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Based on kernel version 4.7.2. Page generated on 2016-08-22 22:45 EST.

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	    <para>This ioctl lets applications enumerate available frame intervals on a
53	    given sub-device pad. Frame intervals only makes sense for sub-devices that
54	    can control the frame period on their own. This includes, for instance,
55	    image sensors and TV tuners.</para>
56	
57	    <para>For the common use case of image sensors, the frame intervals
58	    available on the sub-device output pad depend on the frame format and size
59	    on the same pad. Applications must thus specify the desired format and size
60	    when enumerating frame intervals.</para>
61	
62	    <para>To enumerate frame intervals applications initialize the
63	    <structfield>index</structfield>, <structfield>pad</structfield>,
64	    <structfield>which</structfield>, <structfield>code</structfield>,
65	    <structfield>width</structfield> and <structfield>height</structfield>
66	    fields of &v4l2-subdev-frame-interval-enum; and call the
67	    <constant>VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL</constant> ioctl with a pointer
68	    to this structure. Drivers fill the rest of the structure or return
69	    an &EINVAL; if one of the input fields is invalid. All frame intervals are
70	    enumerable by beginning at index zero and incrementing by one until
71	    <errorcode>EINVAL</errorcode> is returned.</para>
72	
73	    <para>Available frame intervals may depend on the current 'try' formats
74	    at other pads of the sub-device, as well as on the current active links. See
75	    &VIDIOC-SUBDEV-G-FMT; for more information about the try formats.</para>
76	
77	    <para>Sub-devices that support the frame interval enumeration ioctl should
78	    implemented it on a single pad only. Its behaviour when supported on
79	    multiple pads of the same sub-device is not defined.</para>
80	
81	    <table pgwide="1" frame="none" id="v4l2-subdev-frame-interval-enum">
82	      <title>struct <structname>v4l2_subdev_frame_interval_enum</structname></title>
83	      <tgroup cols="3">
84		&cs-str;
85		<tbody valign="top">
86		  <row>
87		    <entry>__u32</entry>
88		    <entry><structfield>index</structfield></entry>
89		    <entry>Number of the format in the enumeration, set by the
90		    application.</entry>
91		  </row>
92		  <row>
93		    <entry>__u32</entry>
94		    <entry><structfield>pad</structfield></entry>
95		    <entry>Pad number as reported by the media controller API.</entry>
96		  </row>
97		  <row>
98		    <entry>__u32</entry>
99		    <entry><structfield>code</structfield></entry>
100		    <entry>The media bus format code, as defined in
101		    <xref linkend="v4l2-mbus-format" />.</entry>
102		  </row>
103		  <row>
104		    <entry>__u32</entry>
105		    <entry><structfield>width</structfield></entry>
106		    <entry>Frame width, in pixels.</entry>
107		  </row>
108		  <row>
109		    <entry>__u32</entry>
110		    <entry><structfield>height</structfield></entry>
111		    <entry>Frame height, in pixels.</entry>
112		  </row>
113		  <row>
114		    <entry>&v4l2-fract;</entry>
115		    <entry><structfield>interval</structfield></entry>
116		    <entry>Period, in seconds, between consecutive video frames.</entry>
117		  </row>
118		  <row>
119		    <entry>__u32</entry>
120		    <entry><structfield>which</structfield></entry>
121		    <entry>Frame intervals to be enumerated, from &v4l2-subdev-format-whence;.</entry>
122		  </row>
123		  <row>
124		    <entry>__u32</entry>
125		    <entry><structfield>reserved</structfield>[8]</entry>
126		    <entry>Reserved for future extensions. Applications and drivers must
127		    set the array to zero.</entry>
128		  </row>
129		</tbody>
130	      </tgroup>
131	    </table>
132	  </refsect1>
133	
134	  <refsect1>
135	    &return-value;
136	
137	    <variablelist>
138	      <varlistentry>
139		<term><errorcode>EINVAL</errorcode></term>
140		<listitem>
141		  <para>The &v4l2-subdev-frame-interval-enum;
142		  <structfield>pad</structfield> references a non-existing pad, one of
143		  the <structfield>code</structfield>, <structfield>width</structfield>
144		  or <structfield>height</structfield> fields are invalid for the given
145		  pad or the <structfield>index</structfield> field is out of bounds.
146		  </para>
147		</listitem>
148	      </varlistentry>
149	    </variablelist>
150	  </refsect1>
151	</refentry>
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