Hi Hans, Thanks for the patch. On Wednesday 23 November 2011 12:12:34 Hans Verkuil wrote: > From: Hans Verkuil <hans.verkuil@xxxxxxxxx> > > Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> > --- [snip] > diff --git a/Documentation/DocBook/media/v4l/vidioc-decoder-cmd.xml > b/Documentation/DocBook/media/v4l/vidioc-decoder-cmd.xml new file mode > 100644 > index 0000000..bf016f0 > --- /dev/null > +++ b/Documentation/DocBook/media/v4l/vidioc-decoder-cmd.xml > @@ -0,0 +1,250 @@ > +<refentry id="vidioc-decoder-cmd"> > + <refmeta> > + <refentrytitle>ioctl VIDIOC_DECODER_CMD, > VIDIOC_TRY_DECODER_CMD</refentrytitle> + &manvol; > + </refmeta> > + > + <refnamediv> > + <refname>VIDIOC_DECODER_CMD</refname> > + <refname>VIDIOC_TRY_DECODER_CMD</refname> > + <refpurpose>Execute an decoder 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_decoder_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_DECODER_CMD, VIDIOC_TRY_DECODER_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-) decoder. > +<constant>VIDIOC_DECODER_CMD</constant> sends a command to the > +decoder, <constant>VIDIOC_TRY_DECODER_CMD</constant> can be used to > +try a command without actually executing it. To send a command > applications +must initialize all fields of a &v4l2-decoder-cmd; and call > +<constant>VIDIOC_DECODER_CMD</constant> or > <constant>VIDIOC_TRY_DECODER_CMD</constant> +with a pointer to this > structure.</para> > + > + <para>The <structfield>cmd</structfield> field must contain the > +command code. Some commands use the <structfield>flags</structfield> field > for +additional information. > +</para> > + > + <para>A <function>write</function>() call sends a START command to > +the decoder if it has not been started yet. > +</para> > + > + <para>A <function>close</function>() call sends an immediate STOP > +to the decoder, and all buffered data is discarded.</para> > + > + <para>These ioctls are optional, not all drivers may support > +them. They were introduced in Linux 3.3.</para> > + > + <table pgwide="1" frame="none" id="v4l2-decoder-cmd"> > + <title>struct <structname>v4l2_decoder_cmd</structname></title> > + <tgroup cols="5"> > + &cs-str; > + <tbody valign="top"> > + <row> > + <entry>__u32</entry> > + <entry><structfield>cmd</structfield></entry> > + <entry></entry> > + <entry></entry> > + <entry>The decoder command, see <xref linkend="decoder-cmds" > />.</entry> + </row> > + <row> > + <entry>__u32</entry> > + <entry><structfield>flags</structfield></entry> > + <entry></entry> > + <entry></entry> > + <entry>Flags to go with the command. If no flags are defined for > +this command, drivers and applications must set this field to > zero.</entry> + </row> > + <row> > + <entry>union</entry> > + <entry>(anonymous)</entry> > + <entry></entry> > + <entry></entry> > + <entry></entry> > + </row> > + <row> > + <entry></entry> > + <entry>struct</entry> > + <entry><structfield>start</structfield></entry> > + <entry></entry> > + <entry>Structure containing additional data for the > +<constant>V4L2_DEC_CMD_START</constant> command.</entry> > + </row> > + <row> > + <entry></entry> > + <entry></entry> > + <entry>__u32</entry> > + <entry><structfield>speed</structfield></entry> > + <entry>Playback speed and direction. The playback speed is > defined as +<structfield>speed</structfield>/1000 of the normal speed. So > 1000 is normal playback. +Negative numbers denote reverse playback, so > -1000 does reverse playback at normal +speed. Speeds -1, 0 and 1 have > special meanings: speed 0 is shorthand for 1000 +(normal playback). A > speed of 1 steps just one frame forward, a speed of -1 steps +just one > frame back. > + </entry> > + </row> > + <row> > + <entry></entry> > + <entry></entry> > + <entry>__u32</entry> > + <entry><structfield>format</structfield></entry> > + <entry>Format restrictions. This field is set by the driver, > not the +application. Possible values are > <constant>V4L2_DEC_START_FMT_NONE</constant> if +there are no format > restrictions or <constant>V4L2_DEC_START_FMT_GOP</constant> +if the > decoder operates on full GOPs (<wordasword>Group Of > Pictures</wordasword>). +This is usually the case for reverse playback: > the decoder needs full GOPs, which +it can then play in reverse order. So > to implement reverse playback the application +must feed the decoder the > last GOP in the video file, then the GOP before that, etc. etc. + > </entry> > + </row> > + <row> > + <entry></entry> > + <entry>struct</entry> > + <entry><structfield>stop</structfield></entry> > + <entry></entry> > + <entry>Structure containing additional data for the > +<constant>V4L2_DEC_CMD_STOP</constant> command.</entry> > + </row> > + <row> > + <entry></entry> > + <entry></entry> > + <entry>__u64</entry> > + <entry><structfield>pts</structfield></entry> > + <entry>Stop playback at this <structfield>pts</structfield> or > immediately +if the playback is already past that timestamp. Leave to 0 if > you want to stop after the +last frame was decoded. > + </entry> > + </row> > + <row> > + <entry></entry> > + <entry>struct</entry> > + <entry><structfield>raw</structfield></entry> > + <entry></entry> > + <entry></entry> > + </row> > + <row> > + <entry></entry> > + <entry></entry> > + <entry>__u32</entry> > + <entry><structfield>data</structfield>[16]</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="decoder-cmds"> > + <title>Decoder Commands</title> > + <tgroup cols="3"> > + &cs-def; > + <tbody valign="top"> > + <row> > + <entry><constant>V4L2_DEC_CMD_START</constant></entry> > + <entry>0</entry> > + <entry>Start the decoder. When the decoder is already > +running or paused, this command does nothing. There are no flags > +associated with this command. > + </entry> > + </row> How does the start command interact with VIDIOC_STREAMON ? Are applications expected to both start the video stream with VIDIOC_STREAMON and start the decoder with V4L2_DEC_CMD_START ? > + <row> > + <entry><constant>V4L2_DEC_CMD_STOP</constant></entry> > + <entry>1</entry> > + <entry>Stop the decoder. When the decoder is already stopped, > +this command does nothing. This command has two flags: > +if <constant>V4L2_DEC_CMD_STOP_TO_BLACK</constant> is set, then the > decoder will +set the picture to black after it stopped decoding. > Otherwise the last image will +repeat. If > <constant>V4L2_DEC_CMD_STOP_IMMEDIATELY</constant> is set, then the > decoder +stops immediately (ignoring the <structfield>pts</structfield> > value), otherwise it +will keep decoding until timestamp >= pts or until > the last of the pending data from +its internal buffers was decoded. > +</entry> > + </row> > + <row> > + <entry><constant>V4L2_DEC_CMD_PAUSE</constant></entry> > + <entry>2</entry> > + <entry>Pause the decoder. When the decoder has not been > +started yet, the driver will return an &EPERM;. When the decoder is > +already paused, this command does nothing. This command has one flag: > +if <constant>V4L2_DEC_CMD_PAUSE_TO_BLACK</constant> is set, then set the > +decoder output to black when paused. > +</entry> > + </row> > + <row> > + <entry><constant>V4L2_DEC_CMD_RESUME</constant></entry> > + <entry>3</entry> > + <entry>Resume decoding after a PAUSE command. When the > +decoder has not been started yet, the driver will return an &EPERM;. > +When the decoder is already running, this command does nothing. No > +flags are defined for this command.</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 decoder was not running.</para> > + </listitem> > + </varlistentry> > + </variablelist> > + </refsect1> > +</refentry> -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
