Quantized color instruction set for media-on-demand applications

This paper presents Quantized Color Pack eXtension (QCPX) ISA to accelerate performance of pixel-oriented media processing applications. The QCPX ISA (with a 32 bit word size) supports two packed, quantized (reduced) 16-bit color pixels represented in a YCbCr (Y: luminance, Cr and Cb: chrominance) color format. Unlike typical multimedia instruction set extensions (e.g., MDMX, MMX, ALTIVEC), QCPX obtains substantial performance and code density improvements through implicit support for color pixel processing rather than depending solely on generic subword parallelism. To fully measure its impact, QCPX is evaluated in the context of a massively data-parallel SIMD execution platform where data parallelism is harnessed by an orthogonal mechanism. Simulation results indicate that the 32-bit QCPX ISA achieves an overall average speedup of 584% over the non-QCPX and 88% over the 32-bit MDMX-like ISA with four media applications in a same machine platform. In addition, QCPX results in a higher system utilization in excess of 95% due to a significant reduction of conditional instructions.