Proportional unequal error protection for MPEG-4 video transmission

Considering the limitations due to channel impairments on the transmission of MPEG-4 video over error prone channels, a technique to apply unequal error protection (UEP) for the MPEG-4 video bitstream is proposed, where UEP is performed through rate compatible punctured convolutional codes (RCPC), with rates chosen according to the perceived importance of bits. The data partitioning tool available in the MPEG-4 standard is exploited, in order to provide a stronger protection for the most significant partitions. The main problem in the application of such a scheme is the fact that packets, like partitions, are not the same length, thus the UEP scheme should be dynamically changed for each packet and the knowledge of each partition length is required. In order to cope with this problem, proportional unequal error protection (P-UEP) is proposed: as the length of each field is not known at the receiver, a proportional scheme may be used, given the length of the packet. The possibility of considering different code rates for the protection of different frames is also proposed: I frames and P frames may be coded with different rates according to their different structure and sensitivity to channel errors.