Quote:
Originally Posted by hanyi
So if given a bitrate,how to choose a proper crf? For example,give a 720p video and assign 1.4Mbps, which crf should set?
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If you want a specific bitrate, use --bitrate instead of CRF and do a 2-pass encode. Internally, x265 figures out and applies the CRF that would give you that ABR. If segments of the video are VBV constrained (and thus encoded with a higher rate factor), CRF will be lowered for the remaining part so the non-VBV constrained segments have as low a CRF as possible within the target ABR.
If you're focusing on PSNR, you don't want to use CRF anyway. CRF is essentially a psychovisual offset to QP, and optimizing PSNR means not using psychovisual optimizations.
Can you share what you're trying to do here?