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| >Video for Linux Two API Specification: Revision 0.24</TH |
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| ><H1 |
| ><A |
| NAME="VIDIOC-G-OUTPUT" |
| ></A |
| >ioctl VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT</H1 |
| ><DIV |
| CLASS="REFNAMEDIV" |
| ><A |
| NAME="AEN11616" |
| ></A |
| ><H2 |
| >Name</H2 |
| >VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT -- Query or select the current video output</DIV |
| ><DIV |
| CLASS="REFSYNOPSISDIV" |
| ><A |
| NAME="AEN11620" |
| ></A |
| ><H2 |
| >Synopsis</H2 |
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| ><A |
| NAME="AEN11621" |
| ></A |
| ><P |
| ><CODE |
| ><CODE |
| CLASS="FUNCDEF" |
| >int ioctl</CODE |
| >(int fd, int request, int *argp);</CODE |
| ></P |
| ><P |
| ></P |
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| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN11631" |
| ></A |
| ><H2 |
| >Arguments</H2 |
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| ></P |
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| 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_OUTPUT, VIDIOC_S_OUTPUT</P |
| ></DD |
| ><DT |
| ><CODE |
| CLASS="PARAMETER" |
| >argp</CODE |
| ></DT |
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| ><A |
| NAME="AEN11651" |
| ></A |
| ><H2 |
| >Description</H2 |
| ><P |
| >To query the current video output applications call the |
| <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_G_OUTPUT</CODE |
| > ioctl with a pointer to an integer |
| where the driver stores the number of the output, as in the |
| struct <A |
| HREF="r9149.htm#V4L2-OUTPUT" |
| >v4l2_output</A |
| > <CODE |
| CLASS="STRUCTFIELD" |
| >index</CODE |
| > field. This ioctl |
| will fail only when there are no video outputs, returning the |
| <SPAN |
| CLASS="ERRORCODE" |
| >EINVAL</SPAN |
| > error code.</P |
| ><P |
| >To select a video output applications store the number of the |
| desired output in an integer and call the |
| <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_S_OUTPUT</CODE |
| > ioctl with a pointer to this integer. |
| Side effects are possible. For example outputs may support different |
| video standards, so the driver may implicitly switch the current |
| standard. It is good practice to select an output before querying or |
| negotiating any other parameters.</P |
| ><P |
| >Information about video outputs is available using the |
| <A |
| HREF="r9149.htm" |
| ><CODE |
| CLASS="CONSTANT" |
| >VIDIOC_ENUMOUTPUT</CODE |
| ></A |
| > ioctl.</P |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN11663" |
| ></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 output is out of bounds, or |
| there are no video outputs 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 output cannot be |
| switched.</P |
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