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5e6a3722ac
Original commit message from CVS: Fixes to various plugins. Removed the eos/qos calls in favour of the soon to be event system. Added a test app to test element reuse (doesn't work)
173 lines
5.9 KiB
Text
173 lines
5.9 KiB
Text
<chapter id="cha-doicare">
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<title>Do I care?</title>
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<para>
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This guide explains how to write new modules for GStreamer. It is
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relevant to:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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Anyone who wants to add support for new input and output
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devices, often called sources and sinks. For example,
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adding the ability to write to a new video output system
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could be done by writing an appropriate sink plugin.
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</para>
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</listitem>
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<listitem>
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<para>
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Anyone who wants to add support for new ways of processing
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data in GStreamer, often called
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filters. For example, a new data format converter could be
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created.
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</para>
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</listitem>
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<listitem>
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<para>
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Anyone who wants to extend GStreamer in
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any way: you need to have an understanding of how the plugin system
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works before you can understand the constraints it places on the
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rest of the code. And you might be surprised at how much can be
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done with plugins.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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This guide is not relevant to you if you only want to use the existing
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functionality of GStreamer, or use an application which uses GStreamer.
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You lot can go away. Shoo... (You might find the <emphasis>GStreamer
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Application Development Manual</emphasis> helpful though.)
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</para>
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</chapter>
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<chapter id="cha-prelimreading">
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<title>Preliminary reading</title>
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<para>
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The reader should be familiar with the basic workings of
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<application>GStreamer</application>. For a gentle introduction to
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GStreamer, you may wish to read the <emphasis>GStreamer Application
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Development Manual</emphasis>. Since <application>GStreamer</application>
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adheres to the GObject programming model, the reader is also assumed to
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understand the basics of GObject.
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</para>
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</chapter>
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<chapter id="cha-structure">
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<title>Structure of this guide</title>
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<para>
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The <application>GStreamer</application> API for developing plugins is
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rather extensive and powerful. We will first try to get you up and running
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with a simple plugin as fast as possible. We will then gradually add more
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features to our example plugin. The basic topics will be:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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Short overview of the GStreamer concepts. People familiar with the
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<emphasis>GStreamer Application Development Manual</emphasis> can use
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this short overview to refresh their memory.
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</para>
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</listitem>
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<listitem>
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<para>
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Introduction to the basic structure of the plugin. We will cover all the
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different steps you have to perform in order to build a plugin. This will
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include a general overview of the structure of your source files.
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</para>
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</listitem>
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<listitem>
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<para>
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Creating the plugin boilerplate. We will show you how to define and set up
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the different aspects for creating a plugin. This will cover extending the
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GstElement class and creating the elementfactory structures. This will include
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setting up the .h and .c files of your plugin.
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</para>
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</listitem>
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<listitem>
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<para>
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Defining the entry point of the plugin and registering the elementfactory.
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After this step your plugin will become available for application programmers.
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</para>
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</listitem>
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<listitem>
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<para>
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Setting up the basic components of the element like adding pads and setting
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up the scheduling entry points of your plugin.
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</para>
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</listitem>
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<listitem>
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<para>
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Adding arguments and signals to the plugin. Users of your plugin will be
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able to listen for specific events your plugin generates as well as change and
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adjust the different properties of your plugin.
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</para>
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</listitem>
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<listitem>
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<para>
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Compiling and testing the basic plugin.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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After this first section, you should be able to create a simple plugin. We will then
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introduce the more advanced concepts of plugins, including:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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Adding padtemplates to the plugin. This will allow your plugin to become fully
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integrated in the GStreamer plugin registry and will allow users of your plugin
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to know what media types your plugin operates on.
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</para>
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</listitem>
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<listitem>
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<para>
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Adding new mime-types to the registry along with typedetect functions. This will allow
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your plugin to operate on a completely new media type.
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</para>
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</listitem>
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<listitem>
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<para>
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Adding caps to the plugins input pads. This will allow other plugins to know what
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media type your plugin is handling at runtime.
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</para>
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</listitem>
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<listitem>
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<para>
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Choosing between a loop-based or a chain-based plugin. We will teach you how to
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create plugins with a more complicated input/output behaviour.
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</para>
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</listitem>
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<listitem>
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<para>
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Adding request pads to the plugin. Request pads allow the application programmer
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to let your plugin dynamically create a pad based on a template.
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</para>
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</listitem>
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<listitem>
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<para>
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Caps negotiation will show you how your plugin can addapt to the plugins it
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is connected to.
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</para>
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</listitem>
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<listitem>
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<para>
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Creating compound and complex elements by extending from a GstBin. This will
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allow you to create plugins that have other plugins embedded in them.
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</para>
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</listitem>
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<listitem>
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<para>
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Creating custom schedulers when the default schedulers are insufficient.
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</para>
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</listitem>
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<listitem>
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<para>
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Creating custom autopluggers when the default ones are insufficient for your needs.
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</para>
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</listitem>
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</itemizedlist>
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<para>
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As you can see, there a lot to learn, so let's get started...
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</para>
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</chapter>
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