Filter graph

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A filter graph is used in multimedia processing. For example to capture video from a webcam.   Filters take input, process it or change the input, and then output the process data. An example of a filter, would be a video codec that takes raw uncompressed video and compresses it using a video standard such as H.264. To compress a multimedia stream a filter graph could have two inputs:

1. Audio
2. Video

Usually these are expressed as file sources. The file sources would feed compression filters, the output of the compression filters would be feed to a multiplexer that would combine the two inputs and produce a single output. An example of a multiplexer would be an MPEG transport stream creator. Finally the multiplexer output would be fed to a file sink, which would create a file from the output.

GStreamer example of a filter graph.

Filter graph of an mp3 file, as rendered by the DirectShow sample GraphEdit. The big boxes represent filters.

A filter graph in multimedia processing is a directed graph. Edges represent one way data flow and nodes represent a data processing step. The term pins or pads are used to describe the connection point between nodes and edges.

[edit] Example of programs that use filter graphs

• GStreamer - Linux based multimedia framework. In Gstreamer a filter is called an element. Filter graphs can be built with the GStreamer Editor.
• GraphEdit - Microsoft tool for building filter graphs
• DirectShow - Windows based multimedia framework.
• GraphEditPlus - another tool for building DirectShow filter graphs and generating C++ source code for them.

[edit] See also

Explanation of filter graph in DirectShow article: DirectShow#Architecture

[edit] External links

[edit] DirectShow

• Explanation of filter graph manager [1]
• Filters what they are
• Example of filter graph usage
• Data Flow in the Filter Graph

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