This is very stupid. Like, really, really stupid.
You know how composite video uses those simple red and white “RCA” cables for left and right sound, and yellow for the picture? The only thing special about component or composite cables is the colour on the ends of them, so if you run an audio channel down a yellow “video” cable it will still work, and vice versa. I know it’s possible bc of those cheap cables that have a headphone jack on one end, leading to composite video and mono sound on the other (because you have to sacrifice one audio channel for the video if you’re doing it that way).

I want to send a shitty composite video signal out of my shitty laptop’s headphone jack to plug into a shitty old CRT so I can use it as a secondary monitor without buying a video converter that would likely do a worse job then my laptop anyway. Also, since I have a spare audio interface, I can shoot the video signal out of a different hole so I don’t even have to sacrifice a sound channel.
I wonder, has anyone tried to write a program like this before? If it exists, I have no clue what to search for to find it, and it’s such an absurd thing to spend your time doing, but I want to try this idea so bad.