summaryrefslogtreecommitdiff
path: root/Documentation/DocBook/media/v4l/vidioc-enum-dv-timings.xml
blob: b9fdfeacdbcbf1e218046c49739f7200619efb47 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
<refentry id="vidioc-enum-dv-timings">
  <refmeta>
    <refentrytitle>ioctl VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS</refentrytitle>
    &manvol;
  </refmeta>

  <refnamediv>
    <refname>VIDIOC_ENUM_DV_TIMINGS</refname>
    <refname>VIDIOC_SUBDEV_ENUM_DV_TIMINGS</refname>
    <refpurpose>Enumerate supported Digital Video timings</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcprototype>
	<funcdef>int <function>ioctl</function></funcdef>
	<paramdef>int <parameter>fd</parameter></paramdef>
	<paramdef>int <parameter>request</parameter></paramdef>
	<paramdef>struct v4l2_enum_dv_timings *<parameter>argp</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Arguments</title>

    <variablelist>
      <varlistentry>
	<term><parameter>fd</parameter></term>
	<listitem>
	  <para>&fd;</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><parameter>request</parameter></term>
	<listitem>
	  <para>VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><parameter>argp</parameter></term>
	<listitem>
	  <para></para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Description</title>

    <note>
      <title>Experimental</title>
      <para>This is an <link linkend="experimental"> experimental </link>
      interface and may change in the future.</para>
    </note>

    <para>While some DV receivers or transmitters support a wide range of timings, others
support only a limited number of timings. With this ioctl applications can enumerate a list
of known supported timings. Call &VIDIOC-DV-TIMINGS-CAP; to check if it also supports other
standards or even custom timings that are not in this list.</para>

    <para>To query the available timings, applications initialize the
<structfield>index</structfield> field and zero the reserved array of &v4l2-enum-dv-timings;
and call the <constant>VIDIOC_ENUM_DV_TIMINGS</constant> ioctl on a video node with a
pointer to this structure. Drivers fill the rest of the structure or return an
&EINVAL; when the index is out of bounds. To enumerate all supported DV timings,
applications shall begin at index zero, incrementing by one until the
driver returns <errorcode>EINVAL</errorcode>. Note that drivers may enumerate a
different set of DV timings after switching the video input or
output.</para>

    <para>When implemented by the driver DV timings of subdevices can be queried
by calling the <constant>VIDIOC_SUBDEV_ENUM_DV_TIMINGS</constant> ioctl directly
on a subdevice node. The DV timings are specific to inputs (for DV receivers) or
outputs (for DV transmitters), applications must specify the desired pad number
in the &v4l2-enum-dv-timings; <structfield>pad</structfield> field. Attempts to
enumerate timings on a pad that doesn't support them will return an &EINVAL;.</para>

    <table pgwide="1" frame="none" id="v4l2-enum-dv-timings">
      <title>struct <structname>v4l2_enum_dv_timings</structname></title>
      <tgroup cols="3">
	&cs-str;
	<tbody valign="top">
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>index</structfield></entry>
	    <entry>Number of the DV timings, set by the
application.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>pad</structfield></entry>
	    <entry>Pad number as reported by the media controller API. This field
	    is only used when operating on a subdevice node. When operating on a
	    video node applications must set this field to zero.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>reserved</structfield>[2]</entry>
	    <entry>Reserved for future extensions. Drivers and applications must
	    set the array to zero.</entry>
	  </row>
	  <row>
	    <entry>&v4l2-dv-timings;</entry>
	    <entry><structfield>timings</structfield></entry>
	    <entry>The timings.</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>
  </refsect1>

  <refsect1>
    &return-value;

    <variablelist>
      <varlistentry>
	<term><errorcode>EINVAL</errorcode></term>
	<listitem>
	  <para>The &v4l2-enum-dv-timings; <structfield>index</structfield>
is out of bounds or the <structfield>pad</structfield> number is invalid.</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><errorcode>ENODATA</errorcode></term>
	<listitem>
	  <para>Digital video presets are not supported for this input or output.</para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>
</refentry>

<!--
Local Variables:
mode: sgml
sgml-parent-document: "v4l2.sgml"
indent-tabs-mode: nil
End:
-->