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.

翻译：现代NVIDIA GPU中的NVIDIA编码器（NVENC）相较于软件编码器具有显著优势，在提供可比的率失真（RD）性能的同时，功耗显著降低。消费级设备拍摄4K和8K超高清（UHD）视频的能力日益增强，这对基于互联网分发的视频转码器提出了高性能要求。为满足这一需求，NVIDIA推出了分帧编码（SFE）技术，该技术利用高端GPU中集成的多个NVENC芯片。SFE将单个UHD帧分割后分配给这些物理编码器进行并行编码，随后拼接编码结果，从而显著提升编码吞吐量。然而，已知该方法会导致RD性能损失。随着生成式人工智能的兴起，NVIDIA GPU在数据中心广泛部署，这意味着NVENC将在超高清视频转码中发挥关键作用。为深入理解SFE在性能与效率间的权衡，本文使用标准化测试序列评估了SFE对RD性能、编码吞吐量、功耗及端到端延迟的影响。结果表明，在实时应用中，SFE能以可忽略的RD性能损失为代价，将编码吞吐量提升近一倍，这使得在4K编码中可采用更高质量的预设参数，并使得实时8K编码成为可能，从而有效抵消了轻微的RD损失。此外，SFE在4K编码中未引入额外延迟，在8K编码中甚至能降低延迟，这使其成为实现高吞吐量、实时超高清转码的关键技术。