Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 149 insertions, 0 deletions

diff --git a/Documentation/media/uapi/v4l/vidioc-g-enc-index.rst b/Documentation/media/uapi/v4l/vidioc-g-enc-index.rst
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+.. -*- coding: utf-8; mode: rst -*-
+
+.. _VIDIOC_G_ENC_INDEX:
+
+************************
+ioctl VIDIOC_G_ENC_INDEX
+************************
+
+Name
+====
+
+VIDIOC_G_ENC_INDEX - Get meta data about a compressed video stream
+
+
+Synopsis
+========
+
+.. c:function:: int ioctl( int fd, VIDIOC_G_ENC_INDEX, struct v4l2_enc_idx *argp )
+    :name: VIDIOC_G_ENC_INDEX
+
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by :ref:`open() <func-open>`.
+
+``argp``
+    Pointer to struct :c:type:`v4l2_enc_idx`.
+
+
+Description
+===========
+
+The :ref:`VIDIOC_G_ENC_INDEX <VIDIOC_G_ENC_INDEX>` ioctl provides meta data about a compressed
+video stream the same or another application currently reads from the
+driver, which is useful for random access into the stream without
+decoding it.
+
+To read the data applications must call :ref:`VIDIOC_G_ENC_INDEX <VIDIOC_G_ENC_INDEX>` with a
+pointer to a struct :c:type:`v4l2_enc_idx`. On success
+the driver fills the ``entry`` array, stores the number of elements
+written in the ``entries`` field, and initializes the ``entries_cap``
+field.
+
+Each element of the ``entry`` array contains meta data about one
+picture. A :ref:`VIDIOC_G_ENC_INDEX <VIDIOC_G_ENC_INDEX>` call reads up to
+``V4L2_ENC_IDX_ENTRIES`` entries from a driver buffer, which can hold up
+to ``entries_cap`` entries. This number can be lower or higher than
+``V4L2_ENC_IDX_ENTRIES``, but not zero. When the application fails to
+read the meta data in time the oldest entries will be lost. When the
+buffer is empty or no capturing/encoding is in progress, ``entries``
+will be zero.
+
+Currently this ioctl is only defined for MPEG-2 program streams and
+video elementary streams.
+
+
+.. tabularcolumns:: |p{3.8cm}|p{5.6cm}|p{8.1cm}|
+
+.. c:type:: v4l2_enc_idx
+
+.. flat-table:: struct v4l2_enc_idx
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 3 8
+
+    * - __u32
+      - ``entries``
+      - The number of entries the driver stored in the ``entry`` array.
+    * - __u32
+      - ``entries_cap``
+      - The number of entries the driver can buffer. Must be greater than
+	zero.
+    * - __u32
+      - ``reserved``\ [4]
+      - Reserved for future extensions. Drivers must set the
+	array to zero.
+    * - struct :c:type:`v4l2_enc_idx_entry`
+      - ``entry``\ [``V4L2_ENC_IDX_ENTRIES``]
+      - Meta data about a compressed video stream. Each element of the
+	array corresponds to one picture, sorted in ascending order by
+	their ``offset``.
+
+
+
+.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
+
+.. c:type:: v4l2_enc_idx_entry
+
+.. flat-table:: struct v4l2_enc_idx_entry
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 2
+
+    * - __u64
+      - ``offset``
+      - The offset in bytes from the beginning of the compressed video
+	stream to the beginning of this picture, that is a *PES packet
+	header* as defined in :ref:`mpeg2part1` or a *picture header* as
+	defined in :ref:`mpeg2part2`. When the encoder is stopped, the
+	driver resets the offset to zero.
+    * - __u64
+      - ``pts``
+      - The 33 bit *Presentation Time Stamp* of this picture as defined in
+	:ref:`mpeg2part1`.
+    * - __u32
+      - ``length``
+      - The length of this picture in bytes.
+    * - __u32
+      - ``flags``
+      - Flags containing the coding type of this picture, see
+	:ref:`enc-idx-flags`.
+    * - __u32
+      - ``reserved``\ [2]
+      - Reserved for future extensions. Drivers must set the array to
+	zero.
+
+
+.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}|
+
+.. _enc-idx-flags:
+
+.. flat-table:: Index Entry Flags
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       3 1 4
+
+    * - ``V4L2_ENC_IDX_FRAME_I``
+      - 0x00
+      - This is an Intra-coded picture.
+    * - ``V4L2_ENC_IDX_FRAME_P``
+      - 0x01
+      - This is a Predictive-coded picture.
+    * - ``V4L2_ENC_IDX_FRAME_B``
+      - 0x02
+      - This is a Bidirectionally predictive-coded picture.
+    * - ``V4L2_ENC_IDX_FRAME_MASK``
+      - 0x0F
+      - *AND* the flags field with this mask to obtain the picture coding
+	type.
+
+
+Return Value
+============
+
+On success 0 is returned, on error -1 and the ``errno`` variable is set
+appropriately. The generic error codes are described at the
+:ref:`Generic Error Codes <gen-errors>` chapter.