Algorithmic and architectural enhancements for real-time MPEG-1 decoding on a general purpose RISC workstation

Abstract

Traditional video decoders require use of specially designed video decompression processors. We present novel algorithmic and architectural enhancements that allowed for the first time the real-time decompression of MPEG-1 video and audio streams on a low-end, general purpose RISC processor. For video decompression, efficient algorithmic implementations were derived by examining the Huffman decoder, the inverse quantizer and the inverse DCT as a single system. For audio decompression, a new DCT based implementation of the subband filtering operation yields 30% speed improvement in the audio decoding process and 17% speed improvement in overall audio and video decoding. Besides algorithmic enhancements, a new set of multimedia instructions and minor changes in the design of a traditional RISC ALU allowed increased parallelism of pixel-based operations with minimal design and control overhead. Experimental results show that with the synergistic combination of algorithmic and architectural enhancements a multimedia-enhanced RISC processor can achieve higher decoding rates than generic RISC and CISC processors, even when these processors operate at higher clock rates and have larger instruction and data caches. >