1<refentry id="vidioc-enum-dv-timings">
2  <refmeta>
3    <refentrytitle>ioctl VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS</refentrytitle>
4    &manvol;
5  </refmeta>
6
7  <refnamediv>
8    <refname>VIDIOC_ENUM_DV_TIMINGS</refname>
9    <refname>VIDIOC_SUBDEV_ENUM_DV_TIMINGS</refname>
10    <refpurpose>Enumerate supported Digital Video timings</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_enum_dv_timings *<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_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS</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    <note>
53      <title>Experimental</title>
54      <para>This is an <link linkend="experimental"> experimental </link>
55      interface and may change in the future.</para>
56    </note>
57
58    <para>While some DV receivers or transmitters support a wide range of timings, others
59support only a limited number of timings. With this ioctl applications can enumerate a list
60of known supported timings. Call &VIDIOC-DV-TIMINGS-CAP; to check if it also supports other
61standards or even custom timings that are not in this list.</para>
62
63    <para>To query the available timings, applications initialize the
64<structfield>index</structfield> field and zero the reserved array of &v4l2-enum-dv-timings;
65and call the <constant>VIDIOC_ENUM_DV_TIMINGS</constant> ioctl on a video node with a
66pointer to this structure. Drivers fill the rest of the structure or return an
67&EINVAL; when the index is out of bounds. To enumerate all supported DV timings,
68applications shall begin at index zero, incrementing by one until the
69driver returns <errorcode>EINVAL</errorcode>. Note that drivers may enumerate a
70different set of DV timings after switching the video input or
71output.</para>
72
73    <para>When implemented by the driver DV timings of subdevices can be queried
74by calling the <constant>VIDIOC_SUBDEV_ENUM_DV_TIMINGS</constant> ioctl directly
75on a subdevice node. The DV timings are specific to inputs (for DV receivers) or
76outputs (for DV transmitters), applications must specify the desired pad number
77in the &v4l2-enum-dv-timings; <structfield>pad</structfield> field. Attempts to
78enumerate timings on a pad that doesn't support them will return an &EINVAL;.</para>
79
80    <table pgwide="1" frame="none" id="v4l2-enum-dv-timings">
81      <title>struct <structname>v4l2_enum_dv_timings</structname></title>
82      <tgroup cols="3">
83	&cs-str;
84	<tbody valign="top">
85	  <row>
86	    <entry>__u32</entry>
87	    <entry><structfield>index</structfield></entry>
88	    <entry>Number of the DV timings, set by the
89application.</entry>
90	  </row>
91	  <row>
92	    <entry>__u32</entry>
93	    <entry><structfield>pad</structfield></entry>
94	    <entry>Pad number as reported by the media controller API. This field
95	    is only used when operating on a subdevice node. When operating on a
96	    video node applications must set this field to zero.</entry>
97	  </row>
98	  <row>
99	    <entry>__u32</entry>
100	    <entry><structfield>reserved</structfield>[2]</entry>
101	    <entry>Reserved for future extensions. Drivers and applications must
102	    set the array to zero.</entry>
103	  </row>
104	  <row>
105	    <entry>&v4l2-dv-timings;</entry>
106	    <entry><structfield>timings</structfield></entry>
107	    <entry>The timings.</entry>
108	  </row>
109	</tbody>
110      </tgroup>
111    </table>
112  </refsect1>
113
114  <refsect1>
115    &return-value;
116
117    <variablelist>
118      <varlistentry>
119	<term><errorcode>EINVAL</errorcode></term>
120	<listitem>
121	  <para>The &v4l2-enum-dv-timings; <structfield>index</structfield>
122is out of bounds or the <structfield>pad</structfield> number is invalid.</para>
123	</listitem>
124      </varlistentry>
125      <varlistentry>
126	<term><errorcode>ENODATA</errorcode></term>
127	<listitem>
128	  <para>Digital video presets are not supported for this input or output.</para>
129	</listitem>
130      </varlistentry>
131    </variablelist>
132  </refsect1>
133</refentry>
134