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 .. c: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 .. ------------------------------------------------------------------------------