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<div class="refentry">
<a name="gstreamer-GstMeta"></a><div class="titlepage"></div>
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<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>
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<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>
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">
<col align="left" valign="top">
<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_LAST = (1 &lt;&lt; 16)
} GstMetaFlags;
</pre>
<p>
Extra metadata flags.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<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 and 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">
<col align="left" valign="top">
<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">
<col align="left" valign="top">
<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">
<col align="left" valign="top">
<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">
<col align="left" valign="top">
<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">
<col align="left" valign="top">
<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">
<col align="left" valign="top">
<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">
<col align="left" valign="top">
<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">
<col align="left" valign="top">
<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">
<col align="left" valign="top">
<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">
<col align="left" valign="top">
<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">
<col align="left" valign="top">
<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">
<col align="left" valign="top">
<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>
<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-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">
<col align="left" valign="top">
<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>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>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>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">
<col align="left" valign="top">
<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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