Compositing on low quality footage

Hi everyone,
Apologies if this has been dealt with here before.
I have some camera tracked footage on which I want to add 3D objects. The problem is that the footage was shot on a 6 megapixel camera and so of a low quality, while the 3D objects are rendered crisp and clean, and look obviously fake. What node settings should I use (in blender internal) to make the 3d render match the quality of footage? It is not exactly grain that I want, but the noisy, pixellated effect that you get on cheap digital cameras. To repeat, I don’t want to improve the quality of footage, but rather make the 3D render layer of the same low quality. For what it’s worth, the tracking has been fairly successful and I don’t have any problems with placement of the objects.
Thanks in advance!

Try rendering your crisp 3D objects out to a JPG sequence with a low compression, like 10% or 15%. Then bring that back in for compositing. You also might want to desaturate the 3D a bit to color match to the 6 megapixel footage. Render your Alpha out in a PNG format to drive the Alpha Over node for JPG the sequence when recombining.

Thanks, I should try that out!

add a bit a blur too.