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Framebuffer Loopback Source

The Framebuffer Loopback source plugin

The Framebuffer Loopback Source reads video data from the current framebuffer and treats it as a data source for an effect. Using this plugin allows you to display something like a file or captured video, then read the display back and put it through another effect. By layering a number of different effect plugins very complicated visuals can be achieved.

You can also use this to do "grab & hold" style effects, where you feed the framebuffer through an effect repeatedly, compounding the effect until the image decays or distorts beyond recognition.

Creating video feedback

The Framebuffer Loopback source was initially designed for doing one thing: Video feedback. If you've ever pointed a video camera at a TV displaying the output from that same camera, you've seen video feedback. Take a picture, apply a small change to it (zoom, rotate, shrink, bend, tint) and then paint it back out again over top of itself, usually with alpha blending so you don't completely replace the previous image. Repeat the process really fast and things get really interesting. Pretty much any MidiVid plugin that distorts an image can be used to create cool feedback effects. Experiementing is encouraged.

For starters, try this:

Assign a "Display Source" plugin with your favourite clip, or better still, a live camera feed.
Set the alpha knob to 20.
Assign a "Warp Source" plugin using the "Framebuffer Loopback" source.
Set it to pulse, then check velocity active, and subtle
Play the first note, and while holding it, play the 2nd note with various velocities