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 <div class="refentry">
 <a name="gstreamer-GstMeta"></a><div class="titlepage"></div>
 <div class="refnamediv"><table width="100%"><tr>
 <td valign="top">
 <h2><span class="refentrytitle"><a name="gstreamer-GstMeta.top_of_page"></a>GstMeta</span></h2>
 <p>GstMeta — Buffer metadata</p>
 </td>
 <td valign="top" align="right"></td>
 </tr></table></div>
 <div class="refsynopsisdiv">
 <a name="gstreamer-GstMeta.synopsis"></a><h2>Synopsis</h2>
 <pre class="synopsis">
 #include &lt;gst/gst.h&gt;

 struct              <a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta">GstMeta</a>;
 enum                <a class="link" href="gstreamer-GstMeta.html#GstMetaFlags" title="enum GstMetaFlags">GstMetaFlags</a>;
 #define             <a class="link" href="gstreamer-GstMeta.html#GST-META-FLAGS:CAPS" title="GST_META_FLAGS()">GST_META_FLAGS</a>                      (meta)
 #define             <a class="link" href="gstreamer-GstMeta.html#GST-META-FLAG-IS-SET:CAPS" title="GST_META_FLAG_IS_SET()">GST_META_FLAG_IS_SET</a>                (meta,
                                                          flag)
 #define             <a class="link" href="gstreamer-GstMeta.html#GST-META-FLAG-SET:CAPS" title="GST_META_FLAG_SET()">GST_META_FLAG_SET</a>                   (meta,
                                                          flag)
 #define             <a class="link" href="gstreamer-GstMeta.html#GST-META-FLAG-UNSET:CAPS" title="GST_META_FLAG_UNSET()">GST_META_FLAG_UNSET</a>                 (meta,
                                                          flag)
 struct              <a class="link" href="gstreamer-GstMeta.html#GstMetaInfo" title="struct GstMetaInfo">GstMetaInfo</a>;
 <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            (<a class="link" href="gstreamer-GstMeta.html#GstMetaInitFunction" title="GstMetaInitFunction ()">*GstMetaInitFunction</a>)              (<em class="parameter"><code><a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a> *meta</code></em>,
                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> params</code></em>,
                                                          <em class="parameter"><code><a class="link" href="gstreamer-GstBuffer.html#GstBuffer" title="struct GstBuffer"><span class="type">GstBuffer</span></a> *buffer</code></em>);
 <span class="returnvalue">void</span>                (<a class="link" href="gstreamer-GstMeta.html#GstMetaFreeFunction" title="GstMetaFreeFunction ()">*GstMetaFreeFunction</a>)              (<em class="parameter"><code><a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a> *meta</code></em>,
                                                          <em class="parameter"><code><a class="link" href="gstreamer-GstBuffer.html#GstBuffer" title="struct GstBuffer"><span class="type">GstBuffer</span></a> *buffer</code></em>);
 <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            (<a class="link" href="gstreamer-GstMeta.html#GstMetaTransformFunction" title="GstMetaTransformFunction ()">*GstMetaTransformFunction</a>)         (<em class="parameter"><code><a class="link" href="gstreamer-GstBuffer.html#GstBuffer" title="struct GstBuffer"><span class="type">GstBuffer</span></a> *transbuf</code></em>,
                                                          <em class="parameter"><code><a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a> *meta</code></em>,
                                                          <em class="parameter"><code><a class="link" href="gstreamer-GstBuffer.html#GstBuffer" title="struct GstBuffer"><span class="type">GstBuffer</span></a> *buffer</code></em>,
                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Quarks.html#GQuark"><span class="type">GQuark</span></a> type</code></em>,
                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> data</code></em>);
                     <a class="link" href="gstreamer-GstMeta.html#GstMetaTransformCopy" title="GstMetaTransformCopy">GstMetaTransformCopy</a>;
 #define             <a class="link" href="gstreamer-GstMeta.html#GST-META-TRANSFORM-IS-COPY:CAPS" title="GST_META_TRANSFORM_IS_COPY()">GST_META_TRANSFORM_IS_COPY</a>          (type)
 <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="returnvalue">GType</span></a>               <a class="link" href="gstreamer-GstMeta.html#gst-meta-api-type-register" title="gst_meta_api_type_register ()">gst_meta_api_type_register</a>          (<em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *api</code></em>,
                                                          <em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> **tags</code></em>);
 <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            <a class="link" href="gstreamer-GstMeta.html#gst-meta-api-type-has-tag" title="gst_meta_api_type_has_tag ()">gst_meta_api_type_has_tag</a>           (<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> api</code></em>,
                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Quarks.html#GQuark"><span class="type">GQuark</span></a> tag</code></em>);
 #define             <a class="link" href="gstreamer-GstMeta.html#GST-META-TAG-MEMORY:CAPS" title="GST_META_TAG_MEMORY">GST_META_TAG_MEMORY</a>
 #define             <a class="link" href="gstreamer-GstMeta.html#GST-META-TAG-MEMORY-STR:CAPS" title="GST_META_TAG_MEMORY_STR">GST_META_TAG_MEMORY_STR</a>
 const <a class="link" href="gstreamer-GstMeta.html#GstMetaInfo" title="struct GstMetaInfo"><span class="returnvalue">GstMetaInfo</span></a> * <a class="link" href="gstreamer-GstMeta.html#gst-meta-register" title="gst_meta_register ()">gst_meta_register</a>                   (<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> api</code></em>,
                                                          <em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *impl</code></em>,
                                                          <em class="parameter"><code><span class="type">gsize</span> size</code></em>,
                                                          <em class="parameter"><code><a class="link" href="gstreamer-GstMeta.html#GstMetaInitFunction" title="GstMetaInitFunction ()"><span class="type">GstMetaInitFunction</span></a> init_func</code></em>,
                                                          <em class="parameter"><code><a class="link" href="gstreamer-GstMeta.html#GstMetaFreeFunction" title="GstMetaFreeFunction ()"><span class="type">GstMetaFreeFunction</span></a> free_func</code></em>,
                                                          <em class="parameter"><code><a class="link" href="gstreamer-GstMeta.html#GstMetaTransformFunction" title="GstMetaTransformFunction ()"><span class="type">GstMetaTransformFunction</span></a> transform_func</code></em>);
 const <a class="link" href="gstreamer-GstMeta.html#GstMetaInfo" title="struct GstMetaInfo"><span class="returnvalue">GstMetaInfo</span></a> * <a class="link" href="gstreamer-GstMeta.html#gst-meta-get-info" title="gst_meta_get_info ()">gst_meta_get_info</a>                   (<em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *impl</code></em>);
 </pre>
 </div>
 <div class="refsect1">
 <a name="gstreamer-GstMeta.description"></a><h2>Description</h2>
 <p>
 The <a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a> structure should be included as the first member of a <a class="link" href="gstreamer-GstBuffer.html#GstBuffer" title="struct GstBuffer"><span class="type">GstBuffer</span></a>
 metadata structure. The structure defines the API of the metadata and should
 be accessible to all elements using the metadata.
 </p>
 <p>
 A metadata API is registered with <a class="link" href="gstreamer-GstMeta.html#gst-meta-api-type-register" title="gst_meta_api_type_register ()"><code class="function">gst_meta_api_type_register()</code></a> which takes a
 name for the metadata API and some tags associated with the metadata.
 With <a class="link" href="gstreamer-GstMeta.html#gst-meta-api-type-has-tag" title="gst_meta_api_type_has_tag ()"><code class="function">gst_meta_api_type_has_tag()</code></a> one can check if a certain metadata API
 contains a given tag.
 </p>
 <p>
 Multiple implementations of a metadata API can be registered.
 To implement a metadata API, <a class="link" href="gstreamer-GstMeta.html#gst-meta-register" title="gst_meta_register ()"><code class="function">gst_meta_register()</code></a> should be used. This
 function takes all parameters needed to create, free and transform metadata
 along with the size of the metadata. The function returns a <a class="link" href="gstreamer-GstMeta.html#GstMetaInfo" title="struct GstMetaInfo"><span class="type">GstMetaInfo</span></a>
 structure that contains the information for the implementation of the API.
 </p>
 <p>
 A specific implementation can be retrieved by name with <a class="link" href="gstreamer-GstMeta.html#gst-meta-get-info" title="gst_meta_get_info ()"><code class="function">gst_meta_get_info()</code></a>.
 </p>
 <p>
 See <a class="link" href="gstreamer-GstBuffer.html#GstBuffer" title="struct GstBuffer"><span class="type">GstBuffer</span></a> for how the metadata can be added, retrieved and removed from
 buffers.
 </p>
 <p>
 Last reviewed on 2012-03-28 (0.11.3)
 </p>
 </div>
 <div class="refsect1">
 <a name="gstreamer-GstMeta.details"></a><h2>Details</h2>
 <div class="refsect2">
 <a name="GstMeta"></a><h3>struct GstMeta</h3>
 <pre class="programlisting">struct GstMeta {
   GstMetaFlags       flags;
   const GstMetaInfo *info;
 };
 </pre>
 <p>
 Base structure for metadata. Custom metadata will put this structure
 as the first member of their structure.
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><span class="term"><a class="link" href="gstreamer-GstMeta.html#GstMetaFlags" title="enum GstMetaFlags"><span class="type">GstMetaFlags</span></a> <em class="structfield"><code><a name="GstMeta.flags"></a>flags</code></em>;</span></p></td>
 <td>extra flags for the metadata</td>
 </tr>
 <tr>
 <td><p><span class="term">const <a class="link" href="gstreamer-GstMeta.html#GstMetaInfo" title="struct GstMetaInfo"><span class="type">GstMetaInfo</span></a> *<em class="structfield"><code><a name="GstMeta.info"></a>info</code></em>;</span></p></td>
 <td>pointer to the <a class="link" href="gstreamer-GstMeta.html#GstMetaInfo" title="struct GstMetaInfo"><span class="type">GstMetaInfo</span></a>
 </td>
 </tr>
 </tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="GstMetaFlags"></a><h3>enum GstMetaFlags</h3>
 <pre class="programlisting">typedef enum {
   GST_META_FLAG_NONE        = 0,
   GST_META_FLAG_READONLY    = (1 &lt;&lt; 0),
   GST_META_FLAG_POOLED      = (1 &lt;&lt; 1),
   GST_META_FLAG_LOCKED      = (1 &lt;&lt; 2),

   GST_META_FLAG_LAST        = (1 &lt;&lt; 16)
 } GstMetaFlags;
 </pre>
 <p>
 Extra metadata flags.
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><a name="GST-META-FLAG-NONE:CAPS"></a><span class="term"><code class="literal">GST_META_FLAG_NONE</code></span></p></td>
 <td>no flags
 </td>
 </tr>
 <tr>
 <td><p><a name="GST-META-FLAG-READONLY:CAPS"></a><span class="term"><code class="literal">GST_META_FLAG_READONLY</code></span></p></td>
 <td>metadata should not be modified
 </td>
 </tr>
 <tr>
 <td><p><a name="GST-META-FLAG-POOLED:CAPS"></a><span class="term"><code class="literal">GST_META_FLAG_POOLED</code></span></p></td>
 <td>metadata is managed by a bufferpool
 </td>
 </tr>
 <tr>
 <td><p><a name="GST-META-FLAG-LOCKED:CAPS"></a><span class="term"><code class="literal">GST_META_FLAG_LOCKED</code></span></p></td>
 <td>metadata should not be removed
 </td>
 </tr>
 <tr>
 <td><p><a name="GST-META-FLAG-LAST:CAPS"></a><span class="term"><code class="literal">GST_META_FLAG_LAST</code></span></p></td>
 <td>additional flags can be added starting from this flag.
 </td>
 </tr>
 </tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="GST-META-FLAGS:CAPS"></a><h3>GST_META_FLAGS()</h3>
 <pre class="programlisting">#define GST_META_FLAGS(meta)  (GST_META_CAST (meta)-&gt;flags)
 </pre>
 <p>
 A flags word containing <a class="link" href="gstreamer-GstMeta.html#GstMetaFlags" title="enum GstMetaFlags"><span class="type">GstMetaFlags</span></a> flags set on <em class="parameter"><code>meta</code></em>
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody><tr>
 <td><p><span class="term"><em class="parameter"><code>meta</code></em> :</span></p></td>
 <td>a <a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a>.</td>
 </tr></tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="GST-META-FLAG-IS-SET:CAPS"></a><h3>GST_META_FLAG_IS_SET()</h3>
 <pre class="programlisting">#define GST_META_FLAG_IS_SET(meta,flag)        !!(GST_META_FLAGS (meta) &amp; (flag))
 </pre>
 <p>
 Gives the status of a specific flag on a metadata.
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>meta</code></em> :</span></p></td>
 <td>a <a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a>.</td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>flag</code></em> :</span></p></td>
 <td>the <a class="link" href="gstreamer-GstMeta.html#GstMetaFlags" title="enum GstMetaFlags"><span class="type">GstMetaFlags</span></a> to check.</td>
 </tr>
 </tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="GST-META-FLAG-SET:CAPS"></a><h3>GST_META_FLAG_SET()</h3>
 <pre class="programlisting">#define GST_META_FLAG_SET(meta,flag)           (GST_META_FLAGS (meta) |= (flag))
 </pre>
 <p>
 Sets a metadata flag on a metadata.
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>meta</code></em> :</span></p></td>
 <td>a <a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a>.</td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>flag</code></em> :</span></p></td>
 <td>the <a class="link" href="gstreamer-GstMeta.html#GstMetaFlags" title="enum GstMetaFlags"><span class="type">GstMetaFlags</span></a> to set.</td>
 </tr>
 </tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="GST-META-FLAG-UNSET:CAPS"></a><h3>GST_META_FLAG_UNSET()</h3>
 <pre class="programlisting">#define GST_META_FLAG_UNSET(meta,flag)         (GST_META_FLAGS (meta) &amp;= ~(flag))
 </pre>
 <p>
 Clears a metadata flag.
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>meta</code></em> :</span></p></td>
 <td>a <a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a>.</td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>flag</code></em> :</span></p></td>
 <td>the <a class="link" href="gstreamer-GstMeta.html#GstMetaFlags" title="enum GstMetaFlags"><span class="type">GstMetaFlags</span></a> to clear.</td>
 </tr>
 </tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="GstMetaInfo"></a><h3>struct GstMetaInfo</h3>
 <pre class="programlisting">struct GstMetaInfo {
   GType                      api;
   GType                      type;
   gsize                      size;

   GstMetaInitFunction        init_func;
   GstMetaFreeFunction        free_func;
   GstMetaTransformFunction   transform_func;
 };
 </pre>
 <p>
 The <a class="link" href="gstreamer-GstMeta.html#GstMetaInfo" title="struct GstMetaInfo"><span class="type">GstMetaInfo</span></a> provides information about a specific metadata
 structure.
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><span class="term"><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> <em class="structfield"><code><a name="GstMetaInfo.api"></a>api</code></em>;</span></p></td>
 <td>tag indentifying the metadata structure and api</td>
 </tr>
 <tr>
 <td><p><span class="term"><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> <em class="structfield"><code><a name="GstMetaInfo.type"></a>type</code></em>;</span></p></td>
 <td>type indentifying the implementor of the api</td>
 </tr>
 <tr>
 <td><p><span class="term"><span class="type">gsize</span> <em class="structfield"><code><a name="GstMetaInfo.size"></a>size</code></em>;</span></p></td>
 <td>size of the metadata</td>
 </tr>
 <tr>
 <td><p><span class="term"><a class="link" href="gstreamer-GstMeta.html#GstMetaInitFunction" title="GstMetaInitFunction ()"><span class="type">GstMetaInitFunction</span></a> <em class="structfield"><code><a name="GstMetaInfo.init-func"></a>init_func</code></em>;</span></p></td>
 <td>function for initializing the metadata</td>
 </tr>
 <tr>
 <td><p><span class="term"><a class="link" href="gstreamer-GstMeta.html#GstMetaFreeFunction" title="GstMetaFreeFunction ()"><span class="type">GstMetaFreeFunction</span></a> <em class="structfield"><code><a name="GstMetaInfo.free-func"></a>free_func</code></em>;</span></p></td>
 <td>function for freeing the metadata</td>
 </tr>
 <tr>
 <td><p><span class="term"><a class="link" href="gstreamer-GstMeta.html#GstMetaTransformFunction" title="GstMetaTransformFunction ()"><span class="type">GstMetaTransformFunction</span></a> <em class="structfield"><code><a name="GstMetaInfo.transform-func"></a>transform_func</code></em>;</span></p></td>
 <td>function for transforming the metadata</td>
 </tr>
 </tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="GstMetaInitFunction"></a><h3>GstMetaInitFunction ()</h3>
 <pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            (*GstMetaInitFunction)              (<em class="parameter"><code><a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a> *meta</code></em>,
                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> params</code></em>,
                                                          <em class="parameter"><code><a class="link" href="gstreamer-GstBuffer.html#GstBuffer" title="struct GstBuffer"><span class="type">GstBuffer</span></a> *buffer</code></em>);</pre>
 <p>
 Function called when <em class="parameter"><code>meta</code></em> is initialized in <em class="parameter"><code>buffer</code></em>.
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>meta</code></em> :</span></p></td>
 <td>a <a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a>
 </td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>params</code></em> :</span></p></td>
 <td>parameters passed to the init function</td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>buffer</code></em> :</span></p></td>
 <td>a <a class="link" href="gstreamer-GstBuffer.html#GstBuffer" title="struct GstBuffer"><span class="type">GstBuffer</span></a>
 </td>
 </tr>
 </tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="GstMetaFreeFunction"></a><h3>GstMetaFreeFunction ()</h3>
 <pre class="programlisting"><span class="returnvalue">void</span>                (*GstMetaFreeFunction)              (<em class="parameter"><code><a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a> *meta</code></em>,
                                                          <em class="parameter"><code><a class="link" href="gstreamer-GstBuffer.html#GstBuffer" title="struct GstBuffer"><span class="type">GstBuffer</span></a> *buffer</code></em>);</pre>
 <p>
 Function called when <em class="parameter"><code>meta</code></em> is freed in <em class="parameter"><code>buffer</code></em>.
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>meta</code></em> :</span></p></td>
 <td>a <a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a>
 </td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>buffer</code></em> :</span></p></td>
 <td>a <a class="link" href="gstreamer-GstBuffer.html#GstBuffer" title="struct GstBuffer"><span class="type">GstBuffer</span></a>
 </td>
 </tr>
 </tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="GstMetaTransformFunction"></a><h3>GstMetaTransformFunction ()</h3>
 <pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            (*GstMetaTransformFunction)         (<em class="parameter"><code><a class="link" href="gstreamer-GstBuffer.html#GstBuffer" title="struct GstBuffer"><span class="type">GstBuffer</span></a> *transbuf</code></em>,
                                                          <em class="parameter"><code><a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a> *meta</code></em>,
                                                          <em class="parameter"><code><a class="link" href="gstreamer-GstBuffer.html#GstBuffer" title="struct GstBuffer"><span class="type">GstBuffer</span></a> *buffer</code></em>,
                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Quarks.html#GQuark"><span class="type">GQuark</span></a> type</code></em>,
                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> data</code></em>);</pre>
 <p>
 Function called for each <em class="parameter"><code>meta</code></em> in <em class="parameter"><code>buffer</code></em> as a result of performing a
 transformation on <em class="parameter"><code>transbuf</code></em>. Additional <em class="parameter"><code>type</code></em> specific transform data
 is passed to the function as <em class="parameter"><code>data</code></em>.
 </p>
 <p>
 Implementations should check the <em class="parameter"><code>type</code></em> of the transform and parse
 additional type specific fields in <em class="parameter"><code>data</code></em> that should be used to update
 the metadata on <em class="parameter"><code>transbuf</code></em>.
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>transbuf</code></em> :</span></p></td>
 <td>a <a class="link" href="gstreamer-GstBuffer.html#GstBuffer" title="struct GstBuffer"><span class="type">GstBuffer</span></a>
 </td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>meta</code></em> :</span></p></td>
 <td>a <a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a>
 </td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>buffer</code></em> :</span></p></td>
 <td>a <a class="link" href="gstreamer-GstBuffer.html#GstBuffer" title="struct GstBuffer"><span class="type">GstBuffer</span></a>
 </td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
 <td>the transform type</td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>data</code></em> :</span></p></td>
 <td>transform specific data.</td>
 </tr>
 <tr>
 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 <td>
 <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if the transform could be performed</td>
 </tr>
 </tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="GstMetaTransformCopy"></a><h3>GstMetaTransformCopy</h3>
 <pre class="programlisting">typedef struct {
   gboolean region;
   gsize offset;
   gsize size;
 } GstMetaTransformCopy;
 </pre>
 <p>
 Extra data passed to a "gst-copy" transform <a class="link" href="gstreamer-GstMeta.html#GstMetaTransformFunction" title="GstMetaTransformFunction ()"><span class="type">GstMetaTransformFunction</span></a>.
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><span class="term"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> <em class="structfield"><code><a name="GstMetaTransformCopy.region"></a>region</code></em>;</span></p></td>
 <td>
 <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if only region is copied</td>
 </tr>
 <tr>
 <td><p><span class="term"><span class="type">gsize</span> <em class="structfield"><code><a name="GstMetaTransformCopy.offset"></a>offset</code></em>;</span></p></td>
 <td>the offset to copy, 0 if <em class="parameter"><code>region</code></em> is <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#FALSE:CAPS"><code class="literal">FALSE</code></a>, otherwise &gt; 0</td>
 </tr>
 <tr>
 <td><p><span class="term"><span class="type">gsize</span> <em class="structfield"><code><a name="GstMetaTransformCopy.size"></a>size</code></em>;</span></p></td>
 <td>the size to copy, -1 or the buffer size when <em class="parameter"><code>region</code></em> is <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#FALSE:CAPS"><code class="literal">FALSE</code></a>
 </td>
 </tr>
 </tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="GST-META-TRANSFORM-IS-COPY:CAPS"></a><h3>GST_META_TRANSFORM_IS_COPY()</h3>
 <pre class="programlisting">#define GST_META_TRANSFORM_IS_COPY(type) ((type) == _gst_meta_transform_copy)
 </pre>
 <p>
 Check if the transform type is a copy transform
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody><tr>
 <td><p><span class="term"><em class="parameter"><code>type</code></em> :</span></p></td>
 <td>a transform type</td>
 </tr></tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="gst-meta-api-type-register"></a><h3>gst_meta_api_type_register ()</h3>
 <pre class="programlisting"><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="returnvalue">GType</span></a>               gst_meta_api_type_register          (<em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *api</code></em>,
                                                          <em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> **tags</code></em>);</pre>
 <p>
 Register and return a GType for the <em class="parameter"><code>api</code></em> and associate it with
 <em class="parameter"><code>tags</code></em>.
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>api</code></em> :</span></p></td>
 <td>an API to register</td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>tags</code></em> :</span></p></td>
 <td>tags for <em class="parameter"><code>api</code></em>
 </td>
 </tr>
 <tr>
 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 <td>a unique GType for <em class="parameter"><code>api</code></em>.</td>
 </tr>
 </tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="gst-meta-api-type-has-tag"></a><h3>gst_meta_api_type_has_tag ()</h3>
 <pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            gst_meta_api_type_has_tag           (<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> api</code></em>,
                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Quarks.html#GQuark"><span class="type">GQuark</span></a> tag</code></em>);</pre>
 <p>
 Check if <em class="parameter"><code>api</code></em> was registered with <em class="parameter"><code>tag</code></em>.
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>api</code></em> :</span></p></td>
 <td>an API</td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>tag</code></em> :</span></p></td>
 <td>the tag to check</td>
 </tr>
 <tr>
 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 <td>
 <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>api</code></em> was registered with <em class="parameter"><code>tag</code></em>.</td>
 </tr>
 </tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="GST-META-TAG-MEMORY:CAPS"></a><h3>GST_META_TAG_MEMORY</h3>
 <pre class="programlisting">#define GST_META_TAG_MEMORY (_gst_meta_tag_memory)
 </pre>
 <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
 <h3 class="title">Warning</h3>
 <p><code class="literal">GST_META_TAG_MEMORY</code> is deprecated and should not be used in newly-written code. The GQuarks are not exported by any public API, use
   GST_META_TAG_MEMORY_STR instead.</p>
 </div>
 <p>
 Metadata tagged with this tag depends on the particular memory
 or buffer that it is on.
 </p>
 </div>
 <hr>
 <div class="refsect2">
 <a name="GST-META-TAG-MEMORY-STR:CAPS"></a><h3>GST_META_TAG_MEMORY_STR</h3>
 <pre class="programlisting">#define GST_META_TAG_MEMORY_STR "memory"
 </pre>
 <p class="since">Since 1.2</p>
 </div>
 <hr>
 <div class="refsect2">
 <a name="gst-meta-register"></a><h3>gst_meta_register ()</h3>
 <pre class="programlisting">const <a class="link" href="gstreamer-GstMeta.html#GstMetaInfo" title="struct GstMetaInfo"><span class="returnvalue">GstMetaInfo</span></a> * gst_meta_register                   (<em class="parameter"><code><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Type-Information.html#GType"><span class="type">GType</span></a> api</code></em>,
                                                          <em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *impl</code></em>,
                                                          <em class="parameter"><code><span class="type">gsize</span> size</code></em>,
                                                          <em class="parameter"><code><a class="link" href="gstreamer-GstMeta.html#GstMetaInitFunction" title="GstMetaInitFunction ()"><span class="type">GstMetaInitFunction</span></a> init_func</code></em>,
                                                          <em class="parameter"><code><a class="link" href="gstreamer-GstMeta.html#GstMetaFreeFunction" title="GstMetaFreeFunction ()"><span class="type">GstMetaFreeFunction</span></a> free_func</code></em>,
                                                          <em class="parameter"><code><a class="link" href="gstreamer-GstMeta.html#GstMetaTransformFunction" title="GstMetaTransformFunction ()"><span class="type">GstMetaTransformFunction</span></a> transform_func</code></em>);</pre>
 <p>
 Register a new <a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a> implementation.
 </p>
 <p>
 The same <em class="parameter"><code>info</code></em> can be retrieved later with <a class="link" href="gstreamer-GstMeta.html#gst-meta-get-info" title="gst_meta_get_info ()"><code class="function">gst_meta_get_info()</code></a> by using
 <em class="parameter"><code>impl</code></em> as the key.
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>api</code></em> :</span></p></td>
 <td>the type of the <a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a> API</td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>impl</code></em> :</span></p></td>
 <td>the name of the <a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a> implementation</td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>size</code></em> :</span></p></td>
 <td>the size of the <a class="link" href="gstreamer-GstMeta.html#GstMeta" title="struct GstMeta"><span class="type">GstMeta</span></a> structure</td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>init_func</code></em> :</span></p></td>
 <td>(scope async) a <a class="link" href="gstreamer-GstMeta.html#GstMetaInitFunction" title="GstMetaInitFunction ()"><span class="type">GstMetaInitFunction</span></a>
 </td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>free_func</code></em> :</span></p></td>
 <td>(scope async) a <a class="link" href="gstreamer-GstMeta.html#GstMetaFreeFunction" title="GstMetaFreeFunction ()"><span class="type">GstMetaFreeFunction</span></a>
 </td>
 </tr>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>transform_func</code></em> :</span></p></td>
 <td>(scope async) a <a class="link" href="gstreamer-GstMeta.html#GstMetaTransformFunction" title="GstMetaTransformFunction ()"><span class="type">GstMetaTransformFunction</span></a>
 </td>
 </tr>
 <tr>
 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 <td>a <a class="link" href="gstreamer-GstMeta.html#GstMetaInfo" title="struct GstMetaInfo"><span class="type">GstMetaInfo</span></a> that can be used to access metadata. <span class="annotation">[<acronym title="Don't free data after the code is done."><span class="acronym">transfer none</span></acronym>]</span>
 </td>
 </tr>
 </tbody>
 </table></div>
 </div>
 <hr>
 <div class="refsect2">
 <a name="gst-meta-get-info"></a><h3>gst_meta_get_info ()</h3>
 <pre class="programlisting">const <a class="link" href="gstreamer-GstMeta.html#GstMetaInfo" title="struct GstMetaInfo"><span class="returnvalue">GstMetaInfo</span></a> * gst_meta_get_info                   (<em class="parameter"><code>const <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gchar"><span class="type">gchar</span></a> *impl</code></em>);</pre>
 <p>
 Lookup a previously registered meta info structure by its implementation name
 <em class="parameter"><code>impl</code></em>.
 </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><span class="term"><em class="parameter"><code>impl</code></em> :</span></p></td>
 <td>the name</td>
 </tr>
 <tr>
 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 <td>a <a class="link" href="gstreamer-GstMeta.html#GstMetaInfo" title="struct GstMetaInfo"><span class="type">GstMetaInfo</span></a> with <em class="parameter"><code>impl</code></em>, or <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#NULL:CAPS"><span class="type">NULL</span></a> when no such
 metainfo exists. <span class="annotation">[<acronym title="Don't free data after the code is done."><span class="acronym">transfer none</span></acronym>]</span>
 </td>
 </tr>
 </tbody>
 </table></div>
 </div>
 </div>
 </div>
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