Say you’re recording a microphone. The audio signal is the voltage that is generated by a membrane inside the microphone that vibrates as it receives changes in pressure in the air, which is what makes sound travel to your ears. When you record an audio signal you get a waveform that faithfully represents the movement of the microphone membrane as it moves back and forth during the recording.
MIDI (Musical Instrument Digital Interface), on the other hand, stores sequence of events, most commonly musical notes. As you press a key on a MIDI keyboard, the keyboard sends a digital representation of which note was pressed at which point in time, and with which intensity (usually referred to as ‘velocity’) to a device (typically a computer, tablet or smartphone) to which the keyboard is connected.
The device can record the MIDI events (e.g. the C# at the 4th octave was pressed and released 3 seconds later) and can include a synth (typically a virtual instrument) that generates a sound based on which event it has received. A piano synth will produce the sound of a piano, other kinds of synths will produce different sounds based on the same note that was played. In fact you can typically record a whole track playing say piano, then later decide that the track sounds better if the same notes are played by a violin – just switch the virtual instrument.
Each MIDI track can be assigned to different virtual instrument channels.
A MIDI signal is usually generated by a keyboard or an electronic device that sends an input containing information about which key was pressed.
MIDI signals can be processed by a DAW (digital audio workstation), a software for music recording by using a “MIDI track”. Virtual instruments usually come as VST (Windows and Mac) or AU (Mac) plug-ins or iOS or Android apps.
Here’s a simple scheme to understand how MIDI works.
You can also find free instrument plugins on the web, on sites such as http://www.vst4free.com
If you want to learn how to manage midi tracks and play your virtual instruments and you don’t yet have a recording app, check out n-Track Studio 8, it’s quite easy to use and the free version lets you play with instruments and record MIDI.
Do you want to experiment with MIDI and get a MIDI keyboard for under 100 bucks!? Then check out our best midi keyboard controller for beginners (under 100$) guide.