Hi, I'm getting a lot of jagged edges on my video I that did in after effects. It's 29.97 fps, and Ive been making it consistent (unless I missed something). It looks great in after effects but then I export it as a FLV and get it in Flash, it looks like crap. When I play it with a white background After Effects it looks fine too.
The video is suppose to have a transparent background, where a person walks onto the site.
In addition to the fact that FLV (like any other web format) is highly compressed and can't retain much of the original resolution, which I'm sure you already know, it looks like you may have one of the two following issues or some combination thereof ...
1] jaggies from interlaced footage -
Are you sure that you interpreted the footage correctly when you brought it into AE? That you rendered it out of AE with the proper field order? Did you deinterlace when you converted the AE render to FLV using separate compression/conversion software? Although AE can render web formats like FLV, it generally doesn't do it as well as compression/conversion software like Adobe Video Encoder, Compressor, Cleaner, Squeeze, etc.
2] edge issues from how the footage was keyed -
Artifacts around the edges of a key that were barely if at all noticeable inside of AE or an ucompressed AE render can be amplified by web compression. I sometimes use the Sapphire Edge Flash compositing plugin for smoothing edges of composites, but its part of an expensive set and there are plenty of other ways to accomplish the same ... chances are at least one of whatever plugins you used to do the key has some adjustable edge smoothing settings.
By the way, this may just be a wording difference, but it's best to always "render" from AE, not "export" ... I'm not in AE right now so I can't confirm, but if I recall correctly, you don't get access to all the available options for FLVs when you export. Again, I'd suggest using separate compression/conversion software anyway, but I mention that just in case you don't have any or don't want to use it.