What does ' wpredp' parameter do in x264 (or FFmpeg)?

Question

I don't understand what 'wpredp' do? I've tried to find the description of 'wpredp' parameter but without success. Can somebody explain what it do?

Answer 1

--weightb (x264)

-flags2 +wpred (FFmpeg)

This allows B-frames to use weighted prediction options other than the default. There is no real speed cost for this, so it should always be enabled.

Source: https://sites.google.com/site/linuxencoding/x264-ffmpeg-mapping

Following the same logic, wpredp applies to P frames.

Weighted prediction allows an encoder to specify the use of a scaling and offset, when performing motion compensation, and providing a significant benefit in performance in special case, such as fade-to-black, fade-in and cross-fade transitions. This includes implicit weighted prediction for B-frames, and explicit weighted prediction for P-frames.

Source: Marios C. Angelides, Harry Agius - The Handbook of MPEG Applications: Standards in Practice