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

   1 .. -*- coding: utf-8; mode: rst -*-
   2
   3 .. _VIDIOC_G_INPUT:
   4
   5 ************************************
   6 ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT
   7 ************************************
   8
   9 *man VIDIOC_G_INPUT(2)*
  10
  11 VIDIOC_S_INPUT
  12 Query or select the current video input
  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_INPUT, VIDIOC_S_INPUT
  28
  29 ``argp``
  30
  31
  32 Description
  33 ===========
  34
  35 To query the current video input applications call the
  36 :ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer to an integer where the driver
  37 stores the number of the input, as in the struct
  38 :ref:`v4l2_input <v4l2-input>` ``index`` field. This ioctl will fail
  39 only when there are no video inputs, returning EINVAL.
  40
  41 To select a video input applications store the number of the desired
  42 input in an integer and call the :ref:`VIDIOC_S_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer
  43 to this integer. Side effects are possible. For example inputs may
  44 support different video standards, so the driver may implicitly switch
  45 the current standard. Because of these possible side effects
  46 applications must select an input before querying or negotiating any
  47 other parameters.
  48
  49 Information about video inputs is available using the
  50 :ref:`VIDIOC_ENUMINPUT` ioctl.
  51
  52
  53 Return Value
  54 ============
  55
  56 On success 0 is returned, on error -1 and the ``errno`` variable is set
  57 appropriately. The generic error codes are described at the
  58 :ref:`Generic Error Codes <gen-errors>` chapter.
  59
  60 EINVAL
  61     The number of the video input is out of bounds.
  62
  63
  64 .. ------------------------------------------------------------------------------
  65 .. This file was automatically converted from DocBook-XML with the dbxml
  66 .. library (https://github.com/return42/sphkerneldoc). The origin XML comes
  67 .. from the linux kernel, refer to:
  68 ..
  69 .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
  70 .. ------------------------------------------------------------------------------