The Bj{\o}ntegaard Delta (BD) measure is widely employed to evaluate and quantify the variations in the rate-distortion(RD) performance across different codecs. Many researchers report the average BD value over multiple videos within a dataset for different codecs. We claim that the current practice in the learned video compression community of computing the average BD value over a dataset based on the average RD curve of multiple videos can lead to misleading conclusions. We show both by analysis of a simplistic case of linear RD curves and experimental results with two recent learned video codecs that averaging RD curves can lead to a single video to disproportionately influence the average BD value especially when the operating bitrate range of different codecs do not exactly match. Instead, we advocate for calculating the BD measure per-video basis, as commonly done by the traditional video compression community, followed by averaging the individual BD values over videos, to provide a fair comparison of learned video codecs. Our experimental results demonstrate that the comparison of two recent learned video codecs is affected by how we evaluate the average BD measure.

本研究针对当前视频压缩领域中，平均BD值计算方法可能导致的误导性结论进行分析，尤其是在不同编码器操作比特率范围不匹配的情况下。提出以单视频为单位计算BD值并对其进行平均的新方法，从而实现对学习视频编码器的更公平评估。实验结果显示，BD值的计算方式显著影响编码器间的比较结果。

视频编码性能公平评估中BD率计算的研究