vidioc-enumaudio.rst

 1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
 2.. c:namespace:: V4L
 3
 4.. _VIDIOC_ENUMAUDIO:
 5
 6**********************
 7ioctl VIDIOC_ENUMAUDIO
 8**********************
 9
10Name
11====
12
13VIDIOC_ENUMAUDIO - Enumerate audio inputs
14
15Synopsis
16========
17
18.. c:macro:: VIDIOC_ENUMAUDIO
19
20``int ioctl(int fd, VIDIOC_ENUMAUDIO, struct v4l2_audio *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_audio`.
30
31Description
32===========
33
34To query the attributes of an audio input applications initialize the
35``index`` field and zero out the ``reserved`` array of a struct
36:c:type:`v4l2_audio` and call the :ref:`VIDIOC_ENUMAUDIO`
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 inputs applications shall begin at index
40zero, incrementing by one until the driver returns ``EINVAL``.
41
42See :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` for a description of struct
43:c:type:`v4l2_audio`.
44
45Return Value
46============
47
48On success 0 is returned, on error -1 and the ``errno`` variable is set
49appropriately. The generic error codes are described at the
50:ref:`Generic Error Codes <gen-errors>` chapter.
51
52EINVAL
53    The number of the audio input is out of bounds.