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| >Video for Linux Two API Specification: Revision 0.24</TH |
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| ><TR |
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| ><H1 |
| ><A |
| NAME="VIDIOC-ENUM-FMT" |
| ></A |
| >ioctl VIDIOC_ENUM_FMT</H1 |
| ><DIV |
| CLASS="REFNAMEDIV" |
| ><A |
| NAME="AEN8371" |
| ></A |
| ><H2 |
| >Name</H2 |
| >VIDIOC_ENUM_FMT -- Enumerate image formats</DIV |
| ><DIV |
| CLASS="REFSYNOPSISDIV" |
| ><A |
| NAME="AEN8374" |
| ></A |
| ><H2 |
| >Synopsis</H2 |
| ><DIV |
| CLASS="FUNCSYNOPSIS" |
| ><P |
| ></P |
| ><A |
| NAME="AEN8375" |
| ></A |
| ><P |
| ><CODE |
| ><CODE |
| CLASS="FUNCDEF" |
| >int ioctl</CODE |
| >(int fd, int request, struct v4l2_fmtdesc |
| *argp);</CODE |
| ></P |
| ><P |
| ></P |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN8385" |
| ></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_ENUM_FMT</P |
| ></DD |
| ><DT |
| ><CODE |
| CLASS="PARAMETER" |
| >argp</CODE |
| ></DT |
| ><DD |
| ><P |
| ></P |
| ></DD |
| ></DL |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN8405" |
| ></A |
| ><H2 |
| >Description</H2 |
| ><P |
| >To enumerate image formats applications initialize the |
| <CODE |
| CLASS="STRUCTFIELD" |
| >type</CODE |
| > and <CODE |
| CLASS="STRUCTFIELD" |
| >index</CODE |
| > |
| field of struct <A |
| HREF="r8367.htm#V4L2-FMTDESC" |
| >v4l2_fmtdesc</A |
| > and call the |
| <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_ENUM_FMT</CODE |
| > ioctl with a pointer to this |
| structure. Drivers fill the rest of the structure or return an |
| <SPAN |
| CLASS="ERRORCODE" |
| >EINVAL</SPAN |
| > error code. All formats are enumerable by beginning at index zero and |
| incrementing by one until <SPAN |
| CLASS="ERRORCODE" |
| >EINVAL</SPAN |
| > is |
| returned.</P |
| ><DIV |
| CLASS="TABLE" |
| ><A |
| NAME="V4L2-FMTDESC" |
| ></A |
| ><P |
| ><B |
| >Table 1. struct <CODE |
| CLASS="STRUCTNAME" |
| >v4l2_fmtdesc</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" |
| >index</CODE |
| ></TD |
| ><TD |
| >Number of the format in the enumeration, set by |
| the application. This is in no way related to the <CODE |
| CLASS="STRUCTFIELD" |
| >pixelformat</CODE |
| > field.</TD |
| ></TR |
| ><TR |
| ><TD |
| >enum <A |
| HREF="x5953.htm#V4L2-BUF-TYPE" |
| >v4l2_buf_type</A |
| ></TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >type</CODE |
| ></TD |
| ><TD |
| >Type of the data stream, set by the application. |
| Only these types are valid here: |
| <CODE |
| CLASS="CONSTANT" |
| >V4L2_BUF_TYPE_VIDEO_CAPTURE</CODE |
| >, |
| <CODE |
| CLASS="CONSTANT" |
| >V4L2_BUF_TYPE_VIDEO_OUTPUT</CODE |
| >, |
| <CODE |
| CLASS="CONSTANT" |
| >V4L2_BUF_TYPE_VIDEO_OVERLAY</CODE |
| >, and custom (driver |
| defined) types with code <CODE |
| CLASS="CONSTANT" |
| >V4L2_BUF_TYPE_PRIVATE</CODE |
| > |
| and higher.</TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >flags</CODE |
| ></TD |
| ><TD |
| >See <A |
| HREF="r8367.htm#FMTDESC-FLAGS" |
| >Table 2</A |
| ></TD |
| ></TR |
| ><TR |
| ><TD |
| >__u8</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >description</CODE |
| >[32]</TD |
| ><TD |
| >Description of the format, a NUL-terminated ASCII |
| string. This information is intended for the user, for example: "YUV |
| 4:2:2".</TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >pixelformat</CODE |
| ></TD |
| ><TD |
| >The image format identifier. This is a |
| four character code as computed by the v4l2_fourcc() |
| macro:</TD |
| ></TR |
| ><TR |
| ><TD |
| COLSPAN="3" |
| ><P |
| ><PRE |
| CLASS="PROGRAMLISTING" |
| >#define v4l2_fourcc(a,b,c,d) (((__u32)(a)<<0)|((__u32)(b)<<8)|((__u32)(c)<<16)|((__u32)(d)<<24))</PRE |
| ></P |
| ><P |
| >Several image formats are already |
| defined by this specification in <A |
| HREF="c2030.htm" |
| >Chapter 2</A |
| >. Note these |
| codes are not the same as those used in the Windows world.</P |
| ></TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >reserved</CODE |
| >[4]</TD |
| ><TD |
| >Reserved for future extensions. Drivers must set |
| the array to zero.</TD |
| ></TR |
| ></TBODY |
| ></TABLE |
| ></DIV |
| ><DIV |
| CLASS="TABLE" |
| ><A |
| NAME="FMTDESC-FLAGS" |
| ></A |
| ><P |
| ><B |
| >Table 2. Image Format Description Flags</B |
| ></P |
| ><TABLE |
| BORDER="0" |
| FRAME="void" |
| WIDTH="100%" |
| CLASS="CALSTABLE" |
| ><COL |
| WIDTH="38%" |
| TITLE="C1"><COL |
| WIDTH="12%" |
| TITLE="C2"><COL |
| WIDTH="50%" |
| TITLE="C3"><TBODY |
| VALIGN="TOP" |
| ><TR |
| ><TD |
| ><CODE |
| CLASS="CONSTANT" |
| >V4L2_FMT_FLAG_COMPRESSED</CODE |
| ></TD |
| ><TD |
| >0x0001</TD |
| ><TD |
| >This is a compressed format.</TD |
| ></TR |
| ></TBODY |
| ></TABLE |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN8479" |
| ></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="r8367.htm#V4L2-FMTDESC" |
| >v4l2_fmtdesc</A |
| > <CODE |
| CLASS="STRUCTFIELD" |
| >type</CODE |
| > |
| is not supported or the <CODE |
| CLASS="STRUCTFIELD" |
| >index</CODE |
| > is out of |
| bounds.</P |
| ></DD |
| ></DL |
| ></DIV |
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