Requirements and constraints in MPEG-4 binary shape decoder at main profile

The MPEG4 video standard allows for the specification of the binary shape information of a video object using binary alpha blocks. The binary alpha blocks are 16×16 blocks of binary pixel data that are co-located with the regular texture macroblocks. These binary alpha blocks are coded using context-based arithmetic coding techniques. Decoding is essentially a serial operation and not particularly amenable to parallelism in hardware implementations. This paper analyzes the computational requirements of the binary shape decoder. Synthetic binary video sequences were generated to analyze the computational complexities. Based on these simulation results, we have identified the worst case throughput constraints of a hardware implementation