crf plus keyint, watching file size...

[cvk_b]

Seeking out a smoother fast forward and rewind for a certain encode I have been playing with adjusting the keyint settings whilst leaving the crf at 18 (thanks jon, for making '-q 18' a precise option). I adjusted both ways up and down, watching file size go up as more keyframes were added and down as less were added. keyint-min=1:keyint=1 @ crf18 shoots bitrate forward of 4000+ while keyint-min=48:keyint=480 can drop some shows down to 1000. Amazing how quality stays the same.

Obviously the keyint-min=1:keyint=1 ff/rew smooooth as butter both ways. Which is what I wanted, but too extreme on keyframes, not practical. I settled on keyint-min=3:keyint=120:scenecut=45 for that movie, but mostly I'll stick with the defaults.

What I wasn't expecting was how dramatic the keyint-min=48:keyint=480 setting was. I can see how in certain situations that would be useful. Definitely diminishing returns on higher than that though.

Anyway, I was wondering if anybody has also played with this, and if so their experiences. There is some developer/code related topics about this here but I thought I'd start an end user topic.

[refulgentis]

Usually with encodes I've seen (not Handbrake, but in general) keyint = framerate*10 and keyint-min=framerate, leaving you within 10 seconds for seeking. Keyint every second is insane, as you saw.

Also, if you're using SVN Handbrake, there's really no reason to go above CRF 20 at this point IMO, thats pretty commonly accepted as transparent with AQ.

EDIT: by above CRF 20, I meant below CRF 20, its hard to remember that >CRF = <quality