saving bitrate by adding black bars in after the fact... how

[graysky]

I have a 480x480 mpeg-2 file that has 'letterbox' black bars such that the actual video only takes up 480x352 of the entire 480x480 (so 64 lines above and 64 lines below are wasted with black). I always encode to XviD 480x480 using virtual dub mod. I'd like to know if there's a way I can encode the video to 480x352, and then insert 64 lines above and 64 lines below of pure black so the total res will be 480x480. I think if I do it this way, I would be saving bits for the actual video instead of wasting them on the black in the original file. So... how do i do it

[johns0]

Just encode to 480x352 without adding any black bars,any reason you want to add them to xvid which doesnt need black borders?

[graysky]

I want the letterbox feel to the picture; it will be watched on a TV.

[graysky]

Nevermind, I figured it out:

1. resize filter to 480x352
2. crop with Y1 offset = 64 and a Y2 offset = 64
3. expand frame and letterbox image back to 480x480 using pure black as color

Doing it this way:

-saves valuable bitrate by not encoding the black lines making up the letterbox of the original source (XviD and DivX are notorious for not getting black right; often introduces visual artifacts to the black which looks like crap, and wastes bits that would otherwise go to your video stream)
-preserves the 480x480 resolution
-gives a nice sharp letterbox