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authorMauro Carvalho Chehab <mchehab@redhat.com>2011-05-31 16:27:44 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2011-07-27 17:52:05 -0300
commit4266129964b8238526936d723de65b419d8069c6 (patch)
tree38c6b5cd3dc99b8599391ffad3b87e399bef56a2 /Documentation/DocBook/media/v4l/vidioc-streamon.xml
parent04893043ae9ea8aa82b712491ed25ba6c4ffbca3 (diff)
[media] DocBook: Move all media docbook stuff into its own directory
This patch addresses several issues pointed by Randy Dunlap <rdunlap@xenotime.net> at changeset ece722c: - In the generated index.html file, "media" is listed first, but it should be listed in alphabetical order, not first. - The generated files are (hidden) in .tmpmedia/ - The link from the top-level index.html file to "media" is to media/index.html, but the file is actually in .tmpmedia/media/index.html - Please build docs with and without using "O=builddir" and test that. - Would it be possible for media to have its own Makefile instead of merging into this one? Due to the way cleandocs target works, I had to rename the media DocBook to media_api, otherwise cleandocs would remove the /media directory. Thanks-to: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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+<refentry id="vidioc-streamon">
+ <refmeta>
+ <refentrytitle>ioctl VIDIOC_STREAMON, VIDIOC_STREAMOFF</refentrytitle>
+ &manvol;
+ </refmeta>
+
+ <refnamediv>
+ <refname>VIDIOC_STREAMON</refname>
+ <refname>VIDIOC_STREAMOFF</refname>
+ <refpurpose>Start or stop streaming I/O</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>int <function>ioctl</function></funcdef>
+ <paramdef>int <parameter>fd</parameter></paramdef>
+ <paramdef>int <parameter>request</parameter></paramdef>
+ <paramdef>const int *<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_STREAMON, VIDIOC_STREAMOFF</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>argp</parameter></term>
+ <listitem>
+ <para></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para>The <constant>VIDIOC_STREAMON</constant> and
+<constant>VIDIOC_STREAMOFF</constant> ioctl start and stop the capture
+or output process during streaming (<link linkend="mmap">memory
+mapping</link> or <link linkend="userp">user pointer</link>) I/O.</para>
+
+ <para>Specifically the capture hardware is disabled and no input
+buffers are filled (if there are any empty buffers in the incoming
+queue) until <constant>VIDIOC_STREAMON</constant> has been called.
+Accordingly the output hardware is disabled, no video signal is
+produced until <constant>VIDIOC_STREAMON</constant> has been called.
+The ioctl will succeed only when at least one output buffer is in the
+incoming queue.</para>
+
+ <para>The <constant>VIDIOC_STREAMOFF</constant> ioctl, apart of
+aborting or finishing any DMA in progress, unlocks any user pointer
+buffers locked in physical memory, and it removes all buffers from the
+incoming and outgoing queues. That means all images captured but not
+dequeued yet will be lost, likewise all images enqueued for output but
+not transmitted yet. I/O returns to the same state as after calling
+&VIDIOC-REQBUFS; and can be restarted accordingly.</para>
+
+ <para>Both ioctls take a pointer to an integer, the desired buffer or
+stream type. This is the same as &v4l2-requestbuffers;
+<structfield>type</structfield>.</para>
+
+ <para>Note applications can be preempted for unknown periods right
+before or after the <constant>VIDIOC_STREAMON</constant> or
+<constant>VIDIOC_STREAMOFF</constant> calls, there is no notion of
+starting or stopping "now". Buffer timestamps can be used to
+synchronize with other events.</para>
+ </refsect1>
+
+ <refsect1>
+ &return-value;
+
+ <variablelist>
+ <varlistentry>
+ <term><errorcode>EINVAL</errorcode></term>
+ <listitem>
+ <para>Streaming I/O is not supported, the buffer
+<structfield>type</structfield> is not supported, or no buffers have
+been allocated (memory mapping) or enqueued (output) yet.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorcode>EPIPE</errorcode></term>
+ <listitem>
+ <para>The driver implements <link
+ linkend="pad-level-formats">pad-level format configuration</link> and
+ the pipeline configuration is invalid.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+</refentry>
+
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+-->