greyscale filter while capturing?

[E-Male]

i'm gonna capture a black&white vhs tape [ntsc, using a nvidia grafics-card]

since
a)capturing to a lossless codec results in huge files
b)i'll use greyscale later in avisynth anyway
c)greyscale copresses better
d)with yuv greyscale is basicly a no cost operation
it seems logical to me to convert the video to greyscale before writing it to the lossless file

so is there a way to do it?
for example a greyscale directshow filter i can use in virtualvcr?

thx
E-Male

[olnima]

with ffdshow.ax You can do it.
But what about simply edit the saturation in the settings of your TV-card?

Olnima

[E-Male]

nice idea, didn't think of that

but would that result in perfect greyscale?