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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>
+    </variablelist>
+  </refsect1>
+</refentry>
+
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+-->