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40>Video for Linux Two API Specification: Revision 0.24</TH
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71><H1
72><A
73NAME="VIDIOC-OVERLAY"
74></A
75>ioctl VIDIOC_OVERLAY</H1
76><DIV
77CLASS="REFNAMEDIV"
78><A
79NAME="AEN12820"
80></A
81><H2
82>Name</H2
83>VIDIOC_OVERLAY&nbsp;--&nbsp;Start or stop video overlay</DIV
84><DIV
85CLASS="REFSYNOPSISDIV"
86><A
87NAME="AEN12823"
88></A
89><H2
90>Synopsis</H2
91><DIV
92CLASS="FUNCSYNOPSIS"
93><P
94></P
95><A
96NAME="AEN12824"
97></A
98><P
99><CODE
100><CODE
101CLASS="FUNCDEF"
102>int ioctl</CODE
103>(int fd, int request, const int *argp);</CODE
104></P
105><P
106></P
107></DIV
108></DIV
109><DIV
110CLASS="REFSECT1"
111><A
112NAME="AEN12834"
113></A
114><H2
115>Arguments</H2
116><P
117></P
118><DIV
119CLASS="VARIABLELIST"
120><DL
121><DT
122><CODE
123CLASS="PARAMETER"
124>fd</CODE
125></DT
126><DD
127><P
128>File descriptor returned by <A
129HREF="r14090.htm"
130><CODE
131CLASS="FUNCTION"
132>open()</CODE
133></A
134>.</P
135></DD
136><DT
137><CODE
138CLASS="PARAMETER"
139>request</CODE
140></DT
141><DD
142><P
143>VIDIOC_OVERLAY</P
144></DD
145><DT
146><CODE
147CLASS="PARAMETER"
148>argp</CODE
149></DT
150><DD
151><P
152></P
153></DD
154></DL
155></DIV
156></DIV
157><DIV
158CLASS="REFSECT1"
159><A
160NAME="AEN12854"
161></A
162><H2
163>Description</H2
164><P
165>This ioctl is part of the <A
166HREF="x6570.htm"
167>video
168    overlay</A
169> I/O method. Applications call
170    <CODE
171CLASS="CONSTANT"
172>VIDIOC_OVERLAY</CODE
173> to start or stop the
174    overlay. It takes a pointer to an integer which must be set to
175    zero by the application to stop overlay, to one to start.</P
176><P
177>Drivers do not support <A
178HREF="r13817.htm"
179><CODE
180CLASS="CONSTANT"
181>VIDIOC_STREAMON</CODE
182></A
183> or
184<A
185HREF="r13817.htm"
186><CODE
187CLASS="CONSTANT"
188>VIDIOC_STREAMOFF</CODE
189></A
190> with <CODE
191CLASS="CONSTANT"
192>V4L2_BUF_TYPE_VIDEO_OVERLAY</CODE
193>.</P
194></DIV
195><DIV
196CLASS="REFSECT1"
197><A
198NAME="AEN12865"
199></A
200><H2
201>Return Value</H2
202><P
203>On success <SPAN
204CLASS="RETURNVALUE"
205>0</SPAN
206> is returned, on error <SPAN
207CLASS="RETURNVALUE"
208>-1</SPAN
209> and the <CODE
210CLASS="VARNAME"
211>errno</CODE
212> variable is set appropriately:</P
213><P
214></P
215><DIV
216CLASS="VARIABLELIST"
217><DL
218><DT
219><SPAN
220CLASS="ERRORCODE"
221>EINVAL</SPAN
222></DT
223><DD
224><P
225>Video overlay is not supported, or the
226parameters have not been set up. See <A
227HREF="x6570.htm"
228>Section 4.2</A
229> for the necessary steps.</P
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