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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-ENCODER-CMD" |
| ></A |
| >ioctl VIDIOC_ENCODER_CMD, VIDIOC_TRY_ENCODER_CMD</H1 |
| ><DIV |
| CLASS="REFNAMEDIV" |
| ><A |
| NAME="AEN8091" |
| ></A |
| ><H2 |
| >Name</H2 |
| >VIDIOC_ENCODER_CMD, VIDIOC_TRY_ENCODER_CMD -- Execute an encoder command</DIV |
| ><DIV |
| CLASS="REFSYNOPSISDIV" |
| ><A |
| NAME="AEN8095" |
| ></A |
| ><H2 |
| >Synopsis</H2 |
| ><DIV |
| CLASS="FUNCSYNOPSIS" |
| ><P |
| ></P |
| ><A |
| NAME="AEN8096" |
| ></A |
| ><P |
| ><CODE |
| ><CODE |
| CLASS="FUNCDEF" |
| >int ioctl</CODE |
| >(int fd, int request, struct v4l2_encoder_cmd *argp);</CODE |
| ></P |
| ><P |
| ></P |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN8106" |
| ></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_ENCODER_CMD, VIDIOC_TRY_ENCODER_CMD</P |
| ></DD |
| ><DT |
| ><CODE |
| CLASS="PARAMETER" |
| >argp</CODE |
| ></DT |
| ><DD |
| ><P |
| ></P |
| ></DD |
| ></DL |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN8126" |
| ></A |
| ><H2 |
| >Description</H2 |
| ><DIV |
| CLASS="NOTE" |
| ><BLOCKQUOTE |
| CLASS="NOTE" |
| ><P |
| ><B |
| >Experimental: </B |
| >This is an <A |
| HREF="x16453.htm" |
| >experimental</A |
| > |
| interface and may change in the future.</P |
| ></BLOCKQUOTE |
| ></DIV |
| ><P |
| >These ioctls control an audio/video (usually MPEG-) encoder. |
| <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_ENCODER_CMD</CODE |
| > sends a command to the |
| encoder, <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_TRY_ENCODER_CMD</CODE |
| > can be used to |
| try a command without actually executing it.</P |
| ><P |
| >To send a command applications must initialize all fields of a |
| struct <A |
| HREF="r8087.htm#V4L2-ENCODER-CMD" |
| >v4l2_encoder_cmd</A |
| > and call |
| <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_ENCODER_CMD</CODE |
| > or |
| <CODE |
| CLASS="CONSTANT" |
| >VIDIOC_TRY_ENCODER_CMD</CODE |
| > with a pointer to this |
| structure.</P |
| ><P |
| >The <CODE |
| CLASS="STRUCTFIELD" |
| >cmd</CODE |
| > field must contain the |
| command code. The <CODE |
| CLASS="STRUCTFIELD" |
| >flags</CODE |
| > field is currently |
| only used by the STOP command and contains one bit: If the |
| <CODE |
| CLASS="CONSTANT" |
| >V4L2_ENC_CMD_STOP_AT_GOP_END</CODE |
| > flag is set, |
| encoding will continue until the end of the current <I |
| CLASS="WORDASWORD" |
| >Group |
| Of Pictures</I |
| >, otherwise it will stop immediately.</P |
| ><P |
| >A <CODE |
| CLASS="FUNCTION" |
| >read</CODE |
| >() call sends a START command to |
| the encoder if it has not been started yet. After a STOP command, |
| <CODE |
| CLASS="FUNCTION" |
| >read</CODE |
| >() calls will read the remaining data |
| buffered by the driver. When the buffer is empty, |
| <CODE |
| CLASS="FUNCTION" |
| >read</CODE |
| >() will return zero and the next |
| <CODE |
| CLASS="FUNCTION" |
| >read</CODE |
| >() call will restart the encoder.</P |
| ><P |
| >A <CODE |
| CLASS="FUNCTION" |
| >close</CODE |
| >() call sends an immediate STOP |
| to the encoder, and all buffered data is discarded.</P |
| ><P |
| >These ioctls are optional, not all drivers may support |
| them. They were introduced in Linux 2.6.21.</P |
| ><DIV |
| CLASS="TABLE" |
| ><A |
| NAME="V4L2-ENCODER-CMD" |
| ></A |
| ><P |
| ><B |
| >Table 1. struct <CODE |
| CLASS="STRUCTNAME" |
| >v4l2_encoder_cmd</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" |
| >cmd</CODE |
| ></TD |
| ><TD |
| >The encoder command, see <A |
| HREF="r8087.htm#ENCODER-CMDS" |
| >Table 2</A |
| >.</TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >flags</CODE |
| ></TD |
| ><TD |
| >Flags to go with the command, see <A |
| HREF="r8087.htm#ENCODER-FLAGS" |
| >Table 3</A |
| >. If no flags are defined for |
| this command, drivers and applications must set this field to |
| zero.</TD |
| ></TR |
| ><TR |
| ><TD |
| >__u32</TD |
| ><TD |
| ><CODE |
| CLASS="STRUCTFIELD" |
| >data</CODE |
| >[8]</TD |
| ><TD |
| >Reserved for future extensions. Drivers and |
| applications must set the array to zero.</TD |
| ></TR |
| ></TBODY |
| ></TABLE |
| ></DIV |
| ><DIV |
| CLASS="TABLE" |
| ><A |
| NAME="ENCODER-CMDS" |
| ></A |
| ><P |
| ><B |
| >Table 2. Encoder Commands</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_ENC_CMD_START</CODE |
| ></TD |
| ><TD |
| >0</TD |
| ><TD |
| >Start the encoder. When the encoder is already |
| running or paused, this command does nothing. No flags are defined for |
| this command.</TD |
| ></TR |
| ><TR |
| ><TD |
| ><CODE |
| CLASS="CONSTANT" |
| >V4L2_ENC_CMD_STOP</CODE |
| ></TD |
| ><TD |
| >1</TD |
| ><TD |
| >Stop the encoder. When the |
| <CODE |
| CLASS="CONSTANT" |
| >V4L2_ENC_CMD_STOP_AT_GOP_END</CODE |
| > flag is set, |
| encoding will continue until the end of the current <I |
| CLASS="WORDASWORD" |
| >Group |
| Of Pictures</I |
| >, otherwise encoding will stop immediately. |
| When the encoder is already stopped, this command does |
| nothing.</TD |
| ></TR |
| ><TR |
| ><TD |
| ><CODE |
| CLASS="CONSTANT" |
| >V4L2_ENC_CMD_PAUSE</CODE |
| ></TD |
| ><TD |
| >2</TD |
| ><TD |
| >Pause the encoder. When the encoder has not been |
| started yet, the driver will return an <SPAN |
| CLASS="ERRORCODE" |
| >EPERM</SPAN |
| > error code. When the encoder is |
| already paused, this command does nothing. No flags are defined for |
| this command.</TD |
| ></TR |
| ><TR |
| ><TD |
| ><CODE |
| CLASS="CONSTANT" |
| >V4L2_ENC_CMD_RESUME</CODE |
| ></TD |
| ><TD |
| >3</TD |
| ><TD |
| >Resume encoding after a PAUSE command. When the |
| encoder has not been started yet, the driver will return an <SPAN |
| CLASS="ERRORCODE" |
| >EPERM</SPAN |
| > error code. |
| When the encoder is already running, this command does nothing. No |
| flags are defined for this command.</TD |
| ></TR |
| ></TBODY |
| ></TABLE |
| ></DIV |
| ><DIV |
| CLASS="TABLE" |
| ><A |
| NAME="ENCODER-FLAGS" |
| ></A |
| ><P |
| ><B |
| >Table 3. Encoder Command 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_ENC_CMD_STOP_AT_GOP_END</CODE |
| ></TD |
| ><TD |
| >0x0001</TD |
| ><TD |
| >Stop encoding at the end of the current <I |
| CLASS="WORDASWORD" |
| >Group Of |
| Pictures</I |
| >, rather than immediately.</TD |
| ></TR |
| ></TBODY |
| ></TABLE |
| ></DIV |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN8224" |
| ></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 driver does not support this ioctl, or the |
| <CODE |
| CLASS="STRUCTFIELD" |
| >cmd</CODE |
| > field is invalid.</P |
| ></DD |
| ><DT |
| ><SPAN |
| CLASS="ERRORCODE" |
| >EPERM</SPAN |
| ></DT |
| ><DD |
| ><P |
| >The application sent a PAUSE or RESUME command when |
| the encoder was not running.</P |
| ></DD |
| ></DL |
| ></DIV |
| ></DIV |
| ><DIV |
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