An analogue radio mic's companding circuit with a picture pushed through it, as an FFGL effect for Resolume and an OpenFX plugin for Resolve. Apply a compander's attack and release to video and they become a distance along the scan, so one control runs from a halo hugging every edge all the way to the whole picture pumping.
This demo runs the plugin's shaders and a port of its CPU half in your browser, so it needs JavaScript and WebGL2. The plugin itself, its source and its downloads are on its repository.