trim and VFR avs file

LoadPlugin("Z:\AviSynthPlugins\DGDecode.dll")
LoadPlugin("Z:\AviSynthPlugins\TIVTC\TIVTC.dll")
LoadPlugin("Z:\AviSynthPlugins\vinverse\Release\vinverse.dll")
LoadPlugin("Z:\AviSynthPlugins\TDeint\TDeint.dll")

MPEG2Source("Z:\Nothing But a Man (Michael Roemer, 1964)\Forty Years Later.d2v", cpu=0)

a=trim(0, 108)
b=trim(109, 480).greyscale()
c=trim(481, 8820)
d=trim(8821, 9147).greyscale()
e=trim(9148, 19369)
f=trim(19370, 19635).greyscale()
g=trim(19636, 0)
a+b+c+d+e+f+g

#A: analysis------------------------------------
#tfm(output="matches.txt")
#tdecimate(mode=4,output="metrics.txt")

#B: encoding------------------------------------
#tfm(input="matches.txt")
#tdecimate(mode=5,hybrid=2,vfrDec=0,input="metrics.txt",tfmIn="matches.txt",mkvOut="mkv-timecodesfile.txt")
#TDeint(full=false)
#vinverse()

Crop(2, 0, -4, -2)

#: Discussion: The info I found suggested running "A" as a first pass then "B" as a second pass.
# I ended up running A as an analysis pass in meGui then B as a regular automated 2-pass job. So I
# probably could have commented out the trim and crop statements for that analysis pass for a slight
# speed increase. The source was hybrid, mostly videotape but with 3 short black and white film
# sections that needed to be greyscaled to remove rainbowing and of course needed an IVTC.