Building a sound visualizer, modulating video with audio?
I want to build an (analog) sound visualizer. I've already read about building a simple oscilloscope (https://www.instructables.com/id/Music-Visualizer-oscilloscope/) but I want to make something more complex, if this is possible. I want to build a sound visualizer that makes psychedelic stuff from audio. Like the sound's frequency modulates the video's frequency, and the sound's volume (amplitude) controls the video's volume (like how much light is created).
How could I build something like this? Just playing sound through a video screen won't work because there is a huge difference in wavelenght.
Do I need to build a vocoder (video=carrier, sound=modulator), like with an audio vocoder?
I know alot of stuff about audio and audio electronics, however I don't know much about video and video electronics.
All help is appreciated!