Evaluation of NVENC Split-Frame Encoding (SFE) for UHD Video Transcoding

TL;DR

This paper evaluates NVIDIA's Split-Frame Encoding (SFE) technique for UHD video transcoding, demonstrating it nearly doubles throughput with minimal RD penalty, enabling real-time 4K and 8K encoding.

Contribution

It provides a comprehensive analysis of SFE's impact on RD performance, throughput, power, and latency, highlighting its advantages for real-time UHD transcoding.

Findings

SFE nearly doubles encoding throughput for UHD videos.

SFE incurs negligible or reduced latency at 4K and 8K.

SFE enables higher quality presets for 4K and real-time 8K encoding.

Abstract

NVIDIA Encoder (NVENC) features in modern NVIDIA GPUs, offer significant advantages over software encoders by providing comparable Rate-Distortion (RD) performance while consuming considerably less power. The increasing capability of consumer devices to capture footage in Ultra High-Definition (UHD) at 4K and 8K resolutions necessitates high-performance video transcoders for internet-based delivery. To address this demand, NVIDIA introduced Split-Frame Encoding (SFE), a technique that leverages multiple on-die NVENC chips available in high-end GPUs. SFE splits a single UHD frame for parallel encoding across these physical encoders and subsequently stitches the results, which significantly improves encoding throughput. However, this approach is known to incur an RD performance penalty. The widespread adoption of NVIDIA GPUs in data centers, driven by the rise of Generative AI, means NVENC is poised to play a critical role in transcoding UHD video. To better understand the performance-efficiency tradeoff of SFE, this paper evaluates SFE's impact on RD performance, encoding throughput, power consumption, and end-to-end latency using standardized test sequences. The results show that for real-time applications, SFE nearly doubles encoding throughput with a negligible RD performance penalty, which enables the use of higher-quality presets for 4K and makes real-time 8K encoding feasible, effectively offsetting the minor RD penalty. Moreover, SFE adds no latency at 4K and can reduce it at 8K, positioning it as a key enabler for high-throughput, real-time UHD transcoding.