Past shape decoding for MPEG-4 video

To achieve fast shape decoding in MPEG-4, it is necessary to have a high speed binary shape decoder. A fast architecture is presented here that is able to decode up to 72.4 Mpixels/s, meeting up to MPEG-4 Main Profile @ Level 3 real time requirement. High performance is achieved by using a lookahead scheme in the probability generation unit and a fast ALU. Simpler shift registers are used in place of large barrel shifters to reduce area. Furthermore, even with the use of low power synchronous ROM it is still possible to decode one bit (shape pixel) every clock cycle. The architecture is synthesized using Avanti's Passport 0,35 mum technology library. The layout of the module is shown and the die area is 2.56mm(2).