Documentation/linux_tv/media/v4l/vidioc-g-std.rst

   1 .. -*- coding: utf-8; mode: rst -*-
   2
   3 .. _VIDIOC_G_STD:
   4
   5 ********************************
   6 ioctl VIDIOC_G_STD, VIDIOC_S_STD
   7 ********************************
   8
   9 *man VIDIOC_G_STD(2)*
  10
  11 VIDIOC_S_STD
  12 Query or select the video standard of the current input
  13
  14
  15 Synopsis
  16 ========
  17
  18 .. c:function:: int ioctl( int fd, int request, v4l2_std_id *argp )
  19
  20 .. c:function:: int ioctl( int fd, int request, const v4l2_std_id *argp )
  21
  22 Arguments
  23 =========
  24
  25 ``fd``
  26     File descriptor returned by :ref:`open() <func-open>`.
  27
  28 ``request``
  29     VIDIOC_G_STD, VIDIOC_S_STD
  30
  31 ``argp``
  32
  33
  34 Description
  35 ===========
  36
  37 To query and select the current video standard applications use the
  38 :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` and :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` ioctls which take a pointer to a
  39 :ref:`v4l2_std_id <v4l2-std-id>` type as argument. :ref:`VIDIOC_G_STD <VIDIOC_G_STD>`
  40 can return a single flag or a set of flags as in struct
  41 :ref:`v4l2_standard <v4l2-standard>` field ``id``. The flags must be
  42 unambiguous such that they appear in only one enumerated
  43 :c:type:`struct v4l2_standard` structure.
  44
  45 :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` accepts one or more flags, being a write-only ioctl it
  46 does not return the actual new standard as :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` does. When
  47 no flags are given or the current input does not support the requested
  48 standard the driver returns an EINVAL error code. When the standard set
  49 is ambiguous drivers may return EINVAL or choose any of the requested
  50 standards. If the current input or output does not support standard
  51 video timings (e.g. if :ref:`VIDIOC_ENUMINPUT`
  52 does not set the ``V4L2_IN_CAP_STD`` flag), then ENODATA error code is
  53 returned.
  54
  55
  56 Return Value
  57 ============
  58
  59 On success 0 is returned, on error -1 and the ``errno`` variable is set
  60 appropriately. The generic error codes are described at the
  61 :ref:`Generic Error Codes <gen-errors>` chapter.
  62
  63 EINVAL
  64     The :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` parameter was unsuitable.
  65
  66 ENODATA
  67     Standard video timings are not supported for this input or output.
  68
  69
  70 .. ------------------------------------------------------------------------------
  71 .. This file was automatically converted from DocBook-XML with the dbxml
  72 .. library (https://github.com/return42/sphkerneldoc). The origin XML comes
  73 .. from the linux kernel, refer to:
  74 ..
  75 .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
  76 .. ------------------------------------------------------------------------------