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35c3017a LP |
1 | <refentry id="vidioc-subdev-enum-frame-interval"> |
2 | <refmeta> | |
3 | <refentrytitle>ioctl VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL</refentrytitle> | |
4 | &manvol; | |
5 | </refmeta> | |
6 | ||
7 | <refnamediv> | |
8 | <refname>VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL</refname> | |
9 | <refpurpose>Enumerate frame intervals</refpurpose> | |
10 | </refnamediv> | |
11 | ||
12 | <refsynopsisdiv> | |
13 | <funcsynopsis> | |
14 | <funcprototype> | |
15 | <funcdef>int <function>ioctl</function></funcdef> | |
16 | <paramdef>int <parameter>fd</parameter></paramdef> | |
17 | <paramdef>int <parameter>request</parameter></paramdef> | |
18 | <paramdef>struct v4l2_subdev_frame_interval_enum * | |
19 | <parameter>argp</parameter></paramdef> | |
20 | </funcprototype> | |
21 | </funcsynopsis> | |
22 | </refsynopsisdiv> | |
23 | ||
24 | <refsect1> | |
25 | <title>Arguments</title> | |
26 | ||
27 | <variablelist> | |
28 | <varlistentry> | |
29 | <term><parameter>fd</parameter></term> | |
30 | <listitem> | |
31 | <para>&fd;</para> | |
32 | </listitem> | |
33 | </varlistentry> | |
34 | <varlistentry> | |
35 | <term><parameter>request</parameter></term> | |
36 | <listitem> | |
37 | <para>VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL</para> | |
38 | </listitem> | |
39 | </varlistentry> | |
40 | <varlistentry> | |
41 | <term><parameter>argp</parameter></term> | |
42 | <listitem> | |
43 | <para></para> | |
44 | </listitem> | |
45 | </varlistentry> | |
46 | </variablelist> | |
47 | </refsect1> | |
48 | ||
49 | <refsect1> | |
50 | <title>Description</title> | |
51 | ||
52 | <note> | |
53 | <title>Experimental</title> | |
54 | <para>This is an <link linkend="experimental">experimental</link> | |
55 | interface and may change in the future.</para> | |
56 | </note> | |
57 | ||
58 | <para>This ioctl lets applications enumerate available frame intervals on a | |
59 | given sub-device pad. Frame intervals only makes sense for sub-devices that | |
60 | can control the frame period on their own. This includes, for instance, | |
61 | image sensors and TV tuners.</para> | |
62 | ||
63 | <para>For the common use case of image sensors, the frame intervals | |
64 | available on the sub-device output pad depend on the frame format and size | |
65 | on the same pad. Applications must thus specify the desired format and size | |
66 | when enumerating frame intervals.</para> | |
67 | ||
68 | <para>To enumerate frame intervals applications initialize the | |
69 | <structfield>index</structfield>, <structfield>pad</structfield>, | |
70 | <structfield>code</structfield>, <structfield>width</structfield> and | |
71 | <structfield>height</structfield> fields of | |
72 | &v4l2-subdev-frame-interval-enum; and call the | |
73 | <constant>VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL</constant> ioctl with a pointer | |
74 | to this structure. Drivers fill the rest of the structure or return | |
75 | an &EINVAL; if one of the input fields is invalid. All frame intervals are | |
76 | enumerable by beginning at index zero and incrementing by one until | |
77 | <errorcode>EINVAL</errorcode> is returned.</para> | |
78 | ||
79 | <para>Available frame intervals may depend on the current 'try' formats | |
80 | at other pads of the sub-device, as well as on the current active links. See | |
81 | &VIDIOC-SUBDEV-G-FMT; for more information about the try formats.</para> | |
82 | ||
83 | <para>Sub-devices that support the frame interval enumeration ioctl should | |
84 | implemented it on a single pad only. Its behaviour when supported on | |
85 | multiple pads of the same sub-device is not defined.</para> | |
86 | ||
87 | <table pgwide="1" frame="none" id="v4l2-subdev-frame-interval-enum"> | |
88 | <title>struct <structname>v4l2_subdev_frame_interval_enum</structname></title> | |
89 | <tgroup cols="3"> | |
90 | &cs-str; | |
91 | <tbody valign="top"> | |
92 | <row> | |
93 | <entry>__u32</entry> | |
94 | <entry><structfield>index</structfield></entry> | |
95 | <entry>Number of the format in the enumeration, set by the | |
96 | application.</entry> | |
97 | </row> | |
98 | <row> | |
99 | <entry>__u32</entry> | |
100 | <entry><structfield>pad</structfield></entry> | |
101 | <entry>Pad number as reported by the media controller API.</entry> | |
102 | </row> | |
103 | <row> | |
104 | <entry>__u32</entry> | |
105 | <entry><structfield>code</structfield></entry> | |
106 | <entry>The media bus format code, as defined in | |
107 | <xref linkend="v4l2-mbus-format" />.</entry> | |
108 | </row> | |
109 | <row> | |
110 | <entry>__u32</entry> | |
111 | <entry><structfield>width</structfield></entry> | |
112 | <entry>Frame width, in pixels.</entry> | |
113 | </row> | |
114 | <row> | |
115 | <entry>__u32</entry> | |
116 | <entry><structfield>height</structfield></entry> | |
117 | <entry>Frame height, in pixels.</entry> | |
118 | </row> | |
119 | <row> | |
120 | <entry>&v4l2-fract;</entry> | |
121 | <entry><structfield>interval</structfield></entry> | |
122 | <entry>Period, in seconds, between consecutive video frames.</entry> | |
123 | </row> | |
124 | <row> | |
125 | <entry>__u32</entry> | |
126 | <entry><structfield>reserved</structfield>[9]</entry> | |
127 | <entry>Reserved for future extensions. Applications and drivers must | |
128 | set the array to zero.</entry> | |
129 | </row> | |
130 | </tbody> | |
131 | </tgroup> | |
132 | </table> | |
133 | </refsect1> | |
134 | ||
135 | <refsect1> | |
136 | &return-value; | |
137 | ||
138 | <variablelist> | |
139 | <varlistentry> | |
140 | <term><errorcode>EINVAL</errorcode></term> | |
141 | <listitem> | |
142 | <para>The &v4l2-subdev-frame-interval-enum; | |
143 | <structfield>pad</structfield> references a non-existing pad, one of | |
144 | the <structfield>code</structfield>, <structfield>width</structfield> | |
145 | or <structfield>height</structfield> fields are invalid for the given | |
146 | pad or the <structfield>index</structfield> field is out of bounds. | |
147 | </para> | |
148 | </listitem> | |
149 | </varlistentry> | |
150 | </variablelist> | |
151 | </refsect1> | |
152 | </refentry> |