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     40 >Video for Linux Two API Specification: Revision 0.24</TH
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     71 ><H1
     72 ><A
     73 NAME="VIDIOC-QUERYSTD"
     74 ></A
     75 >ioctl VIDIOC_QUERYSTD</H1
     76 ><DIV
     77 CLASS="REFNAMEDIV"
     78 ><A
     79 NAME="AEN13645"
     80 ></A
     81 ><H2
     82 >Name</H2
     83 >VIDIOC_QUERYSTD&nbsp;--&nbsp;Sense the video standard received by the current
     84 input</DIV
     85 ><DIV
     86 CLASS="REFSYNOPSISDIV"
     87 ><A
     88 NAME="AEN13648"
     89 ></A
     90 ><H2
     91 >Synopsis</H2
     92 ><DIV
     93 CLASS="FUNCSYNOPSIS"
     94 ><P
     95 ></P
     96 ><A
     97 NAME="AEN13649"
     98 ></A
     99 ><P
    100 ><CODE
    101 ><CODE
    102 CLASS="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
    111 CLASS="REFSECT1"
    112 ><A
    113 NAME="AEN13659"
    114 ></A
    115 ><H2
    116 >Arguments</H2
    117 ><P
    118 ></P
    119 ><DIV
    120 CLASS="VARIABLELIST"
    121 ><DL
    122 ><DT
    123 ><CODE
    124 CLASS="PARAMETER"
    125 >fd</CODE
    126 ></DT
    127 ><DD
    128 ><P
    129 >File descriptor returned by <A
    130 HREF="r14090.htm"
    131 ><CODE
    132 CLASS="FUNCTION"
    133 >open()</CODE
    134 ></A
    135 >.</P
    136 ></DD
    137 ><DT
    138 ><CODE
    139 CLASS="PARAMETER"
    140 >request</CODE
    141 ></DT
    142 ><DD
    143 ><P
    144 >VIDIOC_QUERYSTD</P
    145 ></DD
    146 ><DT
    147 ><CODE
    148 CLASS="PARAMETER"
    149 >argp</CODE
    150 ></DT
    151 ><DD
    152 ><P
    153 ></P
    154 ></DD
    155 ></DL
    156 ></DIV
    157 ></DIV
    158 ><DIV
    159 CLASS="REFSECT1"
    160 ><A
    161 NAME="AEN13679"
    162 ></A
    163 ><H2
    164 >Description</H2
    165 ><P
    166 >The hardware may be able to detect the current video
    167 standard automatically. To do so, applications call <CODE
    168 CLASS="CONSTANT"
    169 >VIDIOC_QUERYSTD</CODE
    170 > with a pointer to a <A
    171 HREF="r9288.htm#V4L2-STD-ID"
    172 >v4l2_std_id</A
    173 > type. The
    174 driver stores here a set of candidates, this can be a single flag or a
    175 set of supported standards if for example the hardware can only
    176 distinguish between 50 and 60 Hz systems. When detection is not
    177 possible or fails, the set must contain all standards supported by the
    178 current video input or output.</P
    179 ></DIV
    180 ><DIV
    181 CLASS="REFSECT1"
    182 ><A
    183 NAME="AEN13684"
    184 ></A
    185 ><H2
    186 >Return Value</H2
    187 ><P
    188 >On success <SPAN
    189 CLASS="RETURNVALUE"
    190 >0</SPAN
    191 > is returned, on error <SPAN
    192 CLASS="RETURNVALUE"
    193 >-1</SPAN
    194 > and the <CODE
    195 CLASS="VARNAME"
    196 >errno</CODE
    197 > variable is set appropriately:</P
    198 ><P
    199 ></P
    200 ><DIV
    201 CLASS="VARIABLELIST"
    202 ><DL
    203 ><DT
    204 ><SPAN
    205 CLASS="ERRORCODE"
    206 >EINVAL</SPAN
    207 ></DT
    208 ><DD
    209 ><P
    210 >This ioctl is not supported.</P
    211 ></DD
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