Real-time adaptive forward error correction for MPEG-2 video communications over RTP networks
We present an algorithm for real-time adaptive forward error correction (FEC) of MPEG-2 video stream, encapsulated using real-time transport protocol (RTP) and delivered over best-effort networks. Our algorithm provides an efficient method to determine the allocation of redundancy to the MPEG-2 video stream. The redundancy is allocated such that the resulting estimated degradation density function for video (DDF) is uniformly distributed. A weight, which indicates the relative importance of RTP packets, together with the communication channel characteristics and FEC scheme are used to model the density function of the video stream and allow us to determine the allocation of FEC packets. The weight is based on the content of RTP packets in the video stream. Parameters extracted from the RTP header are used to determine the weights, so that the proposed algorithm can be implemented in real-time. In our simulations, we have relied on motion compensation and group of picture (GOP) data to determine the relative weights. Simulation results provided establish the significant improvement in performance based on our proposed approach to adaptive FEC.