<title>Error-resilient compression and transmission of scalable video</title>

Abstract

Compressed video bitstreams require protection from channel errors in a wireless channel and protection from packet loss in a wired ATM channel. The three-dimensional (3-D) SPIHT coder has proved its efficiency and its real-time capability in compression of video. A forward-error-correcting (FEC) channel (RCPC) code combined with a single ARQ (automatic- repeat-request) proved to be an effective means for protecting the bitstream. There were two problems with this scheme: the noiseless reverse channel ARQ may not be feasible in practice; and, in the absence of channel coding and ARQ, the decoded sequence was hopelessly corrupted even for relatively clean channels. In this paper, we first show how to make the 3-D SPIHT bitstream more robust to channel errors by breaking the wavelet transform into a number of spatio-temporal tree blocks which can be encoded and decoded independently. This procedure brings the added benefit of parallelization of the compression and decompression algorithms. Then we demonstrate the packetization of the bit stream and the reorganization of these packets to achieve scalability in bit rate and/or resolution in addition to robustness. Then we encode each packet with a channel code. Not only does this protect the integrity of the packets in most cases, but it also allows detection of packet decoding failures, so that only the cleanly recovered packets are reconstructed. This procedure obviates ARQ, because the performance is only about 1 dB worse than normal 3-D SPIHT with FEC and ARQ. Furthermore, the parallelization makes possible real-time implementation in hardware and software.