Loss concealments of subband coded images for real-time transmissions in the Internet

Subband-coded images can be transmitted in the Internet using either the TCP or the UDP protocol. Due to the fact that TCP employs congestion control and retransmissions and that UDP and TCP packets are treated differently by routers, TCP has much longer delays than those of UDP to deliver an image, but packet losses in UDP may lead to poor decoding quality if the image is single-description coded (SDC) and the losses cannot be concealed. We study the use of UDP to deliver multi-description coded (MDC) reconstruction-based subband-transformed (ST) images and the reconstruction of missing information at a receiver based on information received. To facilitate recovery from UDP packet losses, we propose a joint sender-receiver approach for designing optimized reconstruction-based subband transform (ORB-ST) in MDC. We then carefully evaluate the delay-quality trade-offs between the TCP delivery of SDC images and the UDP and combined TCP/UDP delivery of MDC images. Experimental results show that our proposed ORB-ST performs well in real Internet tests, and UDP and combined TCP/UDP delivery of MDC images provide a range of attractive alternatives to TCP delivery.