HLC: A High-Quality Lightweight Mezzanine Codec Featuring High-Throughput Palette
This is an incremental improvement for mezzanine coding in video production and broadcasting, addressing specific bottlenecks in screen content compression.
The paper tackles the problem of mezzanine image codecs struggling with high-quality compression under bandwidth constraints, especially for screen content like text, by introducing HLC, a high-quality lightweight codec featuring a high-throughput palette. The result shows that HLC achieves the same throughput as a 4K@120fps JPEG-XS encoder while using only half the LUT resources and delivers BD-PSNR improvements of 3.461dB, 3.299dB, and 5.312dB on gaming, natural, and text content datasets.
Existing mezzanine image codecs lack specialized screen content coding tools and therefore struggle to maintain high image quality under bandwidth constraints, especially in areas with dense text. Although distribution codecs offer advanced screen content compression techniques, their high computational complexity makes them impractical for mezzanine coding. To address this shortfall, we introduce the High-quality Lightweight Codec (HLC), a solution centered on enabling practical, high-throughput palette for mezzanine coding. The core innovation is a novel data-dependency-free palette that eliminates the throughput bottlenecks. To ensure its effectiveness across all content, a co-designed rate-distortion optimization module arbitrates between the palette and traditional prediction modes, while a data reuse strategy between rate estimation and entropy coding minimizes the overall hardware resources required for the system. Experimental results show that, compared with a 4K@120fps JPEG-XS encoder, HLC achieves the same throughput while using only half the LUT resources and delivers BD-PSNR improvements of 3.461dB, 3.299dB, and 5.312dB on gaming, natural, and text content datasets, respectively.