x264 lookahead-threads vs quality and

[kotuwa]

What are the impacts of x264 lookahead-threads value regarding the quality?

Is it related to to other things such as VBV, MB-Tree, rc-lookahead.. etc?

I heard that too high number of threads like more than 16 may affect the quality a little bit. right?
Is it same with lookahead-threads?
Or different...
lookahead thread count said to be like threads/6 (or threads/4 as I observed, either it is changed now or depends on other parameters)

Among below 3 examples, which would give the better quality theoretically. Is the difference is too insignificant? or not? (Encoding time is irrelevant)

threads 16, lookahead-threads 4
threads 12, lookahead-threads 3
threads 8, lookahead-threads 2
threads 4, lookahead-threads 1
threads 2, lookahead-threads 1
threads 1, lookahead-threads 1

[jagabo]

Threads=1 will give the best result. But I doubt you'll notice any difference at normal playback speed. You might see a difference zooming in and A/B switching between still frames. And even then you might not be able to say which is better without comparing to the original.

But why bother asking when you can just test for yourself?

[kotuwa]

Thanks for the Reply