Documentation/media/uapi/dvb/audio_data_types.rst

   1 .. -*- coding: utf-8; mode: rst -*-
   2
   3 .. _audio_data_types:
   4
   5 ****************
   6 Audio Data Types
   7 ****************
   8
   9 This section describes the structures, data types and defines used when
  10 talking to the audio device.
  11
  12 .. c:type:: audio_stream_source
  13
  14 The audio stream source is set through the AUDIO_SELECT_SOURCE call
  15 and can take the following values, depending on whether we are replaying
  16 from an internal (demux) or external (user write) source.
  17
  18
  19 .. code-block:: c
  20
  21     typedef enum {
  22         AUDIO_SOURCE_DEMUX,
  23         AUDIO_SOURCE_MEMORY
  24     } audio_stream_source_t;
  25
  26 AUDIO_SOURCE_DEMUX selects the demultiplexer (fed either by the
  27 frontend or the DVR device) as the source of the video stream. If
  28 AUDIO_SOURCE_MEMORY is selected the stream comes from the application
  29 through the ``write()`` system call.
  30
  31
  32 .. c:type:: audio_play_state
  33
  34 The following values can be returned by the AUDIO_GET_STATUS call
  35 representing the state of audio playback.
  36
  37
  38 .. code-block:: c
  39
  40     typedef enum {
  41         AUDIO_STOPPED,
  42         AUDIO_PLAYING,
  43         AUDIO_PAUSED
  44     } audio_play_state_t;
  45
  46
  47 .. c:type:: audio_channel_select
  48
  49 The audio channel selected via AUDIO_CHANNEL_SELECT is determined by
  50 the following values.
  51
  52
  53 .. code-block:: c
  54
  55     typedef enum {
  56         AUDIO_STEREO,
  57         AUDIO_MONO_LEFT,
  58         AUDIO_MONO_RIGHT,
  59         AUDIO_MONO,
  60         AUDIO_STEREO_SWAPPED
  61     } audio_channel_select_t;
  62
  63
  64 .. c:type:: audio_status
  65
  66 The AUDIO_GET_STATUS call returns the following structure informing
  67 about various states of the playback operation.
  68
  69
  70 .. code-block:: c
  71
  72     typedef struct audio_status {
  73         boolean AV_sync_state;
  74         boolean mute_state;
  75         audio_play_state_t play_state;
  76         audio_stream_source_t stream_source;
  77         audio_channel_select_t channel_select;
  78         boolean bypass_mode;
  79         audio_mixer_t mixer_state;
  80     } audio_status_t;
  81
  82
  83 .. c:type:: audio_mixer
  84
  85 The following structure is used by the AUDIO_SET_MIXER call to set the
  86 audio volume.
  87
  88
  89 .. code-block:: c
  90
  91     typedef struct audio_mixer {
  92         unsigned int volume_left;
  93         unsigned int volume_right;
  94     } audio_mixer_t;
  95
  96
  97 .. _audio_encodings:
  98
  99 audio encodings
 100 ===============
 101
 102 A call to AUDIO_GET_CAPABILITIES returns an unsigned integer with the
 103 following bits set according to the hardwares capabilities.
 104
 105
 106 .. code-block:: c
 107
 108      #define AUDIO_CAP_DTS    1
 109      #define AUDIO_CAP_LPCM   2
 110      #define AUDIO_CAP_MP1    4
 111      #define AUDIO_CAP_MP2    8
 112      #define AUDIO_CAP_MP3   16
 113      #define AUDIO_CAP_AAC   32
 114      #define AUDIO_CAP_OGG   64
 115      #define AUDIO_CAP_SDDS 128
 116      #define AUDIO_CAP_AC3  256
 117
 118 .. c:type:: audio_karaoke
 119
 120 The ioctl AUDIO_SET_KARAOKE uses the following format:
 121
 122
 123 .. code-block:: c
 124
 125     typedef
 126     struct audio_karaoke {
 127         int vocal1;
 128         int vocal2;
 129         int melody;
 130     } audio_karaoke_t;
 131
 132 If Vocal1 or Vocal2 are non-zero, they get mixed into left and right t
 133 at 70% each. If both, Vocal1 and Vocal2 are non-zero, Vocal1 gets mixed
 134 into the left channel and Vocal2 into the right channel at 100% each. Ff
 135 Melody is non-zero, the melody channel gets mixed into left and right.
 136
 137
 138 .. c:type:: audio_attributes
 139
 140 The following attributes can be set by a call to AUDIO_SET_ATTRIBUTES:
 141
 142
 143 .. code-block:: c
 144
 145      typedef uint16_t audio_attributes_t;
 146      /*   bits: descr. */
 147      /*   15-13 audio coding mode (0=ac3, 2=mpeg1, 3=mpeg2ext, 4=LPCM, 6=DTS, */
 148      /*   12    multichannel extension */
 149      /*   11-10 audio type (0=not spec, 1=language included) */
 150      /*    9- 8 audio application mode (0=not spec, 1=karaoke, 2=surround) */
 151      /*    7- 6 Quantization / DRC (mpeg audio: 1=DRC exists)(lpcm: 0=16bit,  */
 152      /*    5- 4 Sample frequency fs (0=48kHz, 1=96kHz) */
 153      /*    2- 0 number of audio channels (n+1 channels) */