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Laurent Pinchart35c30172010-05-05 11:38:35 -03001<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>