Realtime BPM / tempo


I am using Photon2 for 90% music-to-light shows and 10% static light in the future. Because of this I am using the “Beat Tracker Mode” in nearly every show. The beat tracker, with its one/two bugs, is okay.

I am using the “Automatic mode”. Manual is useless for me, except corrections, and Ableton Link is not useful for the software I am using. The problem is the accuracy of the beat tracker. There are songs with a static bpm of let’s say 120/130. The tracker is working perfectly fine here.

The problem comes with dynamic bpm in a song. Let’s take the song “More Than You Know” from “Axwell /\ Ingrosso”. Nearly static bpm 115 - 125 for the first minute.At about 1:00 it’s rising to the climax at 1:10. From here it’s nearly static again and easily recognizable for the tracker.

What I need is something in the tracker that detects the 10 seconds of rising to the climax. It’s the moment with the most power in the song for special effects like flashlights. The tracker is running in realtime. I have absolutely no problem with the sync of the lights - it’s working fine. But I think you need to change the sampling rate of the tracker. Sometimes it gets the high bpm and jumps to 160 bpm but too late with ending in a hard crash from about 160 bpm down to 120bpm again. This then results in a weird lightning pause for a second (feels like one second).

I hope the battery isn’t the problem for the low sampling rate. If it’s the sampling rate idk. That would be my guess. But everyone running a show on a iPad should connect it to a charging cable.

I think you get the point. I linked the song I was talking about with a timestamp set to 0:50.


Had a look at it again. Probably it’s not the sampling rate. It’s more looking like the time the tracker needs to calculate the actual bpm. Looks like it’s analyzing the bpm over a period of time and then calculating the bpm.

Probably a feature like reaction to highs / lows would be great to. Like binding the tracker to highs / lows in combination with secenes. We are using red colors on our stage for lows for example. A binding of something like that would be gret too!

Another question: What’s the beat tracker looking for? Could the tracking be more accurate with only highs + lows and without mids? Or lows (+100%) and mids + highs at 0%?

The Beat tracker is working correctly as far as I can see
The track you refer to has a constant BPM - the percussion crescendo you refer to at 1:10 does not change the basic BPM
The way to get your light show respond to a track like that would be through MIDI control from the tracks timecode - a more sophisticated controller than an iPad following the audio.
Maybe the new midi implementation in Photon will enable what you are looking for.

1 Like