Commit | Line | Data |
---|---|---|
5377d91f MH |
1 | .. -*- coding: utf-8; mode: rst -*- |
2 | ||
af4a4d0d | 3 | .. _VIDIOC_G_AUDIO: |
5377d91f MH |
4 | |
5 | ************************************ | |
6 | ioctl VIDIOC_G_AUDIO, VIDIOC_S_AUDIO | |
7 | ************************************ | |
8 | ||
15e7d615 | 9 | Name |
586027ce | 10 | ==== |
5377d91f | 11 | |
586027ce | 12 | VIDIOC_G_AUDIO - VIDIOC_S_AUDIO - Query or select the current audio input and its attributes |
5377d91f | 13 | |
15e7d615 MCC |
14 | |
15 | Synopsis | |
5377d91f MH |
16 | ======== |
17 | ||
41d80465 MCC |
18 | .. c:function:: int ioctl( int fd, VIDIOC_G_AUDIO, struct v4l2_audio *argp ) |
19 | :name: VIDIOC_G_AUDIO | |
5377d91f | 20 | |
41d80465 MCC |
21 | .. c:function:: int ioctl( int fd, VIDIOC_S_AUDIO, const struct v4l2_audio *argp ) |
22 | :name: VIDIOC_S_AUDIO | |
5377d91f | 23 | |
586027ce | 24 | |
15e7d615 | 25 | Arguments |
5377d91f MH |
26 | ========= |
27 | ||
28 | ``fd`` | |
29 | File descriptor returned by :ref:`open() <func-open>`. | |
30 | ||
5377d91f MH |
31 | ``argp`` |
32 | ||
33 | ||
15e7d615 | 34 | Description |
5377d91f MH |
35 | =========== |
36 | ||
37 | To query the current audio input applications zero out the ``reserved`` | |
38 | array of a struct :ref:`v4l2_audio <v4l2-audio>` and call the | |
4e03cb76 | 39 | :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` 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 |
5377d91f MH |
41 | has no audio inputs, or none which combine with the current video input. |
42 | ||
43 | Audio inputs have one writable property, the audio mode. To select the | |
44 | current audio input *and* change the audio mode, applications initialize | |
45 | the ``index`` and ``mode`` fields, and the ``reserved`` array of a | |
acf309a2 | 46 | :ref:`struct v4l2_audio <v4l2-audio>` structure and call the :ref:`VIDIOC_S_AUDIO <VIDIOC_G_AUDIO>` |
5377d91f MH |
47 | ioctl. Drivers may switch to a different audio mode if the request |
48 | cannot be satisfied. However, this is a write-only ioctl, it does not | |
49 | return the actual new audio mode. | |
50 | ||
51 | ||
5bd4bb78 MCC |
52 | .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| |
53 | ||
fa92b04d MCC |
54 | .. _v4l2-audio: |
55 | ||
5377d91f MH |
56 | .. flat-table:: struct v4l2_audio |
57 | :header-rows: 0 | |
58 | :stub-columns: 0 | |
59 | :widths: 1 1 2 | |
60 | ||
61 | ||
62 | - .. row 1 | |
63 | ||
64 | - __u32 | |
65 | ||
66 | - ``index`` | |
67 | ||
68 | - Identifies the audio input, set by the driver or application. | |
69 | ||
70 | - .. row 2 | |
71 | ||
72 | - __u8 | |
73 | ||
8968da9b | 74 | - ``name``\ [32] |
5377d91f MH |
75 | |
76 | - Name of the audio input, a NUL-terminated ASCII string, for | |
0579e6e3 MCC |
77 | example: "Line In". This information is intended for the user, |
78 | preferably the connector label on the device itself. | |
5377d91f MH |
79 | |
80 | - .. row 3 | |
81 | ||
82 | - __u32 | |
83 | ||
84 | - ``capability`` | |
85 | ||
86 | - Audio capability flags, see :ref:`audio-capability`. | |
87 | ||
88 | - .. row 4 | |
89 | ||
90 | - __u32 | |
91 | ||
92 | - ``mode`` | |
93 | ||
94 | - Audio mode flags set by drivers and applications (on | |
0579e6e3 | 95 | :ref:`VIDIOC_S_AUDIO <VIDIOC_G_AUDIO>` ioctl), see :ref:`audio-mode`. |
5377d91f MH |
96 | |
97 | - .. row 5 | |
98 | ||
99 | - __u32 | |
100 | ||
8968da9b | 101 | - ``reserved``\ [2] |
5377d91f MH |
102 | |
103 | - Reserved for future extensions. Drivers and applications must set | |
0579e6e3 | 104 | the array to zero. |
5377d91f MH |
105 | |
106 | ||
107 | ||
5bd4bb78 MCC |
108 | .. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}| |
109 | ||
fa92b04d MCC |
110 | .. _audio-capability: |
111 | ||
5377d91f MH |
112 | .. flat-table:: Audio Capability Flags |
113 | :header-rows: 0 | |
114 | :stub-columns: 0 | |
115 | :widths: 3 1 4 | |
116 | ||
117 | ||
118 | - .. row 1 | |
119 | ||
120 | - ``V4L2_AUDCAP_STEREO`` | |
121 | ||
122 | - 0x00001 | |
123 | ||
124 | - This is a stereo input. The flag is intended to automatically | |
0579e6e3 MCC |
125 | disable stereo recording etc. when the signal is always monaural. |
126 | The API provides no means to detect if stereo is *received*, | |
127 | unless the audio input belongs to a tuner. | |
5377d91f MH |
128 | |
129 | - .. row 2 | |
130 | ||
131 | - ``V4L2_AUDCAP_AVL`` | |
132 | ||
133 | - 0x00002 | |
134 | ||
135 | - Automatic Volume Level mode is supported. | |
136 | ||
137 | ||
138 | ||
5bd4bb78 MCC |
139 | .. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}| |
140 | ||
fa92b04d MCC |
141 | .. _audio-mode: |
142 | ||
5377d91f MH |
143 | .. flat-table:: Audio Mode Flags |
144 | :header-rows: 0 | |
145 | :stub-columns: 0 | |
146 | :widths: 3 1 4 | |
147 | ||
148 | ||
149 | - .. row 1 | |
150 | ||
151 | - ``V4L2_AUDMODE_AVL`` | |
152 | ||
153 | - 0x00001 | |
154 | ||
155 | - AVL mode is on. | |
156 | ||
157 | ||
15e7d615 | 158 | Return Value |
5377d91f MH |
159 | ============ |
160 | ||
161 | On success 0 is returned, on error -1 and the ``errno`` variable is set | |
162 | appropriately. The generic error codes are described at the | |
163 | :ref:`Generic Error Codes <gen-errors>` chapter. | |
164 | ||
165 | EINVAL | |
166 | No audio inputs combine with the current video input, or the number | |
167 | of the selected audio input is out of bounds or it does not combine. |