Note that this string doesn’t have a -g switch to set I-frame interval, so it would use the default I-frame interval for WebM files. tile-columns 6 -frame-parallel 1 -auto-alt-ref 1 -lag-in-frames 25 \ Here are the VOD Recommended Settings from the VP9 Encoding Guide in the WebM Wiki:įfmpeg -i -c:v libvpx-vp9 -pass 1 -b:v 1000K -threads 8 -speed 4 \įfmpeg -i -c:v libvpx-vp9 -pass 2 -b:v 1000K -threads 8 -speed 1 \ I’ve bolded the three switches that impact output quality, which I’ll discuss further below.
It’s also interesting that the argument ignores recommendations from Google on the same page, which advise using a speed setting of 2 for the second pass (rather than 4 in the command string) and a tile-columns setting of 2 (rather than 3 in the second pass). This works, but is non-standard and may be confusing to some (if not most) FFmpeg users. minrate 900k -maxrate 2610k -tile-columns 3 -g 240 -threads 8 \įFmpeg newbies should note that the slash (\) is the Linux/Mac line continuation character that tells FFmpeg to ignore the carriage return and run the string as a two-line script the Windows analog is the caret (^) above the number 6 on your keyboard.Īs an initial observation, you see that this command string inserts the file name at the end of the first line instead of the much more familiar NUL command. quality good -crf 31 -c:v libvpx-vp9 -c:a libopus \ minrate 900k -maxrate 2610k -tile-columns 2 -g 240 -threads 8 \ Here’s the recommendation from the Google Core Technologies blog:įfmpeg -i tearsofsteel_4k.mov -vf scale=1920x1080 -b:v 1800k \ There are several sources for command strings. What’s in the Lessons included in Streaming Media 101.Table 2: Adding row-mt cut encoding time by ~36% and boosted VMAF quality slightly.Table 1: These results show that the CRF setting in the Google command string had little impact on output quality.I’m updating the VP9 section of my course Streaming Media 101: Onboarding for Streaming Media Professionals and wanted to share three key findings. This should allow you to drop the data rate of your videos by 30 – 40% and deliver the same quality as H.264.
One of the best options is to encode using the VP9 codec, which plays in most browsers, on Android devices, on Macs and iOS devices in Chrome, and on many OTT devices and SmartTVs. As always, if I’ve gotten anything wrong, please let me know at producers are exploring options to produce quality similar to H.264 at lower bitrates. The three key takeaways are 1) use the command script shown on the bottom of the page, 2) a speed setting of 2 offers the optimal quality/performance tradeoff, and 3) the row-mt setting improves performance significantly with zero quality loss when multiple unused cores are available. This is a long post only of interest to those attempting to optimize their VP9 encodes.
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