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

   1 .. -*- coding: utf-8; mode: rst -*-
   2
   3 .. _vidioc-g-output:
   4
   5 **************************************
   6 ioctl VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT
   7 **************************************
   8
   9 *man VIDIOC_G_OUTPUT(2)*
  10
  11 VIDIOC_S_OUTPUT
  12 Query or select the current video output
  13
  14
  15 Synopsis
  16 ========
  17
  18 .. c:function:: int ioctl( int fd, int request, int *argp )
  19
  20 Arguments
  21 =========
  22
  23 ``fd``
  24     File descriptor returned by :ref:`open() <func-open>`.
  25
  26 ``request``
  27     VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT
  28
  29 ``argp``
  30
  31
  32 Description
  33 ===========
  34
  35 To query the current video output applications call the
  36 ``VIDIOC_G_OUTPUT`` ioctl with a pointer to an integer where the driver
  37 stores the number of the output, as in the struct
  38 :ref:`v4l2_output <v4l2-output>` ``index`` field. This ioctl will
  39 fail only when there are no video outputs, returning the EINVAL error
  40 code.
  41
  42 To select a video output applications store the number of the desired
  43 output in an integer and call the ``VIDIOC_S_OUTPUT`` ioctl with a
  44 pointer to this integer. Side effects are possible. For example outputs
  45 may support different video standards, so the driver may implicitly
  46 switch the current standard. standard. Because of these possible side
  47 effects applications must select an output before querying or
  48 negotiating any other parameters.
  49
  50 Information about video outputs is available using the
  51 :ref:`VIDIOC_ENUMOUTPUT <vidioc-enumoutput>` ioctl.
  52
  53
  54 Return Value
  55 ============
  56
  57 On success 0 is returned, on error -1 and the ``errno`` variable is set
  58 appropriately. The generic error codes are described at the
  59 :ref:`Generic Error Codes <gen-errors>` chapter.
  60
  61 EINVAL
  62     The number of the video output is out of bounds, or there are no
  63     video outputs at all.
  64
  65
  66 .. ------------------------------------------------------------------------------
  67 .. This file was automatically converted from DocBook-XML with the dbxml
  68 .. library (https://github.com/return42/sphkerneldoc). The origin XML comes
  69 .. from the linux kernel, refer to:
  70 ..
  71 .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
  72 .. ------------------------------------------------------------------------------