From Gyro Groove to Garageband

How on earth does a virtual drum kit work?!


The Freedrum sensors consist of four core components: gyroscopes, accelerometers, Bluetooth and MIDI.

We measure what the drummer is doing with our sensors (accelerometers, gyros); we then use Bluetooth to communicate between the sensor and the device (mobile phone or computer) using the language of MIDI. Our device then interprets the MIDI* and triggers a sound, for example a kick drum. Now we are drumming!

Easy tutorial on how Freedrum MIDI can be used with Garageband   

Connect your freedrums with garageband using MIDI*, in Garageband you have a variety of different drum kits from acoustic to electronic drum kits. You can also use Freedrum with other instruments as well! Create basic tracks and add to them as you go!

 

 Putting this all together. What is going on in a Freedrum experience?

Our drum kit is completely virtual, that is to say there are no real drums to hit, we have them mapped in our minds and our software when we play.

Simply put, we have a sensor on each drum stick and on each foot. 

We then use our accelerometers and gyroscopes in the sensor to measure (relative to a start position) which angle we are pointing the sticks/feet (and therefore which drum we are pointing at) and we measure how fast we are moving the sticks/feet (how hard we are hitting the drum). 

 



Great, so we know which drum we are hitting and how loudly we are hitting them. But how do we make a sound in our headphones?

 

Well we need a way to transmit that information: enter Bluetooth. Perfect, bluetooth lets us transfer information from our sensors to a computer / mobile which is at short-range (our drum stick sensor is only a few metres from our mobile / computer).

But what kind of information do we want to send and in which language? We want to do it quickly (so we minimize the delay between hitting the drum and making a sound - lag/latency) so we don’t want to include anything unnecessary when we are talking. We want to convey which drum was hit, when and how loudly. Fantastic we can do all that by talking MIDI.


 

*So what is MIDI?

Musical Instrument Digital Interface (MIDI) is basically the language we use to talk to digital musical instruments. In MIDI messages we communicate a lot of musical information: Including a A note's notation, pitch (which note we play), velocity (which is heard typically as loudness or softness of volume); vibrato; panning to the right or left of stereo (if we hear the note equally in both headphones, more in the left or more in the right); and timing information (which sets the tempo)