Based on kernel version 4.7.2. Page generated on 2016-08-22 22:45 EST.
1 <refentry id="vidioc-enum-framesizes"> 2 3 <refmeta> 4 <refentrytitle>ioctl VIDIOC_ENUM_FRAMESIZES</refentrytitle> 5 &manvol; 6 </refmeta> 7 8 <refnamediv> 9 <refname>VIDIOC_ENUM_FRAMESIZES</refname> 10 <refpurpose>Enumerate frame sizes</refpurpose> 11 </refnamediv> 12 13 <refsynopsisdiv> 14 <funcsynopsis> 15 <funcprototype> 16 <funcdef>int <function>ioctl</function></funcdef> 17 <paramdef>int <parameter>fd</parameter></paramdef> 18 <paramdef>int <parameter>request</parameter></paramdef> 19 <paramdef>struct v4l2_frmsizeenum *<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_ENUM_FRAMESIZES</para> 38 </listitem> 39 </varlistentry> 40 <varlistentry> 41 <term><parameter>argp</parameter></term> 42 <listitem> 43 <para>Pointer to a &v4l2-frmsizeenum; that contains an index 44 and pixel format and receives a frame width and height.</para> 45 </listitem> 46 </varlistentry> 47 </variablelist> 48 </refsect1> 49 50 <refsect1> 51 <title>Description</title> 52 53 <para>This ioctl allows applications to enumerate all frame sizes 54 (&ie; width and height in pixels) that the device supports for the 55 given pixel format.</para> 56 <para>The supported pixel formats can be obtained by using the 57 &VIDIOC-ENUM-FMT; function.</para> 58 <para>The return value and the content of the 59 <structfield>v4l2_frmsizeenum.type</structfield> field depend on the 60 type of frame sizes the device supports. Here are the semantics of the 61 function for the different cases:</para> 62 63 <itemizedlist> 64 <listitem> 65 <para><emphasis role="bold">Discrete:</emphasis> The function 66 returns success if the given index value (zero-based) is valid. The 67 application should increase the index by one for each call until 68 <constant>EINVAL</constant> is returned. The 69 <structfield>v4l2_frmsizeenum.type</structfield> field is set to 70 <constant>V4L2_FRMSIZE_TYPE_DISCRETE</constant> by the driver. Of the 71 union only the <structfield>discrete</structfield> member is 72 valid.</para> 73 </listitem> 74 <listitem> 75 <para><emphasis role="bold">Step-wise:</emphasis> The function 76 returns success if the given index value is zero and 77 <constant>EINVAL</constant> for any other index value. The 78 <structfield>v4l2_frmsizeenum.type</structfield> field is set to 79 <constant>V4L2_FRMSIZE_TYPE_STEPWISE</constant> by the driver. Of the 80 union only the <structfield>stepwise</structfield> member is 81 valid.</para> 82 </listitem> 83 <listitem> 84 <para><emphasis role="bold">Continuous:</emphasis> This is a 85 special case of the step-wise type above. The function returns success 86 if the given index value is zero and <constant>EINVAL</constant> for 87 any other index value. The 88 <structfield>v4l2_frmsizeenum.type</structfield> field is set to 89 <constant>V4L2_FRMSIZE_TYPE_CONTINUOUS</constant> by the driver. Of 90 the union only the <structfield>stepwise</structfield> member is valid 91 and the <structfield>step_width</structfield> and 92 <structfield>step_height</structfield> values are set to 1.</para> 93 </listitem> 94 </itemizedlist> 95 96 <para>When the application calls the function with index zero, it 97 must check the <structfield>type</structfield> field to determine the 98 type of frame size enumeration the device supports. Only for the 99 <constant>V4L2_FRMSIZE_TYPE_DISCRETE</constant> type does it make 100 sense to increase the index value to receive more frame sizes.</para> 101 <para>Note that the order in which the frame sizes are returned 102 has no special meaning. In particular does it not say anything about 103 potential default format sizes.</para> 104 <para>Applications can assume that the enumeration data does not 105 change without any interaction from the application itself. This means 106 that the enumeration data is consistent if the application does not 107 perform any other ioctl calls while it runs the frame size 108 enumeration.</para> 109 </refsect1> 110 111 <refsect1> 112 <title>Structs</title> 113 114 <para>In the structs below, <emphasis>IN</emphasis> denotes a 115 value that has to be filled in by the application, 116 <emphasis>OUT</emphasis> denotes values that the driver fills in. The 117 application should zero out all members except for the 118 <emphasis>IN</emphasis> fields.</para> 119 120 <table pgwide="1" frame="none" id="v4l2-frmsize-discrete"> 121 <title>struct <structname>v4l2_frmsize_discrete</structname></title> 122 <tgroup cols="3"> 123 &cs-str; 124 <tbody valign="top"> 125 <row> 126 <entry>__u32</entry> 127 <entry><structfield>width</structfield></entry> 128 <entry>Width of the frame [pixel].</entry> 129 </row> 130 <row> 131 <entry>__u32</entry> 132 <entry><structfield>height</structfield></entry> 133 <entry>Height of the frame [pixel].</entry> 134 </row> 135 </tbody> 136 </tgroup> 137 </table> 138 139 <table pgwide="1" frame="none" id="v4l2-frmsize-stepwise"> 140 <title>struct <structname>v4l2_frmsize_stepwise</structname></title> 141 <tgroup cols="3"> 142 &cs-str; 143 <tbody valign="top"> 144 <row> 145 <entry>__u32</entry> 146 <entry><structfield>min_width</structfield></entry> 147 <entry>Minimum frame width [pixel].</entry> 148 </row> 149 <row> 150 <entry>__u32</entry> 151 <entry><structfield>max_width</structfield></entry> 152 <entry>Maximum frame width [pixel].</entry> 153 </row> 154 <row> 155 <entry>__u32</entry> 156 <entry><structfield>step_width</structfield></entry> 157 <entry>Frame width step size [pixel].</entry> 158 </row> 159 <row> 160 <entry>__u32</entry> 161 <entry><structfield>min_height</structfield></entry> 162 <entry>Minimum frame height [pixel].</entry> 163 </row> 164 <row> 165 <entry>__u32</entry> 166 <entry><structfield>max_height</structfield></entry> 167 <entry>Maximum frame height [pixel].</entry> 168 </row> 169 <row> 170 <entry>__u32</entry> 171 <entry><structfield>step_height</structfield></entry> 172 <entry>Frame height step size [pixel].</entry> 173 </row> 174 </tbody> 175 </tgroup> 176 </table> 177 178 <table pgwide="1" frame="none" id="v4l2-frmsizeenum"> 179 <title>struct <structname>v4l2_frmsizeenum</structname></title> 180 <tgroup cols="4"> 181 <colspec colname="c1" /> 182 <colspec colname="c2" /> 183 <colspec colname="c3" /> 184 <colspec colname="c4" /> 185 <tbody valign="top"> 186 <row> 187 <entry>__u32</entry> 188 <entry><structfield>index</structfield></entry> 189 <entry></entry> 190 <entry>IN: Index of the given frame size in the enumeration.</entry> 191 </row> 192 <row> 193 <entry>__u32</entry> 194 <entry><structfield>pixel_format</structfield></entry> 195 <entry></entry> 196 <entry>IN: Pixel format for which the frame sizes are enumerated.</entry> 197 </row> 198 <row> 199 <entry>__u32</entry> 200 <entry><structfield>type</structfield></entry> 201 <entry></entry> 202 <entry>OUT: Frame size type the device supports.</entry> 203 </row> 204 <row> 205 <entry>union</entry> 206 <entry></entry> 207 <entry></entry> 208 <entry>OUT: Frame size with the given index.</entry> 209 </row> 210 <row> 211 <entry></entry> 212 <entry>&v4l2-frmsize-discrete;</entry> 213 <entry><structfield>discrete</structfield></entry> 214 <entry></entry> 215 </row> 216 <row> 217 <entry></entry> 218 <entry>&v4l2-frmsize-stepwise;</entry> 219 <entry><structfield>stepwise</structfield></entry> 220 <entry></entry> 221 </row> 222 <row> 223 <entry>__u32</entry> 224 <entry><structfield>reserved[2]</structfield></entry> 225 <entry></entry> 226 <entry>Reserved space for future use. Must be zeroed by drivers and 227 applications.</entry> 228 </row> 229 </tbody> 230 </tgroup> 231 </table> 232 </refsect1> 233 234 <refsect1> 235 <title>Enums</title> 236 237 <table pgwide="1" frame="none" id="v4l2-frmsizetypes"> 238 <title>enum <structname>v4l2_frmsizetypes</structname></title> 239 <tgroup cols="3"> 240 &cs-def; 241 <tbody valign="top"> 242 <row> 243 <entry><constant>V4L2_FRMSIZE_TYPE_DISCRETE</constant></entry> 244 <entry>1</entry> 245 <entry>Discrete frame size.</entry> 246 </row> 247 <row> 248 <entry><constant>V4L2_FRMSIZE_TYPE_CONTINUOUS</constant></entry> 249 <entry>2</entry> 250 <entry>Continuous frame size.</entry> 251 </row> 252 <row> 253 <entry><constant>V4L2_FRMSIZE_TYPE_STEPWISE</constant></entry> 254 <entry>3</entry> 255 <entry>Step-wise defined frame size.</entry> 256 </row> 257 </tbody> 258 </tgroup> 259 </table> 260 </refsect1> 261 262 <refsect1> 263 &return-value; 264 </refsect1> 265 </refentry>
