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linux
1.. -*- coding: utf-8; mode: rst -*-
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
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
50
51Return Value
52============
53
54On success 0 is returned, on error -1 and the ``errno`` variable is set
55appropriately. The generic error codes are described at the
56:ref:`Generic Error Codes <gen-errors>` chapter.
57
58EINVAL
59 The number of the audio output is out of bounds.