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Diffstat (limited to 'Documentation/DocBook/media/v4l/vidioc-encoder-cmd.xml')
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diff --git a/Documentation/DocBook/media/v4l/vidioc-encoder-cmd.xml b/Documentation/DocBook/media/v4l/vidioc-encoder-cmd.xml new file mode 100644 index 00000000..f431b3ba --- /dev/null +++ b/Documentation/DocBook/media/v4l/vidioc-encoder-cmd.xml @@ -0,0 +1,196 @@ +<refentry id="vidioc-encoder-cmd"> + <refmeta> + <refentrytitle>ioctl VIDIOC_ENCODER_CMD, VIDIOC_TRY_ENCODER_CMD</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_ENCODER_CMD</refname> + <refname>VIDIOC_TRY_ENCODER_CMD</refname> + <refpurpose>Execute an encoder command</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_encoder_cmd *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_ENCODER_CMD, VIDIOC_TRY_ENCODER_CMD</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <note> + <title>Experimental</title> + + <para>This is an <link linkend="experimental">experimental</link> +interface and may change in the future.</para> + </note> + + <para>These ioctls control an audio/video (usually MPEG-) encoder. +<constant>VIDIOC_ENCODER_CMD</constant> sends a command to the +encoder, <constant>VIDIOC_TRY_ENCODER_CMD</constant> can be used to +try a command without actually executing it.</para> + + <para>To send a command applications must initialize all fields of a + &v4l2-encoder-cmd; and call + <constant>VIDIOC_ENCODER_CMD</constant> or + <constant>VIDIOC_TRY_ENCODER_CMD</constant> with a pointer to this + structure.</para> + + <para>The <structfield>cmd</structfield> field must contain the +command code. The <structfield>flags</structfield> field is currently +only used by the STOP command and contains one bit: If the +<constant>V4L2_ENC_CMD_STOP_AT_GOP_END</constant> flag is set, +encoding will continue until the end of the current <wordasword>Group +Of Pictures</wordasword>, otherwise it will stop immediately.</para> + + <para>A <function>read</function>() or &VIDIOC-STREAMON; call sends an implicit +START command to the encoder if it has not been started yet. After a STOP command, +<function>read</function>() calls will read the remaining data +buffered by the driver. When the buffer is empty, +<function>read</function>() will return zero and the next +<function>read</function>() call will restart the encoder.</para> + + <para>A <function>close</function>() or &VIDIOC-STREAMOFF; call of a streaming +file descriptor sends an implicit immediate STOP to the encoder, and all buffered +data is discarded.</para> + + <para>These ioctls are optional, not all drivers may support +them. They were introduced in Linux 2.6.21.</para> + + <table pgwide="1" frame="none" id="v4l2-encoder-cmd"> + <title>struct <structname>v4l2_encoder_cmd</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>cmd</structfield></entry> + <entry>The encoder command, see <xref linkend="encoder-cmds" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>flags</structfield></entry> + <entry>Flags to go with the command, see <xref + linkend="encoder-flags" />. If no flags are defined for +this command, drivers and applications must set this field to +zero.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>data</structfield>[8]</entry> + <entry>Reserved for future extensions. Drivers and +applications must set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="encoder-cmds"> + <title>Encoder Commands</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_ENC_CMD_START</constant></entry> + <entry>0</entry> + <entry>Start the encoder. When the encoder is already +running or paused, this command does nothing. No flags are defined for +this command.</entry> + </row> + <row> + <entry><constant>V4L2_ENC_CMD_STOP</constant></entry> + <entry>1</entry> + <entry>Stop the encoder. When the +<constant>V4L2_ENC_CMD_STOP_AT_GOP_END</constant> flag is set, +encoding will continue until the end of the current <wordasword>Group +Of Pictures</wordasword>, otherwise encoding will stop immediately. +When the encoder is already stopped, this command does +nothing.</entry> + </row> + <row> + <entry><constant>V4L2_ENC_CMD_PAUSE</constant></entry> + <entry>2</entry> + <entry>Pause the encoder. When the encoder has not been +started yet, the driver will return an &EPERM;. When the encoder is +already paused, this command does nothing. No flags are defined for +this command.</entry> + </row> + <row> + <entry><constant>V4L2_ENC_CMD_RESUME</constant></entry> + <entry>3</entry> + <entry>Resume encoding after a PAUSE command. When the +encoder has not been started yet, the driver will return an &EPERM;. +When the encoder is already running, this command does nothing. No +flags are defined for this command.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="encoder-flags"> + <title>Encoder Command Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_ENC_CMD_STOP_AT_GOP_END</constant></entry> + <entry>0x0001</entry> + <entry>Stop encoding at the end of the current <wordasword>Group Of +Pictures</wordasword>, rather than immediately.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The <structfield>cmd</structfield> field is invalid.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EPERM</errorcode></term> + <listitem> + <para>The application sent a PAUSE or RESUME command when +the encoder was not running.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> |