Commit | Line | Data |
---|---|---|
5377d91f MH |
1 | .. -*- coding: utf-8; mode: rst -*- |
2 | ||
9f97b306 | 3 | .. _VIDIOC_G_AUDOUT: |
5377d91f MH |
4 | |
5 | ************************************** | |
6 | ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT | |
7 | ************************************** | |
8 | ||
15e7d615 | 9 | Name |
586027ce | 10 | ==== |
5377d91f | 11 | |
586027ce | 12 | VIDIOC_G_AUDOUT - VIDIOC_S_AUDOUT - Query or select the current audio output |
5377d91f | 13 | |
15e7d615 MCC |
14 | |
15 | Synopsis | |
5377d91f MH |
16 | ======== |
17 | ||
b7e67f6c | 18 | .. cpp:function:: int ioctl( int fd, int request, struct v4l2_audioout *argp ) |
5377d91f | 19 | |
b7e67f6c | 20 | .. cpp:function:: int ioctl( int fd, int request, const struct v4l2_audioout *argp ) |
5377d91f | 21 | |
586027ce | 22 | |
15e7d615 | 23 | Arguments |
5377d91f MH |
24 | ========= |
25 | ||
26 | ``fd`` | |
27 | File descriptor returned by :ref:`open() <func-open>`. | |
28 | ||
29 | ``request`` | |
30 | VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT | |
31 | ||
32 | ``argp`` | |
33 | ||
34 | ||
15e7d615 | 35 | Description |
5377d91f MH |
36 | =========== |
37 | ||
38 | To query the current audio output applications zero out the ``reserved`` | |
39 | array of a struct :ref:`v4l2_audioout <v4l2-audioout>` and call the | |
40 | ``VIDIOC_G_AUDOUT`` ioctl with a pointer to this structure. Drivers fill | |
cdb4af0f | 41 | the rest of the structure or return an ``EINVAL`` error code when the device |
5377d91f MH |
42 | has no audio inputs, or none which combine with the current video |
43 | output. | |
44 | ||
45 | Audio outputs have no writable properties. Nevertheless, to select the | |
46 | current audio output applications can initialize the ``index`` field and | |
47 | ``reserved`` array (which in the future may contain writable properties) | |
acf309a2 | 48 | of a :ref:`struct v4l2_audioout <v4l2-audioout>` structure and call the |
5377d91f | 49 | ``VIDIOC_S_AUDOUT`` ioctl. Drivers switch to the requested output or |
cdb4af0f | 50 | return the ``EINVAL`` error code when the index is out of bounds. This is a |
5377d91f MH |
51 | write-only ioctl, it does not return the current audio output attributes |
52 | as ``VIDIOC_G_AUDOUT`` does. | |
53 | ||
706f8a99 MCC |
54 | .. note:: Connectors on a TV card to loop back the received audio signal |
55 | to a sound card are not audio outputs in this sense. | |
5377d91f MH |
56 | |
57 | ||
58 | .. _v4l2-audioout: | |
59 | ||
60 | .. flat-table:: struct v4l2_audioout | |
61 | :header-rows: 0 | |
62 | :stub-columns: 0 | |
63 | :widths: 1 1 2 | |
64 | ||
65 | ||
66 | - .. row 1 | |
67 | ||
68 | - __u32 | |
69 | ||
70 | - ``index`` | |
71 | ||
72 | - Identifies the audio output, set by the driver or application. | |
73 | ||
74 | - .. row 2 | |
75 | ||
76 | - __u8 | |
77 | ||
8968da9b | 78 | - ``name``\ [32] |
5377d91f MH |
79 | |
80 | - Name of the audio output, a NUL-terminated ASCII string, for | |
0579e6e3 MCC |
81 | example: "Line Out". This information is intended for the user, |
82 | preferably the connector label on the device itself. | |
5377d91f MH |
83 | |
84 | - .. row 3 | |
85 | ||
86 | - __u32 | |
87 | ||
88 | - ``capability`` | |
89 | ||
90 | - Audio capability flags, none defined yet. Drivers must set this | |
0579e6e3 | 91 | field to zero. |
5377d91f MH |
92 | |
93 | - .. row 4 | |
94 | ||
95 | - __u32 | |
96 | ||
97 | - ``mode`` | |
98 | ||
99 | - Audio mode, none defined yet. Drivers and applications (on | |
0579e6e3 | 100 | ``VIDIOC_S_AUDOUT``) must set this field to zero. |
5377d91f MH |
101 | |
102 | - .. row 5 | |
103 | ||
104 | - __u32 | |
105 | ||
8968da9b | 106 | - ``reserved``\ [2] |
5377d91f MH |
107 | |
108 | - Reserved for future extensions. Drivers and applications must set | |
0579e6e3 | 109 | the array to zero. |
5377d91f MH |
110 | |
111 | ||
15e7d615 | 112 | Return Value |
5377d91f MH |
113 | ============ |
114 | ||
115 | On success 0 is returned, on error -1 and the ``errno`` variable is set | |
116 | appropriately. The generic error codes are described at the | |
117 | :ref:`Generic Error Codes <gen-errors>` chapter. | |
118 | ||
119 | EINVAL | |
120 | No audio outputs combine with the current video output, or the | |
121 | number of the selected audio output is out of bounds or it does not | |
122 | combine. |