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>
