docs/libs/html/gst-plugins-base-libs-appsink.html

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  24 <a href="#gst-plugins-base-libs-appsink.synopsis" class="shortcut">Top</a>
  25                    |
  26                   <a href="#gst-plugins-base-libs-appsink.description" class="shortcut">Description</a>
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  29 <div class="refentry">
  30 <a name="gst-plugins-base-libs-appsink"></a><div class="titlepage"></div>
  31 <div class="refnamediv"><table width="100%"><tr>
  32 <td valign="top">
  33 <h2><span class="refentrytitle"><a name="gst-plugins-base-libs-appsink.top_of_page"></a>appsink</span></h2>
  34 <p>appsink — Easy way for applications to extract buffers from a
  35     pipeline</p>
  36 </td>
  37 <td valign="top" align="right"></td>
  38 </tr></table></div>
  39 <div class="refsynopsisdiv">
  40 <a name="gst-plugins-base-libs-appsink.synopsis"></a><h2>Synopsis</h2>
  41 <pre class="synopsis">
  42 #include &lt;gst/app/gstappsink.h&gt;
  43
  44 <span class="returnvalue">void</span>                <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-set-caps" title="gst_app_sink_set_caps ()">gst_app_sink_set_caps</a>               (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>,
  45                                                          <em class="parameter"><code>const <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstCaps.html#GstCaps"><span class="type">GstCaps</span></a> *caps</code></em>);
  46 <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstCaps.html#GstCaps"><span class="returnvalue">GstCaps</span></a> *           <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-get-caps" title="gst_app_sink_get_caps ()">gst_app_sink_get_caps</a>               (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);
  47 <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-is-eos" title="gst_app_sink_is_eos ()">gst_app_sink_is_eos</a>                 (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);
  48 <span class="returnvalue">void</span>                <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-set-emit-signals" title="gst_app_sink_set_emit_signals ()">gst_app_sink_set_emit_signals</a>       (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>,
  49                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> emit</code></em>);
  50 <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-get-emit-signals" title="gst_app_sink_get_emit_signals ()">gst_app_sink_get_emit_signals</a>       (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);
  51 <span class="returnvalue">void</span>                <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-set-max-buffers" title="gst_app_sink_set_max_buffers ()">gst_app_sink_set_max_buffers</a>        (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>,
  52                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a> max</code></em>);
  53 <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#guint"><span class="returnvalue">guint</span></a>               <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-get-max-buffers" title="gst_app_sink_get_max_buffers ()">gst_app_sink_get_max_buffers</a>        (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);
  54 <span class="returnvalue">void</span>                <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-set-drop" title="gst_app_sink_set_drop ()">gst_app_sink_set_drop</a>               (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>,
  55                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> drop</code></em>);
  56 <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-get-drop" title="gst_app_sink_get_drop ()">gst_app_sink_get_drop</a>               (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);
  57 <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstBuffer.html#GstBuffer"><span class="returnvalue">GstBuffer</span></a> *         <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-pull-preroll" title="gst_app_sink_pull_preroll ()">gst_app_sink_pull_preroll</a>           (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);
  58 <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstBuffer.html#GstBuffer"><span class="returnvalue">GstBuffer</span></a> *         <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-pull-buffer" title="gst_app_sink_pull_buffer ()">gst_app_sink_pull_buffer</a>            (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);
  59 <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstBufferList.html#GstBufferList"><span class="returnvalue">GstBufferList</span></a> *     <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-pull-buffer-list" title="gst_app_sink_pull_buffer_list ()">gst_app_sink_pull_buffer_list</a>       (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);
  60                     <a class="link" href="gst-plugins-base-libs-appsink.html#GstAppSinkCallbacks" title="GstAppSinkCallbacks">GstAppSinkCallbacks</a>;
  61 <span class="returnvalue">void</span>                <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-set-callbacks" title="gst_app_sink_set_callbacks ()">gst_app_sink_set_callbacks</a>          (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>,
  62                                                          <em class="parameter"><code><a class="link" href="gst-plugins-base-libs-appsink.html#GstAppSinkCallbacks" title="GstAppSinkCallbacks"><span class="type">GstAppSinkCallbacks</span></a> *callbacks</code></em>,
  63                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data</code></em>,
  64                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Datasets.html#GDestroyNotify"><span class="type">GDestroyNotify</span></a> notify</code></em>);
  65 </pre>
  66 </div>
  67 <div class="refsect1">
  68 <a name="gst-plugins-base-libs-appsink.description"></a><h2>Description</h2>
  69 <p>
  70 Appsink is a sink plugin that supports many different methods for making
  71 the application get a handle on the GStreamer data in a pipeline. Unlike
  72 most GStreamer elements, Appsink provides external API functions.
  73 </p>
  74 <p>
  75 appsink can be used by linking to the gstappsink.h header file to access the
  76 methods or by using the appsink action signals and properties.
  77 </p>
  78 <p>
  79 The normal way of retrieving buffers from appsink is by using the
  80 <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-pull-buffer" title="gst_app_sink_pull_buffer ()"><code class="function">gst_app_sink_pull_buffer()</code></a> and <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-pull-preroll" title="gst_app_sink_pull_preroll ()"><code class="function">gst_app_sink_pull_preroll()</code></a> methods.
  81 These methods block until a buffer becomes available in the sink or when the
  82 sink is shut down or reaches EOS.
  83 </p>
  84 <p>
  85 Appsink will internally use a queue to collect buffers from the streaming
  86 thread. If the application is not pulling buffers fast enough, this queue
  87 will consume a lot of memory over time. The "max-buffers" property can be
  88 used to limit the queue size. The "drop" property controls whether the
  89 streaming thread blocks or if older buffers are dropped when the maximum
  90 queue size is reached. Note that blocking the streaming thread can negatively
  91 affect real-time performance and should be avoided.
  92 </p>
  93 <p>
  94 If a blocking behaviour is not desirable, setting the "emit-signals" property
  95 to <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> will make appsink emit the "new-buffer" and "new-preroll" signals
  96 when a buffer can be pulled without blocking.
  97 </p>
  98 <p>
  99 The "caps" property on appsink can be used to control the formats that
 100 appsink can receive. This property can contain non-fixed caps, the format of
 101 the pulled buffers can be obtained by getting the buffer caps.
 102 </p>
 103 <p>
 104 If one of the pull-preroll or pull-buffer methods return <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>, the appsink
 105 is stopped or in the EOS state. You can check for the EOS state with the
 106 "eos" property or with the <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-is-eos" title="gst_app_sink_is_eos ()"><code class="function">gst_app_sink_is_eos()</code></a> method.
 107 </p>
 108 <p>
 109 The eos signal can also be used to be informed when the EOS state is reached
 110 to avoid polling.
 111 </p>
 112 <p>
 113 Last reviewed on 2008-12-17 (0.10.22)
 114 </p>
 115 </div>
 116 <div class="refsect1">
 117 <a name="gst-plugins-base-libs-appsink.details"></a><h2>Details</h2>
 118 <div class="refsect2">
 119 <a name="gst-app-sink-set-caps"></a><h3>gst_app_sink_set_caps ()</h3>
 120 <pre class="programlisting"><span class="returnvalue">void</span>                gst_app_sink_set_caps               (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>,
 121                                                          <em class="parameter"><code>const <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstCaps.html#GstCaps"><span class="type">GstCaps</span></a> *caps</code></em>);</pre>
 122 <p>
 123 Set the capabilities on the appsink element.  This function takes
 124 a copy of the caps structure. After calling this method, the sink will only
 125 accept caps that match <em class="parameter"><code>caps</code></em>. If <em class="parameter"><code>caps</code></em> is non-fixed, you must check the caps
 126 on the buffers to get the actual used caps.
 127 </p>
 128 <div class="variablelist"><table border="0">
 129 <col align="left" valign="top">
 130 <tbody>
 131 <tr>
 132 <td><p><span class="term"><em class="parameter"><code>appsink</code></em> :</span></p></td>
 133 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a>
 134 </td>
 135 </tr>
 136 <tr>
 137 <td><p><span class="term"><em class="parameter"><code>caps</code></em> :</span></p></td>
 138 <td>caps to set</td>
 139 </tr>
 140 </tbody>
 141 </table></div>
 142 <p class="since">Since 0.10.22</p>
 143 </div>
 144 <hr>
 145 <div class="refsect2">
 146 <a name="gst-app-sink-get-caps"></a><h3>gst_app_sink_get_caps ()</h3>
 147 <pre class="programlisting"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstCaps.html#GstCaps"><span class="returnvalue">GstCaps</span></a> *           gst_app_sink_get_caps               (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);</pre>
 148 <p>
 149 Get the configured caps on <em class="parameter"><code>appsink</code></em>.
 150 </p>
 151 <div class="variablelist"><table border="0">
 152 <col align="left" valign="top">
 153 <tbody>
 154 <tr>
 155 <td><p><span class="term"><em class="parameter"><code>appsink</code></em> :</span></p></td>
 156 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a>
 157 </td>
 158 </tr>
 159 <tr>
 160 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 161 <td>the <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstCaps.html#GstCaps"><span class="type">GstCaps</span></a> accepted by the sink. <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstCaps.html#gst-caps-unref"><code class="function">gst_caps_unref()</code></a> after usage.</td>
 162 </tr>
 163 </tbody>
 164 </table></div>
 165 <p class="since">Since 0.10.22</p>
 166 </div>
 167 <hr>
 168 <div class="refsect2">
 169 <a name="gst-app-sink-is-eos"></a><h3>gst_app_sink_is_eos ()</h3>
 170 <pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            gst_app_sink_is_eos                 (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);</pre>
 171 <p>
 172 Check if <em class="parameter"><code>appsink</code></em> is EOS, which is when no more buffers can be pulled because
 173 an EOS event was received.
 174 </p>
 175 <p>
 176 This function also returns <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> when the appsink is not in the PAUSED or
 177 PLAYING state.
 178 </p>
 179 <div class="variablelist"><table border="0">
 180 <col align="left" valign="top">
 181 <tbody>
 182 <tr>
 183 <td><p><span class="term"><em class="parameter"><code>appsink</code></em> :</span></p></td>
 184 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a>
 185 </td>
 186 </tr>
 187 <tr>
 188 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 189 <td>
 190 <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if no more buffers can be pulled and the appsink is EOS.</td>
 191 </tr>
 192 </tbody>
 193 </table></div>
 194 <p class="since">Since 0.10.22</p>
 195 </div>
 196 <hr>
 197 <div class="refsect2">
 198 <a name="gst-app-sink-set-emit-signals"></a><h3>gst_app_sink_set_emit_signals ()</h3>
 199 <pre class="programlisting"><span class="returnvalue">void</span>                gst_app_sink_set_emit_signals       (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>,
 200                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> emit</code></em>);</pre>
 201 <p>
 202 Make appsink emit the "new-preroll" and "new-buffer" signals. This option is
 203 by default disabled because signal emission is expensive and unneeded when
 204 the application prefers to operate in pull mode.
 205 </p>
 206 <div class="variablelist"><table border="0">
 207 <col align="left" valign="top">
 208 <tbody>
 209 <tr>
 210 <td><p><span class="term"><em class="parameter"><code>appsink</code></em> :</span></p></td>
 211 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a>
 212 </td>
 213 </tr>
 214 <tr>
 215 <td><p><span class="term"><em class="parameter"><code>emit</code></em> :</span></p></td>
 216 <td>the new state</td>
 217 </tr>
 218 </tbody>
 219 </table></div>
 220 <p class="since">Since 0.10.22</p>
 221 </div>
 222 <hr>
 223 <div class="refsect2">
 224 <a name="gst-app-sink-get-emit-signals"></a><h3>gst_app_sink_get_emit_signals ()</h3>
 225 <pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            gst_app_sink_get_emit_signals       (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);</pre>
 226 <p>
 227 Check if appsink will emit the "new-preroll" and "new-buffer" signals.
 228 </p>
 229 <div class="variablelist"><table border="0">
 230 <col align="left" valign="top">
 231 <tbody>
 232 <tr>
 233 <td><p><span class="term"><em class="parameter"><code>appsink</code></em> :</span></p></td>
 234 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a>
 235 </td>
 236 </tr>
 237 <tr>
 238 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 239 <td>
 240 <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if <em class="parameter"><code>appsink</code></em> is emitting the "new-preroll" and "new-buffer"
 241 signals.</td>
 242 </tr>
 243 </tbody>
 244 </table></div>
 245 <p class="since">Since 0.10.22</p>
 246 </div>
 247 <hr>
 248 <div class="refsect2">
 249 <a name="gst-app-sink-set-max-buffers"></a><h3>gst_app_sink_set_max_buffers ()</h3>
 250 <pre class="programlisting"><span class="returnvalue">void</span>                gst_app_sink_set_max_buffers        (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>,
 251                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#guint"><span class="type">guint</span></a> max</code></em>);</pre>
 252 <p>
 253 Set the maximum amount of buffers that can be queued in <em class="parameter"><code>appsink</code></em>. After this
 254 amount of buffers are queued in appsink, any more buffers will block upstream
 255 elements until a buffer is pulled from <em class="parameter"><code>appsink</code></em>.
 256 </p>
 257 <div class="variablelist"><table border="0">
 258 <col align="left" valign="top">
 259 <tbody>
 260 <tr>
 261 <td><p><span class="term"><em class="parameter"><code>appsink</code></em> :</span></p></td>
 262 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a>
 263 </td>
 264 </tr>
 265 <tr>
 266 <td><p><span class="term"><em class="parameter"><code>max</code></em> :</span></p></td>
 267 <td>the maximum number of buffers to queue</td>
 268 </tr>
 269 </tbody>
 270 </table></div>
 271 <p class="since">Since 0.10.22</p>
 272 </div>
 273 <hr>
 274 <div class="refsect2">
 275 <a name="gst-app-sink-get-max-buffers"></a><h3>gst_app_sink_get_max_buffers ()</h3>
 276 <pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#guint"><span class="returnvalue">guint</span></a>               gst_app_sink_get_max_buffers        (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);</pre>
 277 <p>
 278 Get the maximum amount of buffers that can be queued in <em class="parameter"><code>appsink</code></em>.
 279 </p>
 280 <div class="variablelist"><table border="0">
 281 <col align="left" valign="top">
 282 <tbody>
 283 <tr>
 284 <td><p><span class="term"><em class="parameter"><code>appsink</code></em> :</span></p></td>
 285 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a>
 286 </td>
 287 </tr>
 288 <tr>
 289 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 290 <td>The maximum amount of buffers that can be queued.</td>
 291 </tr>
 292 </tbody>
 293 </table></div>
 294 <p class="since">Since 0.10.22</p>
 295 </div>
 296 <hr>
 297 <div class="refsect2">
 298 <a name="gst-app-sink-set-drop"></a><h3>gst_app_sink_set_drop ()</h3>
 299 <pre class="programlisting"><span class="returnvalue">void</span>                gst_app_sink_set_drop               (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>,
 300                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> drop</code></em>);</pre>
 301 <p>
 302 Instruct <em class="parameter"><code>appsink</code></em> to drop old buffers when the maximum amount of queued
 303 buffers is reached.
 304 </p>
 305 <div class="variablelist"><table border="0">
 306 <col align="left" valign="top">
 307 <tbody>
 308 <tr>
 309 <td><p><span class="term"><em class="parameter"><code>appsink</code></em> :</span></p></td>
 310 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a>
 311 </td>
 312 </tr>
 313 <tr>
 314 <td><p><span class="term"><em class="parameter"><code>drop</code></em> :</span></p></td>
 315 <td>the new state</td>
 316 </tr>
 317 </tbody>
 318 </table></div>
 319 <p class="since">Since 0.10.22</p>
 320 </div>
 321 <hr>
 322 <div class="refsect2">
 323 <a name="gst-app-sink-get-drop"></a><h3>gst_app_sink_get_drop ()</h3>
 324 <pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            gst_app_sink_get_drop               (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);</pre>
 325 <p>
 326 Check if <em class="parameter"><code>appsink</code></em> will drop old buffers when the maximum amount of queued
 327 buffers is reached.
 328 </p>
 329 <div class="variablelist"><table border="0">
 330 <col align="left" valign="top">
 331 <tbody>
 332 <tr>
 333 <td><p><span class="term"><em class="parameter"><code>appsink</code></em> :</span></p></td>
 334 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a>
 335 </td>
 336 </tr>
 337 <tr>
 338 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 339 <td>
 340 <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if <em class="parameter"><code>appsink</code></em> is dropping old buffers when the queue is
 341 filled.</td>
 342 </tr>
 343 </tbody>
 344 </table></div>
 345 <p class="since">Since 0.10.22</p>
 346 </div>
 347 <hr>
 348 <div class="refsect2">
 349 <a name="gst-app-sink-pull-preroll"></a><h3>gst_app_sink_pull_preroll ()</h3>
 350 <pre class="programlisting"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstBuffer.html#GstBuffer"><span class="returnvalue">GstBuffer</span></a> *         gst_app_sink_pull_preroll           (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);</pre>
 351 <p>
 352 Get the last preroll buffer in <em class="parameter"><code>appsink</code></em>. This was the buffer that caused the
 353 appsink to preroll in the PAUSED state. This buffer can be pulled many times
 354 and remains available to the application even after EOS.
 355 </p>
 356 <p>
 357 This function is typically used when dealing with a pipeline in the PAUSED
 358 state. Calling this function after doing a seek will give the buffer right
 359 after the seek position.
 360 </p>
 361 <p>
 362 Note that the preroll buffer will also be returned as the first buffer
 363 when calling <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-pull-buffer" title="gst_app_sink_pull_buffer ()"><code class="function">gst_app_sink_pull_buffer()</code></a>.
 364 </p>
 365 <p>
 366 If an EOS event was received before any buffers, this function returns
 367 <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>. Use <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-is-eos" title="gst_app_sink_is_eos ()"><code class="function">gst_app_sink_is_eos()</code></a> to check for the EOS condition.
 368 </p>
 369 <p>
 370 This function blocks until a preroll buffer or EOS is received or the appsink
 371 element is set to the READY/NULL state.
 372 </p>
 373 <div class="variablelist"><table border="0">
 374 <col align="left" valign="top">
 375 <tbody>
 376 <tr>
 377 <td><p><span class="term"><em class="parameter"><code>appsink</code></em> :</span></p></td>
 378 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a>
 379 </td>
 380 </tr>
 381 <tr>
 382 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 383 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstBuffer.html#GstBuffer"><span class="type">GstBuffer</span></a> or NULL when the appsink is stopped or EOS.</td>
 384 </tr>
 385 </tbody>
 386 </table></div>
 387 <p class="since">Since 0.10.22</p>
 388 </div>
 389 <hr>
 390 <div class="refsect2">
 391 <a name="gst-app-sink-pull-buffer"></a><h3>gst_app_sink_pull_buffer ()</h3>
 392 <pre class="programlisting"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstBuffer.html#GstBuffer"><span class="returnvalue">GstBuffer</span></a> *         gst_app_sink_pull_buffer            (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);</pre>
 393 <p>
 394 This function blocks until a buffer or EOS becomes available or the appsink
 395 element is set to the READY/NULL state.
 396 </p>
 397 <p>
 398 This function will only return buffers when the appsink is in the PLAYING
 399 state. All rendered buffers will be put in a queue so that the application
 400 can pull buffers at its own rate. Note that when the application does not
 401 pull buffers fast enough, the queued buffers could consume a lot of memory,
 402 especially when dealing with raw video frames.
 403 </p>
 404 <p>
 405 If an EOS event was received before any buffers, this function returns
 406 <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>. Use <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-is-eos" title="gst_app_sink_is_eos ()"><code class="function">gst_app_sink_is_eos()</code></a> to check for the EOS condition.
 407 </p>
 408 <div class="variablelist"><table border="0">
 409 <col align="left" valign="top">
 410 <tbody>
 411 <tr>
 412 <td><p><span class="term"><em class="parameter"><code>appsink</code></em> :</span></p></td>
 413 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a>
 414 </td>
 415 </tr>
 416 <tr>
 417 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 418 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstBuffer.html#GstBuffer"><span class="type">GstBuffer</span></a> or NULL when the appsink is stopped or EOS.</td>
 419 </tr>
 420 </tbody>
 421 </table></div>
 422 <p class="since">Since 0.10.22</p>
 423 </div>
 424 <hr>
 425 <div class="refsect2">
 426 <a name="gst-app-sink-pull-buffer-list"></a><h3>gst_app_sink_pull_buffer_list ()</h3>
 427 <pre class="programlisting"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstBufferList.html#GstBufferList"><span class="returnvalue">GstBufferList</span></a> *     gst_app_sink_pull_buffer_list       (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>);</pre>
 428 <p>
 429 This function blocks until a buffer list or EOS becomes available or the
 430 appsink element is set to the READY/NULL state.
 431 </p>
 432 <p>
 433 This function will only return buffer lists when the appsink is in the
 434 PLAYING state. All rendered buffer lists will be put in a queue so that
 435 the application can pull buffer lists at its own rate. Note that when
 436 the application does not pull buffer lists fast enough, the queued buffer
 437 lists could consume a lot of memory, especially when dealing with raw
 438 video frames.
 439 </p>
 440 <p>
 441 If an EOS event was received before any buffer lists, this function returns
 442 <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>. Use <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-is-eos" title="gst_app_sink_is_eos ()"><code class="function">gst_app_sink_is_eos()</code></a> to check for the EOS condition.
 443 </p>
 444 <div class="variablelist"><table border="0">
 445 <col align="left" valign="top">
 446 <tbody>
 447 <tr>
 448 <td><p><span class="term"><em class="parameter"><code>appsink</code></em> :</span></p></td>
 449 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a>
 450 </td>
 451 </tr>
 452 <tr>
 453 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 454 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstBufferList.html#GstBufferList"><span class="type">GstBufferList</span></a> or NULL when the appsink is stopped or EOS.</td>
 455 </tr>
 456 </tbody>
 457 </table></div>
 458 </div>
 459 <hr>
 460 <div class="refsect2">
 461 <a name="GstAppSinkCallbacks"></a><h3>GstAppSinkCallbacks</h3>
 462 <pre class="programlisting">typedef struct {
 463   void          (*eos)              (GstAppSink *sink, gpointer user_data);
 464   GstFlowReturn (*new_preroll)      (GstAppSink *sink, gpointer user_data);
 465   GstFlowReturn (*new_buffer)       (GstAppSink *sink, gpointer user_data);
 466   GstFlowReturn (*new_buffer_list)  (GstAppSink *sink, gpointer user_data);
 467 } GstAppSinkCallbacks;
 468 </pre>
 469 <p>
 470 A set of callbacks that can be installed on the appsink with
 471 <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-set-callbacks" title="gst_app_sink_set_callbacks ()"><code class="function">gst_app_sink_set_callbacks()</code></a>.
 472 </p>
 473 <div class="variablelist"><table border="0">
 474 <col align="left" valign="top">
 475 <tbody>
 476 <tr>
 477 <td><p><span class="term"><em class="structfield"><code><a name="GstAppSinkCallbacks.eos"></a>eos</code></em> ()</span></p></td>
 478 <td>Called when the end-of-stream has been reached. This callback
 479 is called from the steaming thread.</td>
 480 </tr>
 481 <tr>
 482 <td><p><span class="term"><em class="structfield"><code><a name="GstAppSinkCallbacks.new-preroll"></a>new_preroll</code></em> ()</span></p></td>
 483 <td>Called when a new preroll buffer is available.
 484 This callback is called from the steaming thread.
 485 The new preroll buffer can be retrieved with
 486 <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-pull-preroll" title="gst_app_sink_pull_preroll ()"><code class="function">gst_app_sink_pull_preroll()</code></a> either from this callback
 487 or from any other thread.</td>
 488 </tr>
 489 <tr>
 490 <td><p><span class="term"><em class="structfield"><code><a name="GstAppSinkCallbacks.new-buffer"></a>new_buffer</code></em> ()</span></p></td>
 491 <td>Called when a new buffer is available.
 492 This callback is called from the steaming thread.
 493 The new buffer can be retrieved with
 494 <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-pull-buffer" title="gst_app_sink_pull_buffer ()"><code class="function">gst_app_sink_pull_buffer()</code></a> either from this callback
 495 or from any other thread.</td>
 496 </tr>
 497 <tr>
 498 <td><p><span class="term"><em class="structfield"><code><a name="GstAppSinkCallbacks.new-buffer-list"></a>new_buffer_list</code></em> ()</span></p></td>
 499 <td>Called when a new bufferlist is available.
 500 This callback is called from the steaming thread.
 501 The new bufferlist can be retrieved with
 502 <a class="link" href="gst-plugins-base-libs-appsink.html#gst-app-sink-pull-buffer-list" title="gst_app_sink_pull_buffer_list ()"><code class="function">gst_app_sink_pull_buffer_list()</code></a> either from this callback
 503 or from any other thread.</td>
 504 </tr>
 505 </tbody>
 506 </table></div>
 507 <p class="since">Since 0.10.23</p>
 508 </div>
 509 <hr>
 510 <div class="refsect2">
 511 <a name="gst-app-sink-set-callbacks"></a><h3>gst_app_sink_set_callbacks ()</h3>
 512 <pre class="programlisting"><span class="returnvalue">void</span>                gst_app_sink_set_callbacks          (<em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a> *appsink</code></em>,
 513                                                          <em class="parameter"><code><a class="link" href="gst-plugins-base-libs-appsink.html#GstAppSinkCallbacks" title="GstAppSinkCallbacks"><span class="type">GstAppSinkCallbacks</span></a> *callbacks</code></em>,
 514                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data</code></em>,
 515                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Datasets.html#GDestroyNotify"><span class="type">GDestroyNotify</span></a> notify</code></em>);</pre>
 516 <p>
 517 Set callbacks which will be executed for each new preroll, new buffer and eos.
 518 This is an alternative to using the signals, it has lower overhead and is thus
 519 less expensive, but also less flexible.
 520 </p>
 521 <p>
 522 If callbacks are installed, no signals will be emitted for performance
 523 reasons.
 524 </p>
 525 <div class="variablelist"><table border="0">
 526 <col align="left" valign="top">
 527 <tbody>
 528 <tr>
 529 <td><p><span class="term"><em class="parameter"><code>appsink</code></em> :</span></p></td>
 530 <td>a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base/html/gst-plugins-base-plugins-appsink.html#GstAppSink"><span class="type">GstAppSink</span></a>
 531 </td>
 532 </tr>
 533 <tr>
 534 <td><p><span class="term"><em class="parameter"><code>callbacks</code></em> :</span></p></td>
 535 <td>the callbacks</td>
 536 </tr>
 537 <tr>
 538 <td><p><span class="term"><em class="parameter"><code>user_data</code></em> :</span></p></td>
 539 <td>a user_data argument for the callbacks</td>
 540 </tr>
 541 <tr>
 542 <td><p><span class="term"><em class="parameter"><code>notify</code></em> :</span></p></td>
 543 <td>a destroy notify function</td>
 544 </tr>
 545 </tbody>
 546 </table></div>
 547 <p class="since">Since 0.10.23</p>
 548 </div>
 549 </div>
 550 <div class="refsect1">
 551 <a name="gst-plugins-base-libs-appsink.see-also"></a><h2>See Also</h2>
 552 <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer-libs/html/GstBaseSink.html"><span class="type">GstBaseSink</span></a>, appsrc
 553 </div>
 554 </div>
 555 <div class="footer">
 556 <hr>
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