I've found it quite helpful to compare two clips with this "Show" function:
Language: avisynth
function Show(clip a, clip b, string "text_a", string "text_b") {
text_a = default(text_a, "clip a")
text_b = default(text_b, "clip b")
a = a.ConvertToRGB32
b = b.ConvertToRGB32
c = Subtract(a, b)
y = a.Height / 2
StackVertical(
\ StackHorizontal(
\ StackVertical(a.Crop(0, 0, 0, -y).Outline($FF0000).Subtitle(text_a, text_color=$FFFFFF), a.Crop(0, y, 0, 0).Outline($0000FF)),
\ StackVertical(b.Crop(0, 0, 0, -y).Outline($FF0000).Subtitle(text_b, text_color=$FFFFFF), b.Crop(0, y, 0, 0).Outline($0000FF))
\ ),
\ StackHorizontal(
\ c.Crop(0, 0, 0, -y).Outline($FF0000).Subtitle("top" , text_color=$FFFFFF, halo_color=$FF0000),
\ c.Crop(0, y, 0, 0).Outline($0000FF).Subtitle("bottom", text_color=$FFFFFF, halo_color=$0000FF)
\ )
\)
}
function Outline(clip c, int color) {
c
ConvertToRGB32
Crop (1, 1, -1, -1)
AddBorders(1, 1, 1, 1, color)
}