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1 | .. -*- coding: utf-8; mode: rst -*- |
2 | ||
af4a4d0d | 3 | .. _VIDIOC_G_AUDIOOUT: |
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4 | |
5 | ************************************** | |
6 | ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT | |
7 | ************************************** | |
8 | ||
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9 | NAME |
10 | ==== | |
5377d91f | 11 | |
586027ce | 12 | VIDIOC_G_AUDOUT - VIDIOC_S_AUDOUT - Query or select the current audio output |
5377d91f | 13 | |
586027ce | 14 | SYNOPSIS |
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15 | ======== |
16 | ||
b7e67f6c | 17 | .. cpp:function:: int ioctl( int fd, int request, struct v4l2_audioout *argp ) |
5377d91f | 18 | |
b7e67f6c | 19 | .. cpp:function:: int ioctl( int fd, int request, const struct v4l2_audioout *argp ) |
5377d91f | 20 | |
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21 | |
22 | ARGUMENTS | |
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23 | ========= |
24 | ||
25 | ``fd`` | |
26 | File descriptor returned by :ref:`open() <func-open>`. | |
27 | ||
28 | ``request`` | |
29 | VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT | |
30 | ||
31 | ``argp`` | |
32 | ||
33 | ||
586027ce | 34 | DESCRIPTION |
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35 | =========== |
36 | ||
37 | To query the current audio output applications zero out the ``reserved`` | |
38 | array of a struct :ref:`v4l2_audioout <v4l2-audioout>` and call the | |
39 | ``VIDIOC_G_AUDOUT`` ioctl with a pointer to this structure. Drivers fill | |
cdb4af0f | 40 | the rest of the structure or return an ``EINVAL`` error code when the device |
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41 | has no audio inputs, or none which combine with the current video |
42 | output. | |
43 | ||
44 | Audio outputs have no writable properties. Nevertheless, to select the | |
45 | current audio output applications can initialize the ``index`` field and | |
46 | ``reserved`` array (which in the future may contain writable properties) | |
acf309a2 | 47 | of a :ref:`struct v4l2_audioout <v4l2-audioout>` structure and call the |
5377d91f | 48 | ``VIDIOC_S_AUDOUT`` ioctl. Drivers switch to the requested output or |
cdb4af0f | 49 | return the ``EINVAL`` error code when the index is out of bounds. This is a |
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50 | write-only ioctl, it does not return the current audio output attributes |
51 | as ``VIDIOC_G_AUDOUT`` does. | |
52 | ||
53 | Note connectors on a TV card to loop back the received audio signal to a | |
54 | sound card are not audio outputs in this sense. | |
55 | ||
56 | ||
57 | .. _v4l2-audioout: | |
58 | ||
59 | .. flat-table:: struct v4l2_audioout | |
60 | :header-rows: 0 | |
61 | :stub-columns: 0 | |
62 | :widths: 1 1 2 | |
63 | ||
64 | ||
65 | - .. row 1 | |
66 | ||
67 | - __u32 | |
68 | ||
69 | - ``index`` | |
70 | ||
71 | - Identifies the audio output, set by the driver or application. | |
72 | ||
73 | - .. row 2 | |
74 | ||
75 | - __u8 | |
76 | ||
77 | - ``name``\ [32] | |
78 | ||
79 | - Name of the audio output, a NUL-terminated ASCII string, for | |
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80 | example: "Line Out". This information is intended for the user, |
81 | preferably the connector label on the device itself. | |
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82 | |
83 | - .. row 3 | |
84 | ||
85 | - __u32 | |
86 | ||
87 | - ``capability`` | |
88 | ||
89 | - Audio capability flags, none defined yet. Drivers must set this | |
0579e6e3 | 90 | field to zero. |
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91 | |
92 | - .. row 4 | |
93 | ||
94 | - __u32 | |
95 | ||
96 | - ``mode`` | |
97 | ||
98 | - Audio mode, none defined yet. Drivers and applications (on | |
0579e6e3 | 99 | ``VIDIOC_S_AUDOUT``) must set this field to zero. |
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100 | |
101 | - .. row 5 | |
102 | ||
103 | - __u32 | |
104 | ||
105 | - ``reserved``\ [2] | |
106 | ||
107 | - Reserved for future extensions. Drivers and applications must set | |
0579e6e3 | 108 | the array to zero. |
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109 | |
110 | ||
586027ce | 111 | RETURN VALUE |
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112 | ============ |
113 | ||
114 | On success 0 is returned, on error -1 and the ``errno`` variable is set | |
115 | appropriately. The generic error codes are described at the | |
116 | :ref:`Generic Error Codes <gen-errors>` chapter. | |
117 | ||
118 | EINVAL | |
119 | No audio outputs combine with the current video output, or the | |
120 | number of the selected audio output is out of bounds or it does not | |
121 | combine. |