motion trail based on frame differences

[smok3]

so i have some night footage, the exposure is about 1/3 second, what i want is fluid motion trails from this (static kamera, cars passing bye)

a. what i'am doing now is using dedup plugin to get rid of all the repeated frames
b. evil plan is to do mvtools slomo to get back to approximately same duration as original
c. but how would i keep exposed portions on previous frames? (or at least how to prolong life on those parts)

you know like motion trail effect of some sort?

tia for any clues

p.s. probably b. and c. are work for some after effects, however if there is a way with avisynth that would be better.

edit: is dedup supposed to merge frames that it thinks they look similar? or just delete dups?

[Comatose]

DeDup is meant for creating VFR video, so it drops frames. You have to change the settings though as it has a limit on how many frames to drop (as a new subtitle can't be rendered if there are no new frames, and it's mostly used on anime)

[Adub]

Dedup drops frames, dup merges similar frames to create a new one.

[smok3]

tnx for answers,


various:
dedup seems to work fine (but next time i need to use dup then), vector slomo wont work at this specific footage. After effects echo effect seems to do what i want.

i have used for the 2nd pass
DeDup(threshold=15,trigger2=16, maxcopies=20, maxdrops=20, log="log.dup.txt", times="blah.times.txt")