Metrics

If you’re comparing codecs with video quality metrics, you should consider tuning for that metric. However, x264 and x265 don’t have a VMAF tuning option. According to my analysis, it appears that tuning for PSNR is the best option and one you should strongly consider. When working with VP9, there’s an additional complication; tuning for PSNR doesn’t appear to work.  …

Producing the chart above involved encoding 35 files using 5 different presets and then recording start and stop times. Since the files were about 20-seconds long, seconds were important. I’m sure a smarter compressionist than I could write a Python script to harvest the start and stop times but I do it by hand, which is complicated because Windows Explorer …

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 VMAF it was quickly added …

This lesson teaches you how to compute VMAF with FFmpeg. It includes a download link to a specially compiled version of FFmpeg that can compute VMAF and to a zipped file that contains the batch files and input/output files shown in the lesson. I’m adding it as a lesson to my course Computing and Using Video Quality Metrics. If you’re …

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 this to “everyone agrees that …

My Streaming Media session on using video quality metrics is now available for replay immediately below. You can download the handout here. Here’s the session description. T101. HOW-TO: Fine-Tuning Your Encoding With Objective Quality Metrics Tuesday, November 19: 10:30 a.m. – 11:15 a.m. Choosing the number of streams in an adaptive group and configuring them is usually a subjective, touchy-feely …

The Moscow State University Video Quality Measurement Tool has long been my go-to desktop tool for computing video quality metric scores. When I created my course on Video Quality Metrics, I included six lessons on using the tool. Here’s a brief video that shows operation and the new features in Version 12.  Lessons in the tutorial cover operations like …

Moscow State University’s Video Quality Measurement Tool (VQMT, $999 with volume discounts available) is my go-to desktop tool for computing metrics like VMAF, PSNR, and SSIM. The program is easy to use, has great visualization tools, and lets me inspect videos on a frame-by-frame basis. MSU recently released version 12 which has three great enhancements.This article covers these plus this …

I had a 45-minute session at Streaming Media West 2019 entitled HOW-TO: Fine-Tuning Your Encoding With Objective Quality Metrics You can download the handout here. This version is about 200 MB because it contains three video demonstrations of the SSIMPLUS VOD Monitor and several other videos, but you’ll need Flash installed to run them (it’s PowerPoint, not me). You can …

A colleague asked for some resources relating to VMAF. Rather than answer in an email I thought I would create a post around it. Some of these are from Netflix, most from me (Jan Ozer). I’ve broken the items into three groups; Computing VMAF, Using VMAF, and About VMAF. I hope you find this collection useful. Computing VMAF My default way …