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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-G-JPEGCOMP" |
| ></A |
| >ioctl VIDIOC_G_JPEGCOMP, VIDIOC_S_JPEGCOMP</H1 |
| ><DIV |
| CLASS="REFNAMEDIV" |
| ><A |
| NAME="AEN11289" |
| ></A |
| ><H2 |
| >Name</H2 |
| >VIDIOC_G_JPEGCOMP, VIDIOC_S_JPEGCOMP -- </DIV |
| ><DIV |
| CLASS="REFSYNOPSISDIV" |
| ><A |
| NAME="AEN11293" |
| ></A |
| ><H2 |
| >Synopsis</H2 |
| ><DIV |
| CLASS="FUNCSYNOPSIS" |
| ><P |
| ></P |
| ><A |
| NAME="AEN11294" |
| ></A |
| ><P |
| ><CODE |
| ><CODE |
| CLASS="FUNCDEF" |
| >int ioctl</CODE |
| >(int fd, int request, v4l2_jpegcompression *argp);</CODE |
| ></P |
| ><P |
| ></P |
| ></DIV |
| ><DIV |
| CLASS="FUNCSYNOPSIS" |
| ><P |
| ></P |
| ><A |
| NAME="AEN11304" |
| ></A |
| ><P |
| ><CODE |
| ><CODE |
| CLASS="FUNCDEF" |
| >int ioctl</CODE |
| >(int fd, int request, const v4l2_jpegcompression *argp);</CODE |
| ></P |
| ><P |
| ></P |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN11314" |
| ></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_JPEGCOMP, VIDIOC_S_JPEGCOMP</P |
| ></DD |
| ><DT |
| ><CODE |
| CLASS="PARAMETER" |
| >argp</CODE |
| ></DT |
| ><DD |
| ><P |
| ></P |
| ></DD |
| ></DL |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN11334" |
| ></A |
| ><H2 |
| >Description</H2 |
| ><P |
| >[to do]</P |
| ><P |
| >Ronald Bultje elaborates:</P |
| ><P |
| >APP is some application-specific information. The |
| application can set it itself, and it'll be stored in the JPEG-encoded |
| fields (eg; interlacing information for in an AVI or so). COM is the |
| same, but it's comments, like 'encoded by me' or so.</P |
| ><P |
| >jpeg_markers describes whether the huffman tables, |
| quantization tables and the restart interval information (all |
| JPEG-specific stuff) should be stored in the JPEG-encoded fields. |
| These define how the JPEG field is encoded. If you omit them, |
| applications assume you've used standard encoding. You usually do want |
| to add them.</P |
| ><DIV |
| CLASS="TABLE" |
| ><A |
| NAME="V4L2-JPEGCOMPRESSION" |
| ></A |
| ><P |
| ><B |
| >Table 1. struct <CODE |
| CLASS="STRUCTNAME" |
| >v4l2_jpegcompression</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 |
| >int</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >quality</CODE |
| ></TD |
| ><TD |
| > </TD |
| ></TR |
| ><TR |
| ><TD |
| >int</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >APPn</CODE |
| ></TD |
| ><TD |
| > </TD |
| ></TR |
| ><TR |
| ><TD |
| >int</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >APP_len</CODE |
| ></TD |
| ><TD |
| > </TD |
| ></TR |
| ><TR |
| ><TD |
| >char</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >APP_data</CODE |
| >[60]</TD |
| ><TD |
| > </TD |
| ></TR |
| ><TR |
| ><TD |
| >int</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >COM_len</CODE |
| ></TD |
| ><TD |
| > </TD |
| ></TR |
| ><TR |
| ><TD |
| >char</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >COM_data</CODE |
| >[60]</TD |
| ><TD |
| > </TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >jpeg_markers</CODE |
| ></TD |
| ><TD |
| >See <A |
| HREF="r11285.htm#JPEG-MARKERS" |
| >Table 2</A |
| >.</TD |
| ></TR |
| ></TBODY |
| ></TABLE |
| ></DIV |
| ><DIV |
| CLASS="TABLE" |
| ><A |
| NAME="JPEG-MARKERS" |
| ></A |
| ><P |
| ><B |
| >Table 2. JPEG Markers 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_JPEG_MARKER_DHT</CODE |
| ></TD |
| ><TD |
| >(1<<3)</TD |
| ><TD |
| >Define Huffman Tables</TD |
| ></TR |
| ><TR |
| ><TD |
| ><CODE |
| CLASS="CONSTANT" |
| >V4L2_JPEG_MARKER_DQT</CODE |
| ></TD |
| ><TD |
| >(1<<4)</TD |
| ><TD |
| >Define Quantization Tables</TD |
| ></TR |
| ><TR |
| ><TD |
| ><CODE |
| CLASS="CONSTANT" |
| >V4L2_JPEG_MARKER_DRI</CODE |
| ></TD |
| ><TD |
| >(1<<5)</TD |
| ><TD |
| >Define Restart Interval</TD |
| ></TR |
| ><TR |
| ><TD |
| ><CODE |
| CLASS="CONSTANT" |
| >V4L2_JPEG_MARKER_COM</CODE |
| ></TD |
| ><TD |
| >(1<<6)</TD |
| ><TD |
| >Comment segment</TD |
| ></TR |
| ><TR |
| ><TD |
| ><CODE |
| CLASS="CONSTANT" |
| >V4L2_JPEG_MARKER_APP</CODE |
| ></TD |
| ><TD |
| >(1<<7)</TD |
| ><TD |
| >App segment, driver will always use APP0</TD |
| ></TR |
| ></TBODY |
| ></TABLE |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN11418" |
| ></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 |
| >This ioctl is not supported.</P |
| ></DD |
| ></DL |
| ></DIV |
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