Cascade
Find the BPM and offset of any song
Timing is the part of mapping that nothing else survives without. If the BPM is off by a hundredth or the offset is off by a few milliseconds, every snapped note in the chart is wrong and no amount of good patterning saves it. Cascade gives you three ways to get it right and a metronome to prove it.
Open the editor and start timingDetected from the audio
Drop in a song and Cascade analyses the waveform to propose a tempo before you have tapped anything. For a track with a steady beat that is usually the answer, or close enough that a small nudge finishes the job.
Tap it yourself
Tap tempo is still the most reliable check for anything the detector finds ambiguous, like a song with a heavy off-beat or a slow intro. Tap along for a few bars and Cascade averages your taps into a BPM and an offset you can apply directly. If your tapped tempo and the detected one agree, you are done.
Nail the offset
Put the playhead on the first beat and set the offset from it, then nudge in small steps while the song plays. Turn the metronome on and the click either sits exactly on the sound or it does not, which is a far faster test than staring at the waveform.
BPM changes and gimmicks
Songs that speed up, slow down or drop a bar get more red lines, each with its own tempo, and the beat grid follows. Once the timing is right, the snap divisor actually means something and you can build the chart on top of it, then add scroll velocity for effects that move the notes without moving them in time.
Timing first, patterns second. Re-timing a finished chart means re-snapping every note in it.