Synopsis
========
-.. cpp:function:: int ioctl( int fd, int request, struct v4l2_decoder_cmd *argp )
+.. c:function:: int ioctl( int fd, VIDIOC_DECODER_CMD, struct v4l2_decoder_cmd *argp )
+ :name: VIDIOC_DECODER_CMD
+
+
+.. c:function:: int ioctl( int fd, VIDIOC_TRY_DECODER_CMD, struct v4l2_decoder_cmd *argp )
+ :name: VIDIOC_TRY_DECODER_CMD
Arguments
``fd``
File descriptor returned by :ref:`open() <func-open>`.
-``request``
- VIDIOC_DECODER_CMD, VIDIOC_TRY_DECODER_CMD
-
``argp``
+ pointer to struct :c:type:`v4l2_decoder_cmd`.
Description
``VIDIOC_DECODER_CMD`` sends a command to the decoder,
``VIDIOC_TRY_DECODER_CMD`` can be used to try a command without actually
executing it. To send a command applications must initialize all fields
-of a struct :ref:`v4l2_decoder_cmd <v4l2-decoder-cmd>` and call
+of a struct :c:type:`v4l2_decoder_cmd` and call
``VIDIOC_DECODER_CMD`` or ``VIDIOC_TRY_DECODER_CMD`` with a pointer to
this structure.
introduced in Linux 3.3.
-.. _v4l2-decoder-cmd:
+.. tabularcolumns:: |p{1.1cm}|p{2.4cm}|p{1.2cm}|p{1.6cm}|p{10.6cm}|
+
+.. c:type:: v4l2_decoder_cmd
+
+.. cssclass:: longtable
.. flat-table:: struct v4l2_decoder_cmd
:header-rows: 0
:stub-columns: 0
- :widths: 1 1 2 1 1
-
-
- - .. row 1
-
- - __u32
-
- - ``cmd``
-
- -
- -
- - The decoder command, see :ref:`decoder-cmds`.
-
- - .. row 2
-
- - __u32
-
- - ``flags``
-
- -
- -
- - Flags to go with the command. If no flags are defined for this
- command, drivers and applications must set this field to zero.
-
- - .. row 3
-
- - union
-
- - (anonymous)
-
- -
- -
- -
-
- - .. row 4
-
- -
- - struct
-
- - ``start``
-
- -
- - Structure containing additional data for the
- ``V4L2_DEC_CMD_START`` command.
-
- - .. row 5
-
- -
- -
- - __s32
-
- - ``speed``
-
- - Playback speed and direction. The playback speed is defined as
- ``speed``/1000 of the normal speed. So 1000 is normal playback.
- Negative numbers denote reverse playback, so -1000 does reverse
- playback at normal speed. Speeds -1, 0 and 1 have special
- meanings: speed 0 is shorthand for 1000 (normal playback). A speed
- of 1 steps just one frame forward, a speed of -1 steps just one
- frame back.
-
- - .. row 6
-
- -
- -
- - __u32
-
- - ``format``
-
- - Format restrictions. This field is set by the driver, not the
- application. Possible values are ``V4L2_DEC_START_FMT_NONE`` if
- there are no format restrictions or ``V4L2_DEC_START_FMT_GOP`` if
- the decoder operates on full GOPs (*Group Of Pictures*). This is
- usually the case for reverse playback: the decoder needs full
- GOPs, which it can then play in reverse order. So to implement
- reverse playback the application must feed the decoder the last
- GOP in the video file, then the GOP before that, etc. etc.
-
- - .. row 7
-
- -
- - struct
-
- - ``stop``
-
- -
- - Structure containing additional data for the ``V4L2_DEC_CMD_STOP``
- command.
-
- - .. row 8
-
- -
- -
- - __u64
-
- - ``pts``
-
- - Stop playback at this ``pts`` or immediately if the playback is
- already past that timestamp. Leave to 0 if you want to stop after
- the last frame was decoded.
-
- - .. row 9
-
- -
- - struct
-
- - ``raw``
-
- -
- -
-
- - .. row 10
-
- -
- -
- - __u32
-
- - ``data``\ [16]
-
- - Reserved for future extensions. Drivers and applications must set
- the array to zero.
-
-
+ :widths: 11 24 12 16 106
+
+ * - __u32
+ - ``cmd``
+ -
+ -
+ - The decoder command, see :ref:`decoder-cmds`.
+ * - __u32
+ - ``flags``
+ -
+ -
+ - Flags to go with the command. If no flags are defined for this
+ command, drivers and applications must set this field to zero.
+ * - union
+ - (anonymous)
+ -
+ -
+ -
+ * -
+ - struct
+ - ``start``
+ -
+ - Structure containing additional data for the
+ ``V4L2_DEC_CMD_START`` command.
+ * -
+ -
+ - __s32
+ - ``speed``
+ - Playback speed and direction. The playback speed is defined as
+ ``speed``/1000 of the normal speed. So 1000 is normal playback.
+ Negative numbers denote reverse playback, so -1000 does reverse
+ playback at normal speed. Speeds -1, 0 and 1 have special
+ meanings: speed 0 is shorthand for 1000 (normal playback). A speed
+ of 1 steps just one frame forward, a speed of -1 steps just one
+ frame back.
+ * -
+ -
+ - __u32
+ - ``format``
+ - Format restrictions. This field is set by the driver, not the
+ application. Possible values are ``V4L2_DEC_START_FMT_NONE`` if
+ there are no format restrictions or ``V4L2_DEC_START_FMT_GOP`` if
+ the decoder operates on full GOPs (*Group Of Pictures*). This is
+ usually the case for reverse playback: the decoder needs full
+ GOPs, which it can then play in reverse order. So to implement
+ reverse playback the application must feed the decoder the last
+ GOP in the video file, then the GOP before that, etc. etc.
+ * -
+ - struct
+ - ``stop``
+ -
+ - Structure containing additional data for the ``V4L2_DEC_CMD_STOP``
+ command.
+ * -
+ -
+ - __u64
+ - ``pts``
+ - Stop playback at this ``pts`` or immediately if the playback is
+ already past that timestamp. Leave to 0 if you want to stop after
+ the last frame was decoded.
+ * -
+ - struct
+ - ``raw``
+ -
+ -
+ * -
+ -
+ - __u32
+ - ``data``\ [16]
+ - Reserved for future extensions. Drivers and applications must set
+ the array to zero.
+
+
+
+.. tabularcolumns:: |p{5.6cm}|p{0.6cm}|p{11.3cm}|
.. _decoder-cmds:
.. flat-table:: Decoder Commands
:header-rows: 0
:stub-columns: 0
- :widths: 3 1 4
-
-
- - .. row 1
-
- - ``V4L2_DEC_CMD_START``
-
- - 0
-
- - Start the decoder. When the decoder is already running or paused,
- this command will just change the playback speed. That means that
- calling ``V4L2_DEC_CMD_START`` when the decoder was paused will
- *not* resume the decoder. You have to explicitly call
- ``V4L2_DEC_CMD_RESUME`` for that. This command has one flag:
- ``V4L2_DEC_CMD_START_MUTE_AUDIO``. If set, then audio will be
- muted when playing back at a non-standard speed.
-
- - .. row 2
-
- - ``V4L2_DEC_CMD_STOP``
-
- - 1
-
- - Stop the decoder. When the decoder is already stopped, this
- command does nothing. This command has two flags: if
- ``V4L2_DEC_CMD_STOP_TO_BLACK`` is set, then the decoder will set
- the picture to black after it stopped decoding. Otherwise the last
- image will repeat. mem2mem decoders will stop producing new frames
- altogether. They will send a ``V4L2_EVENT_EOS`` event when the
- last frame has been decoded and all frames are ready to be
- dequeued and will set the ``V4L2_BUF_FLAG_LAST`` buffer flag on
- the last buffer of the capture queue to indicate there will be no
- new buffers produced to dequeue. This buffer may be empty,
- indicated by the driver setting the ``bytesused`` field to 0. Once
- the ``V4L2_BUF_FLAG_LAST`` flag was set, the
- :ref:`VIDIOC_DQBUF <VIDIOC_QBUF>` ioctl will not block anymore,
- but return an ``EPIPE`` error code. If
- ``V4L2_DEC_CMD_STOP_IMMEDIATELY`` is set, then the decoder stops
- immediately (ignoring the ``pts`` value), otherwise it will keep
- decoding until timestamp >= pts or until the last of the pending
- data from its internal buffers was decoded.
-
- - .. row 3
-
- - ``V4L2_DEC_CMD_PAUSE``
-
- - 2
-
- - Pause the decoder. When the decoder has not been started yet, the
- driver will return an ``EPERM`` error code. When the decoder is
- already paused, this command does nothing. This command has one
- flag: if ``V4L2_DEC_CMD_PAUSE_TO_BLACK`` is set, then set the
- decoder output to black when paused.
-
- - .. row 4
-
- - ``V4L2_DEC_CMD_RESUME``
-
- - 3
-
- - Resume decoding after a PAUSE command. When the decoder has not
- been started yet, the driver will return an ``EPERM`` error code. When
- the decoder is already running, this command does nothing. No
- flags are defined for this command.
+ :widths: 56 6 113
+
+ * - ``V4L2_DEC_CMD_START``
+ - 0
+ - Start the decoder. When the decoder is already running or paused,
+ this command will just change the playback speed. That means that
+ calling ``V4L2_DEC_CMD_START`` when the decoder was paused will
+ *not* resume the decoder. You have to explicitly call
+ ``V4L2_DEC_CMD_RESUME`` for that. This command has one flag:
+ ``V4L2_DEC_CMD_START_MUTE_AUDIO``. If set, then audio will be
+ muted when playing back at a non-standard speed.
+ * - ``V4L2_DEC_CMD_STOP``
+ - 1
+ - Stop the decoder. When the decoder is already stopped, this
+ command does nothing. This command has two flags: if
+ ``V4L2_DEC_CMD_STOP_TO_BLACK`` is set, then the decoder will set
+ the picture to black after it stopped decoding. Otherwise the last
+ image will repeat. mem2mem decoders will stop producing new frames
+ altogether. They will send a ``V4L2_EVENT_EOS`` event when the
+ last frame has been decoded and all frames are ready to be
+ dequeued and will set the ``V4L2_BUF_FLAG_LAST`` buffer flag on
+ the last buffer of the capture queue to indicate there will be no
+ new buffers produced to dequeue. This buffer may be empty,
+ indicated by the driver setting the ``bytesused`` field to 0. Once
+ the ``V4L2_BUF_FLAG_LAST`` flag was set, the
+ :ref:`VIDIOC_DQBUF <VIDIOC_QBUF>` ioctl will not block anymore,
+ but return an ``EPIPE`` error code. If
+ ``V4L2_DEC_CMD_STOP_IMMEDIATELY`` is set, then the decoder stops
+ immediately (ignoring the ``pts`` value), otherwise it will keep
+ decoding until timestamp >= pts or until the last of the pending
+ data from its internal buffers was decoded.
+ * - ``V4L2_DEC_CMD_PAUSE``
+ - 2
+ - Pause the decoder. When the decoder has not been started yet, the
+ driver will return an ``EPERM`` error code. When the decoder is
+ already paused, this command does nothing. This command has one
+ flag: if ``V4L2_DEC_CMD_PAUSE_TO_BLACK`` is set, then set the
+ decoder output to black when paused.
+ * - ``V4L2_DEC_CMD_RESUME``
+ - 3
+ - Resume decoding after a PAUSE command. When the decoder has not
+ been started yet, the driver will return an ``EPERM`` error code. When
+ the decoder is already running, this command does nothing. No
+ flags are defined for this command.
Return Value
projects / cascardo / linux.git / blobdiff