GStreamer is an extremely 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, writing new applications is not always easy. This guide is intended to help you understand the GStreamer framework (version 1.10) 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. This book is available as a PDF for free at gstreamer.freedesktop.org. The color images and text in this textbook are grayscale.