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1 | <refentry id="vidioc-g-audio"> |
2 | <refmeta> | |
3 | <refentrytitle>ioctl VIDIOC_G_AUDIO, VIDIOC_S_AUDIO</refentrytitle> | |
4 | &manvol; | |
5 | </refmeta> | |
6 | ||
7 | <refnamediv> | |
8 | <refname>VIDIOC_G_AUDIO</refname> | |
9 | <refname>VIDIOC_S_AUDIO</refname> | |
10 | <refpurpose>Query or select the current audio input and its | |
11 | attributes</refpurpose> | |
12 | </refnamediv> | |
13 | ||
14 | <refsynopsisdiv> | |
15 | <funcsynopsis> | |
16 | <funcprototype> | |
17 | <funcdef>int <function>ioctl</function></funcdef> | |
18 | <paramdef>int <parameter>fd</parameter></paramdef> | |
19 | <paramdef>int <parameter>request</parameter></paramdef> | |
20 | <paramdef>struct v4l2_audio *<parameter>argp</parameter></paramdef> | |
21 | </funcprototype> | |
22 | </funcsynopsis> | |
23 | <funcsynopsis> | |
24 | <funcprototype> | |
25 | <funcdef>int <function>ioctl</function></funcdef> | |
26 | <paramdef>int <parameter>fd</parameter></paramdef> | |
27 | <paramdef>int <parameter>request</parameter></paramdef> | |
28 | <paramdef>const struct v4l2_audio *<parameter>argp</parameter></paramdef> | |
29 | </funcprototype> | |
30 | </funcsynopsis> | |
31 | </refsynopsisdiv> | |
32 | ||
33 | <refsect1> | |
34 | <title>Arguments</title> | |
35 | ||
36 | <variablelist> | |
37 | <varlistentry> | |
38 | <term><parameter>fd</parameter></term> | |
39 | <listitem> | |
40 | <para>&fd;</para> | |
41 | </listitem> | |
42 | </varlistentry> | |
43 | <varlistentry> | |
44 | <term><parameter>request</parameter></term> | |
45 | <listitem> | |
46 | <para>VIDIOC_G_AUDIO, VIDIOC_S_AUDIO</para> | |
47 | </listitem> | |
48 | </varlistentry> | |
49 | <varlistentry> | |
50 | <term><parameter>argp</parameter></term> | |
51 | <listitem> | |
52 | <para></para> | |
53 | </listitem> | |
54 | </varlistentry> | |
55 | </variablelist> | |
56 | </refsect1> | |
57 | ||
58 | <refsect1> | |
59 | <title>Description</title> | |
60 | ||
61 | <para>To query the current audio input applications zero out the | |
62 | <structfield>reserved</structfield> array of a &v4l2-audio; | |
63 | and call the <constant>VIDIOC_G_AUDIO</constant> ioctl with a pointer | |
64 | to this structure. Drivers fill the rest of the structure or return an | |
65 | &EINVAL; when the device has no audio inputs, or none which combine | |
66 | with the current video input.</para> | |
67 | ||
68 | <para>Audio inputs have one writable property, the audio mode. To | |
69 | select the current audio input <emphasis>and</emphasis> change the | |
70 | audio mode, applications initialize the | |
71 | <structfield>index</structfield> and <structfield>mode</structfield> | |
72 | fields, and the | |
73 | <structfield>reserved</structfield> array of a | |
74 | <structname>v4l2_audio</structname> structure and call the | |
75 | <constant>VIDIOC_S_AUDIO</constant> ioctl. Drivers may switch to a | |
76 | different audio mode if the request cannot be satisfied. However, this | |
77 | is a write-only ioctl, it does not return the actual new audio | |
78 | mode.</para> | |
79 | ||
80 | <table pgwide="1" frame="none" id="v4l2-audio"> | |
81 | <title>struct <structname>v4l2_audio</structname></title> | |
82 | <tgroup cols="3"> | |
83 | &cs-str; | |
84 | <tbody valign="top"> | |
85 | <row> | |
86 | <entry>__u32</entry> | |
87 | <entry><structfield>index</structfield></entry> | |
88 | <entry>Identifies the audio input, set by the | |
89 | driver or application.</entry> | |
90 | </row> | |
91 | <row> | |
92 | <entry>__u8</entry> | |
93 | <entry><structfield>name</structfield>[32]</entry> | |
94 | <entry>Name of the audio input, a NUL-terminated ASCII | |
95 | string, for example: "Line In". This information is intended for the | |
96 | user, preferably the connector label on the device itself.</entry> | |
97 | </row> | |
98 | <row> | |
99 | <entry>__u32</entry> | |
100 | <entry><structfield>capability</structfield></entry> | |
101 | <entry>Audio capability flags, see <xref | |
102 | linkend="audio-capability" />.</entry> | |
103 | </row> | |
104 | <row> | |
105 | <entry>__u32</entry> | |
106 | <entry><structfield>mode</structfield></entry> | |
107 | <entry>Audio mode flags set by drivers and applications (on | |
108 | <constant>VIDIOC_S_AUDIO</constant> ioctl), see <xref linkend="audio-mode" />.</entry> | |
109 | </row> | |
110 | <row> | |
111 | <entry>__u32</entry> | |
112 | <entry><structfield>reserved</structfield>[2]</entry> | |
113 | <entry>Reserved for future extensions. Drivers and | |
114 | applications must set the array to zero.</entry> | |
115 | </row> | |
116 | </tbody> | |
117 | </tgroup> | |
118 | </table> | |
119 | ||
120 | <table pgwide="1" frame="none" id="audio-capability"> | |
121 | <title>Audio Capability Flags</title> | |
122 | <tgroup cols="3"> | |
123 | &cs-def; | |
124 | <tbody valign="top"> | |
125 | <row> | |
126 | <entry><constant>V4L2_AUDCAP_STEREO</constant></entry> | |
127 | <entry>0x00001</entry> | |
128 | <entry>This is a stereo input. The flag is intended to | |
129 | automatically disable stereo recording etc. when the signal is always | |
130 | monaural. The API provides no means to detect if stereo is | |
131 | <emphasis>received</emphasis>, unless the audio input belongs to a | |
132 | tuner.</entry> | |
133 | </row> | |
134 | <row> | |
135 | <entry><constant>V4L2_AUDCAP_AVL</constant></entry> | |
136 | <entry>0x00002</entry> | |
137 | <entry>Automatic Volume Level mode is supported.</entry> | |
138 | </row> | |
139 | </tbody> | |
140 | </tgroup> | |
141 | </table> | |
142 | ||
143 | <table pgwide="1" frame="none" id="audio-mode"> | |
144 | <title>Audio Mode Flags</title> | |
145 | <tgroup cols="3"> | |
146 | &cs-def; | |
147 | <tbody valign="top"> | |
148 | <row> | |
149 | <entry><constant>V4L2_AUDMODE_AVL</constant></entry> | |
150 | <entry>0x00001</entry> | |
151 | <entry>AVL mode is on.</entry> | |
152 | </row> | |
153 | </tbody> | |
154 | </tgroup> | |
155 | </table> | |
156 | </refsect1> | |
157 | ||
158 | <refsect1> | |
159 | &return-value; | |
160 | ||
161 | <variablelist> | |
162 | <varlistentry> | |
163 | <term><errorcode>EINVAL</errorcode></term> | |
164 | <listitem> | |
165 | <para>No audio inputs combine with the current video input, | |
166 | or the number of the selected audio input is out of bounds or it does | |
167 | not combine, or there are no audio inputs at all and the ioctl is not | |
168 | supported.</para> | |
169 | </listitem> | |
170 | </varlistentry> | |
171 | <varlistentry> | |
172 | <term><errorcode>EBUSY</errorcode></term> | |
173 | <listitem> | |
174 | <para>I/O is in progress, the input cannot be | |
175 | switched.</para> | |
176 | </listitem> | |
177 | </varlistentry> | |
178 | </variablelist> | |
179 | </refsect1> | |
180 | </refentry> | |
181 | ||
182 | <!-- | |
183 | Local Variables: | |
184 | mode: sgml | |
185 | sgml-parent-document: "v4l2.sgml" | |
186 | indent-tabs-mode: nil | |
187 | End: | |
188 | --> |