Experiments in best-effort multimedia networking for a distributed virtual environment

Until there is greater consensus on proposals for realizing better-than-best-effort services on the Internet, developers of multimedia and distributed virtual environment applications must rely on best-effort media adaptations to ameliorate the effects of network congestion. We present the results of a study on the use of adaptations originally developed for audio and video applications for the data-flows generated by the UNC nanoManipulator. The nanoManipulator is a virtual environment interface to a scanned-probe microscope that has been used by scientists as a tool for basic research in the material and biological sciences. We are building a distributed version of the system for operation over the Internet and are investigating media adaptations for realizing application performance requirements. The results of early experiments with audio and video-centric media adaptations applied to the flows generated by a microscope and a haptic force feedback device are promising. A simple forward error correction scheme provides good recovery from packet loss and an elastic display-queue management scheme limits the impact of delay-Jitter and results in more continuous playout of media samples. These preliminary results provide evidence that a sophisticated virtual environment interface can operate over modest distances over the Internet to control a remote microscope in real-time.