I once thought about building this, but it's much harder than you think. The data has to be processed very quickly. I believe you should think in terms of 0.3m

I once thought about building this, but it's much harder than you think. The data has to be processed very quickly. I believe you should think in terms of 0.3m groove per second. If you put a camera above the groove you also need something like a stepper motor to control the arm. But I believe the biggest problem is dust. A needle will move small particles out of the way, but a camera does not. This is also why laser turntables need 'clipping' filters. Dust will create all kinds of noise you don't want to hear.