What you get
A tempo in BPM to two decimal places, a confidence band, and — when the call was close — the alternative named.
Why two decimal places
Not for show. If you are stretching a loop into a 128 BPM session, the difference between 127.5 and 128.0 is a beat of drift every four bars. That is exactly the kind of error you notice at bar 33 and then spend twenty minutes hunting.
The decimals are a real estimate, not a rounded integer with digits added.
The grid survives a breakdown
The common failure in tempo detection is a reading that collapses the moment the kick drops out, because the kick was carrying the whole measurement.
DropWave reads the pulse from across the spectrum — hats, snares, rim clicks and percussion all contribute, not just the low end. A breakdown, a half-time section, a percussion-led arrangement with no four-to-the-floor at all: the grid holds.
Half time and double time
When DropWave says 103.16, could also be 206.32, both numbers describe the same grid counted at different levels. Neither is wrong.
- A drum & bass tune at 174 has a half-time feel at 87.
- A trap beat at 140 is frequently written as 70 with double-time hats.
Pick whichever matches how you count the track. Naming the alternative is the point: a tool that picks silently is making a decision about your music without telling you.
When there is no tempo to find
- Vocals and other soft-transient material. Sung transients are soft and there is often no beat present. Low confidence here is the correct answer, not a failure — and in the plugin, a vocal channel showing a key and no tempo is it working properly.
- Rubato, live and unquantised playing. The tempo moves, so there is no single number.
- One-shots. Nothing periodic to measure.
- Ambient, drones and pads. Same.
Related
Key · BPM finder · How to find the BPM of a sample · How to find the BPM of a drum loop