I was looking for validation for my startup idea. Please flag if this is off-topic.

Idea: CRF's as a service - When encoding h.264 and libvpx videos, I tend to guess good Constant Rate Factors(CRF's) to make my videos smaller. I bet you guys experience the same. Instead of guessing, why not send the video to a dedicated 'crf-finder' then encode it later? The "crf-finder" would take a single video frame and find the best crf value.


  1. Do you think this is dumb?
  2. How much would you pay for this? This is my landing page. Perhaps you could look at it, subscribe to my mailing list or even try it out. I'm not charging - only trying to figure out if this is useful.

This is what crf-finding looks like phoneworker finding a crf

1 Answer 1


I assume you want to identify the CRF value that will either achieve a target file size or a target score on a quality metric like PSNR or VMAF. However, a single frame is not enough to assess that.

The obtained average bit rate for a CRF encode of a file depends on the visual texture complexity and motion within each scene. So, you would need to process a set of representative range of frames from each scene. That doesn't fit with your proposal which appears to be a rapid assessment tool that looks at one frame (on a mobile device?).

There is an appreciable need for such a service, but it would run on the final encoding machine and examine the whole file, so probably a piece of software or script.

  • Thank you! I appreciate this. Apr 17, 2022 at 9:00
  • Yes, it's rapid assessment on a mobile device. My target video consumer would be anyone watching a video on a mobile phone. Apr 17, 2022 at 9:47

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