I'm using H264 encoding to encode video capture from a webcam. How do I turn of rc lookahead? I want minimize encoding latency per frame. Right now, there is a high increase in encoding latency on the 46th frame. I think lowering the lookahead value might help with this. How do I do this? 
Capture Resolution is 1080p.
If you're using x264 directly, it's --rc-lookahead 20 for 20 frames. If it's via ffmpeg, it's -x264-params rc_lookahead=10.

Although I would suggest to use faster presets. Default is medum.