Max 8 Tutorial # 13: Introduction to MIDI
Channel: dearjohnreed
Date: 2019-02-04

MIDI stands for Musical Instrument Digital Interface.  It is, essentially, a standard computer language for communicating data between musical devices, whether they be instruments, mixers, recorders, computers, effects, etc. In the Tutorials this week, you will need to have MIDI installed on your computer. I have been told by people with PC's that "LoopMIDI" is one of the easier ones to use. You are welcome to search for other MIDI programs/freeware on the net, but do keep in mind that some of these could be malware or have viruses.
"Digital" audio "measures" the sound-pressure or wave height -usually- about 48,000 times per second. So, 48,000 numbers every second for a 3 minute song is (180 secs x 48,000 =) 8,640,000 numbers. 

With MIDI, there is a standardized set of sounds on a synthesizer.  When you want to play one, you send it a set of numbers (a MIDI message) asking for a pitch and a velocity (like volume).  When you are done, you send that pitch again and a volume of zero.  The advantage of this system over regular audio is that there is FAR less data.  The disadvantage is that the sounds need to be standardized and are, therefore, less nuanced.  However, it lets you download a song (think "ringtones") that are tiny, maybe 4K bytes instead of 4 Megabytes (1000 times larger).

MIDI is also cool in that -since every song is just a set of instructions- you can change the instruments (voices) in a song, the tempo, the overall pitch,...  you can really mess with it, because you have control of where the instructions go.