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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-QUERYSTD"
74></A
75>ioctl VIDIOC_QUERYSTD</H1
76><DIV
77CLASS="REFNAMEDIV"
78><A
79NAME="AEN13645"
80></A
81><H2
82>Name</H2
83>VIDIOC_QUERYSTD&nbsp;--&nbsp;Sense the video standard received by the current
84input</DIV
85><DIV
86CLASS="REFSYNOPSISDIV"
87><A
88NAME="AEN13648"
89></A
90><H2
91>Synopsis</H2
92><DIV
93CLASS="FUNCSYNOPSIS"
94><P
95></P
96><A
97NAME="AEN13649"
98></A
99><P
100><CODE
101><CODE
102CLASS="FUNCDEF"
103>int ioctl</CODE
104>(int fd, int request, v4l2_std_id *argp);</CODE
105></P
106><P
107></P
108></DIV
109></DIV
110><DIV
111CLASS="REFSECT1"
112><A
113NAME="AEN13659"
114></A
115><H2
116>Arguments</H2
117><P
118></P
119><DIV
120CLASS="VARIABLELIST"
121><DL
122><DT
123><CODE
124CLASS="PARAMETER"
125>fd</CODE
126></DT
127><DD
128><P
129>File descriptor returned by <A
130HREF="r14090.htm"
131><CODE
132CLASS="FUNCTION"
133>open()</CODE
134></A
135>.</P
136></DD
137><DT
138><CODE
139CLASS="PARAMETER"
140>request</CODE
141></DT
142><DD
143><P
144>VIDIOC_QUERYSTD</P
145></DD
146><DT
147><CODE
148CLASS="PARAMETER"
149>argp</CODE
150></DT
151><DD
152><P
153></P
154></DD
155></DL
156></DIV
157></DIV
158><DIV
159CLASS="REFSECT1"
160><A
161NAME="AEN13679"
162></A
163><H2
164>Description</H2
165><P
166>The hardware may be able to detect the current video
167standard automatically. To do so, applications call <CODE
168CLASS="CONSTANT"
169>VIDIOC_QUERYSTD</CODE
170> with a pointer to a <A
171HREF="r9288.htm#V4L2-STD-ID"
172>v4l2_std_id</A
173> type. The
174driver stores here a set of candidates, this can be a single flag or a
175set of supported standards if for example the hardware can only
176distinguish between 50 and 60 Hz systems. When detection is not
177possible or fails, the set must contain all standards supported by the
178current video input or output.</P
179></DIV
180><DIV
181CLASS="REFSECT1"
182><A
183NAME="AEN13684"
184></A
185><H2
186>Return Value</H2
187><P
188>On success <SPAN
189CLASS="RETURNVALUE"
190>0</SPAN
191> is returned, on error <SPAN
192CLASS="RETURNVALUE"
193>-1</SPAN
194> and the <CODE
195CLASS="VARNAME"
196>errno</CODE
197> variable is set appropriately:</P
198><P
199></P
200><DIV
201CLASS="VARIABLELIST"
202><DL
203><DT
204><SPAN
205CLASS="ERRORCODE"
206>EINVAL</SPAN
207></DT
208><DD
209><P
210>This ioctl is not supported.</P
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