sipXmediaLib - the media processing library

The sipXmediaLib includes all of the audio processing used in the sipXtapi, sipXezPhone and sipXvxml projects. For example, the library contains audio bridges, audio splitters, echo supression, tone generation (e.g. DTMF), streaming support, RTCP, audio codecs, etc.

The highest level object in the sipXMediaLib is the MpFlowGraph. The flow graph assembles a number of media resources in a defined order of media flow where each resource has zero or more inputs and zero or more outputs. The resouces are process in the oreder implied by the connection topology. The following illustrates the logical connections of the MpCallFlowGraph. Resources may be added dynamically to the flowgraph and new resouce types can be derived. A connection is a logical construct containing the resources related to a single remote media source. There may be zero or more connections in a MpCallFlowGraph.

Internals

(This is basically a capture for posterity of a posting from the email list. It should be polished and improved over time.)

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(Thanks to Brian Cuthie at Systemix for the above info.)

About MpFlowGraphBase and MpCallFlowGraph

The MpFlowGraphBase is a skeleton used by the MpMediaTask for generic media processing. Essentially, it consists a network of media resources, which are generic processing blocks of media operations. The MpCallFlowGraph is derived from that base class, and consists of a particular set of media resources that are each derived from the generic resource base class to perform various media processing functions. The MpFlowGraphBase provides the basic manipulations that the MpMediaTask performs without any inherent knowledge of the processing performed by the flowgraph, while the MpCallFlowGraph provides to the application code an interface for manipulations of the audio processing for a call (for example, add or remove a remote connection, start or stop sending RTP, start or stop playing a tone).