There is a lot going on in the composite signal that’s way above the nyquist frequency, the audible part of it is jsut a tiny bit of the bandwidth.
You don’t need an expensive analog system to do really interesting stuff, though. Grab an old switcher or two of eBay cheap (if you wait for a good deal you can get a lower end late 90s switcherfor like $40 or less), an old camcorder (the tape transport doesn’t have to even work as long as you can get live video out of it) and any kind of TV set or monitor that has a composite or S-video input and start doing some video feedback loops. That’s how most of the experimental video stuff was done for decades anyway, because until the last few years there were maybe a dozen analog video synths in the world, they were the size of an entire room, and they cost millions of dollars.
If you need to trigger video clips or something you can always get an older Windows laptop with a VGA output, a chepa VGA to composite converte, and install VisualJockey on it. You won’t be able to life-sample the video but you can use it to trigger clips live and do all sorts of dated early 12000s video effects with a pretty modest machine . Combine that with some hardware and you have a killer old-school experimental video rig for maybe $150 total if you take your time and wait for good deals. The only real problem is the space it can take up, some of the older switchers are pretty big.
EDIT: jsut to be clear about the Audacity stuff, databending is great but it’s not auio. You’re using Audacity to manipulate the binary data of a digital video file, you could do the same thing with a hex editortechnichally but you wouldn’t have any interesting tools to mess with. Don’t want peple to think that you could patch the composite output of a VCR into your audio interface, record it in your DAW, and then play it back to a TV set and get anything even vaguely like the original video. You’d get SOMETHING for sure but it would be more like a bunch of white bars across the screens or maybe some semi-random noise. It’s the sync signals that get you, even if you separate the individual channels of an RGB signal so you can run the color channels through analog audio gear and leave the sync channels untouched, it’s still hard to make it do anything very interesting. Misusing old video equpment is the way to go.
Again, a component video signal’s subcarrier frequency is up near 5mHz, you can sample it but you’re not sampling video. It’ll do SOMETHING if you play it back into the composite input of an analog TV (and get the gain set right) but it’s not going to be playing back composite video. Believe my I tried when I got my first sampler.
You might get more interesting results if you had a VCR with a component input and drove the individual chroma channels with oscillators or audio signals or something, but you’d still need a blackburst source if you wanted any kind of frame sync (a more high end VTR with built in genock or a standalone timebase corrector would probably manage to do something without blackburst) You can get simple patterns of horizontal lines by sending an audio signal into a CRT TV set’s composite input, but you’d absolutely need a timebase corrector if you wanted to capture that kind of stuff digitally.
On the up side, all of this stuff is still prety affordable on eBay for now, since every local TV station and video production house had a bunch of them and there’s literally no professional use for equipment that works with standard definition analog video anymore. The only thing anyone uses that stuff for now is experimental video and archival preservation, and that’s not goign to make a dent in the amount of stuff out there, so until it all gets dumped in landfills it’s dirt cheap. M setup for doing analog video stuff is one broadcast S-VHS deck, two timebase correctors, three switchers, two 14" CRTs and three analog video cameras of different kinds (usually I only use a few of those things at any one time though). Total cost for all of that was around $230 between 2015 and 2018 - most of it was free (I paid $45 for the pro VCR, $40 for the high end TBC, $80 for one switcher, $30 for the other, and about $35 total for the second TBC and third switcher combined; everything else was either in the trash or given to me by friends). So yeah, old broadcast equipment is a pretty unbeatable value for money these days, even though CRTs aren’t so easy to find anymore.
