mute wrote:Well, then you just start trying different BPM values until that doesn't happen. 162.100? Better, but still off. 162.150? A little too far. 162.125? A little off, but in the other direction. 162.130? Very close, but there's a little drift by the end. 162.132? Absolutely everything in the song lines up perfectly with the measure markers in StepMania.
Trial and error seems too haphazard and time consuming to me, at least if it's all you use. What I do is I note the millisecond of say, the first 20-30 beats. Then I take the average of the difference between them, and convert that to an exact bpm. Then I just note the millisecond of some beat every 10 seconds to the end of the song. When I get to edit mode, I first set the bpm to what I calculated, then start checking it at the various points I noted down, adjusting it by tiny increments to make them match.