before i forget, my last question is - is the audio watermarking / digital copyright / whatever its called encoded into an audio track at the mastering stage? or is this done before or after mastering??
it's a (fast) fourier transform. i actually enjoyed slaving over this subject in 2nd / 3rd year calc/math and signals/systems
you don't need to understand the math to do watermarking, i'm sure there's a tool somewhere. just read some overview (like this one maybe) if you want to know a bit more about the math/physics behind audio signal sampling and frequency analysis.