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fa92b04d98
Sphinx is really pedantic with respect to the order where table tags and references are created. Putting things at the wrong order causes troubles. The order that seems to work is: .. raw:: latex .. tabularcolumns:: .. _foo_name: .. cssclass: longtable .. flat-table:: Reorder the tags to the above order, to avoid troubles, and fix remaining warnings introduced by media recent patches. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
174 lines
3.4 KiB
ReStructuredText
174 lines
3.4 KiB
ReStructuredText
.. -*- coding: utf-8; mode: rst -*-
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.. _VIDIOC_ENUM_FMT:
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*********************
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ioctl VIDIOC_ENUM_FMT
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*********************
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Name
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====
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VIDIOC_ENUM_FMT - Enumerate image formats
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Synopsis
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========
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.. cpp:function:: int ioctl( int fd, int request, struct v4l2_fmtdesc *argp )
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Arguments
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=========
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``fd``
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File descriptor returned by :ref:`open() <func-open>`.
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``request``
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VIDIOC_ENUM_FMT
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``argp``
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Description
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===========
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To enumerate image formats applications initialize the ``type`` and
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``index`` field of struct :ref:`v4l2_fmtdesc <v4l2-fmtdesc>` and call
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the :ref:`VIDIOC_ENUM_FMT` ioctl with a pointer to this structure. Drivers
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fill the rest of the structure or return an ``EINVAL`` error code. All
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formats are enumerable by beginning at index zero and incrementing by
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one until ``EINVAL`` is returned.
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.. note::
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After switching input or output the list of enumerated image
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formats may be different.
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.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
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.. _v4l2-fmtdesc:
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.. flat-table:: struct v4l2_fmtdesc
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 1 2
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- .. row 1
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- __u32
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- ``index``
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- Number of the format in the enumeration, set by the application.
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This is in no way related to the ``pixelformat`` field.
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- .. row 2
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- __u32
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- ``type``
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- Type of the data stream, set by the application. Only these types
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are valid here: ``V4L2_BUF_TYPE_VIDEO_CAPTURE``,
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``V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE``,
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``V4L2_BUF_TYPE_VIDEO_OUTPUT``,
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``V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE`` and
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``V4L2_BUF_TYPE_VIDEO_OVERLAY``. See :ref:`v4l2-buf-type`.
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- .. row 3
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- __u32
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- ``flags``
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- See :ref:`fmtdesc-flags`
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- .. row 4
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- __u8
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- ``description``\ [32]
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- Description of the format, a NUL-terminated ASCII string. This
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information is intended for the user, for example: "YUV 4:2:2".
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- .. row 5
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- __u32
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- ``pixelformat``
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- The image format identifier. This is a four character code as
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computed by the v4l2_fourcc() macro:
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- .. row 6
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- :cspan:`2`
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.. _v4l2-fourcc:
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``#define v4l2_fourcc(a,b,c,d)``
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``(((__u32)(a)<<0)|((__u32)(b)<<8)|((__u32)(c)<<16)|((__u32)(d)<<24))``
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Several image formats are already defined by this specification in
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:ref:`pixfmt`.
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.. attention::
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These codes are not the same as those used
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in the Windows world.
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- .. row 7
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- __u32
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- ``reserved``\ [4]
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- Reserved for future extensions. Drivers must set the array to
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zero.
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.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}|
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.. _fmtdesc-flags:
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.. flat-table:: Image Format Description Flags
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:header-rows: 0
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:stub-columns: 0
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:widths: 3 1 4
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- .. row 1
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- ``V4L2_FMT_FLAG_COMPRESSED``
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- 0x0001
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- This is a compressed format.
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- .. row 2
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- ``V4L2_FMT_FLAG_EMULATED``
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- 0x0002
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- This format is not native to the device but emulated through
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software (usually libv4l2), where possible try to use a native
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format instead for better performance.
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Return Value
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============
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On success 0 is returned, on error -1 and the ``errno`` variable is set
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appropriately. The generic error codes are described at the
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:ref:`Generic Error Codes <gen-errors>` chapter.
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EINVAL
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The struct :ref:`v4l2_fmtdesc <v4l2-fmtdesc>` ``type`` is not
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supported or the ``index`` is out of bounds.
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