This guide explains how to write new modules for &GStreamer;. The guide is relevant to several groups of people: Anyone who wants to add support for new ways of processing data in &GStreamer;. For example, a person in this group might want to create a new data format converter, a new visualization tool, or a new decoder or encoder. Anyone who wants to add support for new input and output devices. For example, people in this group might want to add the ability to write to a new video output system or read data from a digital camera or special microphone. Anyone who wants to extend &GStreamer; in any way. You need to have an understanding of how the plugin system works before you can understand the constraints that the plugin system places on the rest of the code. Also, you might be surprised after reading this at how much can be done with plugins. This guide is not relevant to you if you only want to use the existing functionality of &GStreamer;, or if you just want to use an application that uses &GStreamer;. If you are only interested in using existing plugins to write a new application — and there are quite a lot of plugins already — you might want to check the &GstAppDevMan;. If you are just trying to get help with a &GStreamer; application, then you should check with the user manual for that particular application. This guide assumes that you are somewhat familiar with the basic workings of &GStreamer;. For a gentle introduction to programming concepts in &GStreamer;, you may wish to read the &GstAppDevMan; first. Also check out the documentation available on the &GStreamer; web site, particularly the documents available in the &GStreamer; wiki. Since &GStreamer; adheres to the GObject programming model, this guide also assumes that you understand the basics of GObject programming. There are several good introductions to the GObject library, including the GTK+ Tutorial. To help you navigate through this guide, it is divided into several large parts. Each part addresses a particular broad topic concerning &GStreamer; plugin development. The parts of this guide are laid out in the following order: — Introduction to the structure of a plugin. This part covers all the different steps you have to perform to build a basic audio filter plugin. The discussion begins by giving examples of generating the basic structures with . Then you will learn how to write the code to get a basic filter plugin working. Several chapters cover these concepts, including , , , and . After you have finished these chapters, you will have a working plugin, but your new plugin might not have all the functionality you need. To provide some standard functionality, you will learn how to add features to a filter in the chapters on and . Finally, you will learn to test your new plugin in . — Information on advanced features of &GStreamer; plugin development. After learning about the basic steps, you should be able to create a functional audio or video filter plugin with some nice features. However, &GStreamer; offers more for plugin writers. This part of the guide includes chapters on , , , , and . Since these features are more advanced, the chapters can basically be read in any order, as you need the features for your custom plugins. — Explanation of writing source and sink plugins. Although the concepts introduced in the two previous parts of this guide apply to filter plugins, many of the concepts apply equally to source and sink plugins. This part will take a look at creating source and sink type plugins for &GStreamer; in the chapters on and . The chapter on describes writing autoplugger plugins. — The appendices contain some information that stubbornly refused to fit cleanly in other sections of this guide, like the and . FIXME: organize better. The remainder of this introductory part presents a short overview of the basic concepts involved in &GStreamer; plugin development. People familiar with the &GstAppDevMan; can use this short overview to refresh their memory. Topics covered include , , , , and . As you can see, there a lot to learn, so let's get started! Creating compound and complex elements by extending from a GstBin. This will allow you to create plugins that have other plugins embedded in them. Adding new mime-types to the registry along with typedetect functions. This will allow your plugin to operate on a completely new media type. Creating custom schedulers when the default schedulers are insufficient. Creating custom autopluggers when the default ones are insufficient for your needs.