What is MIDI?

[ironwolg]

What exactly is MIDI? If someone can give me a full explanation of what it is, what it can be used for, and how to use it, that would be extremely helpful. This is probably a very stupid question but I'm still new to the whole technological music world. I'm primarily a guitar player so amps are pretty much the most technologically advanced things I work with daily haha.

[Bastardo Demono]

not to be a jerk but this is easily one of the most google-able questions you could ask related to music. type the thread title exactly like that into google an you'll find some pretty awesome explanation

[ironwolg]

not to be a jerk but this is easily one of the most google-able questions you could ask related to music. type the thread title exactly like that into google an you'll find some pretty awesome explanation

well, i've googled it before and i've got a basic idea of what it is, but when it gets real deep into it i have trouble understanding. i'm not really used to working with keyboards and computers for making music so i was hoping someone could give me a thorough yet simple explanation. i'm more interested in what it does and how i can use it than what it is really. from what i've been told, i can basically use different sounds on the computer that aren't on my keyboard. like if i want to use a different synth for recording purposes i could find one on the computer and use it instead. can midi do that? that's the kind of stuff i'm really looking for

[Enigma™]

Sure:

MIDI = Musical Instrument Digital Interface.

Basically, when you push a key, you record the event properties. Things like: Note Press Velocity (how hard), Key pressed (C4 as an example) and any other attributes like controller values (Mod Wheel at value 62 of 127)

These events are based on a horizontal time line so that the events are "triggered" or played.

Think of MIDI as a digital player piano strip but for more instruments than just the piano.

The disadvantage for some musicians is that when they hear MIDI they immediately think of crappy sounds, bad mixes, etc.

But the reality is that a LOT of musicians have crazy amounts of keyboard racks, offboard gear and things that all need controlling. MIDI allows you to control the properties of sounds remotely and in an automated fashion.

Think of MIDI as the message with a remote control. The keyboard is the controller, the sound interface is the TV. You're telling the interface what to do.

What MIDI is not:

MIDI is NOT the sound you hear when you play a digital instrument. That's the AUDIO output. MIDI is the digital notation of the events that were recorded.

Hopefully that clears things up for you?

[ironwolg]

Sure:

MIDI = Musical Instrument Digital Interface.

Basically, when you push a key, you record the event properties. Things like: Note Press Velocity (how hard), Key pressed (C4 as an example) and any other attributes like controller values (Mod Wheel at value 62 of 127)

These events are based on a horizontal time line so that the events are "triggered" or played.

Think of MIDI as a digital player piano strip but for more instruments than just the piano.

The disadvantage for some musicians is that when they hear MIDI they immediately think of crappy sounds, bad mixes, etc.

But the reality is that a LOT of musicians have crazy amounts of keyboard racks, offboard gear and things that all need controlling. MIDI allows you to control the properties of sounds remotely and in an automated fashion.

Think of MIDI as the message with a remote control. The keyboard is the controller, the sound interface is the TV. You're telling the interface what to do.

What MIDI is not:

MIDI is NOT the sound you hear when you play a digital instrument. That's the AUDIO output. MIDI is the digital notation of the events that were recorded.

Hopefully that clears things up for you?

yes, very much! thanks :D

[osiris]

To anyone who uses MIDI or wants to get into it, I would highly recommend this book by Paul White.

Basic MIDI by Paul White (http://www.amazon.co.uk/Basic-MIDI-Paul-White/dp/1860742629)

Don't let the title or size of the book decieve you. It is a great for explaining MIDI from simple messages such as Note on/off to sysex.
Also a brilliant resource. I use it a lot to check what a certain CC number is and other stuff.

Check it out, definately worth it, and for the price of under £4 GBP, you can't really complain if it doesn't suit your needs.

EDIT: Read the review by "Key42" on the above link. I'm not the only one who thinks it's amazing :tongue:

[osiris]

Also found this book which is probably just as good.

Midi for the technophobe (http://www.musicroom.com/se/ID_No/030295/details.html?kbid=1582)

[glassprison]

This site has a lot of great information on recording. And, some really helpful info on midi. (Also has some nice illustrations)

http://www.tweakheadz.com/how_to_get_started_with_midi.html

List of CC Events....
http://www.tweakheadz.com/midi_controllers.htm

Advanced midi....
http://www.tweakheadz.com/midi_interfaces.htm

[Grey Loki]

...attributes like controller values (Mod Wheel at value 62 of 127)

Pedantry: MIDI works off of 128 values, running 0-127 - 0=off!

The wikipedia article on MIDI is also quite informative :)

[Enigma™]

Pedantry: MIDI works off of 128 values, running 0-127 - 0=off!

The wikipedia article on MIDI is also quite informative :)

You're exactly right, which is why I said 62 of 127 - 0 is a value as well.

More Pedantry: MIDI works off of 7 Binary bits, which means the highest value it can contain is 0x01111111, where 0x00000000 is the lowest value.

Also when you look up values on any MIDI program, 127 is the highest value you can have before getting into the 8th bit :)
The thing I don't know: Where did the 8th bit go? What's it used for?

[mmichaelc]

MIDI actually has the capability to use 14 bits for some of the controllers.
If you look on this site mentioned above: http://www.tweakheadz.com/midi_controllers.htm
controllers 33-45 are the second 7 bits for the controllers 1-13. The majority of instruments only use the first 7 though which results in lower precision.
You could design an instrument to have a range of 16,384 for the mod wheel or whatever.

[eric13579]

I will try to put this in a way where everyone can understand this.

First off, one thing that should never be mistaken: 8 bits = 1 byte. Just because there are many applications where it uses only 7 out of 8 available bits, 7 bits do not make a byte. If the 8th bit is not used, most likely it serves another purpose (error checking, data parsing, etc).

There are two types of MIDI messages: MIDI Data Messages, MIDI System Messages. I will only focus on Data Messages because they are channel specific, which plays a huge part in MIDI's data structure.

Whenever something is done on the MIDI controller, it usually sends 3 bytes out: Status byte, and 2 Data bytes. The status byte tells the opposite interface what happens (note on, note off, etc), the first data byte indicates where it happened (which note), and the second data byte indicates the details to what happened (velocity, pressure, etc). The first bit of the status byte is ALWAYS 1, and the first bit of the data byte is ALWAYS 0. This is the "missing 8th bit" that people have been wondering about.



Going into further detail:


Status byte -

As mentioned before, 1 byte = 8 bits, and the first bit of the status byte is always 1. Therefore we have the following min/max values for the status byte:

1000 0000
1111 1111

Or in hexadecimal:

80
FF

If you're not familiar with converting between binary and hexadecimal, do a quick google search =p

The first 4 bits tells the controller what the action was, and the last 4 bits specifies the MIDI channel it applies to. As you can see, 4 bits are used for the MIDI channel, yielding 16 (2^4) channels maximum.



Data bytes -

Most of the time, the first data byte indicates what note is being pressed, and since the first bit in the data byte is always 0, it leaves 128 (2^7) different values for each distinct key.

The second data byte details on the pressure pressed on the key. Once again the first bit is always 0 so it leaves the last 7 bits to be used as a measurement that will be send to the other side of the interface.