Construction of error resilient synchronization codeword for variable-length code in image transmission

Variable-length code (VLC), also called Huffman (1952) code, is the most popular data compression technique used for image compression and transmission. But, it is vulnerable to loss of synchronization under transmission in a noisy channel. It will result in large drops in video transmission quality. For stopping error propagation, a synchronization codeword (SC) is mostly used to localize the error propagation effect. However, most of the SC cannot tolerate noise errors. We propose an iterative and efficient algorithm to construct error resilient and variable-length SC for any application defined VLC table. They can be used for synchronization of packet (ERVL-SOP). It can be appended at the end of certain number of symbols to form a packet. Thus, channel noise error can be localized. With the use of the constructed SC as the SOP, the result shows that it can achieve high signal-to-noise ratio (PSNR=26 dB) compared to the use of the normal VLC code as SOP at a bit error rate (BER) of 10/sup -3/. In addition, the incorrect ERVL-SOP detection rate can be decreased to less than 0.0013% effectively.