Creating a video processing system from VYA modules requires frontend and backend modules which produce and consume video data, respectively. The video data itself may be stored in files of various formats or come from a real-time source; each option requires a specific frontend/backend. Video processing modules should always be independent of any frontend and backend, i.e., no information specific to a particular frontend/backend should be communicated to these modules. The frontend and backend are controlled by a subsystem consisting of one or several control processes. This control subsystem may for instance read the system configuration from initialization files and send optional, module-specific control parameters to the video processing modules at the proper data rate. An example is shown in Figure 6, in which dataX symbolizes video channels, sizeX indicates channels for communicating VYAlineLength, etc., and inSeqInfo and outSeqInfo are channels for communicating information about the input and output video sequences. The control subsystem receives an imgSync token for synchronizing control parameters with the video. As indicated by the arrows, the flow of control parameters may be bidirectional.
