Algorithm and VLSI Architecture Designs of a Lossless Embedded Compression Encoder for HD Video Coding Systems

The demand for visual quality has been advanced by high display resolutions and frame rates. Nevertheless, these two issues have caused tremendous memory bandwidth in a video coding system. In this study, an efficient lossless embedded compression (EC) algorithm is proposed to save memory bandwidth, while keeping visual quality. The proposed lossless EC algorithm incorporates three core techniques: tree partition, half-pixel prediction and group-based binary coding. Tree partition classifies a [Formula: see text] block into Trunk, Branch and Leaf. With tree partition, half-pixel prediction produces individual residues for Trunk, Branch and Leaf. Group-based binary coding converts theses residues to efficient codewords. The lossless compression ratio (CR) of the proposed EC is as high as 2.24 on average, saving memory bandwidth by 55.4%. This EC algorithm is implemented using CMOS 0.18[Formula: see text][Formula: see text]m technology. The maximum throughput can reach 6.4[Formula: see text]Gpixels/s, which can accommodate [Formula: see text]@60fps. The experiment results demonstrate that this study presents better hardware efficiency of 337[Formula: see text]Gpixels/J and 83.5[Formula: see text]Kpixels/s/gate.

Optimized Lossless Embedded Compression for Mobile Multimedia Applications

Power consumption is a critical design factor in modern mobile chip design, in which the memory system with dynamic random-access memory (DRAM) consumes more than half of the entire system’s power. Without DRAM bandwidth compression, extreme multimedia operations such as 8K high dynamic range (HDR) recording and 8K video conference calling are not possible without sacrificing image quality or trimming because of thermal limitations or battery time sustainability constraints. Since heterogeneous processors are substantially involved in managing various types of fallbacks or software solutions, complicated compression algorithms for high-compression ratios are not actually adaptable owing to timing closure problems or high throughput requirements. In this paper, we propose evaluation metrics to assess lossless embedded compression (LEC) algorithms to reflect realistic design considerations for mobile multimedia scenarios. Furthermore, we introduce an optimized LEC implementation for contemporary multimedia applications in mobile devices based on the proposed metrics. The proposed LEC implementation enhances the compression ratio of LEC algorithms in other commercial application processors for contemporary premium smartphones by up to 9.2% on average, while maintaining the same timing closure condition.