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