Comparison of transmitter - based packet-loss recovery techniques for voice transmission

To facilitate real-time voice communication through the Internet, forward error correction (FEC) and multiple description coding (MDC) can be used as low-delay packet-loss recovery techniques. We use both a Gilbert channel model and data obtained from real IP connections to compare the rate-distortion performance of different variants of FEC and MDC. Using identical overall rates with stringent delay constraints, we find that side-distortion optimized MDC generally performs better than Reed-Solomon based FEC. If the channel condition is known from feedback through the Real-Time Control Protocol (RTCP), then channel-optimized MDC can be used to exploit this information, resulting in significantly improved performance.