Posts about video quality metrics

Netflix Addresses VMAF Hackability with New Model

TL/DR: Netflix updates VMAF to include a new model that reverses out the effects of techniques like sharpening, contrasting, and histogram equalization.  As I reported in VMAF is Hackable: What Now?, you can increase VMAF scores via simple image enhancement techniques like sharpening, contrasting, and histogram equalization, which, when applied inappropriately, may not actually improve…

Five Star Review for Video Quality Metrics Course

Happy to report a five-star review for my course, Computing and Using Video Quality Metrics: A Course for Encoding Professionals. As far as I know, it’s the only course available that teaches how to compute and use metrics like VMAF, PSNR, SSIMPLUS, and SSIM, including how to create rate-distortion curves and BD-Rate comparisons. The review…

VMAF is Hackable: What Now?

Just a quick note to let you know about some recent findings relating to the Netflix VMAF metric. By way of background, VMAF launched in June 2016 as the metric that powered Netflix’s per-title encoding engine, replacing PSNR. The fact that Netflix created and used VMAF gave the metric tremendous credibility and because Netflix open-sourced…

When and How to Use Objective Quality Metrics

Recently, video quality metrics have gotten a lot of hate, primarily from codec vendors. For example, yesterday on LinkedIn, respected Beamr CTO Dror Gill wrote, “everyone agrees that subjective (human) testing is the only accurate way to measure true perceptual quality.” After I pointed out industry support for using video quality metrics, Gill graciously changed…