Best way to chart rhythm game songs?

I am starting to make a rhythm game based on pressing random keys to the beat of a song, and have run into an issue with making charts.

I currently have a system where I contain a bunch of numbers in a table (these numbers being the frame delay between each press, using delta time), but to feel out and set these numbers is such a pain. Does anyone know a good method to accurately record the beats of a song?

You could use the audio analyzers and try analyze the volume / frequencies then create the spaces based on that