BD-rate calculator (BD-rate + BD-quality)

A dependency-free (pure standard-library) Python tool that computes BD-rate AND BD-quality from two sets of (bitrate, quality) points, the way the research recommends: SHAPE-PRESERVING monotone PCHIP interpolation (no overshoot), integration in the LOG10-bitrate domain, integration ONLY over the overlapping quality range (IoU reported, thin-overlap warning), and the recommended -10*log10(1-q/qmax) VMAF/SSIM log transform. Point it at your own CSV (bitrate_kbps,quality), or run --dataset on the b