<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>GstDmaBufAllocator: GStreamer Base Plugins 1.0 Library Reference Manual</title>
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
<link rel="home" href="index.html" title="GStreamer Base Plugins 1.0 Library Reference Manual">
<link rel="up" href="gstreamer-allocators.html" title="Allocators Library">
<link rel="prev" href="gstreamer-allocators.html" title="Allocators Library">
<link rel="next" href="gst-plugins-base-libs-fdmemory.html" title="GstFdAllocator">
<meta name="generator" content="GTK-Doc V1.27 (XML mode)">
<link rel="stylesheet" href="style.css" type="text/css">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table class="navigation" id="top" width="100%" summary="Navigation header" cellpadding="2" cellspacing="5"><tr valign="middle">
<td width="100%" align="left" class="shortcuts">
<a href="#" class="shortcut">Top</a><span id="nav_description"> <span class="dim">|</span>
<a href="#gst-plugins-base-libs-dmabuf.description" class="shortcut">Description</a></span>
</td>
<td><a accesskey="h" href="index.html"><img src="home.png" width="16" height="16" border="0" alt="Home"></a></td>
<td><a accesskey="u" href="gstreamer-allocators.html"><img src="up.png" width="16" height="16" border="0" alt="Up"></a></td>
<td><a accesskey="p" href="gstreamer-allocators.html"><img src="left.png" width="16" height="16" border="0" alt="Prev"></a></td>
<td><a accesskey="n" href="gst-plugins-base-libs-fdmemory.html"><img src="right.png" width="16" height="16" border="0" alt="Next"></a></td>
</tr></table>
<div class="refentry">
<a name="gst-plugins-base-libs-dmabuf"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
<td valign="top">
<h2><span class="refentrytitle"><a name="gst-plugins-base-libs-dmabuf.top_of_page"></a>GstDmaBufAllocator</span></h2>
<p>GstDmaBufAllocator — Memory wrapper for Linux dmabuf memory</p>
</td>
<td class="gallery_image" valign="top" align="right"></td>
</tr></table></div>
<div class="refsect1">
<a name="gst-plugins-base-libs-dmabuf.functions"></a><h2>Functions</h2>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="functions_return">
<col class="functions_name">
</colgroup>
<tbody>
<tr>
<td class="function_type">
<a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstAllocator.html#GstAllocator-struct"><span class="returnvalue">GstAllocator</span></a> *
</td>
<td class="function_name">
<a class="link" href="gst-plugins-base-libs-dmabuf.html#gst-dmabuf-allocator-new" title="gst_dmabuf_allocator_new ()">gst_dmabuf_allocator_new</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstMemory.html#GstMemory-struct"><span class="returnvalue">GstMemory</span></a> *
</td>
<td class="function_name">
<a class="link" href="gst-plugins-base-libs-dmabuf.html#gst-dmabuf-allocator-alloc" title="gst_dmabuf_allocator_alloc ()">gst_dmabuf_allocator_alloc</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint"><span class="returnvalue">gint</span></a>
</td>
<td class="function_name">
<a class="link" href="gst-plugins-base-libs-dmabuf.html#gst-dmabuf-memory-get-fd" title="gst_dmabuf_memory_get_fd ()">gst_dmabuf_memory_get_fd</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a href="/usr/share/gtk-doc/html/gobject/gobject-Type-Information.html#GType"><span class="returnvalue">GType</span></a>
</td>
<td class="function_name">
<a class="link" href="gst-plugins-base-libs-dmabuf.html#gst-dmabuf-allocator-get-type" title="gst_dmabuf_allocator_get_type ()">gst_dmabuf_allocator_get_type</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>
</td>
<td class="function_name">
<a class="link" href="gst-plugins-base-libs-dmabuf.html#gst-is-dmabuf-memory" title="gst_is_dmabuf_memory ()">gst_is_dmabuf_memory</a> <span class="c_punctuation">()</span>
</td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect1">
<a name="gst-plugins-base-libs-dmabuf.other"></a><h2>Types and Values</h2>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="name">
<col class="description">
</colgroup>
<tbody><tr>
<td class="define_keyword">#define</td>
<td class="function_name"><a class="link" href="gst-plugins-base-libs-dmabuf.html#GST-CAPS-FEATURE-MEMORY-DMABUF:CAPS" title="GST_CAPS_FEATURE_MEMORY_DMABUF">GST_CAPS_FEATURE_MEMORY_DMABUF</a></td>
</tr></tbody>
</table></div>
</div>
<div class="refsect1">
<a name="gst-plugins-base-libs-dmabuf.includes"></a><h2>Includes</h2>
<pre class="synopsis">#include <gst/allocators/gstdmabuf.h>
</pre>
</div>
<div class="refsect1">
<a name="gst-plugins-base-libs-dmabuf.description"></a><h2>Description</h2>
</div>
<div class="refsect1">
<a name="gst-plugins-base-libs-dmabuf.functions_details"></a><h2>Functions</h2>
<div class="refsect2">
<a name="gst-dmabuf-allocator-new"></a><h3>gst_dmabuf_allocator_new ()</h3>
<pre class="programlisting"><a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstAllocator.html#GstAllocator-struct"><span class="returnvalue">GstAllocator</span></a> *
gst_dmabuf_allocator_new (<em class="parameter"><code><span class="type">void</span></code></em>);</pre>
<p>Return a new dmabuf allocator.</p>
<div class="refsect3">
<a name="gst-dmabuf-allocator-new.returns"></a><h4>Returns</h4>
<p>a new dmabuf allocator, or NULL if the allocator
isn't available. Use <a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstObject.html#gst-object-unref"><code class="function">gst_object_unref()</code></a> to release the allocator after
usage. </p>
<p><span class="annotation">[<acronym title="Free data after the code is done."><span class="acronym">transfer full</span></acronym>]</span></p>
</div>
<p class="since">Since: <a class="link" href="ix13.html#api-index-1.2">1.2</a></p>
</div>
<hr>
<div class="refsect2">
<a name="gst-dmabuf-allocator-alloc"></a><h3>gst_dmabuf_allocator_alloc ()</h3>
<pre class="programlisting"><a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstMemory.html#GstMemory-struct"><span class="returnvalue">GstMemory</span></a> *
gst_dmabuf_allocator_alloc (<em class="parameter"><code><a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstAllocator.html#GstAllocator-struct"><span class="type">GstAllocator</span></a> *allocator</code></em>,
<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint"><span class="type">gint</span></a> fd</code></em>,
<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gsize"><span class="type">gsize</span></a> size</code></em>);</pre>
<p>Return a <a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstMemory.html#GstMemory-struct"><code class="literal">GstMemory</code></a> that wraps a dmabuf file descriptor.</p>
<div class="refsect3">
<a name="gst-dmabuf-allocator-alloc.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>allocator</p></td>
<td class="parameter_description"><p>allocator to be used for this memory</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>fd</p></td>
<td class="parameter_description"><p>dmabuf file descriptor</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>size</p></td>
<td class="parameter_description"><p>memory size</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="gst-dmabuf-allocator-alloc.returns"></a><h4>Returns</h4>
<p>a GstMemory based on <em class="parameter"><code>allocator</code></em>
.
When the buffer will be released dmabuf allocator will close the <em class="parameter"><code>fd</code></em>
.
The memory is only mmapped on <code class="function">gst_buffer_mmap()</code> request. </p>
<p><span class="annotation">[<acronym title="Free data after the code is done."><span class="acronym">transfer full</span></acronym>]</span></p>
</div>
<p class="since">Since: <a class="link" href="ix13.html#api-index-1.2">1.2</a></p>
</div>
<hr>
<div class="refsect2">
<a name="gst-dmabuf-memory-get-fd"></a><h3>gst_dmabuf_memory_get_fd ()</h3>
<pre class="programlisting"><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint"><span class="returnvalue">gint</span></a>
gst_dmabuf_memory_get_fd (<em class="parameter"><code><a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstMemory.html#GstMemory-struct"><span class="type">GstMemory</span></a> *mem</code></em>);</pre>
<p>Return the file descriptor associated with <em class="parameter"><code>mem</code></em>
.</p>
<div class="refsect3">
<a name="gst-dmabuf-memory-get-fd.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>mem</p></td>
<td class="parameter_description"><p>the memory to get the file descriptor</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="gst-dmabuf-memory-get-fd.returns"></a><h4>Returns</h4>
<p> the file descriptor associated with the memory, or -1. The file
descriptor is still owned by the GstMemory. Use dup to take a copy
if you intend to use it beyond the lifetime of this GstMemory.</p>
</div>
<p class="since">Since: <a class="link" href="ix13.html#api-index-1.2">1.2</a></p>
</div>
<hr>
<div class="refsect2">
<a name="gst-dmabuf-allocator-get-type"></a><h3>gst_dmabuf_allocator_get_type ()</h3>
<pre class="programlisting"><a href="/usr/share/gtk-doc/html/gobject/gobject-Type-Information.html#GType"><span class="returnvalue">GType</span></a>
gst_dmabuf_allocator_get_type (<em class="parameter"><code><span class="type">void</span></code></em>);</pre>
</div>
<hr>
<div class="refsect2">
<a name="gst-is-dmabuf-memory"></a><h3>gst_is_dmabuf_memory ()</h3>
<pre class="programlisting"><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>
gst_is_dmabuf_memory (<em class="parameter"><code><a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstMemory.html#GstMemory-struct"><span class="type">GstMemory</span></a> *mem</code></em>);</pre>
<p>Check if <em class="parameter"><code>mem</code></em>
is dmabuf memory.</p>
<div class="refsect3">
<a name="gst-is-dmabuf-memory.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>mem</p></td>
<td class="parameter_description"><p>the memory to be check</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="gst-is-dmabuf-memory.returns"></a><h4>Returns</h4>
<p> <a href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if <em class="parameter"><code>mem</code></em>
is dmabuf memory, otherwise <a href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#FALSE:CAPS"><code class="literal">FALSE</code></a></p>
</div>
<p class="since">Since: <a class="link" href="ix13.html#api-index-1.2">1.2</a></p>
</div>
</div>
<div class="refsect1">
<a name="gst-plugins-base-libs-dmabuf.other_details"></a><h2>Types and Values</h2>
<div class="refsect2">
<a name="GST-CAPS-FEATURE-MEMORY-DMABUF:CAPS"></a><h3>GST_CAPS_FEATURE_MEMORY_DMABUF</h3>
<pre class="programlisting">#define GST_CAPS_FEATURE_MEMORY_DMABUF "memory:DMABuf"
</pre>
<p>Constant that defines the caps feature name for DMA buffer sharing.</p>
<p>It has to be used for non-mappable dma-buf only, i.e. when the underlying
memory is not mappable to user space. Or when the mapped memory contains
non meaningful data. It can be the case for protected content or when the
user wants explicitly avoid any software post processing.</p>
<p>In these cases all elements between the exported and the importer has to work
in passthrough mode. This is done by adding this caps feature.</p>
<p>When the memory is mappable for read and write requests then it is assumes
to be a fast path and so this caps feature should not be used. Though
according to the dma-buf protocal, while it is mapped it prevents the
exporter to migrate the buffer.</p>
<p>This caps feature should not serve at all the purpose of selecting the
<em class="parameter"><code>GST_ALLOCATOR_DMABUF</code></em>
allocator during caps negotiation.
When the exporter is the upstream element from the importer point of view,
the exporter should try to map the dma buffer at runtime (preferrably during
decide_allocation phase). When it succeeds for <a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstMemory.html#GST-MAP-READWRITE:CAPS"><span class="type">GST_MAP_READWRITE</span></a> this caps
feature should not be used. This allows scalers, color converts and any image
processing filters to work directly on the dma buffer.
In this case the importer element should check all incomming memory using
<a class="link" href="gst-plugins-base-libs-dmabuf.html#gst-is-dmabuf-memory" title="gst_is_dmabuf_memory ()"><code class="function">gst_is_dmabuf_memory()</code></a>.</p>
<p class="since">Since: <a class="link" href="ix04.html#api-index-1.12">1.12</a></p>
</div>
</div>
<div class="refsect1">
<a name="gst-plugins-base-libs-dmabuf.see-also"></a><h2>See Also</h2>
<p><a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstMemory.html#GstMemory-struct"><span class="type">GstMemory</span></a></p>
</div>
</div>
<div class="footer">
<hr>Generated by GTK-Doc V1.27</div>
</body>
</html>