Video editor that lets me code my own effects from scratch? I'm the type of guy who likes to produce beauty from code - I mostly experiment with shaders.

Up to this day, I've only been doing so for the sake of games, but an idea popped up in my mind that I could decorate an actual film footage using handwritten postprocessing.

Is there any software that, apart from facilitating basic video editing tasks, lets me code (and later apply) my own effect completely from scratch, that is, lets me manipulate each input frame pixel by pixel? Either in some shader language or maybe CUDA or even C++?
You should check out Processing dot org.