Cropping AVI to decrease file size?

[fLYtRap]

I have an AVI file that I was thinking about cropping it to save some space. Currently size of the file is 3.5GB. I was wondering if I can remove black bars without changing resolution and aspect ratio? I heard somwhere that a AVI file can have the black bars removed and a player (WMP) will fill empty space with its own black bars. If my theory is correct I can make the file smaller.

[redwudz]

That might make the framesize smaller, but it won't have much effect on the filesize unless you change the bitrate also. I just tried a sample clip that was 1.1MB and cropped 50 pixels from all sides. I re-encoded it with the same settings as before and it went down to 968K for a savings of 132K. The frame size went from 320 X 240 to 220 X 140 pixels, so I cut close to 1/3 of the video out. Not much gain for the amount of framesize change.

Most software video players will just fill in the edges with black.

[fLYtRap]

Most software video players will just fill in the edges with black.

This is what am talking about. Now there is some data in black bars, so by removing it a file should get smaller. Empty space will be filled while playing, only question is what software can do it.

[manono]

No. If you crop away the black bars, you have to reencode. If you reencode at the same bitrate, the size will be the same. The black part, as redwudz said, takes up only a small part of the overall bitrate. So, after cropping and reencoding for the same quality, the filesize savings will be insignificant.

...only question is what software can do it.

Any AVI encoder (VDubMod, for example) can do it. If your original is really 3.5 GB, depending on just what it is (DV? Uncompressed? XviD?) and how long it is, cropping and shrinking should be quite easy.

I was wondering if I can remove black bars without changing resolution and aspect ratio?

Not exactly. If you crop away the black above and below, the AR is the same, but the height, and thus the resolution, changes. You can resize it if you wish.