July, 2020

June, 2020

April, 2020

  • 29 April

    Lesson of the Week: More Efficient Chart Title Creation in Excel

    I just finished one consulting project that involved testing 22 clips with three codecs to produce nine rate-distortion charts per clip (1080p, 720p, 480p for VMAF, SSIM, and PSNR) and am working another with 35 clips with 4 RD charts each with two encoding modes. So efficient chart creation in …

  • 17 April

    Tuning for Metrics: What About VMAF and VP9?

    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 …

  • 9 April

    Lesson of the Week: Accessing hr:min:sec Info in Chrome to Speed Data Entry

    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 …

  • 3 April

    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 …

March, 2020

  • 9 March

    Lesson of the Week: Computing VMAF with FFmpeg

    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 …

December, 2019

  • 18 December

    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 …

  • 11 December

    Fine-Tune Your Encoding With Objective Quality Metrics – Video and Handout

    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 …