Memory bandwidth reduction in video coding systems through context adaptive lossless reference frame compression

This paper presents the Reference Frame Context Adaptive Variable-Length Compressor (RFCAVLC) for video coding systems. RFCAVLC aims to reduce the external memory bandwidth required to carry out this process. Six experiments were performed, all based on adaptations of the Huffman algorithm, and the best experiment achieved an average compression rate of more than 24% without any loss in quality for all targeted resolutions. This result is similar to the best solutions proposed in the literature, but it is the only one without losses in this process. The presented RFCAVLC splits the reference frames in 4×4 blocks and compresses these blocks using one of four static code tables in a context-adaptive way. An architecture that implements the encoder of the RFCAVLC solution was described in VHDL and synthesized to an Altera Stratix IV FPGA. The synthesis results achieved by the designed architecture indicate that this solution can be easily coupled to a complete video encoder system with negligible hardware overhead and without compromising throughput.