Documentation/linux_tv/media/v4l/vidioc-enumaudioout.rst

   1 .. -*- coding: utf-8; mode: rst -*-
   2
   3 .. _VIDIOC_ENUMAUDIOOUT:
   4
   5 ***********************
   6 ioctl VIDIOC_ENUMAUDOUT
   7 ***********************
   8
   9 *man VIDIOC_ENUMAUDOUT(2)*
  10
  11 Enumerate audio outputs
  12
  13
  14 Synopsis
  15 ========
  16
  17 .. cpp:function:: int ioctl( int fd, int request, struct v4l2_audioout *argp )
  18
  19 Arguments
  20 =========
  21
  22 ``fd``
  23     File descriptor returned by :ref:`open() <func-open>`.
  24
  25 ``request``
  26     VIDIOC_ENUMAUDOUT
  27
  28 ``argp``
  29
  30
  31 Description
  32 ===========
  33
  34 To query the attributes of an audio output applications initialize the
  35 ``index`` field and zero out the ``reserved`` array of a struct
  36 :ref:`v4l2_audioout <v4l2-audioout>` and call the ``VIDIOC_G_AUDOUT``
  37 ioctl with a pointer to this structure. Drivers fill the rest of the
  38 structure or return an ``EINVAL`` error code when the index is out of
  39 bounds. To enumerate all audio outputs applications shall begin at index
  40 zero, incrementing by one until the driver returns ``EINVAL``.
  41
  42 Note connectors on a TV card to loop back the received audio signal to a
  43 sound card are not audio outputs in this sense.
  44
  45 See :ref:`VIDIOC_G_AUDIOout <VIDIOC_G_AUDIOout>` for a description of struct
  46 :ref:`v4l2_audioout <v4l2-audioout>`.
  47
  48
  49 Return Value
  50 ============
  51
  52 On success 0 is returned, on error -1 and the ``errno`` variable is set
  53 appropriately. The generic error codes are described at the
  54 :ref:`Generic Error Codes <gen-errors>` chapter.
  55
  56 EINVAL
  57     The number of the audio output is out of bounds.
  58
  59
  60 .. ------------------------------------------------------------------------------
  61 .. This file was automatically converted from DocBook-XML with the dbxml
  62 .. library (https://github.com/return42/sphkerneldoc). The origin XML comes
  63 .. from the linux kernel, refer to:
  64 ..
  65 .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
  66 .. ------------------------------------------------------------------------------