Identify your DVD

Before you start ripping you need to identify the format of the DVD to determine the best output settings. AoA won't tell you this. It can be PAL or NTSC, in 4:3 or 16:9, interlaced or progressive.

PAL or NTSC?

PAL is standard in Europe and most of the world, NTSC in the USA and Japan. If you're not sure look on the back of the DVD case. Don't have a case? Play the DVD (the feature you want to rip not just the menus) with VLC or similar, take a screenshot and find its dimensions with an image editor or the status bar in Explorer. PAL will be 576 pixels high, NTSC 480.

4:3 or 16:9?

Fullscreen (1.33:1 or 1.37:1) is 4:3 format, but just because it says "Widescreen" (1.66:1, 1.78:1, 1.85:1, 2.35:1 etc.) on the case doesn't mean it's actually in 16:9 format. Look for labels like "anamorphic" or "enhanced for widescreen TVs".

Interlaced or not?

Almost all film and TV DVDs are recorded in interlaced format, and this can be a problem. If you're not sure assume it is interlaced, unless it's a PAL cinema film in which case interlacing shouldn't be a problem.

Now you can choose the correct frame dimensions from the table. For best results only use these (though YouTube unfortunately prefers 640 x 360 - if you insist on using other sizes always choose multiples of 8). Normally you'll want full size, but half size saves disc space and ripping / uploading time and still looks acceptable. Thumbnail is for quick previews.

Format	Frames	Full size	Half size	Thumbnail
PAL 4:3	25	768 x 576	384 x 288	192 x 144
PAL 16:9	25	1024 x 576	512 x 288	256 x 144
NTSC 4:3	29.97	640 x 480	320 x 240	160 x 120
NTSC 16:9	29.97	856 x 480	424 x 240	216 x 120

Note that these resolutions are for square pixels. The actual resolution of the image on the disc will be 720 (or 704) x 576 (or 480) whether it's "widescreen" or not. This would be the ideal output resolution, but these pixels are not square. There is no way of setting the aspect ratio in an AVI file, so unless you configure your player correctly for each clip then the image will be distorted.