You can indeed add --psnr to the command line for quality measurement. Ignore the error warning of x264, it does NOT effect the encoding process. I always use it. Only speed is getting smaller (< -1 fps).
PSNR:
>= 45 dB = very good, your eyes don't see any difference
>= 44 dB = (very) good
>= 43 dB = satisfaying, good for grainy movies
My encoding of Big Friendly Giant:
BFG 3D (hTAB): CRF=20, PSNR=45.3 dB, 5023 kbit/s
EXCELLENT result!
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There are big issues in the german GUI of Potplayer, especially the 3d-tabs.
So I have corrected my post #1088 (
http://forum.doom9.net/showpost.php?...postcount=1088).