gstreamer/docs/pwg/gst-plugin-writers-guide.xml

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<?xml version='1.0'?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" [
<!ENTITY % magic-entities SYSTEM "magic">
%magic-entities;
<!ENTITY TITLEPAGE SYSTEM "titlepage.xml">
<!ENTITY INTRO_PREFACE SYSTEM "intro_preface.xml">
<!ENTITY INTRO_BASICS SYSTEM "intro_basics.xml">
<!ENTITY BUILDING_BOILER SYSTEM "building_boiler.xml">
<!ENTITY BUILDING_PADS SYSTEM "building_pads.xml">
<!ENTITY BUILDING_CHAINFN SYSTEM "building_chainfn.xml">
<!ENTITY BUILDING_STATE SYSTEM "building_state.xml">
<!ENTITY BUILDING_PROPS SYSTEM "building_props.xml">
<!ENTITY BUILDING_SIGNALS SYSTEM "building_signals.xml">
<!ENTITY BUILDING_TESTAPP SYSTEM "building_testapp.xml">
<!ENTITY ADVANCED_SCHEDULING SYSTEM "advanced_scheduling.xml">
<!ENTITY ADVANCED_TYPES SYSTEM "advanced_types.xml">
<!ENTITY ADVANCED_REQUEST SYSTEM "advanced_request.xml">
<!ENTITY ADVANCED_CLOCK SYSTEM "advanced_clock.xml">
<!ENTITY ADVANCED_DPARAMS SYSTEM "advanced_dparams.xml">
<!ENTITY ADVANCED_MIDI SYSTEM "advanced_midi.xml">
<!ENTITY OTHER_SOURCE SYSTEM "other_source.xml">
<!ENTITY OTHER_SINK SYSTEM "other_sink.xml">
<!ENTITY OTHER_AUTOPLUGGER SYSTEM "other_autoplugger.xml">
<!ENTITY APPENDIX_CHECKLIST SYSTEM "appendix_checklist.xml">
<!ENTITY APPENDIX_PYTHON SYSTEM "appendix_python.xml">
<!ENTITY GStreamer "<application>GStreamer</application>">
<!ENTITY GstVersion "0.4.2.2">
<!ENTITY GstAppDevMan "<emphasis>GStreamer Application Development Manual</emphasis>">
<!ENTITY GstLibRef "<emphasis>GStreamer Library Reference</emphasis>">
]>
<book id="book-gst-plugin-writers-guide">
&TITLEPAGE;
<!-- ############# part ############### -->
<part id="part-introduction" xreflabel="Introduction">
<title>Introduction</title>
<partintro>
<para>
&GStreamer; is an exremely powerful and versatile framework for creating
streaming media applications. Many of the virtues of the &GStreamer;
framework come from its modularity: &GStreamer; can seamlessly
incorporate new plugin modules. But because modularity and power often
come at a cost of greater complexity (consider, for example, <ulink
type="http" url="http://www.omg.org/">CORBA</ulink>), writing new
plugins is not always easy.
</para>
<para>
This guide is intended to help you understand the &GStreamer; framework
(version &GstVersion;) so you can develop new plugins to extend the
existing functionality. The guide addresses most issues by following the
development of an example plugin - an audio filter plugin -
written in C. However, the later parts of the guide also present some
issues involved in writing other types of plugins, and the end of the
guide describes some of the Python bindings for &GStreamer;.
</para>
</partintro>
&INTRO_PREFACE;
&INTRO_BASICS;
</part>
<!-- ############ part ############# -->
<part id="part-building" xreflabel="Building a Filter">
<title>Building a Filter</title>
<partintro>
<para>
You are now ready to learn how to build a plugin. In this part of the
guide, you will learn how to apply basic &GStreamer; and GNOME
programming concepts to write a simple plugin. The previous parts of the
guide have contained no explicit example code, perhaps making things a
bit abstract and difficult to understand. In contrast, this section will
present both applications and code by following the development of an
example audio filter plugin called <quote>ExampleFilter</quote>.
</para>
<para>
The example filter will begin with a single input pad and a single
output pad. The filter will, at first, simply pass media and event data
from its sink pad to its source pad without modification. But by the end
of this part of the guide, you will learn to add some more interesting
functionality, including properties and signal handlers. And after
reading the next part of the guide, <xref linkend="part-advanced"/>, you
will be able to add even more functionality to your plugins.
</para>
<para>
The example code used in this part of the guide can be found in
<filename class="directory">examples/pwg/examplefilter/</filename> in
your &GStreamer; directory.
</para>
</partintro>
&BUILDING_BOILER;
&BUILDING_PADS;
&BUILDING_CHAINFN;
&BUILDING_STATE;
&BUILDING_PROPS;
&BUILDING_SIGNALS;
&BUILDING_TESTAPP;
</part>
<!-- ############ part ############# -->
<part id="part-advanced" xreflabel="Advanced Filter Concepts">
<title>Advanced Filter Concepts</title>
<partintro>
<para>
</para>
</partintro>
&ADVANCED_SCHEDULING;
&ADVANCED_TYPES;
&ADVANCED_REQUEST;
&ADVANCED_CLOCK;
&ADVANCED_DPARAMS;
&ADVANCED_MIDI;
</part>
<!-- ############ part ############# -->
<part id="part-other" xreflabel="Other Element Types">
<title>Other Element Types</title>
<partintro>
<para>
</para>
</partintro>
&OTHER_SOURCE;
&OTHER_SINK;
&OTHER_AUTOPLUGGER;
</part>
<!-- ############ part ############# -->
<part id="part-appendix" xreflabel="Appendices">
<title>Appendices</title>
<partintro>
<para>
</para>
</partintro>
&APPENDIX_CHECKLIST;
&APPENDIX_PYTHON;
</part>
</book>