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
44and 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>
57interface 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
62given 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
67type of frame sizes the device supports. Here are the semantics of the
68function for the different cases:</para>
69
70    <itemizedlist>
71      <listitem>
72	<para><emphasis role="bold">Discrete:</emphasis> The function
73returns success if the given index value (zero-based) is valid. The
74application 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
78union only the <structfield>discrete</structfield> member is
79valid.</para>
80      </listitem>
81      <listitem>
82	<para><emphasis role="bold">Step-wise:</emphasis> The function
83returns 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
87union only the <structfield>stepwise</structfield> member is
88valid.</para>
89      </listitem>
90      <listitem>
91	<para><emphasis role="bold">Continuous:</emphasis> This is a
92special case of the step-wise type above. The function returns success
93if the given index value is zero and <constant>EINVAL</constant> for
94any 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
97the union only the <structfield>stepwise</structfield> member is valid
98and 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
104must check the <structfield>type</structfield> field to determine the
105type of frame size enumeration the device supports. Only for the
106<constant>V4L2_FRMSIZE_TYPE_DISCRETE</constant> type does it make
107sense to increase the index value to receive more frame sizes.</para>
108    <para>Note that the order in which the frame sizes are returned
109has no special meaning. In particular does it not say anything about
110potential default format sizes.</para>
111    <para>Applications can assume that the enumeration data does not
112change without any interaction from the application itself. This means
113that the enumeration data is consistent if the application does not
114perform any other ioctl calls while it runs the frame size
115enumeration.</para>
116  </refsect1>
117
118  <refsect1>
119    <title>Structs</title>
120
121    <para>In the structs below, <emphasis>IN</emphasis> denotes a
122value that has to be filled in by the application,
123<emphasis>OUT</emphasis> denotes values that the driver fills in. The
124application 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  </refsect1>
271</refentry>
272