A Rate-Distortion Based Comparison of Media-Dependent FEC and MDC for Real-Time Audio

Applications that require low loss probabilities in today's Internet have to employ some end-to-end error-recovery mechanism. For interactive applications with strict delay constraints, the delay introduced by the applied schemes has to be low as well. In this paper we compare two schemes proposed for error recovery for real-time audio applications: media-dependent forward error correction (MD-FEC) and multiple description coding (MDC). We conclude that MDC always performs better than MD-FEC, and that the stationary loss probability plays a key role in the choice of the optimal parameters for these schemes. Combining the analytical results with the loss characteristics of measured traces of VoIP calls we conclude that in the current Internet these schemes give considerable gains for streams with a high code rate only, and for these streams MDC can decrease the average distortion significantly better than MD-FEC.