V4L/DVB (12761): DocBook: add media API specs
The V4L and DVB API's are there for a long time. however, up to now, no efforts were done to merge them to kernel DocBook. This patch adds the current versions of the specs as an unique compendium. Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Mauro Carvalho Chehab
204
Documentation/DocBook/v4l/vidioc-encoder-cmd.xml
Normal file
204
Documentation/DocBook/v4l/vidioc-encoder-cmd.xml
Normal file
@@ -0,0 +1,204 @@
|
||||
<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>() call sends a 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>() call sends an 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 driver does not support this ioctl, or 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>
|
||||
|
||||
<!--
|
||||
Local Variables:
|
||||
mode: sgml
|
||||
sgml-parent-document: "v4l2.sgml"
|
||||
indent-tabs-mode: nil
|
||||
End:
|
||||
-->
|
||||
Reference in New Issue
Block a user