Guest Editorial: Adaptive Real-Time Multimedia Transmission over Packet Switching Networks

Real-time multimedia transmission over packet switching networks requires strict guarantees of network bandwidth and several quality of service (QoS) parameters, such as end-to-end delay, delay variation and packet loss. Unfortunately, most of the current packet switching networks, such as the Internet, do not provide such guarantees. The available bandwidth of these networks varies dynamically depending on the congestion level within the network. However, in the case of adaptive multimedia applications which can tolerate graceful degradation of audio or video quality as a result of network congestion, bandwidth of the media stream can be scaled down to provide a degraded audio or video quality at the destination. A number of schemes to adapt the media rate have been studied in the literature for both real-time and precoded media.