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| >Video for Linux Two API Specification: Revision 0.24</TH |
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| ><H1 |
| ><A |
| NAME="VIDIOC-G-EXT-CTRLS" |
| ></A |
| >ioctl VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, |
| VIDIOC_TRY_EXT_CTRLS</H1 |
| ><DIV |
| CLASS="REFNAMEDIV" |
| ><A |
| NAME="AEN10390" |
| ></A |
| ><H2 |
| >Name</H2 |
| >VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, VIDIOC_TRY_EXT_CTRLS -- Get or set the value of several controls, try control |
| values</DIV |
| ><DIV |
| CLASS="REFSYNOPSISDIV" |
| ><A |
| NAME="AEN10395" |
| ></A |
| ><H2 |
| >Synopsis</H2 |
| ><DIV |
| CLASS="FUNCSYNOPSIS" |
| ><P |
| ></P |
| ><A |
| NAME="AEN10396" |
| ></A |
| ><P |
| ><CODE |
| ><CODE |
| CLASS="FUNCDEF" |
| >int ioctl</CODE |
| >(int fd, int request, struct v4l2_ext_controls |
| *argp);</CODE |
| ></P |
| ><P |
| ></P |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN10406" |
| ></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_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, |
| VIDIOC_TRY_EXT_CTRLS</P |
| ></DD |
| ><DT |
| ><CODE |
| CLASS="PARAMETER" |
| >argp</CODE |
| ></DT |
| ><DD |
| ><P |
| ></P |
| ></DD |
| ></DL |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN10426" |
| ></A |
| ><H2 |
| >Description</H2 |
| ><P |
| >These ioctls allow the caller to get or set multiple |
| controls atomically. Control IDs are grouped into control classes (see |
| <A |
| HREF="r10386.htm#CTRL-CLASS" |
| >Table 3</A |
| >) and all controls in the control array |
| must belong to the same control class.</P |
| ><P |
| >Applications must always fill in the |
| <CODE |
| CLASS="STRUCTFIELD" |
| >count</CODE |
| >, |
| <CODE |
| CLASS="STRUCTFIELD" |
| >ctrl_class</CODE |
| >, |
| <CODE |
| CLASS="STRUCTFIELD" |
| >controls</CODE |
| > and |
| <CODE |
| CLASS="STRUCTFIELD" |
| >reserved</CODE |
| > fields of struct <A |
| HREF="r10386.htm#V4L2-EXT-CONTROLS" |
| >v4l2_ext_controls</A |
| >, and |
| initialize the struct <A |
| HREF="r10386.htm#V4L2-EXT-CONTROL" |
| >v4l2_ext_control</A |
| > array pointed to by the |
| <CODE |
| CLASS="STRUCTFIELD" |
| >controls</CODE |
| > fields.</P |
| ><P |
| >To get the current value of a set of controls applications |
| initialize the <CODE |
| CLASS="STRUCTFIELD" |
| >id</CODE |
| > field of each |
| struct <A |
| HREF="r10386.htm#V4L2-EXT-CONTROL" |
| >v4l2_ext_control</A |
| > and call the |
| <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_G_EXT_CTRLS</CODE |
| > ioctl.</P |
| ><P |
| >To change the value of a set of controls applications |
| initialize the <CODE |
| CLASS="STRUCTFIELD" |
| >id</CODE |
| > and |
| <CODE |
| CLASS="STRUCTFIELD" |
| >value</CODE |
| > fields of a struct <A |
| HREF="r10386.htm#V4L2-EXT-CONTROL" |
| >v4l2_ext_control</A |
| > and |
| call the <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_S_EXT_CTRLS</CODE |
| > ioctl. The controls |
| will only be set if <SPAN |
| CLASS="emphasis" |
| ><I |
| CLASS="EMPHASIS" |
| >all</I |
| ></SPAN |
| > control values are |
| valid.</P |
| ><P |
| >To check if the a set of controls have correct values |
| applications initialize the <CODE |
| CLASS="STRUCTFIELD" |
| >id</CODE |
| > and |
| <CODE |
| CLASS="STRUCTFIELD" |
| >value</CODE |
| > fields of a struct <A |
| HREF="r10386.htm#V4L2-EXT-CONTROL" |
| >v4l2_ext_control</A |
| > and |
| call the <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_TRY_EXT_CTRLS</CODE |
| > ioctl. It is up to |
| the driver whether wrong values are automatically adjusted to a valid |
| value or if an error is returned.</P |
| ><P |
| >When the <CODE |
| CLASS="STRUCTFIELD" |
| >id</CODE |
| > or |
| <CODE |
| CLASS="STRUCTFIELD" |
| >ctrl_class</CODE |
| > is invalid drivers return an |
| <SPAN |
| CLASS="ERRORCODE" |
| >EINVAL</SPAN |
| > error code. When the value 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. In the first case the new value is set in |
| struct <A |
| HREF="r10386.htm#V4L2-EXT-CONTROL" |
| >v4l2_ext_control</A |
| >.</P |
| ><P |
| >The driver will only set/get these controls if all control |
| values are correct. This prevents the situation where only some of the |
| controls were set/get. Only low-level errors (e. g. a failed i2c |
| command) can still cause this situation.</P |
| ><DIV |
| CLASS="TABLE" |
| ><A |
| NAME="V4L2-EXT-CONTROL" |
| ></A |
| ><P |
| ><B |
| >Table 1. struct <CODE |
| CLASS="STRUCTNAME" |
| >v4l2_ext_control</CODE |
| ></B |
| ></P |
| ><TABLE |
| BORDER="0" |
| FRAME="void" |
| WIDTH="100%" |
| CLASS="CALSTABLE" |
| ><COL |
| WIDTH="20%" |
| TITLE="C1"><COL |
| WIDTH="20%" |
| TITLE="C2"><COL |
| WIDTH="20%" |
| TITLE="C3"><COL |
| WIDTH="40%" |
| TITLE="C4"><TBODY |
| VALIGN="TOP" |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >id</CODE |
| ></TD |
| ><TD |
| > </TD |
| ><TD |
| >Identifies the control, set by the |
| application.</TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >reserved2</CODE |
| >[2]</TD |
| ><TD |
| > </TD |
| ><TD |
| >Reserved for future extensions. Drivers and |
| applications must set the array to zero.</TD |
| ></TR |
| ><TR |
| ><TD |
| >union</TD |
| ><TD |
| >(anonymous)</TD |
| ><TD |
| > </TD |
| ><TD |
| > </TD |
| ></TR |
| ><TR |
| ><TD |
| > </TD |
| ><TD |
| >__s32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >value</CODE |
| ></TD |
| ><TD |
| >New value or current value.</TD |
| ></TR |
| ><TR |
| ><TD |
| > </TD |
| ><TD |
| >__s64</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >value64</CODE |
| ></TD |
| ><TD |
| >New value or current value.</TD |
| ></TR |
| ><TR |
| ><TD |
| > </TD |
| ><TD |
| >void *</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >reserved</CODE |
| ></TD |
| ><TD |
| >Reserved for future pointer-type controls. Currently unused.</TD |
| ></TR |
| ></TBODY |
| ></TABLE |
| ></DIV |
| ><DIV |
| CLASS="TABLE" |
| ><A |
| NAME="V4L2-EXT-CONTROLS" |
| ></A |
| ><P |
| ><B |
| >Table 2. struct <CODE |
| CLASS="STRUCTNAME" |
| >v4l2_ext_controls</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" |
| >ctrl_class</CODE |
| ></TD |
| ><TD |
| >The control class to which all controls belong, see |
| <A |
| HREF="r10386.htm#CTRL-CLASS" |
| >Table 3</A |
| >.</TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >count</CODE |
| ></TD |
| ><TD |
| >The number of controls in the controls array. May |
| also be zero.</TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >error_idx</CODE |
| ></TD |
| ><TD |
| >Set by the driver in case of an error. It is the |
| index of the control causing the error or equal to 'count' when the |
| error is not associated with a particular control. Undefined when the |
| ioctl returns 0 (success).</TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >reserved</CODE |
| >[2]</TD |
| ><TD |
| >Reserved for future extensions. Drivers and |
| applications must set the array to zero.</TD |
| ></TR |
| ><TR |
| ><TD |
| >struct <A |
| HREF="r10386.htm#V4L2-EXT-CONTROL" |
| >v4l2_ext_control</A |
| > *</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >controls</CODE |
| ></TD |
| ><TD |
| >Pointer to an array of |
| <CODE |
| CLASS="STRUCTFIELD" |
| >count</CODE |
| > v4l2_ext_control structures. Ignored |
| if <CODE |
| CLASS="STRUCTFIELD" |
| >count</CODE |
| > equals zero.</TD |
| ></TR |
| ></TBODY |
| ></TABLE |
| ></DIV |
| ><DIV |
| CLASS="TABLE" |
| ><A |
| NAME="CTRL-CLASS" |
| ></A |
| ><P |
| ><B |
| >Table 3. Control classes</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_CTRL_CLASS_USER</CODE |
| ></TD |
| ><TD |
| >0x980000</TD |
| ><TD |
| >The class containing user controls. These controls |
| are described in <A |
| HREF="x542.htm" |
| >Section 1.8</A |
| >. All controls that can be set |
| using the <A |
| HREF="r10104.htm" |
| ><CODE |
| CLASS="CONSTANT" |
| >VIDIOC_S_CTRL</CODE |
| ></A |
| > and <A |
| HREF="r10104.htm" |
| ><CODE |
| CLASS="CONSTANT" |
| >VIDIOC_G_CTRL</CODE |
| ></A |
| > ioctl belong to this |
| class.</TD |
| ></TR |
| ><TR |
| ><TD |
| ><CODE |
| CLASS="CONSTANT" |
| >V4L2_CTRL_CLASS_MPEG</CODE |
| ></TD |
| ><TD |
| >0x990000</TD |
| ><TD |
| >The class containing MPEG compression controls. |
| These controls are described in section <A |
| HREF="x802.htm#MPEG-CONTROLS" |
| >Section 1.9.5</A |
| >.</TD |
| ></TR |
| ></TBODY |
| ></TABLE |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN10565" |
| ></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="r10386.htm#V4L2-EXT-CONTROL" |
| >v4l2_ext_control</A |
| > <CODE |
| CLASS="STRUCTFIELD" |
| >id</CODE |
| > |
| is invalid or the struct <A |
| HREF="r10386.htm#V4L2-EXT-CONTROLS" |
| >v4l2_ext_controls</A |
| > |
| <CODE |
| CLASS="STRUCTFIELD" |
| >ctrl_class</CODE |
| > is invalid. This error code is |
| also returned by the <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_S_EXT_CTRLS</CODE |
| > and |
| <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_TRY_EXT_CTRLS</CODE |
| > ioctls if two or more |
| control values are in conflict.</P |
| ></DD |
| ><DT |
| ><SPAN |
| CLASS="ERRORCODE" |
| >ERANGE</SPAN |
| ></DT |
| ><DD |
| ><P |
| >The struct <A |
| HREF="r10386.htm#V4L2-EXT-CONTROL" |
| >v4l2_ext_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 |
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