.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
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.. _video_types:
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****************
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Video Data Types
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****************
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.. _video-format-t:
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video_format_t
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==============
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The ``video_format_t`` data type defined by
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.. code-block:: c
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typedef enum {
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VIDEO_FORMAT_4_3, /* Select 4:3 format */
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VIDEO_FORMAT_16_9, /* Select 16:9 format. */
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VIDEO_FORMAT_221_1 /* 2.21:1 */
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} video_format_t;
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is used in the VIDEO_SET_FORMAT function (??) to tell the driver which
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aspect ratio the output hardware (e.g. TV) has. It is also used in the
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data structures video_status (??) returned by VIDEO_GET_STATUS (??)
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and video_event (??) returned by VIDEO_GET_EVENT (??) which report
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about the display format of the current video stream.
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.. _video-displayformat-t:
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video_displayformat_t
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=====================
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In case the display format of the video stream and of the display
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hardware differ the application has to specify how to handle the
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cropping of the picture. This can be done using the
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VIDEO_SET_DISPLAY_FORMAT call (??) which accepts
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.. code-block:: c
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typedef enum {
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VIDEO_PAN_SCAN, /* use pan and scan format */
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VIDEO_LETTER_BOX, /* use letterbox format */
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VIDEO_CENTER_CUT_OUT /* use center cut out format */
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} video_displayformat_t;
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as argument.
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.. _video-stream-source-t:
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video_stream_source_t
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=====================
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The video stream source is set through the VIDEO_SELECT_SOURCE call
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and can take the following values, depending on whether we are replaying
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from an internal (demuxer) or external (user write) source.
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.. code-block:: c
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typedef enum {
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VIDEO_SOURCE_DEMUX, /* Select the demux as the main source */
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VIDEO_SOURCE_MEMORY /* If this source is selected, the stream
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comes from the user through the write
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system call */
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} video_stream_source_t;
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VIDEO_SOURCE_DEMUX selects the demultiplexer (fed either by the
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frontend or the DVR device) as the source of the video stream. If
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VIDEO_SOURCE_MEMORY is selected the stream comes from the application
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through the **write()** system call.
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.. _video-play-state-t:
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video_play_state_t
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==================
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The following values can be returned by the VIDEO_GET_STATUS call
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representing the state of video playback.
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.. code-block:: c
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typedef enum {
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VIDEO_STOPPED, /* Video is stopped */
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VIDEO_PLAYING, /* Video is currently playing */
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VIDEO_FREEZED /* Video is freezed */
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} video_play_state_t;
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.. c:type:: video_command
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struct video_command
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====================
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The structure must be zeroed before use by the application This ensures
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it can be extended safely in the future.
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.. code-block:: c
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struct video_command {
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__u32 cmd;
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__u32 flags;
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union {
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struct {
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__u64 pts;
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} stop;
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struct {
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/* 0 or 1000 specifies normal speed,
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1 specifies forward single stepping,
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-1 specifies backward single stepping,
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>>1: playback at speed/1000 of the normal speed,
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<-1: reverse playback at (-speed/1000) of the normal speed. */
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__s32 speed;
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__u32 format;
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} play;
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struct {
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__u32 data[16];
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} raw;
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};
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};
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.. _video-size-t:
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video_size_t
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============
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.. code-block:: c
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typedef struct {
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int w;
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int h;
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video_format_t aspect_ratio;
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} video_size_t;
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.. c:type:: video_event
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struct video_event
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==================
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The following is the structure of a video event as it is returned by the
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VIDEO_GET_EVENT call.
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.. code-block:: c
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struct video_event {
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__s32 type;
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#define VIDEO_EVENT_SIZE_CHANGED 1
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#define VIDEO_EVENT_FRAME_RATE_CHANGED 2
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#define VIDEO_EVENT_DECODER_STOPPED 3
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#define VIDEO_EVENT_VSYNC 4
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long timestamp;
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union {
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video_size_t size;
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unsigned int frame_rate; /* in frames per 1000sec */
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unsigned char vsync_field; /* unknown/odd/even/progressive */
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} u;
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};
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.. c:type:: video_status
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struct video_status
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===================
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The VIDEO_GET_STATUS call returns the following structure informing
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about various states of the playback operation.
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.. code-block:: c
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struct video_status {
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int video_blank; /* blank video on freeze? */
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video_play_state_t play_state; /* current state of playback */
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video_stream_source_t stream_source; /* current source (demux/memory) */
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video_format_t video_format; /* current aspect ratio of stream */
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video_displayformat_t display_format;/* selected cropping mode */
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};
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If video_blank is set video will be blanked out if the channel is
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changed or if playback is stopped. Otherwise, the last picture will be
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displayed. play_state indicates if the video is currently frozen,
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stopped, or being played back. The stream_source corresponds to the
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selected source for the video stream. It can come either from the
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demultiplexer or from memory. The video_format indicates the aspect
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ratio (one of 4:3 or 16:9) of the currently played video stream.
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Finally, display_format corresponds to the selected cropping mode in
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case the source video format is not the same as the format of the output
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device.
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.. c:type:: video_still_picture
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struct video_still_picture
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==========================
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An I-frame displayed via the VIDEO_STILLPICTURE call is passed on
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within the following structure.
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.. code-block:: c
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/* pointer to and size of a single iframe in memory */
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struct video_still_picture {
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char *iFrame; /* pointer to a single iframe in memory */
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int32_t size;
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};
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.. _video_caps:
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video capabilities
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==================
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A call to VIDEO_GET_CAPABILITIES returns an unsigned integer with the
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following bits set according to the hardwares capabilities.
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.. code-block:: c
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/* bit definitions for capabilities: */
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/* can the hardware decode MPEG1 and/or MPEG2? */
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#define VIDEO_CAP_MPEG1 1
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#define VIDEO_CAP_MPEG2 2
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/* can you send a system and/or program stream to video device?
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(you still have to open the video and the audio device but only
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send the stream to the video device) */
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#define VIDEO_CAP_SYS 4
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#define VIDEO_CAP_PROG 8
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/* can the driver also handle SPU, NAVI and CSS encoded data?
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(CSS API is not present yet) */
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#define VIDEO_CAP_SPU 16
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#define VIDEO_CAP_NAVI 32
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#define VIDEO_CAP_CSS 64
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