1<refentry id="vidioc-enumoutput">
2  <refmeta>
3    <refentrytitle>ioctl VIDIOC_ENUMOUTPUT</refentrytitle>
4    &manvol;
5  </refmeta>
6
7  <refnamediv>
8    <refname>VIDIOC_ENUMOUTPUT</refname>
9    <refpurpose>Enumerate video outputs</refpurpose>
10  </refnamediv>
11
12  <refsynopsisdiv>
13    <funcsynopsis>
14      <funcprototype>
15	<funcdef>int <function>ioctl</function></funcdef>
16	<paramdef>int <parameter>fd</parameter></paramdef>
17	<paramdef>int <parameter>request</parameter></paramdef>
18	<paramdef>struct v4l2_output *<parameter>argp</parameter></paramdef>
19      </funcprototype>
20    </funcsynopsis>
21  </refsynopsisdiv>
22
23  <refsect1>
24    <title>Arguments</title>
25
26    <variablelist>
27      <varlistentry>
28	<term><parameter>fd</parameter></term>
29	<listitem>
30	  <para>&fd;</para>
31	</listitem>
32      </varlistentry>
33      <varlistentry>
34	<term><parameter>request</parameter></term>
35	<listitem>
36	  <para>VIDIOC_ENUMOUTPUT</para>
37	</listitem>
38      </varlistentry>
39      <varlistentry>
40	<term><parameter>argp</parameter></term>
41	<listitem>
42	  <para></para>
43	</listitem>
44      </varlistentry>
45    </variablelist>
46  </refsect1>
47
48  <refsect1>
49    <title>Description</title>
50
51    <para>To query the attributes of a video outputs applications
52initialize the <structfield>index</structfield> field of &v4l2-output;
53and call the <constant>VIDIOC_ENUMOUTPUT</constant> ioctl with a
54pointer to this structure. Drivers fill the rest of the structure or
55return an &EINVAL; when the index is out of bounds. To enumerate all
56outputs applications shall begin at index zero, incrementing by one
57until the driver returns <errorcode>EINVAL</errorcode>.</para>
58
59    <table frame="none" pgwide="1" id="v4l2-output">
60      <title>struct <structname>v4l2_output</structname></title>
61      <tgroup cols="3">
62	&cs-str;
63	<tbody valign="top">
64	  <row>
65	    <entry>__u32</entry>
66	    <entry><structfield>index</structfield></entry>
67	    <entry>Identifies the output, set by the
68application.</entry>
69	  </row>
70	  <row>
71	    <entry>__u8</entry>
72	    <entry><structfield>name</structfield>[32]</entry>
73	    <entry>Name of the video output, a NUL-terminated ASCII
74string, for example: "Vout". This information is intended for the
75user, preferably the connector label on the device itself.</entry>
76	  </row>
77	  <row>
78	    <entry>__u32</entry>
79	    <entry><structfield>type</structfield></entry>
80	    <entry>Type of the output, see <xref
81		linkend="output-type" />.</entry>
82	  </row>
83	  <row>
84	    <entry>__u32</entry>
85	    <entry><structfield>audioset</structfield></entry>
86	    <entry><para>Drivers can enumerate up to 32 video and
87audio outputs. This field shows which audio outputs were
88selectable as the current output if this was the currently selected
89video output. It is a bit mask. The LSB corresponds to audio output 0,
90the MSB to output 31. Any number of bits can be set, or
91none.</para><para>When the driver does not enumerate audio outputs no
92bits must be set. Applications shall not interpret this as lack of
93audio support. Drivers may automatically select audio outputs without
94enumerating them.</para><para>For details on audio outputs and how to
95select the current output see <xref linkend="audio" />.</para></entry>
96	  </row>
97	  <row>
98	    <entry>__u32</entry>
99	    <entry><structfield>modulator</structfield></entry>
100	    <entry>Output devices can have zero or more RF modulators.
101When the <structfield>type</structfield> is
102<constant>V4L2_OUTPUT_TYPE_MODULATOR</constant> this is an RF
103connector and this field identifies the modulator. It corresponds to
104&v4l2-modulator; field <structfield>index</structfield>. For details
105on modulators see <xref linkend="tuner" />.</entry>
106	  </row>
107	  <row>
108	    <entry>&v4l2-std-id;</entry>
109	    <entry><structfield>std</structfield></entry>
110	    <entry>Every video output supports one or more different
111video standards. This field is a set of all supported standards. For
112details on video standards and how to switch see <xref
113		linkend="standard" />.</entry>
114	  </row>
115	  <row>
116	    <entry>__u32</entry>
117	    <entry><structfield>capabilities</structfield></entry>
118	    <entry>This field provides capabilities for the
119output. See <xref linkend="output-capabilities" /> for flags.</entry>
120	  </row>
121	  <row>
122	    <entry>__u32</entry>
123	    <entry><structfield>reserved</structfield>[3]</entry>
124	    <entry>Reserved for future extensions. Drivers must set
125the array to zero.</entry>
126	  </row>
127	</tbody>
128      </tgroup>
129    </table>
130
131    <table frame="none" pgwide="1" id="output-type">
132      <title>Output Type</title>
133      <tgroup cols="3">
134	&cs-def;
135	<tbody valign="top">
136	  <row>
137	    <entry><constant>V4L2_OUTPUT_TYPE_MODULATOR</constant></entry>
138	    <entry>1</entry>
139	    <entry>This output is an analog TV modulator.</entry>
140	  </row>
141	  <row>
142	    <entry><constant>V4L2_OUTPUT_TYPE_ANALOG</constant></entry>
143	    <entry>2</entry>
144	    <entry>Analog baseband output, for example Composite /
145CVBS, S-Video, RGB.</entry>
146	  </row>
147	  <row>
148	    <entry><constant>V4L2_OUTPUT_TYPE_ANALOGVGAOVERLAY</constant></entry>
149	    <entry>3</entry>
150	    <entry>[?]</entry>
151	  </row>
152	</tbody>
153      </tgroup>
154    </table>
155
156    <!-- Capabilities flags based on video timings RFC by Muralidharan
157Karicheri, titled RFC (v1.2): V4L - Support for video timings at the
158input/output interface to linux-media@vger.kernel.org on 19 Oct 2009.
159	-->
160    <table frame="none" pgwide="1" id="output-capabilities">
161      <title>Output capabilities</title>
162      <tgroup cols="3">
163	&cs-def;
164	<tbody valign="top">
165	  <row>
166	    <entry><constant>V4L2_OUT_CAP_DV_TIMINGS</constant></entry>
167	    <entry>0x00000002</entry>
168	    <entry>This output supports setting video timings by using VIDIOC_S_DV_TIMINGS.</entry>
169	  </row>
170	  <row>
171	    <entry><constant>V4L2_OUT_CAP_STD</constant></entry>
172	    <entry>0x00000004</entry>
173	    <entry>This output supports setting the TV standard by using VIDIOC_S_STD.</entry>
174	  </row>
175	  <row>
176	    <entry><constant>V4L2_OUT_CAP_NATIVE_SIZE</constant></entry>
177	    <entry>0x00000008</entry>
178	    <entry>This output supports setting the native size using
179	    the <constant>V4L2_SEL_TGT_NATIVE_SIZE</constant>
180	    selection target, see <xref
181	    linkend="v4l2-selections-common"/>.</entry>
182	  </row>
183	</tbody>
184      </tgroup>
185    </table>
186
187  </refsect1>
188  <refsect1>
189    &return-value;
190
191    <variablelist>
192      <varlistentry>
193	<term><errorcode>EINVAL</errorcode></term>
194	<listitem>
195	  <para>The &v4l2-output; <structfield>index</structfield>
196is out of bounds.</para>
197	</listitem>
198      </varlistentry>
199    </variablelist>
200  </refsect1>
201</refentry>
202