Adding a letterbox using VirtualDub (resize filter)

[DonKeyDoo]

I'm trying to convert an .avi movie to an SVCD, and inject permanent subtitles in the process. I'm using VirtualDub to frameserve the movie to TMPGEnc, using TextSub (VobSub) 2.23 filter for the subtitles. So far so good.

The problem is that the movie is 576x304, (DAR 36:19). TMPGEnc converts the movie to 4:3, keeping the aspect ratio, and creating two black stripes, above and below the picture.

I wanted to use the stripes for the subtitles, so that they do not "invade" the picture. I went back to VirtualDub, and added a resize filter, maintaining the samed height and width, and applying a letterbox (same width, increased frame height), using the precise bicubic (A=-0.75) filter mode. In theory, the subtitles should then be displayed below the picture, in the designated letterbox. The preview pane in VirtualDub shows exactly that: the subtitles are shown below the picture, inside the letterbox I've added - a satisfying result. Unfortunately, that only works for preview...

I frameserve the movie to TMPGEnc, which outputs a corrupt picture as shown in the screenshot below. VirtualDub's letterbox has been dyed teal (#408080) on purpose, in order to emphasize the difference between the letterbox I've added, and the black stripe which has been infused against my will, just above the picture, looking as though it was "pushing" the picture below. In essence, the lower part of the picture has simply been cut off, and I have no idea why (no cropping has been done).

Any thoughts? What am I doing wrong?

[DonKeyDoo]

Here's the screenshot:

[DonKeyDoo]

Still no luck?
Hmm. Let's try again.

[DonKeyDoo]

Lovely, I can't even post the screenshot. It's a 24KB jpg... Why doesn't it work??
Last try:

[DonKeyDoo]

Finally. Anyway, as a comparison, here's a screenshot of the same frame (taken from TMPGEnc, just like the screenshot above), only without the resize filter.

Flawless...

[Abond]

I would use FitCD to get the values for resizing and leterboxing. Then would apply the subtitle filter and frameserve to TMPG where I would select Center for arange method.

[DonKeyDoo]

I would use FitCD to get the values for resizing and leterboxing. Then would apply the subtitle filter and frameserve to TMPG where I would select Center for arange method.

Thanks for the advice. I'll try that. The arrange method, though, any arrange method for that matter (I've tried 'em all) does not retrieve the "lost" picture. It still remains cut. It's as thought to movie is frameserved that way...
Hmpf. I'll try FitCD.

[DonKeyDoo]

FitCD didn't really help. I don't want to resize the movie in VirtualDub. I want to keep it as is, adding, say, 100 pixels for letterbox, and then frameserving it to TMPGEnc and have it do it's thing.
Besides, I've already tried resizing the movie in VirtualDub first, to 448x240 + 32x240 for letterbox, just as FitCD recommended. Althought the preview pane in VirtualDub showed it right, TMPGEnc showed a corrupt stream (can screenshot it if you want).

[DonKeyDoo]

Oh my God. I ran Nandub and did exactly what I had done in VirtualDub and it works. Why??? HOW???