<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REL="HOME" TITLE="Video for Linux Two API Specification" HREF="book1.htm"><LINK REL="UP" TITLE="Function Reference" HREF="r7624.htm"><LINK REL="PREVIOUS" TITLE="ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY" HREF="r11094.htm"><LINK REL="NEXT" TITLE="ioctl VIDIOC_G_JPEGCOMP, VIDIOC_S_JPEGCOMP" HREF="r11285.htm"></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >Video for Linux Two API Specification: Revision 0.24</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="r11094.htm" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="r11285.htm" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="VIDIOC-G-INPUT" ></A >ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN11221" ></A ><H2 >Name</H2 >VIDIOC_G_INPUT, VIDIOC_S_INPUT -- Query or select the current video input</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN11225" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><P ></P ><A NAME="AEN11226" ></A ><P ><CODE ><CODE CLASS="FUNCDEF" >int ioctl</CODE >(int fd, int request, int *argp);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN11236" ></A ><H2 >Arguments</H2 ><P ></P ><DIV CLASS="VARIABLELIST" ><DL ><DT ><CODE CLASS="PARAMETER" >fd</CODE ></DT ><DD ><P >File descriptor returned by <A HREF="r14090.htm" ><CODE CLASS="FUNCTION" >open()</CODE ></A >.</P ></DD ><DT ><CODE CLASS="PARAMETER" >request</CODE ></DT ><DD ><P >VIDIOC_G_INPUT, VIDIOC_S_INPUT</P ></DD ><DT ><CODE CLASS="PARAMETER" >argp</CODE ></DT ><DD ><P ></P ></DD ></DL ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN11256" ></A ><H2 >Description</H2 ><P >To query the current video input applications call the <CODE CLASS="CONSTANT" >VIDIOC_G_INPUT</CODE > ioctl with a pointer to an integer where the driver stores the number of the input, as in the struct <A HREF="r8936.htm#V4L2-INPUT" >v4l2_input</A > <CODE CLASS="STRUCTFIELD" >index</CODE > field. This ioctl will fail only when there are no video inputs, returning <SPAN CLASS="ERRORCODE" >EINVAL</SPAN >.</P ><P >To select a video input applications store the number of the desired input in an integer and call the <CODE CLASS="CONSTANT" >VIDIOC_S_INPUT</CODE > ioctl with a pointer to this integer. Side effects are possible. For example inputs may support different video standards, so the driver may implicitly switch the current standard. It is good practice to select an input before querying or negotiating any other parameters.</P ><P >Information about video inputs is available using the <A HREF="r8936.htm" ><CODE CLASS="CONSTANT" >VIDIOC_ENUMINPUT</CODE ></A > ioctl.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN11268" ></A ><H2 >Return Value</H2 ><P >On success <SPAN CLASS="RETURNVALUE" >0</SPAN > is returned, on error <SPAN CLASS="RETURNVALUE" >-1</SPAN > and the <CODE CLASS="VARNAME" >errno</CODE > variable is set appropriately:</P ><P ></P ><DIV CLASS="VARIABLELIST" ><DL ><DT ><SPAN CLASS="ERRORCODE" >EINVAL</SPAN ></DT ><DD ><P >The number of the video input is out of bounds, or there are no video inputs at all and this ioctl is not supported.</P ></DD ><DT ><SPAN CLASS="ERRORCODE" >EBUSY</SPAN ></DT ><DD ><P >I/O is in progress, the input cannot be switched.</P ></DD ></DL ></DIV ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="r11094.htm" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="book1.htm" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="r11285.htm" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="r7624.htm" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >ioctl VIDIOC_G_JPEGCOMP, VIDIOC_S_JPEGCOMP</TD ></TR ></TABLE ></DIV ></BODY ></HTML >