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diff --git a/Documentation/userspace-api/media/dvb/legacy_dvb_audio.rst b/Documentation/userspace-api/media/dvb/legacy_dvb_audio.rst new file mode 100644 index 000000000000..d15088748f55 --- /dev/null +++ b/Documentation/userspace-api/media/dvb/legacy_dvb_audio.rst @@ -0,0 +1,447 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later OR GPL-2.0 + +.. c:namespace:: dtv.legacy.audio + +.. _dvb_audio: + +================ +DVB Audio Device +================ + +.. attention:: Do **not** use in new drivers! + See: :ref:`legacy_dvb_decoder_notes` + +The DVB audio device controls the MPEG2 audio decoder of the DVB +hardware. It can be accessed through ``/dev/dvb/adapter?/audio?``. Data +types and ioctl definitions can be accessed by including +``linux/dvb/audio.h`` in your application. + +Please note that most DVB cards don’t have their own MPEG decoder, which +results in the omission of the audio and video device. + +These ioctls were also used by V4L2 to control MPEG decoders implemented +in V4L2. The use of these ioctls for that purpose has been made obsolete +and proper V4L2 ioctls or controls have been created to replace that +functionality. Use :ref:`V4L2 ioctls<audio>` for new drivers! + + +Audio Data Types +================ + +This section describes the structures, data types and defines used when +talking to the audio device. + + +----- + + +audio_stream_source_t +--------------------- + +Synopsis +~~~~~~~~ + +.. c:enum:: audio_stream_source_t + +.. code-block:: c + + typedef enum { + AUDIO_SOURCE_DEMUX, + AUDIO_SOURCE_MEMORY + } audio_stream_source_t; + +Constants +~~~~~~~~~ + +.. flat-table:: + :header-rows: 0 + :stub-columns: 0 + + - .. + + - ``AUDIO_SOURCE_DEMUX`` + + - :cspan:`1` Selects the demultiplexer (fed either by the frontend + or the DVR device) as the source of the video stream. + + - .. + + - ``AUDIO_SOURCE_MEMORY`` + + - Selects the stream from the application that comes through + the `write()`_ system call. + +Description +~~~~~~~~~~~ + +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. + +The data fed to the decoder is also controlled by the PID-filter. +Output selection: :c:type:`dmx_output` ``DMX_OUT_DECODER``. + + +----- + + +audio_play_state_t +------------------ + +Synopsis +~~~~~~~~ + +.. c:enum:: audio_play_state_t + +.. code-block:: c + + typedef enum { + AUDIO_STOPPED, + AUDIO_PLAYING, + AUDIO_PAUSED + } audio_play_state_t; + +Constants +~~~~~~~~~ + +.. flat-table:: + :header-rows: 0 + :stub-columns: 0 + + - .. + + - ``AUDIO_STOPPED`` + + - Audio is stopped. + + - .. + + - ``AUDIO_PLAYING`` + + - Audio is currently playing. + + - .. + + - ``AUDIO_PAUSE`` + + - Audio is frozen. + +Description +~~~~~~~~~~~ + +This values can be returned by the `AUDIO_GET_STATUS`_ call +representing the state of audio playback. + + +----- + + +audio_channel_select_t +---------------------- + +Synopsis +~~~~~~~~ + +.. c:enum:: audio_channel_select_t + +.. code-block:: c + + typedef enum { + AUDIO_STEREO, + AUDIO_MONO_LEFT, + AUDIO_MONO_RIGHT, + AUDIO_MONO, + AUDIO_STEREO_SWAPPED + } audio_channel_select_t; + +Constants +~~~~~~~~~ + +.. flat-table:: + :header-rows: 0 + :stub-columns: 0 + + - .. + + - ``AUDIO_STEREO`` + + - Stereo. + + - .. + + - ``AUDIO_MONO_LEFT`` + + - Mono, select left stereo channel as source. + + - .. + + - ``AUDIO_MONO_RIGHT`` + + - Mono, select right stereo channel as source. + + - .. + + - ``AUDIO_MONO`` + + - Mono source only. + + - .. + + - ``AUDIO_STEREO_SWAPPED`` + + - Stereo, swap L & R. + +Description +~~~~~~~~~~~ + +The audio channel selected via `AUDIO_CHANNEL_SELECT`_ is determined by +this values. + + +----- + + +audio_mixer_t +------------- + +Synopsis +~~~~~~~~ + +.. c:struct:: audio_mixer + +.. code-block:: c + + typedef struct audio_mixer { + unsigned int volume_left; + unsigned int volume_right; + } audio_mixer_t; + +Variables +~~~~~~~~~ + +.. flat-table:: + :header-rows: 0 + :stub-columns: 0 + + - .. + + - ``unsigned int volume_left`` + + - Volume left channel. + Valid range: 0 ... 255 + + - .. + + - ``unsigned int volume_right`` + + - Volume right channel. + Valid range: 0 ... 255 + +Description +~~~~~~~~~~~ + +This structure is used by the `AUDIO_SET_MIXER`_ call to set the +audio volume. + + +----- + + +audio_status +------------ + +Synopsis +~~~~~~~~ + +.. c:struct:: audio_status + +.. code-block:: c + + typedef struct audio_status { + int AV_sync_state; + int mute_state; + audio_play_state_t play_state; + audio_stream_source_t stream_source; + audio_channel_select_t channel_select; + int bypass_mode; + audio_mixer_t mixer_state; + } audio_status_t; + +Variables +~~~~~~~~~ + +.. flat-table:: + :header-rows: 0 + :stub-columns: 0 + + - .. + + - :rspan:`2` ``int AV_sync_state`` + + - :cspan:`1` Shows if A/V synchronization is ON or OFF. + + - .. + + - TRUE ( != 0 ) + + - AV-sync ON. + + - .. + + - FALSE ( == 0 ) + + - AV-sync OFF. + + - .. + + - :rspan:`2` ``int mute_state`` + + - :cspan:`1` Indicates if audio is muted or not. + + - .. + + - TRUE ( != 0 ) + + - mute audio + + - .. + + - FALSE ( == 0 ) + + - unmute audio + + - .. + + - `audio_play_state_t`_ ``play_state`` + + - Current playback state. + + - .. + + - `audio_stream_source_t`_ ``stream_source`` + + - Current source of the data. + + - .. + + - :rspan:`2` ``int bypass_mode`` + + - :cspan:`1` Is the decoding of the current Audio stream in + the DVB subsystem enabled or disabled. + + - .. + + - TRUE ( != 0 ) + + - Bypass disabled. + + - .. + + - FALSE ( == 0 ) + + - Bypass enabled. + + - .. + + - `audio_mixer_t`_ ``mixer_state`` + + - Current volume settings. + +Description +~~~~~~~~~~~ + +The `AUDIO_GET_STATUS`_ call returns this structure as information +about various states of the playback operation. + + +----- + + +audio encodings +--------------- + +Synopsis +~~~~~~~~ + +.. 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 + +Constants +~~~~~~~~~ + +.. flat-table:: + :header-rows: 0 + :stub-columns: 0 + + - .. + + - ``AUDIO_CAP_DTS`` + + - :cspan:`1` The hardware accepts DTS audio tracks. + + - .. + + - ``AUDIO_CAP_LPCM`` + + - The hardware accepts uncompressed audio with + Linear Pulse-Code Modulation (LPCM) + + - .. + + - ``AUDIO_CAP_MP1`` + + - The hardware accepts MPEG-1 Audio Layer 1. + + - .. + + - ``AUDIO_CAP_MP2`` + + - The hardware accepts MPEG-1 Audio Layer 2. + Also known as MUSICAM. + + - .. + + - ``AUDIO_CAP_MP3`` + + - The hardware accepts MPEG-1 Audio Layer III. + Commomly known as .mp3. + + - .. + + - ``AUDIO_CAP_AAC`` + + - The hardware accepts AAC (Advanced Audio Coding). + + - .. + + - ``AUDIO_CAP_OGG`` + + - The hardware accepts Vorbis audio tracks. + + - .. + + - ``AUDIO_CAP_SDDS`` + + - The hardware accepts Sony Dynamic Digital Sound (SDDS). + + - .. + + - ``AUDIO_CAP_AC3`` + + - The hardware accepts Dolby Digital ATSC A/52 audio. + Also known as AC-3. + +Description +~~~~~~~~~~~ + +A call to `AUDIO_GET_CAPABILITIES`_ returns an unsigned integer with the +following bits set according to the hardwares capabilities. |