1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2
3.. _VIDIOC_ENUMAUDOUT:
4
5***********************
6ioctl VIDIOC_ENUMAUDOUT
7***********************
8
9Name
10====
11
12VIDIOC_ENUMAUDOUT - Enumerate audio outputs
13
14
15Synopsis
16========
17
18.. c:function:: int ioctl( int fd, VIDIOC_ENUMAUDOUT, struct v4l2_audioout *argp )
19    :name: VIDIOC_ENUMAUDOUT
20
21
22Arguments
23=========
24
25``fd``
26    File descriptor returned by :ref:`open() <func-open>`.
27
28``argp``
29    Pointer to struct :c:type:`v4l2_audioout`.
30
31
32Description
33===========
34
35To query the attributes of an audio output applications initialize the
36``index`` field and zero out the ``reserved`` array of a struct
37:c:type:`v4l2_audioout` and call the ``VIDIOC_G_AUDOUT``
38ioctl with a pointer to this structure. Drivers fill the rest of the
39structure or return an ``EINVAL`` error code when the index is out of
40bounds. To enumerate all audio outputs applications shall begin at index
41zero, incrementing by one until the driver returns ``EINVAL``.
42
43.. note::
44
45    Connectors on a TV card to loop back the received audio signal
46    to a sound card are not audio outputs in this sense.
47
48See :ref:`VIDIOC_G_AUDIOout <VIDIOC_G_AUDOUT>` for a description of struct
49:c:type:`v4l2_audioout`.
50
51
52Return Value
53============
54
55On success 0 is returned, on error -1 and the ``errno`` variable is set
56appropriately. The generic error codes are described at the
57:ref:`Generic Error Codes <gen-errors>` chapter.
58
59EINVAL
60    The number of the audio output is out of bounds.
61