BPM Detector by Spectralite
The input, controls, outputs, HAPTIC, Action Button and Live Activity of BPM Detector by Spectralite for iPhone.
BPM Detector by Spectralite listens through an input on your iPhone and sends the tempo and beat to other software. It needs iOS 16 or later. A web version with the same beat tracker runs on the BPM Detector page.
Input
Press the input name at the top of the main screen to choose from the inputs the phone offers, such as its microphone. Press START to listen. The first time, iOS asks for microphone access, and the app asks for local network access so it can reach other devices. If the microphone is refused, the display reads NO MIC and START opens the iOS settings.
Controls
| Key | What it does |
|---|---|
| ÷2, ×2 | Moves the locked tempo down or up an octave. |
| CUE ALIGN | Press it on the downbeat to line the beat up with the room. |
| HAPTIC | Taps on every beat. It is off until you turn it on, and the app remembers the choice. |
| RESET | Listens afresh, clearing the displays and the cue offset. |
| SYNC | Opens the outputs settings as a sheet. Press Done to close it. |
Outputs
The settings sheet has the same sections as the Outputs window of BPM Sync: OSC with its host, port, prefix and message list, MIDI clock with Start and Stop, and an Offset for each output. OSC is off until you switch it on.
MIDI clock on iPhone goes to the app's own virtual MIDI source, which other MIDI apps on the phone list as an input, or to a connected device.
Ableton Link
Ableton Link is coming soon. It needs Ableton's licence and Apple's multicast entitlement for iOS.
Background listening
The app keeps listening and sending when you lock the phone or switch to another app. While it listens, the screen does not auto-lock.
Action Button
On an iPhone with an Action Button, assign the shortcut Listen for the BPM to it. A press starts listening, and the next press stops. Listening starts on the input you last used in the app, and the app does not need to be in front.
Lock Screen and Dynamic Island
While the app listens, a Live Activity shows the lock state (LISTEN, SEEKING or LOCKED), the input, the tempo and the confidence meter on the Lock Screen. In the Dynamic Island, the compact form shows a metronome icon and the tempo, the minimal form shows the whole-number tempo, and the expanded form adds the input and the confidence meter. The Live Activity has no controls.