green red blotches when I make xvid or mkv

[spiritgumm]

getting red/green hue over a b&w video. I can usually make xvid/mkv without this problem, so I'm thinking it's the combination of filters in my script (unless ffdshow has something to do with it - I installed it recently).
Can someone let me know why it's happening, and if I should change the order? I could make 2 or 3 scripts and process the video in stages, although I'm not sure that will work if a filter needs a particular setting. Attaching a few screengrabs - hard to tell but the color is noticeable in playback.
I'm making an MKV so not resizing to 16mod, but I believe I also got the hues when I made a test at 640x480.

LoadcPlugin("C:\Program Files (x86)\AviSynth 2.5\plugins\yadif.dll")
LoadPlugin("C:\Program Files (x86)\AviSynth 2.5\plugins\RemoveGrain\Repair.dll")
import("C:\Program Files (x86)\AviSynth 2.5\plugins\Stab.avsi")
LoadPlugin("C:\Program Files (x86)\AviSynth 2.5\plugins\SmoothAdjust-v2.62\x86\SmoothAdjust.dll")
v=MPEG2Source("D:\movie\VTS_01_1.d2v", cpu=0)
a=nicac3Source("D:\movie\VTS_01_1 T80 2_0ch 384Kbps DELAY 0ms.ac3")
audiodub(a,v)
yadif(1)
SRestore(Frate=23.976)
grayscale()
crop(32,8,-20,-10)#668x462
#fixing line across screen
base=crop(0,0,0,-6)#670x456
top=crop(0,456,0,0)#670x6
Overlay(base,top,y=450)
#cropping additional borders after jump in film
x=trim(0, 41071)
y=trim(41072,0).crop(0,8,-14,0).spline36resize(668,456)
x+y
#fixing rolling horiz. and jumpy vert.
mdata = DePanEstimate(dxmax=20, dymax=50)
DePanStabilize(data=mdata,mirror=15, method=1)

[smrpix]

Move grayscale() to the end.

[jagabo]

Depan messes up the chroma channels -- lowering them by 1 unit on some frames. So, yes, move GreyScale() to the end.

[spiritgumm]

thanks! I was curious to see if this was a notorious greyscale issue, and sure enough:
https://forum.videohelp.com/threads/312518-color-blotches-in-black-and-white-encode

[jagabo]

That's a different filter causing similar problems. DePan always has this issue, though it's less noticeable with color video

[spiritgumm]

your solution was the same, but I guess you're right about the different cause.

Unless those color splotches are in your source the only filter I see that might be causing them is MSU Denoiser.

If you put Grayscale() at the end of the script you'll guaranty that the output from AviSynth will be grayscale. But you can put it anywhere after the splotches show up.