Quote:
Originally Posted by TEB
I did some tests the other day with a Prores source, comparing 2pass VBR, constrained CRF and CRF "free". CRF Free won the SSIM tests overall and had the smallest filesize as a end result of the 10000 frames in my testcase. 2pass VBR actually came up ontop of CRF constrained within the same bitrate limits.
So to conclude from my perspektive.. CRF "free" gives the encoder the ability to maximize its ratecontrol to the fullest and best way, whilst constraining it (restricting it) gives a worse result than 2pass VBR
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I think this makes sense because only 2-pass has the global view for bitrate distribution and optimum placement of I,B and P frames, which may pay off in bitrate constrained scenarios.