Error control for scalable image and video coding

Abstract

Scalable image and video has been proposed to transmit image and video signals over lossy networks, such as the Internet and wireless networks. However, scalability alone is not a complete solution since there is a conflict between the unequal importance of the scalable bit stream and the agnostic nature of packet losses in the network.

This thesis investigates three methods to combat the detrimental effects of random packet losses to scalable images and video, namely the error resilient method, the error concealment method, and the unequal error protection method within the joint source-channel coding framework. For the error resilient method, an optimal bit allocation algorithm is proposed without considering the distortion caused by packet losses. The allocation algorithm is then extended to accommodate packet losses. For the error concealment method, a simple temporal error concealment mechanism is designed to work for video signals. For the unequal error protection method, the optimal protection allocation problem is formulated and solved.

These methods are tested on the wavelet-based Set Partitioning in Hierarchical Trees(SPIHT) scalable image coder. Performance gains and losses in lossy and lossless environments are studied for both the original coder and the error-controlled coders. The results show performance advantages of all three methods over the original SPIHT coder. Particularly, the unequal error protection method and error concealment method are promising for future Internet/wireless image and video transmission, because the former has very good performance even at heavy packet loss (a PSNR of 22.00 dB has been seen at nearly 60% packet loss) and the latter does not introduce any extra overhead.