: audio_status
The AUDIO_GET_STATUS call returns the following structure informing
about various states of the playback operation.
.. code-block:: c
typedef struct audio_status {
boolean AV_sync_state;
boolean mute_state;
audio_play_state_t play_state;
audio_stream_source_t stream_source;
audio_channel_select_t channel_select;
boolean bypass_mode;
audio_mixer_t mixer_state;
} audio_status_t;
.. c:type:: audio_mixer
The following structure is used by the AUDIO_SET_MIXER call to set the
audio volume.
.. code-block:: c
typedef struct audio_mixer {
unsigned int volume_left;
unsigned int volume_right;
} audio_mixer_t;
.. _audio_encodings:
audio encodings
A call to AUDIO_GET_CAPABILITIES returns an unsigned integer with the
following bits set according to the hardwares capabilities.
.. code-block:: c
#define AUDIO_CAP_DTS 1
#define AUDIO_CAP_LPCM 2
#define AUDIO_CAP_MP1 4
#define AUDIO_CAP_MP2 8
#define AUDIO_CAP_MP3 16
#define AUDIO_CAP_AAC 32
#define AUDIO_CAP_OGG 64
#define AUDIO_CAP_SDDS 128
#define AUDIO_CAP_AC3 256