Data efficient quantization table for a digital video signal processor

AN MPEG CODED AN COMPRESSED VIDEO SIGNAL IS RECEIVED AND DECOMPRESSED FOR DISPLAY. PRIOR TO STORING FRAMES REQUIRED FOR MOTION COMPENSATION IN MEMORY (14), PIXEL BLOCKS ARE RECOMPRESSED BY QUANTIZING (20) DPCM PREDICTION ERROR VALUES (18) TO REDUCE BANDWIDTH AND FRAME MEMORY REQUIREMENTS. FIXED LENGTH QUANTIZATION AND DEQUANTIZATION TABLES (FIG. 2) HAVE N LEVELS (E.G., 15 LEVELS), AND EACH LEVEL HAS AN ASSOCIATED OUTPUT SYMBOL OF PREDOMINANTLY M BITS (E.G., 4 BITS), EXCEPT THAT AT LEAST ONE OF SAID N LEVELS (E.G., LEVEL 7) IS DEFINED BY A UNIQUE SHORT SYMBOL HAVING LESS THAN M BITS (E.G., 3 BITS), AND INPUT DATA FOR THAT LEVEL IS RECEIVED AT A DESIRED RATE. EACH TIME A SHORT SYMBOL IS USED TO REPRESENT A DATA VALUE, BANDWIDTH AND MEMORY ARE REDUCED AND/OR PRESERVED FOR OTHER USES, FOR EXAMPLE, INSERTING OVERHEAD DATA INTO A FIXED-SIZE DATA STREAM. FOR LARGE SEQUENCES OF DATA, SUCH AS EXISTS FOR VIDEO DATA FOR EXAMPLE, THE REDUCTION IN MEMORY AND BANDWIDTH IS SIGNIFICANT.(FIGURE 3)