I was thinking about re-rendering a section of a composition, like the upper right corner, to fix an issue. I would just overlay the fix onto the rest (maybe with a feather applied).. The renders are 1080p which will be downscaled to 720 and are high bitrate so i figure it should be ok.
The comp is a template with a lot of layers of lighting, motion blur and 3D planes, extremely demanding... i guess AE will have to calculate the offscreen elements even with a crop. So is this realy going to make much of a difference in render time? the cropped region is 1/16th.
I don't have AE in front of me now but i assume cropping a comp is as easy as crop in Photoshop, like setting a corner to align and punching in the dimensions...is this true?..am i going about this process the wrong way?
thanks for any advice.
Cropping in AE isn't the best idea. I'd figure out the precise area to be rendered (in the proper pixels aspect ratio, if necessary) and create a like-sized comp. Then nest a duplicate of the original comp in it, position it properly and render.
Since it's a small area, you can probably delete a lot of layers; hence the duplicate comp.
The easiest thing to do would be to duplicate your comp then select the area you want to crop with the region of interest tool. Then all you have to do is right-click inside the region and select crop to region of interest. That's the way I would do it.
There is a possibility that simply nesting your composition in a smaller one would give you some strange differences in motion blur and other things. It all depends on the composition setting. By using the crop to region of interest you'll end up with exactly the same comp that rendered your original footage.
The other problem you may run into deals with compression. If you're using HDV or other video codec you will run into size problems. These bad boys only render two specific sizes. They are very testy when you try to do something outside of the norm. The best option, the only real option, is to render your project to a production codec like animation codec QuickTime's or photo JPEG at 95%.