resize lanczos to orig Testing Reveals that Scaling Algorithms Really Matter Obviously, the manual has more details should you want to adjust the other variables. In the command line, you add this switch to accomplish the same computation as shown in the Figure. The only real variable you’d want to adjust would be the algorithm, which I’ll get back to in a moment. There are multiple options for size and scale strategy, though none appear appropriate for simple metric computations.

Using the settings shown in the figure, VQMT will scale the 640×360 MP4 file back to the 1920x1080p resolution of the source file and use the Lanczos scaling method as opposed to the default Bicubic. In the GUI, you enable the feature on the left by clicking Geometry transform and choosing the size, strategy, and algorithm. MSU added auto-scaling to version 11.1 of VMQT, which shipped around the end of May 2019. If you use video quality metrics to analyze lower resolution streams in encoding ladders you’re going to want to read the rest of this article, even if you don’t use VQMT.īut first, the facts. What was surprising was that your choice of scaling technique can swing your VMAF score by as much as 6 points for a 640×360 file scaled back to 1080p resolution. First, that the feature is fast and accurate, so I’ll never pre-scale for VQMT again. In testing this new feature, I learned two things.

Yup, VQMT can now autoscale your lower-resolution video files back to source resolution in both the GUI and command line, saving time and disk space. Thankfully, for those not familiar with FFmpeg, as of VQMT version 11.1, this operation is no longer necessary. One of the first operations I learned in FFmpeg was how to scale subsampled video files back to the source resolution to compute PSNR in the Moscow State University (MSU) Video Quality Measurement Tool (VQMT).

Ffmpeg resize algorithm