arXiv:2411.00547eess.IVcs.ET2024-11被引 1

测试压缩技术对虚拟制作画质影响,发现低码率下仍可保持高质量。

Demystifying the use of Compression in Virtual Production

  • 对比无损与有损压缩在虚拟屏上显示并拍摄的画质差异
  • 2 Mbps 至 2000 Mbps 码率下,AV1/H.265 可实现与无损相当的画质
  • 适合影视制作、虚拟拍摄团队优化存储与传输资源

虚拟制作(VP)依赖高分辨率、高亮度LED屏幕实时渲染视频内容,但存在画面分块同步、跨屏色温校准及视角变化导致的色彩波动等挑战。行业通常采用无损压缩素材以保障质量,但需大量存储与带宽。现代有损压缩标准如AV1、H.265可在更低码率下维持相近画质。本文提出评估方法,通过比较无损与有损压缩视频在VP屏幕上播放并摄像记录后的画质差异,测试了从2 Mb/s到2000 Mb/s的多种码率及不同GOP大小下的HAP/NotchLC/Daniel2和AV1/HEVC/H.264编码方案。利用多组感知质量指标自动评估摄像画质,并以原始未压缩源作为参考。结果表明,使用混合编解码器可在数个数量级更低的码率和存储需求下达到与中间编码器相当的画质。

原文摘要 · Abstract (English)

Virtual Production (VP) technologies have continued to improve the flexibility of on-set filming and enhance the live concert experience. The core technology of VP relies on high-resolution, high-brightness LED panels to playback/render video content. There are a number of technical challenges to effective deployment e.g. image tile synchronisation across the panels, cross panel colour balancing and compensating for colour fluctuations due to changes in camera angles. Given the complexity and potential quality degradation, the industry prefers "pristine" or lossless compressed source material for displays, which requires significant storage and bandwidth. Modern lossy compression standards like AV1 or H.265 could maintain the same quality at significantly lower bitrates and resource demands. There is yet no agreed methodology for assessing the impact of these standards on quality when the VP scene is recorded in-camera. We present a methodology to assess this impact by comparing lossless and lossy compressed footage displayed through VP screens and recorded in-camera. We assess the quality impact of HAP/NotchLC/Daniel2 and AV1/HEVC/H.264 compression bitrates from 2 Mb/s to 2000 Mb/s with various GOP sizes. Several perceptual quality metrics are then used to automatically evaluate in-camera picture quality, referencing the original uncompressed source content through the LED wall. Our results show that we can achieve the same quality with hybrid codecs as with intermediate encoders at orders of magnitude less bitrate and storage requirements.

虚拟制作视频压缩画质评估AV1

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