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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<a href="#gst-plugins-bad-plugins-videodetect.synopsis" class="shortcut">Top</a>
                   | 
                  <a href="#gst-plugins-bad-plugins-videodetect.description" class="shortcut">Description</a>
                   | 
                  <a href="#gst-plugins-bad-plugins-videodetect.properties" class="shortcut">Properties</a>
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<div class="refentry">
<a name="gst-plugins-bad-plugins-videodetect"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
<td valign="top">
<h2><span class="refentrytitle"><a name="gst-plugins-bad-plugins-videodetect.top_of_page"></a>videodetect</span></h2>
<p>videodetect — Detect patterns in a video signal</p>
</td>
<td valign="top" align="right"></td>
</tr></table></div>
<div class="refsynopsisdiv">
<a name="gst-plugins-bad-plugins-videodetect.synopsis"></a><h2>Synopsis</h2>
<pre class="synopsis">struct              <a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect" title="struct GstVideoDetect">GstVideoDetect</a>;
</pre>
</div>
<div class="refsect1">
<a name="gst-plugins-bad-plugins-videodetect.properties"></a><h2>Properties</h2>
<pre class="synopsis">
  "<a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect--message" title='The "message" property'>message</a>"                  <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a>              : Read / Write / Construct
  "<a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect--pattern-count" title='The "pattern-count" property'>pattern-count</a>"            <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write / Construct
  "<a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect--pattern-data-count" title='The "pattern-data-count" property'>pattern-data-count</a>"       <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write / Construct
  "<a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect--pattern-height" title='The "pattern-height" property'>pattern-height</a>"           <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write / Construct
  "<a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect--pattern-sensitivity" title='The "pattern-sensitivity" property'>pattern-sensitivity</a>"      <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a>               : Read / Write / Construct
  "<a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect--pattern-width" title='The "pattern-width" property'>pattern-width</a>"            <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write / Construct
  "<a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect--bottom-offset" title='The "bottom-offset" property'>bottom-offset</a>"            <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write / Construct
  "<a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect--left-offset" title='The "left-offset" property'>left-offset</a>"              <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write / Construct
  "<a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect--pattern-center" title='The "pattern-center" property'>pattern-center</a>"           <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a>               : Read / Write / Construct
</pre>
</div>
<div class="refsect1">
<a name="gst-plugins-bad-plugins-videodetect.description"></a><h2>Description</h2>
<p>
This plugin detects <a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect--pattern-count" title='The "pattern-count" property'><span class="type">"pattern-count"</span></a> squares in the bottom left
corner of the video frames. The squares have a width and height of
respectively <a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect--pattern-width" title='The "pattern-width" property'><span class="type">"pattern-width"</span></a> and <a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect--pattern-height" title='The "pattern-height" property'><span class="type">"pattern-height"</span></a>.
Even squares must be black and odd squares must be white.
</p>
<p>
When the pattern has been found, <a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect--pattern-data-count" title='The "pattern-data-count" property'><span class="type">"pattern-data-count"</span></a> squares
after the pattern squares are read as a bitarray. White squares represent a 1
bit and black squares a 0 bit. The bitarray will will included in the element
message that is posted (see below).
</p>
<p>
After the pattern has been found and the data pattern has been read, an
element message called <code class="classname">"GstVideoDetect"</code> will
be posted on the bus. If the pattern is no longer found in the frame, the
same element message is posted with the have-pattern field set to <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#FALSE:CAPS"><span class="type">FALSE</span></a>.
The message is only posted if the <a class="link" href="gst-plugins-bad-plugins-videodetect.html#GstVideoDetect--message" title='The "message" property'><span class="type">"message"</span></a> property is <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><span class="type">TRUE</span></a>.
</p>
<p>
The message's structure contains these fields:
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem"><p>
  <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a>
  <code class="classname">"have-pattern"</code>:
  if the pattern was found. This field will be set to <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><span class="type">TRUE</span></a> for as long as
  the pattern was found in the frame and set to FALSE for the first frame
  that does not contain the pattern anymore.
  </p></li>
<li class="listitem"><p>
  <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstClock.html#GstClockTime"><span class="type">GstClockTime</span></a>
  <code class="classname">"timestamp"</code>:
  the timestamp of the buffer that triggered the message.
  </p></li>
<li class="listitem"><p>
  <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstClock.html#GstClockTime"><span class="type">GstClockTime</span></a>
  <code class="classname">"stream-time"</code>:
  the stream time of the buffer.
  </p></li>
<li class="listitem"><p>
  <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstClock.html#GstClockTime"><span class="type">GstClockTime</span></a>
  <code class="classname">"running-time"</code>:
  the running_time of the buffer.
  </p></li>
<li class="listitem"><p>
  <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstClock.html#GstClockTime"><span class="type">GstClockTime</span></a>
  <code class="classname">"duration"</code>:
  the duration of the buffer.
  </p></li>
<li class="listitem"><p>
  <span class="type">guint64</span>
  <code class="classname">"data-uint64"</code>:
  the data-pattern found after the pattern or 0 when have-signal is <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#FALSE:CAPS"><span class="type">FALSE</span></a>.
  </p></li>
<li class="listitem"><p>
  <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a>
  <code class="classname">"data"</code>:
  the data-pattern found after the pattern or 0 when have-signal is <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#FALSE:CAPS"><span class="type">FALSE</span></a>.
  </p></li>
</ul></div>
<p>
</p>
<p>
</p>
<div class="refsect2">
<a name="idp23138592"></a><h3>Example launch line</h3>
<div class="informalexample">
  <table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
    <tbody>
      <tr>
        <td class="listing_lines" align="right"><pre>1</pre></td>
        <td class="listing_code"><pre class="programlisting">gst<span class="gtkdoc opt">-</span>launch videotestsrc <span class="gtkdoc opt">!</span> videodetect <span class="gtkdoc opt">!</span> ffmpegcolorspace <span class="gtkdoc opt">!</span> ximagesink</pre></td>
      </tr>
    </tbody>
  </table>
</div>

</div>
<p>
</p>
<p>
Last reviewed on 2007-05-30 (0.10.5)
</p>
<div class="refsynopsisdiv">
<h2>Synopsis</h2>
<div class="refsect2">
<a name="idp23141696"></a><h3>Element Information</h3>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term">plugin</span></p></td>
<td>
            <a class="link" href="gst-plugins-bad-plugins-plugin-videosignal.html#plugin-videosignal">videosignal</a>
          </td>
</tr>
<tr>
<td><p><span class="term">author</span></p></td>
<td>Wim Taymans &lt;wim@fluendo.com&gt;</td>
</tr>
<tr>
<td><p><span class="term">class</span></p></td>
<td>Filter/Effect/Video</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="idp23149152"></a><h3>Element Pads</h3>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term">name</span></p></td>
<td>sink</td>
</tr>
<tr>
<td><p><span class="term">direction</span></p></td>
<td>sink</td>
</tr>
<tr>
<td><p><span class="term">presence</span></p></td>
<td>always</td>
</tr>
<tr>
<td><p><span class="term">details</span></p></td>
<td>video/x-raw-yuv, format=(fourcc){ I420, YV12, Y41B, Y42B, Y444, YUY2, UYVY, AYUV, YVYU }, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]</td>
</tr>
</tbody>
</table></div>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term">name</span></p></td>
<td>src</td>
</tr>
<tr>
<td><p><span class="term">direction</span></p></td>
<td>source</td>
</tr>
<tr>
<td><p><span class="term">presence</span></p></td>
<td>always</td>
</tr>
<tr>
<td><p><span class="term">details</span></p></td>
<td>video/x-raw-yuv, format=(fourcc){ I420, YV12, Y41B, Y42B, Y444, YUY2, UYVY, AYUV, YVYU }, width=(int)[ 1, 2147483647 ], height=(int)[ 1, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]</td>
</tr>
</tbody>
</table></div>
</div>
</div>
<p>
</p>
</div>
<div class="refsect1">
<a name="gst-plugins-bad-plugins-videodetect.details"></a><h2>Details</h2>
<div class="refsect2">
<a name="GstVideoDetect"></a><h3>struct GstVideoDetect</h3>
<pre class="programlisting">struct GstVideoDetect {
  GstVideoFilter videofilter;
  
  gint width, height;
  GstVideoFormat format;

  gboolean message;
  gint pattern_width;
  gint pattern_height;
  gint pattern_count;
  gint pattern_data_count;
  gdouble pattern_center;
  gdouble pattern_sensitivity;
  gint left_offset;
  gint bottom_offset;

  gboolean in_pattern;
};
</pre>
<p>
Opaque datastructure.
</p>
</div>
</div>
<div class="refsect1">
<a name="gst-plugins-bad-plugins-videodetect.property-details"></a><h2>Property Details</h2>
<div class="refsect2">
<a name="GstVideoDetect--message"></a><h3>The <code class="literal">"message"</code> property</h3>
<pre class="programlisting">  "message"                  <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a>              : Read / Write / Construct</pre>
<p>Post statics messages.</p>
<p>Default value: TRUE</p>
</div>
<hr>
<div class="refsect2">
<a name="GstVideoDetect--pattern-count"></a><h3>The <code class="literal">"pattern-count"</code> property</h3>
<pre class="programlisting">  "pattern-count"            <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write / Construct</pre>
<p>The number of pattern markers.</p>
<p>Allowed values: &gt;= 0</p>
<p>Default value: 4</p>
</div>
<hr>
<div class="refsect2">
<a name="GstVideoDetect--pattern-data-count"></a><h3>The <code class="literal">"pattern-data-count"</code> property</h3>
<pre class="programlisting">  "pattern-data-count"       <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write / Construct</pre>
<p>The number of extra data pattern markers.</p>
<p>Allowed values: &gt;= 0</p>
<p>Default value: 5</p>
</div>
<hr>
<div class="refsect2">
<a name="GstVideoDetect--pattern-height"></a><h3>The <code class="literal">"pattern-height"</code> property</h3>
<pre class="programlisting">  "pattern-height"           <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write / Construct</pre>
<p>The height of the pattern markers.</p>
<p>Allowed values: &gt;= 1</p>
<p>Default value: 16</p>
</div>
<hr>
<div class="refsect2">
<a name="GstVideoDetect--pattern-sensitivity"></a><h3>The <code class="literal">"pattern-sensitivity"</code> property</h3>
<pre class="programlisting">  "pattern-sensitivity"      <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a>               : Read / Write / Construct</pre>
<p>The sensitivity around the center for detecting the markers (0.0 = lowest, 1.0 highest).</p>
<p>Allowed values: [0,1]</p>
<p>Default value: 0.3</p>
</div>
<hr>
<div class="refsect2">
<a name="GstVideoDetect--pattern-width"></a><h3>The <code class="literal">"pattern-width"</code> property</h3>
<pre class="programlisting">  "pattern-width"            <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write / Construct</pre>
<p>The width of the pattern markers.</p>
<p>Allowed values: &gt;= 1</p>
<p>Default value: 4</p>
</div>
<hr>
<div class="refsect2">
<a name="GstVideoDetect--bottom-offset"></a><h3>The <code class="literal">"bottom-offset"</code> property</h3>
<pre class="programlisting">  "bottom-offset"            <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write / Construct</pre>
<p>The offset from the bottom border where the pattern starts.</p>
<p>Allowed values: &gt;= 0</p>
<p>Default value: 0</p>
</div>
<hr>
<div class="refsect2">
<a name="GstVideoDetect--left-offset"></a><h3>The <code class="literal">"left-offset"</code> property</h3>
<pre class="programlisting">  "left-offset"              <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write / Construct</pre>
<p>The offset from the left border where the pattern starts.</p>
<p>Allowed values: &gt;= 0</p>
<p>Default value: 0</p>
</div>
<hr>
<div class="refsect2">
<a name="GstVideoDetect--pattern-center"></a><h3>The <code class="literal">"pattern-center"</code> property</h3>
<pre class="programlisting">  "pattern-center"           <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a>               : Read / Write / Construct</pre>
<p>The center of the black/white separation (0.0 = lowest, 1.0 highest).</p>
<p>Allowed values: [0,1]</p>
<p>Default value: 0.5</p>
</div>
</div>
<div class="refsect1">
<a name="gst-plugins-bad-plugins-videodetect.see-also"></a><h2>See Also</h2>
<a class="link" href="gst-plugins-bad-plugins-videomark.html#GstVideoMark" title="struct GstVideoMark"><span class="type">GstVideoMark</span></a>
</div>
</div>
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