17.02.2025, 11:33
Hello,
when I set up Hybrid x264 options and disable mbtree, rc-lookahead gets greyed-out. The underlying x264 command then uses rc_lookahead=0. This is catastrophic: x264 ratecontrol code becomes unable to anticipate the complexity of the next N frames ahead of the current one. ratecontrol becomes strictly reactive to the current frame encoding complexity. The outcome is just low quality encodes or overshoot of VBV.
mbtree uses rc_lookahead value, but disabling mbtree does not mean rc_lookahead is not needed in x264. It would be nice to not default the value and let the user choose it freely (without capping at framerate/2 occasionally?)
when I set up Hybrid x264 options and disable mbtree, rc-lookahead gets greyed-out. The underlying x264 command then uses rc_lookahead=0. This is catastrophic: x264 ratecontrol code becomes unable to anticipate the complexity of the next N frames ahead of the current one. ratecontrol becomes strictly reactive to the current frame encoding complexity. The outcome is just low quality encodes or overshoot of VBV.
mbtree uses rc_lookahead value, but disabling mbtree does not mean rc_lookahead is not needed in x264. It would be nice to not default the value and let the user choose it freely (without capping at framerate/2 occasionally?)