| <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd"> |
| <HTML |
| ><HEAD |
| ><TITLE |
| >ioctl VIDIOC_G_CTRL, VIDIOC_S_CTRL</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_CROP, VIDIOC_S_CROP" |
| HREF="r9994.htm"><LINK |
| REL="NEXT" |
| TITLE="ioctl VIDIOC_G_ENC_INDEX" |
| HREF="r10211.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="r9994.htm" |
| ACCESSKEY="P" |
| >Prev</A |
| ></TD |
| ><TD |
| WIDTH="80%" |
| ALIGN="center" |
| VALIGN="bottom" |
| ></TD |
| ><TD |
| WIDTH="10%" |
| ALIGN="right" |
| VALIGN="bottom" |
| ><A |
| HREF="r10211.htm" |
| ACCESSKEY="N" |
| >Next</A |
| ></TD |
| ></TR |
| ></TABLE |
| ><HR |
| ALIGN="LEFT" |
| WIDTH="100%"></DIV |
| ><H1 |
| ><A |
| NAME="VIDIOC-G-CTRL" |
| ></A |
| >ioctl VIDIOC_G_CTRL, VIDIOC_S_CTRL</H1 |
| ><DIV |
| CLASS="REFNAMEDIV" |
| ><A |
| NAME="AEN10108" |
| ></A |
| ><H2 |
| >Name</H2 |
| >VIDIOC_G_CTRL, VIDIOC_S_CTRL -- Get or set the value of a control</DIV |
| ><DIV |
| CLASS="REFSYNOPSISDIV" |
| ><A |
| NAME="AEN10112" |
| ></A |
| ><H2 |
| >Synopsis</H2 |
| ><DIV |
| CLASS="FUNCSYNOPSIS" |
| ><P |
| ></P |
| ><A |
| NAME="AEN10113" |
| ></A |
| ><P |
| ><CODE |
| ><CODE |
| CLASS="FUNCDEF" |
| >int ioctl</CODE |
| >(int fd, int request, struct v4l2_control |
| *argp);</CODE |
| ></P |
| ><P |
| ></P |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN10123" |
| ></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_CTRL, VIDIOC_S_CTRL</P |
| ></DD |
| ><DT |
| ><CODE |
| CLASS="PARAMETER" |
| >argp</CODE |
| ></DT |
| ><DD |
| ><P |
| ></P |
| ></DD |
| ></DL |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN10143" |
| ></A |
| ><H2 |
| >Description</H2 |
| ><P |
| >To get the current value of a control applications |
| initialize the <CODE |
| CLASS="STRUCTFIELD" |
| >id</CODE |
| > field of a struct |
| <CODE |
| CLASS="STRUCTNAME" |
| >v4l2_control</CODE |
| > and call the |
| <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_G_CTRL</CODE |
| > ioctl with a pointer to this |
| structure. To change the value of a control applications initialize |
| the <CODE |
| CLASS="STRUCTFIELD" |
| >id</CODE |
| > and <CODE |
| CLASS="STRUCTFIELD" |
| >value</CODE |
| > |
| fields of a struct <CODE |
| CLASS="STRUCTNAME" |
| >v4l2_control</CODE |
| > and call the |
| <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_S_CTRL</CODE |
| > ioctl.</P |
| ><P |
| >When the <CODE |
| CLASS="STRUCTFIELD" |
| >id</CODE |
| > is invalid drivers |
| return an <SPAN |
| CLASS="ERRORCODE" |
| >EINVAL</SPAN |
| > error code. When the <CODE |
| CLASS="STRUCTFIELD" |
| >value</CODE |
| > is out |
| of bounds drivers can choose to take the closest valid value or return |
| an <SPAN |
| CLASS="ERRORCODE" |
| >ERANGE</SPAN |
| > error code, whatever seems more appropriate. However, |
| <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_S_CTRL</CODE |
| > is a write-only ioctl, it does not |
| return the actual new value.</P |
| ><P |
| >These ioctls work only with user controls. For other |
| control classes the <A |
| HREF="r10386.htm" |
| ><CODE |
| CLASS="CONSTANT" |
| >VIDIOC_G_EXT_CTRLS</CODE |
| ></A |
| >, <A |
| HREF="r10386.htm" |
| ><CODE |
| CLASS="CONSTANT" |
| >VIDIOC_S_EXT_CTRLS</CODE |
| ></A |
| > or |
| <A |
| HREF="r10386.htm" |
| ><CODE |
| CLASS="CONSTANT" |
| >VIDIOC_TRY_EXT_CTRLS</CODE |
| ></A |
| > must be used.</P |
| ><DIV |
| CLASS="TABLE" |
| ><A |
| NAME="V4L2-CONTROL" |
| ></A |
| ><P |
| ><B |
| >Table 1. struct <CODE |
| CLASS="STRUCTNAME" |
| >v4l2_control</CODE |
| ></B |
| ></P |
| ><TABLE |
| BORDER="0" |
| FRAME="void" |
| WIDTH="100%" |
| CLASS="CALSTABLE" |
| ><COL |
| WIDTH="25%" |
| TITLE="C1"><COL |
| WIDTH="25%" |
| TITLE="C2"><COL |
| WIDTH="50%" |
| TITLE="C3"><TBODY |
| VALIGN="TOP" |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >id</CODE |
| ></TD |
| ><TD |
| >Identifies the control, set by the |
| application.</TD |
| ></TR |
| ><TR |
| ><TD |
| >__s32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >value</CODE |
| ></TD |
| ><TD |
| >New value or current value.</TD |
| ></TR |
| ></TBODY |
| ></TABLE |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN10185" |
| ></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 struct <A |
| HREF="r10104.htm#V4L2-CONTROL" |
| >v4l2_control</A |
| > <CODE |
| CLASS="STRUCTFIELD" |
| >id</CODE |
| > is |
| invalid.</P |
| ></DD |
| ><DT |
| ><SPAN |
| CLASS="ERRORCODE" |
| >ERANGE</SPAN |
| ></DT |
| ><DD |
| ><P |
| >The struct <A |
| HREF="r10104.htm#V4L2-CONTROL" |
| >v4l2_control</A |
| > <CODE |
| CLASS="STRUCTFIELD" |
| >value</CODE |
| > |
| is out of bounds.</P |
| ></DD |
| ><DT |
| ><SPAN |
| CLASS="ERRORCODE" |
| >EBUSY</SPAN |
| ></DT |
| ><DD |
| ><P |
| >The control is temporarily not changeable, possibly |
| because another applications took over control of the device function |
| this control belongs to.</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="r9994.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="r10211.htm" |
| ACCESSKEY="N" |
| >Next</A |
| ></TD |
| ></TR |
| ><TR |
| ><TD |
| WIDTH="33%" |
| ALIGN="left" |
| VALIGN="top" |
| >ioctl VIDIOC_G_CROP, VIDIOC_S_CROP</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_ENC_INDEX</TD |
| ></TR |
| ></TABLE |
| ></DIV |
| ></BODY |
| ></HTML |
| > |