I'm looking for a way to read the whole video memory that a video card outputs to a display. That includes also hardware accelerated output, video playback and output in fullscreen mode (that somehow I feel could be different from windowed mode).
In short: I want to be able to capture everything that is going to be represented on a display.
I suppose that IF that's possible it would be os-dependant. The targets I'm interested in are Windows OSX and Linux.
Do you have any hint?