Quality-delay trade-offs can be made in transmitting subband-coded images in the Internet by using either the TCP or the UDP protocol. Delivery by TCP gives superior decoding quality but with very long delays when the network is unreliable, whereas delivery by UDP has negligible delays but with degraded quality when packets are lost. Although images are delivered primarily by TCP today, we study in this paper the use of UDP to deliver multi-description reconstruction-based subband-coded images and the reconstruction of missing information at the receiver based on information received. We first determine empirically the interleaving factors that should be used in order to keep the probability of unrecoverable packet losses sufficiently small. Next, we propose a joint sender-receiver approach for designing transforms in multi-description subband coding. In the receiver, we use a simple interpolation-based reconstruction algorithm, as sophisticated concealment techniques cannot be employed in practice. In the sender, we design an optimized reconstruction-based subband transform (ORB-ST), with an objective of minimizing the mean squared error, assuming that some of the descriptions are lost and that the missing information is reconstructed by simple averaging at the destination. Experimental results show that our proposed ORB-ST performs well in real Internet tests, and UDP delivery of MDC images is an attractive alternative to TCP delivery.
- UDP transmissions,
Available at: http://works.bepress.com/xiao_su/11/