Turning a colour mpeg2 file into black and white

[netmask]

I'm making a sort of visual catalogue of my DVD collection and making a 20 second montage from each disc. For consistency of look I would like to remove the colour and end up with a black and white rendition. What is the easiest way to do this starting with VOB's, region 4 PAL ? ie remove colour from a mpeg 2 file is the basic question I guess..

[manono]

Greyscale()

http://avisynth.org/mediawiki/GreyScale

I don't think you can greyscale a video without reencoding it.

[netmask]

Many thanks - I thought that may be the answer...... I don't know enough about the structure of MPEG files and I was hoping colour could simply be turned off with a switch without re-encoding, always the optimist!

As the segments are only around 10 to 20 seconds I can load them sequentially into Vegas and re-encode the lot overnight and then chop them up into individual segments again - :) ah well...