1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2.. c:namespace:: V4L
3
4.. _VIDIOC_ENUMAUDOUT:
5
6***********************
7ioctl VIDIOC_ENUMAUDOUT
8***********************
9
10Name
11====
12
13VIDIOC_ENUMAUDOUT - Enumerate audio outputs
14
15Synopsis
16========
17
18.. c:macro:: VIDIOC_ENUMAUDOUT
19
20``int ioctl(int fd, VIDIOC_ENUMAUDOUT, struct v4l2_audioout *argp)``
21
22Arguments
23=========
24
25``fd``
26    File descriptor returned by :c:func:`open()`.
27
28``argp``
29    Pointer to struct :c:type:`v4l2_audioout`.
30
31Description
32===========
33
34To query the attributes of an audio output applications initialize the
35``index`` field and zero out the ``reserved`` array of a struct
36:c:type:`v4l2_audioout` and call the ``VIDIOC_G_AUDOUT``
37ioctl with a pointer to this structure. Drivers fill the rest of the
38structure or return an ``EINVAL`` error code when the index is out of
39bounds. To enumerate all audio outputs applications shall begin at index
40zero, incrementing by one until the driver returns ``EINVAL``.
41
42.. note::
43
44    Connectors on a TV card to loop back the received audio signal
45    to a sound card are not audio outputs in this sense.
46
47See :ref:`VIDIOC_G_AUDIOout <VIDIOC_G_AUDOUT>` for a description of struct
48:c:type:`v4l2_audioout`.
49
50Return Value
51============
52
53On success 0 is returned, on error -1 and the ``errno`` variable is set
54appropriately. The generic error codes are described at the
55:ref:`Generic Error Codes <gen-errors>` chapter.
56
57EINVAL
58    The number of the audio output is out of bounds.
59