Based on kernel version 3.0.4. Page generated on 2011-10-03 22:07 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 <note> 54 <title>Experimental</title> 55 56 <para>This is an <link linkend="experimental">experimental</link> 57 interface and may change in the future.</para> 58 </note> 59 60 <para>This ioctl allows applications to enumerate all frame sizes 61 (&ie; width and height in pixels) that the device supports for the 62 given pixel format.</para> 63 <para>The supported pixel formats can be obtained by using the 64 &VIDIOC-ENUM-FMT; function.</para> 65 <para>The return value and the content of the 66 <structfield>v4l2_frmsizeenum.type</structfield> field depend on the 67 type of frame sizes the device supports. Here are the semantics of the 68 function for the different cases:</para> 69 70 <itemizedlist> 71 <listitem> 72 <para><emphasis role="bold">Discrete:</emphasis> The function 73 returns success if the given index value (zero-based) is valid. The 74 application should increase the index by one for each call until 75 <constant>EINVAL</constant> is returned. The 76 <structfield>v4l2_frmsizeenum.type</structfield> field is set to 77 <constant>V4L2_FRMSIZE_TYPE_DISCRETE</constant> by the driver. Of the 78 union only the <structfield>discrete</structfield> member is 79 valid.</para> 80 </listitem> 81 <listitem> 82 <para><emphasis role="bold">Step-wise:</emphasis> The function 83 returns success if the given index value is zero and 84 <constant>EINVAL</constant> for any other index value. The 85 <structfield>v4l2_frmsizeenum.type</structfield> field is set to 86 <constant>V4L2_FRMSIZE_TYPE_STEPWISE</constant> by the driver. Of the 87 union only the <structfield>stepwise</structfield> member is 88 valid.</para> 89 </listitem> 90 <listitem> 91 <para><emphasis role="bold">Continuous:</emphasis> This is a 92 special case of the step-wise type above. The function returns success 93 if the given index value is zero and <constant>EINVAL</constant> for 94 any other index value. The 95 <structfield>v4l2_frmsizeenum.type</structfield> field is set to 96 <constant>V4L2_FRMSIZE_TYPE_CONTINUOUS</constant> by the driver. Of 97 the union only the <structfield>stepwise</structfield> member is valid 98 and the <structfield>step_width</structfield> and 99 <structfield>step_height</structfield> values are set to 1.</para> 100 </listitem> 101 </itemizedlist> 102 103 <para>When the application calls the function with index zero, it 104 must check the <structfield>type</structfield> field to determine the 105 type of frame size enumeration the device supports. Only for the 106 <constant>V4L2_FRMSIZE_TYPE_DISCRETE</constant> type does it make 107 sense to increase the index value to receive more frame sizes.</para> 108 <para>Note that the order in which the frame sizes are returned 109 has no special meaning. In particular does it not say anything about 110 potential default format sizes.</para> 111 <para>Applications can assume that the enumeration data does not 112 change without any interaction from the application itself. This means 113 that the enumeration data is consistent if the application does not 114 perform any other ioctl calls while it runs the frame size 115 enumeration.</para> 116 </refsect1> 117 118 <refsect1> 119 <title>Structs</title> 120 121 <para>In the structs below, <emphasis>IN</emphasis> denotes a 122 value that has to be filled in by the application, 123 <emphasis>OUT</emphasis> denotes values that the driver fills in. The 124 application should zero out all members except for the 125 <emphasis>IN</emphasis> fields.</para> 126 127 <table pgwide="1" frame="none" id="v4l2-frmsize-discrete"> 128 <title>struct <structname>v4l2_frmsize_discrete</structname></title> 129 <tgroup cols="3"> 130 &cs-str; 131 <tbody valign="top"> 132 <row> 133 <entry>__u32</entry> 134 <entry><structfield>width</structfield></entry> 135 <entry>Width of the frame [pixel].</entry> 136 </row> 137 <row> 138 <entry>__u32</entry> 139 <entry><structfield>height</structfield></entry> 140 <entry>Height of the frame [pixel].</entry> 141 </row> 142 </tbody> 143 </tgroup> 144 </table> 145 146 <table pgwide="1" frame="none" id="v4l2-frmsize-stepwise"> 147 <title>struct <structname>v4l2_frmsize_stepwise</structname></title> 148 <tgroup cols="3"> 149 &cs-str; 150 <tbody valign="top"> 151 <row> 152 <entry>__u32</entry> 153 <entry><structfield>min_width</structfield></entry> 154 <entry>Minimum frame width [pixel].</entry> 155 </row> 156 <row> 157 <entry>__u32</entry> 158 <entry><structfield>max_width</structfield></entry> 159 <entry>Maximum frame width [pixel].</entry> 160 </row> 161 <row> 162 <entry>__u32</entry> 163 <entry><structfield>step_width</structfield></entry> 164 <entry>Frame width step size [pixel].</entry> 165 </row> 166 <row> 167 <entry>__u32</entry> 168 <entry><structfield>min_height</structfield></entry> 169 <entry>Minimum frame height [pixel].</entry> 170 </row> 171 <row> 172 <entry>__u32</entry> 173 <entry><structfield>max_height</structfield></entry> 174 <entry>Maximum frame height [pixel].</entry> 175 </row> 176 <row> 177 <entry>__u32</entry> 178 <entry><structfield>step_height</structfield></entry> 179 <entry>Frame height step size [pixel].</entry> 180 </row> 181 </tbody> 182 </tgroup> 183 </table> 184 185 <table pgwide="1" frame="none" id="v4l2-frmsizeenum"> 186 <title>struct <structname>v4l2_frmsizeenum</structname></title> 187 <tgroup cols="4"> 188 <colspec colname="c1" /> 189 <colspec colname="c2" /> 190 <colspec colname="c3" /> 191 <colspec colname="c4" /> 192 <tbody valign="top"> 193 <row> 194 <entry>__u32</entry> 195 <entry><structfield>index</structfield></entry> 196 <entry></entry> 197 <entry>IN: Index of the given frame size in the enumeration.</entry> 198 </row> 199 <row> 200 <entry>__u32</entry> 201 <entry><structfield>pixel_format</structfield></entry> 202 <entry></entry> 203 <entry>IN: Pixel format for which the frame sizes are enumerated.</entry> 204 </row> 205 <row> 206 <entry>__u32</entry> 207 <entry><structfield>type</structfield></entry> 208 <entry></entry> 209 <entry>OUT: Frame size type the device supports.</entry> 210 </row> 211 <row> 212 <entry>union</entry> 213 <entry></entry> 214 <entry></entry> 215 <entry>OUT: Frame size with the given index.</entry> 216 </row> 217 <row> 218 <entry></entry> 219 <entry>&v4l2-frmsize-discrete;</entry> 220 <entry><structfield>discrete</structfield></entry> 221 <entry></entry> 222 </row> 223 <row> 224 <entry></entry> 225 <entry>&v4l2-frmsize-stepwise;</entry> 226 <entry><structfield>stepwise</structfield></entry> 227 <entry></entry> 228 </row> 229 <row> 230 <entry>__u32</entry> 231 <entry><structfield>reserved[2]</structfield></entry> 232 <entry></entry> 233 <entry>Reserved space for future use.</entry> 234 </row> 235 </tbody> 236 </tgroup> 237 </table> 238 </refsect1> 239 240 <refsect1> 241 <title>Enums</title> 242 243 <table pgwide="1" frame="none" id="v4l2-frmsizetypes"> 244 <title>enum <structname>v4l2_frmsizetypes</structname></title> 245 <tgroup cols="3"> 246 &cs-def; 247 <tbody valign="top"> 248 <row> 249 <entry><constant>V4L2_FRMSIZE_TYPE_DISCRETE</constant></entry> 250 <entry>1</entry> 251 <entry>Discrete frame size.</entry> 252 </row> 253 <row> 254 <entry><constant>V4L2_FRMSIZE_TYPE_CONTINUOUS</constant></entry> 255 <entry>2</entry> 256 <entry>Continuous frame size.</entry> 257 </row> 258 <row> 259 <entry><constant>V4L2_FRMSIZE_TYPE_STEPWISE</constant></entry> 260 <entry>3</entry> 261 <entry>Step-wise defined frame size.</entry> 262 </row> 263 </tbody> 264 </tgroup> 265 </table> 266 </refsect1> 267 268 <refsect1> 269 &return-value; 270 271 <para>See the description section above for a list of return 272 values that <varname>errno</varname> can have.</para> 273 </refsect1> 274 </refentry> 275 276 <!-- 277 Local Variables: 278 mode: sgml 279 sgml-parent-document: "v4l2.sgml" 280 indent-tabs-mode: nil 281 End: 282 -->
