UHD video encoding on a server CPU with an integrated media transcode accelerator: A measurement-based rate-distortion and throughput study

Integrated media transcode accelerators have recently moved onto server-class CPUs such as Intel’s Xeon 6 system-on-chip (SoC), which integrates a dedicated media transcode engine on die for data-center video workloads; earlier server deployments relied on software-only FFmpeg encoding on CPU cores or on discrete GPU/VPU devices. We characterize 4K ultra-high-definition (3840×2160) video encoding on this CPU-integrated media engine using Xeon 6 as a case study. A unified FFmpeg workflow compares software encoders (libx264, libx265, libaom-av1) on CPU cores with Video Acceleration API (VAAPI) offload to the on-die accelerator for H.264/AVC, H.265/HEVC, and AV1. Using the UVG 4K dataset and a shared bitrate ladder, we derive rate-distortion curves and compute Bjøntegaard-Delta rate (BD-Rate) from peak signal-to-noise ratio (PSNR), multi-scale structural similarity (MS-SSIM), and Video Multi-Method Assessment Fusion (VMAF). We also measure per-stream latency, multi-stream throughput under high concurrency, and, in multi-stream experiments, package-level power via Intel’s Running Average Power Limit (RAPL) interface to obtain energy per frame and throughput per Watt. The results show a consistent trade-off: the integrated accelerator substantially reduces latency and increases throughput compared with CPU-only encoding, at the cost of a moderate bitrate increase and moderate PSNR/MS-SSIM/VMAF loss. For AVC, it achieves nearly the same per-stream latency as the software encoder with a small bitrate increase, whereas for HEVC and AV1 it shortens encoding time by several-fold and by more than an order of magnitude, respectively, significantly increasing the number of 4K channels that can be supported per socket for throughput- and energy-oriented UHD services.