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131 lines
4 KiB
Text
131 lines
4 KiB
Text
<chapter id="cha-goals">
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<title>Goals</title>
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<para>
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GStreamer was designed to provide a solution to the current Linux media
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problems.
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</para>
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<sect1 id="sec-goals-design">
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<title>The design goals</title>
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<para>
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We descibe what we try to achieve with GStreamer.
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</para>
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<sect2 id="sec-goals-clean">
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<title>Clean and powerfull</title>
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<para>
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GStreamer wants to provide a clean interface 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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The application programmer who wants to build a media pipeline.
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The programmer can use an extensive set of powerfull tools to create
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media pipelines without writing a single line of code. Performing
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complex media manipulations becomes very easy.
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</para>
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</listitem>
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<listitem>
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<para>
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The plugin programmer. Plugin programmers are provided a clean and
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simple API to create self contained plugins. An extensive debugging
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and tracing mechanism has been integrated. GStreamer also comes with
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an extensive set of real-life plugins that serve as an example too.
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</para>
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</listitem>
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</itemizedlist>
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</sect2>
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<sect2 id="sec-goals-object">
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<title>Object oriented</title>
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<para>
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Adhere as much as possible to the glib2.0 object model. A programmer familiar
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with glib2 and GTK+ will be confortable with GStreamer.
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</para>
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<para>
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GStreamer uses the mechanism of signals and object arguments.
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</para>
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<para>
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All objects can be queried at runtime for their various properties and
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capabilities.
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</para>
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</sect2>
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<sect2 id="sec-goals-extensible">
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<title>Extensible</title>
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<para>
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All GStreamer Objects can be extended using the glib2 inheritance methods.
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</para>
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<para>
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All plugins are loaded dynamically and can be extended and upgraded
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independently.
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</para>
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</sect2>
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<sect2 id="sec-goals-binary">
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<title>Allow binary only plugins</title>
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<para>
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plugins are shared libraries that are loaded at runtime. since all the
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properties of the plugin can be set using the GObject properties, there
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is no need to have any header files installed for the plugins.
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</para>
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<para>
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Special care has been taking into making the plugin completely self
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contained. This is in the operations, specification of the capabilities
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of the plugin and properties.
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</para>
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</sect2>
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<sect2 id="sec-goals-performance">
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<title>High performance</title>
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<para>
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High performance is obtained by:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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Using glib g_mem_chunk where possible to minimize dynamic memory
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allocation.
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</para>
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</listitem>
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<listitem>
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<para>
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Connections between plugins are extremely light-weight. Data can travel
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the pipeline with minimal overhead.
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</para>
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</listitem>
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<listitem>
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<para>
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Provide a mechanism to directly work on the target memory. A
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plugin can for example directly write to the X servers shared mem.
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Buffers can also point to arbitrary memory like kernel 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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Refcounting and copy on write to minimize the amount of memcpy.
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Subbufers to efficiently split the data in a buffer.
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</para>
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</listitem>
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<listitem>
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<para>
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Pipelines can be constructed using cothreads to minimize the
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threading overhead. Cothreads are a simple user-space method for
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switching between subtasks.
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</para>
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</listitem>
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<listitem>
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<para>
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HW acceleration is possible by writing a specialized 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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Uses a plugin registry with the specifications of the plugins so
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that the plugin loading can be delayed until the plugin is actually
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used.
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</para>
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</listitem>
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</itemizedlist>
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</sect2>
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</sect1>
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</chapter>
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