Does anybody know formula ?
I tried following: 1000 / ((BPM * 24) / 60). But seems not correct.
I don't think my answer is MIDI-specific, but to convert beats-per-minute to ms-per-beat, would this work?
ms_per_beat = 1000 * 60 / bpm
In other words, I think you have an extra "24" in there.