Filter graph
Encyclopedia
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:
Usually these are expressed as file sources. The file sources would feed compression filters, the output of the compression filters would be fed 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.
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.
Multimedia
Multimedia is media and content that uses a combination of different content forms. The term can be used as a noun or as an adjective describing a medium as having multiple content forms. The term is used in contrast to media which use only rudimentary computer display such as text-only, or...
processing. For example to capture video from a webcam
Webcam
A webcam is a video camera that feeds its images in real time to a computer or computer network, often via USB, ethernet, or Wi-Fi.Their most popular use is the establishment of video links, permitting computers to act as videophones or videoconference stations. This common use as a video camera...
. Filters
Filter (software)
A filter is a computer program to process a data stream. Some operating systems such as Unix are rich with filter programs. Even Windows has some simple filters built into its command shell, most of which have significant enhancements relative to the similar filter commands that were available in...
take input, process it or change the input, and then output the process data. An example of a filter, would be a video codec
Video codec
A video codec is a device or software that enables video compression and/or decompression for digital video. The compression usually employs lossy data compression. Historically, video was stored as an analog signal on magnetic tape...
that takes raw uncompressed video
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
and compresses it using a video standard such as H.264. To compress a multimedia stream a filter graph could have two inputs:
- Audio
- Video
Usually these are expressed as file sources. The file sources would feed compression filters, the output of the compression filters would be fed to a multiplexer
Multiplexer
In electronics, a multiplexer is a device that selects one of several analog or digital input signals and forwards the selected input into a single line. A multiplexer of 2n inputs has n select lines, which are used to select which input line to send to the output...
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.
Directed graph
A directed graph or digraph is a pair G= of:* a set V, whose elements are called vertices or nodes,...
. 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.
Example of programs that use filter graphs
- GStreamerGStreamerGStreamer is a pipeline-based multimedia framework written in the C programming language with the type system based on GObject.GStreamer allows a programmer to create a variety of media-handling components, including simple audio playback, audio and video playback, recording, streaming and editing...
- Linux based multimedia framework. In Gstreamer a filter is called an element. Filter graphs can be built with the GStreamer Editor. - GraphEditGraphEditGraphEdit is a utility which is part of the Microsoft DirectShow SDK. It is a visual tool for building and testing filter graphs for DirectShow. Filters are displayed as boxes, with a text caption showing the name of the filter. Pins appear as small squares along the edge of the filter...
- Microsoft tool for building filter graphs - DirectShowDirectShowDirectShow , codename Quartz, is a multimedia framework and API produced by Microsoft for software developers to perform various operations with media files or streams. It is the replacement for Microsoft's earlier Video for Windows technology...
- Windows based multimedia framework. - GraphEditPlus - another tool for building DirectShow filter graphs and generating C++ source code for them.