2pass vs rc-lookahead

[aapp]

If my understanding of rc-lookahead is correct, isn't essentially trying to solve the same problem as 2pass? I.e. use knowledge of future frames to make more intelligent bitrate allocation?

Is using 2pass with rc-lookahead complete overkill?

[LoRd_MuldeR]

No it doesn't. RC-Lookahead is related to MB-Tree Ratecontrol.

So if you use MB-Tree, then RC-Lookahead will be used - no matter if you use 1-Pass mode or run the first pass of a 2-Pass encode.

During the second pass MB-Tree uses the information collected during the first pass...

[nurbs]

No. Lookahead helps with vbv, but knowing what the next 40 frames look like doesn't help with deciding what parts of the movie need what bitrate while still ensuring an optimal distribution throughout the movie.

[Dark Shikari]

Is using 2pass with rc-lookahead complete overkill?It still helps prediction on the first pass, which improves the second pass. And it's required for MB-tree.

Notably though, for CBR, 2-pass mode is generally pointless.

[aapp]

Got it now, thanks for setting be straight guys.