Building a heart-rate monitor for Mac without a wearable – what we learned

Hey ph 👋

I'm launching GlowPulse on June 2nd – a menu-bar app for mac that reads your heart rate from the built-in camera (rPPG, no wearable). Started as a python prototype, rewrote in swift, took a detour through CoreML.

Some things i didn't expect:

- vision face detection every 10 frames creates a ~90 bpm ghost peak right inside the heart-rate band fixed by running every frame with ema-smoothed bounding box (=0.35);

- POS algorithm (Wang 2017) and a DeepPhys CoreML backend both track within +-3 bpm of apple watch in stationary conditions – too close to pick a winner, so i ship both and let users toggle;

- 15 fps capture is enough for bpm (Nyquist needs >=6 hz for the 3 hz max heart rate). 30 fps only helps hrv precision during breathing sessions where RMSSD needs finer beat-to-beat timing – so it's a toggle, not default;

- heavy makeup blocks the pulse signal almost entirely. Bare skin matters more than lighting (mostly).

Curious – anyone on ph actually using biometric input in productivity apps? Or is it still "wearable-only" territory in your stack? Trying to gauge interest before launch day.