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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
+========
+
+.. cpp:function:: int ioctl( int fd, int request, struct v4l2_enc_idx *argp )
+
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by :ref:`open() <func-open>`.
+
+``request``
+    VIDIOC_G_ENC_INDEX
+
+``argp``
+
+
+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 :ref:`v4l2_enc_idx <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.
+
+
+.. _v4l2-enc-idx:
+
+.. flat-table:: struct v4l2_enc_idx
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 2 1 1
+
+
+    -  .. row 1
+
+       -  __u32
+
+       -  ``entries``
+
+       -  The number of entries the driver stored in the ``entry`` array.
+
+    -  .. row 2
+
+       -  __u32
+
+       -  ``entries_cap``
+
+       -  The number of entries the driver can buffer. Must be greater than
+	  zero.
+
+    -  .. row 3
+
+       -  __u32
+
+       -  ``reserved``\ [4]
+
+       -  :cspan:`2` Reserved for future extensions. Drivers must set the
+	  array to zero.
+
+    -  .. row 4
+
+       -  struct :ref:`v4l2_enc_idx_entry <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``.
+
+
+
+.. _v4l2-enc-idx-entry:
+
+.. flat-table:: struct v4l2_enc_idx_entry
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 2
+
+
+    -  .. row 1
+
+       -  __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.
+
+    -  .. row 2
+
+       -  __u64
+
+       -  ``pts``
+
+       -  The 33 bit *Presentation Time Stamp* of this picture as defined in
+	  :ref:`mpeg2part1`.
+
+    -  .. row 3
+
+       -  __u32
+
+       -  ``length``
+
+       -  The length of this picture in bytes.
+
+    -  .. row 4
+
+       -  __u32
+
+       -  ``flags``
+
+       -  Flags containing the coding type of this picture, see
+	  :ref:`enc-idx-flags`.
+
+    -  .. row 5
+
+       -  __u32
+
+       -  ``reserved``\ [2]
+
+       -  Reserved for future extensions. Drivers must set the array to
+	  zero.
+
+
+
+.. _enc-idx-flags:
+
+.. flat-table:: Index Entry Flags
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       3 1 4
+
+
+    -  .. row 1
+
+       -  ``V4L2_ENC_IDX_FRAME_I``
+
+       -  0x00
+
+       -  This is an Intra-coded picture.
+
+    -  .. row 2
+
+       -  ``V4L2_ENC_IDX_FRAME_P``
+
+       -  0x01
+
+       -  This is a Predictive-coded picture.
+
+    -  .. row 3
+
+       -  ``V4L2_ENC_IDX_FRAME_B``
+
+       -  0x02
+
+       -  This is a Bidirectionally predictive-coded picture.
+
+    -  .. row 4
+
+       -  ``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.