advice converting to XviD + removing commercials

[Colbey]

Hi, all. Thanks in advance for any help you can give.

I have some files that I exported from my ReplayTV (standard-def set-top DVR). They're MPEGs in some weird format that normal software (like VirtualDub) can handle fine, but they're very space-inefficient, on the order of 800MB-1600MB per hour for standard def. (I can do more research on the file format if that's necessary for my question; just ask.) I'd like to future-proof the files in a better format, save some space without sacrificing quality, and ideally remove the commercials.

So my thought was to remove the commercials with VirtualDub, and then use AutoGK to get it down to a good size in the form of an XviD AVI. My questions are, first, is this a good plan? Second, in what format should I save the files after VirtualDub but before AutoGK? I don't want to lose quality twice, so I'm happy to have the intermediate file be very large, but I'm just not sure what a good lossless or nearly-lossless way to remove the commercials is. Or does VirtualDub just save it in the same format without transcoding, just removing the commercials losslessly? Is that even possible with MPEGs?

I'm pretty good at computers in general, but I'm very new to video stuff, so go easy on me! Thanks again.

[jagabo]

If you're going to remove commercials with VirtualDub why don't you compress it to Xvid AVI right there?

[Colbey]

Mainly because I like how AutoGK is basically one-click. I tell it that I want my 30-minute file to take up 233 MB (or whatever), and it just does it, with multiple passes to tweak bitrates if necessary. I'm a bit intimidated by VirtualDub. I'd happily use it if someone could walk me through the equivalent settings to do what I want, but that seems a bit much to ask of this forum. Though do you have any really basic VirtualDub advice for this n00b? If so, much appreciated.