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
  13 .. _audio-stream-source-t:
  14
  15 audio_stream_source_t
  16 =====================
  17
  18 The audio stream source is set through the AUDIO_SELECT_SOURCE call
  19 and can take the following values, depending on whether we are replaying
  20 from an internal (demux) or external (user write) source.
  21
  22
  23 .. code-block:: c
  24
  25     typedef enum {
  26         AUDIO_SOURCE_DEMUX,
  27         AUDIO_SOURCE_MEMORY
  28     } audio_stream_source_t;
  29
  30 AUDIO_SOURCE_DEMUX selects the demultiplexer (fed either by the
  31 frontend or the DVR device) as the source of the video stream. If
  32 AUDIO_SOURCE_MEMORY is selected the stream comes from the application
  33 through the ``write()`` system call.
  34
  35
  36 .. _audio-play-state-t:
  37
  38 audio_play_state_t
  39 ==================
  40
  41 The following values can be returned by the AUDIO_GET_STATUS call
  42 representing the state of audio playback.
  43
  44
  45 .. code-block:: c
  46
  47     typedef enum {
  48         AUDIO_STOPPED,
  49         AUDIO_PLAYING,
  50         AUDIO_PAUSED
  51     } audio_play_state_t;
  52
  53
  54 .. _audio-channel-select-t:
  55
  56 audio_channel_select_t
  57 ======================
  58
  59 The audio channel selected via AUDIO_CHANNEL_SELECT is determined by
  60 the following values.
  61
  62
  63 .. code-block:: c
  64
  65     typedef enum {
  66         AUDIO_STEREO,
  67         AUDIO_MONO_LEFT,
  68         AUDIO_MONO_RIGHT,
  69         AUDIO_MONO,
  70         AUDIO_STEREO_SWAPPED
  71     } audio_channel_select_t;
  72
  73
  74 .. _audio-status:
  75
  76 struct audio_status
  77 ===================
  78
  79 The AUDIO_GET_STATUS call returns the following structure informing
  80 about various states of the playback operation.
  81
  82
  83 .. code-block:: c
  84
  85     typedef struct audio_status {
  86         boolean AV_sync_state;
  87         boolean mute_state;
  88         audio_play_state_t play_state;
  89         audio_stream_source_t stream_source;
  90         audio_channel_select_t channel_select;
  91         boolean bypass_mode;
  92         audio_mixer_t mixer_state;
  93     } audio_status_t;
  94
  95
  96 .. _audio-mixer:
  97
  98 struct audio_mixer
  99 ==================
 100
 101 The following structure is used by the AUDIO_SET_MIXER call to set the
 102 audio volume.
 103
 104
 105 .. code-block:: c
 106
 107     typedef struct audio_mixer {
 108         unsigned int volume_left;
 109         unsigned int volume_right;
 110     } audio_mixer_t;
 111
 112
 113 .. _audio_encodings:
 114
 115 audio encodings
 116 ===============
 117
 118 A call to AUDIO_GET_CAPABILITIES returns an unsigned integer with the
 119 following bits set according to the hardwares capabilities.
 120
 121
 122 .. code-block:: c
 123
 124      #define AUDIO_CAP_DTS    1
 125      #define AUDIO_CAP_LPCM   2
 126      #define AUDIO_CAP_MP1    4
 127      #define AUDIO_CAP_MP2    8
 128      #define AUDIO_CAP_MP3   16
 129      #define AUDIO_CAP_AAC   32
 130      #define AUDIO_CAP_OGG   64
 131      #define AUDIO_CAP_SDDS 128
 132      #define AUDIO_CAP_AC3  256
 133
 134
 135 .. _audio-karaoke:
 136
 137 struct audio_karaoke
 138 ====================
 139
 140 The ioctl AUDIO_SET_KARAOKE uses the following format:
 141
 142
 143 .. code-block:: c
 144
 145     typedef
 146     struct audio_karaoke {
 147         int vocal1;
 148         int vocal2;
 149         int melody;
 150     } audio_karaoke_t;
 151
 152 If Vocal1 or Vocal2 are non-zero, they get mixed into left and right t
 153 at 70% each. If both, Vocal1 and Vocal2 are non-zero, Vocal1 gets mixed
 154 into the left channel and Vocal2 into the right channel at 100% each. Ff
 155 Melody is non-zero, the melody channel gets mixed into left and right.
 156
 157
 158 .. _audio-attributes-t:
 159
 160 audio attributes
 161 ================
 162
 163 The following attributes can be set by a call to AUDIO_SET_ATTRIBUTES:
 164
 165
 166 .. code-block:: c
 167
 168      typedef uint16_t audio_attributes_t;
 169      /*   bits: descr. */
 170      /*   15-13 audio coding mode (0=ac3, 2=mpeg1, 3=mpeg2ext, 4=LPCM, 6=DTS, */
 171      /*   12    multichannel extension */
 172      /*   11-10 audio type (0=not spec, 1=language included) */
 173      /*    9- 8 audio application mode (0=not spec, 1=karaoke, 2=surround) */
 174      /*    7- 6 Quantization / DRC (mpeg audio: 1=DRC exists)(lpcm: 0=16bit,  */
 175      /*    5- 4 Sample frequency fs (0=48kHz, 1=96kHz) */
 176      /*    2- 0 number of audio channels (n+1 channels) */