- This lecture is an introduction to MIDI.
MIDI is an acronym.
It stands for Musical Instrument Digital Interface.
And the first important thing to understand about MIDI
is what it is not.
MIDI is not audio.
A MIDI signal is not an audio signal.
A MIDI cable is not an audio cable.
A MIDI file is not an audio file.
In fact, a MIDI file
will be many, many times smaller than a typical audio file.
And that's because what MIDI is,
is performance information.
MIDI doesn't make sounds, rather MIDI instructs
a sound producing-device, "Do your thing."
So for instance, audio is like
I put a CD in my CD player
and the CD instructs the CD player's
digital to analog converter,
how to make a sound, an audio signal,
from scratch sample by sample
using, as we've seen, 11 megabytes of information
for every minute of audio the CD player generates.
MIDI is more like telling somebody,
"Hey, go over there to that CD player and hit play."
And these performance instructions
can be sent to any sound producing device
that is MIDI-compatible, that has implemented MIDI.
So MIDI instructions, a MIDI file,
could be sent to an analog synthesizer.
It could be sent to a digital synthesizer or to a sampler.
It could be sent to a software synthesizer
like the synthesizer that's on your computer or in your DAW.
It could even be sent to an acoustic instrument.
So people have built MIDI pianos
and even other instruments
that respond to MIDI information, to MIDI signals.
It's not even necessarily a sound producing device.
So although it was invented for music,
it's been adopted in other areas,
particularly in the area of stage lighting.
A lot of stage lighting people use something
called MIDI Machine Control, MMC, to run their light boards.
So even though it's a digital,
MIDI actually has more in common
with the mechanical precursors
to acoustical and digital recording,
than it does to an audio file or an audio signal.
So if we think of the playing mechanism of this music box
like a synthesizer,
or like the built-in synthesizer
in your computer's sound card,
then the barrel of the music box
with the little protuberances that pluck the tines
is like the MIDI signal or the MIDI file
that drives the playback of the machine.
(gentle music box music)
So the tines are making the actual sound
but this is the information, the performance information,
that tells them what to do.
Another well-known mechanical music device
is the player piano,
which works on a very similar principle.
(upbeat ragtime jazz music)
So the piano has a very sophisticated mechanical mechanism,
but what drives it is the piano role, the player piano role.
And it's literally just a roll of strong paper.
And there are perforations, holes, cut in the paper,
which correspond to notes
that are being played on the piano.
So from here to here, represents the 88 keys of the piano.
Then somebody on a special piano
called a reproducing piano,
plays the piece, performs the piece,
and this piano cuts holes in the roles
as the role streams by,
corresponding to the keys that have been pushed down,
then on playback, there's a bellows mechanism
that blows air through the paper
and where there's a hole, the air goes through
and that signals, that pushes on a little mechanical device
that's hooked up and amplified
so that it's strong enough to push the keys themselves.
This is easier to see if we look at a modern visualization
in what's called piano roll notation,
because it's based on this.
Here, the keys are actually visible,
the keys of the keyboard down here,
so that you can see what's happening.
(dramatic piano music)
So, as you can see,
each little area along the left to right axis
corresponds to a note on the piano,
and here the time element, the time axis is vertical.
This is called piano roll notation.
And it's actually used in a lot of MIDI sequencers,
maybe part of the MIDI component
of your own DAW like Logic or Pro Tools.
It's often tipped 90 degrees like this
so that the piano keyboard is on the vertical axis
and then the time element goes left to right,
horizontally, as we're used to.
So MIDI is a digital format, but it's not an audio format.
In fact, MIDI came into existence in the early 1980s.
It was first mused or proposed about around 1980, 1981.
And the actual MIDI standard or protocol as it's called,
MIDI 1.0 was unveiled in 1985.
And at that point,
PC-based digital audio was still in its very infancy.
So for instance, the first Macintosh, the Apple Macintosh,
released in 1984 had very limited
sound producing capabilities.
It had an internal sound card,
which is basically a digital to analog converter,
that could produce sine tones and square waves.
It could beep, essentially.
And that was the Mac.
Apple has always been at the forefront
of musical and graphical applications.
So the sound capabilities of the IBM-based machines, PCs,
were even more limited than the Macs.
So MIDI was not designed with the idea
of driving, of controlling computer-based audio,
as much as it was initially invented
to drive standalone analog and digital synthesizers.
If you're wondering,
"Wait how could there be digital synthesizers if I just said
that computer-based audio was in its infancy?"
At that time, the personal computer
did not have enormous audio capabilities
but remember, a personal computer is a sort of
one-size-fits-all, do everything machine.
A personal computer is to a Yamaha DX7
something like a Swiss Army knife
is to an electric can opener.
The Swiss Army knife tries to do a little bit of everything,
but the electric can opener is doing just one thing
and can do it a little bit more fancy.
So the first personal computers,
the Macintosh, the IBM PC,
were basically designed to do desktop publishing,
some word processing and simple graphics, spreadsheets,
maybe some primitive computer games like Tetris.
You know, you could set the alarm clock.
That was like a big deal.
I remember in the late '80s
when a friend of mine figured out
how to get his Macintosh to act like an alarm clock.
And, woo-hoo, that was like the greatest thing.
They did have internal sound cards, as I said,
but their capabilities were pretty primitive.
On the other hand, if you take
the 1980s level of computer technology
and you put everything into,
how can we make just sounds?
So you take, instead of taking 1 or $2,000 of computer chips
and putting them into a general-purpose machine,
you take 1 or $2,000 of computer chips
and design them specifically to be really good
digital to analog converters
or analog to digital converters,
then you can do a lot more.
So the first digital synthesizers
were in these standalone devices like the Yamaha DX7.
And there were also analog synthesizers
still very much in the mix as well.
So what would happen was,
people would have all these synthesizers
and each synthesizer had
its own sort of specialty, its thing
that it maybe did a little differently
or better than the others.
The Yamaha DX7 was famous for its digital FM synthesis
which was great at producing
percussive and bell-like sounds, piano sounds,
metal percussion and so on.
People had drum machines
whose specialty was making all sorts of drum sounds.
There were machines like the Moog synthesizer,
which was an analog synthesizer
that was particularly good at sustained sounds,
interesting sort of synth paths
and brass-like or woodwind-like sounds.
So people would have all these devices
and they would be trying to control them all at once.
And you would sometimes get
into some very sort of crazy Rube Goldberg-like situations.
So maybe you've noticed this image
in the side menu of my course website.
This is the album cover to a 1978 album
by the jazz pianist and innovator Herbie Hancock.
And as you can see in the late '70s, early '80s,
people have these wild setups.
He's got like a dozen different machines here,
right, synthesizers, all making different kinds of sounds.
That's a Minimoog right there, Moog synthesizer.
and all of them, or at least most of them
have their own keyboard controller,
that is a keyboard that tells the synthesizer what to do.
Like I just pushed down the middle C,
do that thing that I want you to do when I hit middle C.
Or I pushed down that middle C key really hard,
that means I want you to play the sound loud
or whatever it is you're programmed to do
when I push it down harder.
And you can see crazy setups like this.
If you go to YouTube and look up Keith Emerson,
you'll see he's, you can see him performing live
on these wild, you know, multi-rack things.
So a bunch of music manufacturers got together
and started thinking, and they're saying,
"You know, all of these machines
are sending pretty much the same kinds of message
from their keyboard to their sound engine.
They're saying things like, 'I push down this key,
how hard did I push it down?
When did I push it down?
And when did I let go of it?'"
So they were saying, "Wouldn't it be nice
if we could use just one controller, such as a keyboard,
and send a message from that controller
that could be understood by any musical synthesizer?"
So I could be sitting at my Yamaha DX7,
that could be my master MIDI device,
well, they didn't call it MIDI yet,
but that could be my master controller.
And I play a note on my DX7
and it can tell my DX7 what to do
but it could also take that message
and send it out from my DX7 in a cable
and connect it to my Moog synthesizer,
and then say, "Hey, Moog synthesizer,
that guy over there on the DX7, just played a C,
maybe you wanna do something with that?
Maybe you should do something with that MIDI,
that performance information
and produce a sound on the Moog device."
So that's how he came to be.
Now we're gonna look a little bit
at the actual content of MIDI data, MIDI information.
What is conveyed in a MIDI message?
Well, again, MIDI is not audio.
What MIDI is, is a protocol,
that is to say, a commonly understood code or language
that standardizes performance information.
What do we mean by performance information?
Things like what note are you gonna play, what's the pitch?
When is that going to start?
When is the note initiated?
When is the note released?
When does it stop? Basically the rhythm.
How loud is the note?
What sort of sound should that note be?
What patch are we going to assign it to?
Is it going to sound like a flute
or is it going to be assigned to the drum kit?
What's the tempo?
What's the expression,
besides just how loud the note is?
Is there vibrato?
Is there some sort of portamento between pitches?
Is there a change in the tone color
in the course of the pitch, and so on?
This is gonna result in far fewer messages per second
than an audio file.
Instead of having to send tens of thousands
of bits of information per second
just to describe the air pressure,
the sound pressure, at every moment,
I could send a Note On message saying,
"I just started middle C,"
and it could go on for 10 minutes,
and then I could send a Note Off message
and that's literally two messages,
instead of millions and millions of messages.
And each message, each MIDI message,
is typically much, much shorter in length,
in its depth, in its bit length,
how many digits are required to convey that message,
typically much shorter messages
than in an audio file.
So instead of needing 16-bit or 32-bit words
as we do for good resolution in audio,
it might be just a few bits,
maybe just a single byte to convey the information
note on, note off, and so on, okay?
So MIDI, the MIDI protocol
defines a number of different channels, okay?
MIDI works with channels.
So if I'm sending out MIDI information, for instance,
I might send one MIDI message
to go play a note on the Moog synthesizer.
So I say, that's channel one.
And the Moog is assigned
to respond to messages on channel one
channel two might be assigned to my Fairlight Synclavier
and channel three is assigned to my Kawai keyboard.
And maybe my Kawai keyboard is a polyphonic keyboard.
That is this single keyboard synthesizer itself
can play many different tone colors at the same time.
So it could create a flute sound and a bass sound.
So maybe channel four is the Kawai flute patch
and channel five is
to the same instrument, a Kawai bass patch, okay?
This is how MIDI works, in channels.
If you use a modern
software-based digital audio workstation,
or a MIDI sequencer like Logic or Pro Tools
or Reason or Cubase or whatever,
you probably won't see MIDI channels
because they've been implemented
in the graphical user interface as tracks,
as if you were looking at tracks
in a multi-track tape environment.
So you see tracks and you'll probably just think
in terms of tracks, but in the background,
so under the hood,
when you say track one, track two,
track three onto your MIDI tracks,
but those are actually our different MIDI channels.
So most of the messages, the bulk,
the bread and butter of MIDI messages
are gonna be Channel Messages.
There's also something called a System Message
which is something that applies
to all the MIDI messages on all the channels.
We'll talk about those in a little bit.
But the basic messages are Channel Messages.
And most of those are Channel Note Messages.
And the most basic channel message
is the Note On and Note Off message.
So in order for this to work,
remember, MIDI is a protocol
where all these different instruments,
any MIDI-compatible instrument,
has to understand the information in the same way,
it has to speak the same language as every other instrument.
So one thing that happened in the MIDI protocol
is that all the notes are numbered,
numbered from zero to 127.
And, as it happens, like a byte of information
is assigned to the range of values
so you get a total of 2 to the 1/8
or 128 possible different values,
which means you can have notes numbered from zero to 127,
which is plenty, right?
That's far more than the 88 notes of the piano keyboard.
So every note is given a number,
by agreement middle C or C4 is assigned the number 60.
So then the C-sharp immediately above is note number 61.
The D is note number 62.
The B immediately below middle C
is note number 59, and so on.
So every note, every pitch,
every key on the keyboard has a number.
Note messages are also assigned a velocity.
Now that doesn't actually have anything to do
with the speed or the tempo.
The velocity means literally,
how fast was that key moving down when I hit it?
Which, more intuitively we think of
how hard did I hit the key
or how hard did I depress the key?
That's the note velocity.
It isn't necessarily determined by a keyboard.
If you're playing a wind controller,
maybe it's determined by
how much air pressure there was at the time.
If you're playing a MIDI guitar controller,
maybe it's determined
by the perceived volume, amplitude,
of the guitar string vibration,
which is then translated into a velocity message.
One way or another though,
usually with a keyboard controller,
the Note On message is also associated with a velocity,
and these are also a numbered from zero to 127.
So if I sort of hit it right in the middle range,
it'll be about velocity equals 63 or so.
If I hit it as hard as possible,
it's velocity equals 128, and so on.
Now that's just a number, how that number is interpreted
by the receiving MIDI instrument
that actually generates a sound
in response to this MIDI message,
that's up to the instrument
or how the instrument has been programmed.
So, normally, I would say 99 times out of 100,
note velocity is programmed
to correspond to loudness, right?
The harder I hit the note,
the louder I expect the sound to be.
It doesn't have to be programmed that way,
but that's usually what people do,
although it's a little bit more nuanced than that.
Because, for instance,
if you are using a sample-based instrument,
which is to say an instrument
that produces sounds, generate sounds,
based on a stored library of recorded samples,
for instance of a piano, if I'm using a piano sound.
So if I play a really loud note on the piano,
it actually has a different harmonic spectrum
than a really, really quiet note on the piano.
That's why you can tell the difference,
say, if you're listening to a recording of a piano
even if somebody turns the volume way down,
if somebody's pounding massive
virtuoso cores on that piano,
it still has that loud tone color,
even though the actual volume
of the playback may be quite low.
So, in other words,
instruments have a different tone color
at different volume levels.
So a sophisticated, well programmed sample-based instrument
will have a different sample for
I played a really soft note or I played a medium note
or I played a really loud note.
So if I receive a high velocity number like 100,
velocity equals 100,
not only will it play the sound back louder,
but it will select a loud sample,
a sample of a piano playing loud.
If I play velocity equals 10, super quiet,
it will not only play a lower volume,
but it will base that
on a sample of a piano being played quietly.
Anyway, that's note velocity.
Then there are a number of messages
which are not note on or off messages,
but are what's called control change or CC messages.
And these are also usually typically assigned
a range of values from zero to 127.
One of these is channel volume.
Remembering that channels are usually implemented as tracks,
you can think of this as the volume of a track.
How loud is that track relative
to the other tracks in your mix?
So it's assigned a MIDI volume, a channel volume.
Then there's something called expression,
which is also assigned to loudness, to volume.
But this is within whatever the channel volume level is set.
Then it can be temporarily louder or softer
than the sort of base mid-level volume of that track.
In other words, a track or the notes on a track,
can get louder and can get softer across time.
That's called expression
and that's control change number 11.
Modulation, this doesn't refer
to changing key in that sense,
but modulation meaning changing the tone color of the sound.
Most synthesizers, going back to the Moog synthesizer,
have a mod wheel.
Like the pitch bend wheel,
there's also a mod or modulation wheel
where if you push it up, usually intensifies the sound.
Maybe it adds vibrato,
maybe it's been programmed to increase the vibrato.
Or, say it's a guitar, electric guitar sound,
maybe if you turn up the mod wheel you get more distortion.
It typically makes sounds brighter too.
So maybe it gives them a brighter, higher harmonic spectrum.
That's how modulation is typically programmed.
That's continuous controller 01,
and if I turn up the mod wheel on my keyboard controller,
that will send a message to increase
the modulation value on that channel.
Pan, position left right, in the stereo field,
control change number 10, from zero to 127.
Pitch bend, so most synthesizers
have a pitch bend wheel or a pitch ribbon
so that you can increase
or decrease the frequency of a note
that's already being triggered.
Pitch bend is special,
because our ears are enormously sensitive
to very small changes in pitch,
128 possible values might not be enough.
It might sound like
there were sort of jumps, jerkiness, in the pitch.
So that actually has more bytes assigned to it
so that there are actually 65,536 possible values
for the pitch bend parameter.
The sustain pedal.
You can depress the foot pedal,
say on your keyboard which normally sustains the note.
This is also a little bit different
although it still has 128 possible values,
it's an on/off, either the sustain pedal is down
and the notes are sustaining,
or the sustain pedal is up and the notes are not sustained.
It only has two states.
So any value between like zero and 63 will be depressed,
any value between 64 and 127
will be undepressed or vice versa.
That's control change number 64.
And there are others,
for instance, aftertouch.
Many synthesizers and many sounds
are programmed to respond
to how hard you press the key after you've played the note.
So you can make them respond to key pressure and so on.
So all of these things are examples
of Channel Note Messages,
and then Control Change Channel Messages
that will affect the sound
of the information of the notes that you're playing.
There are also, as I said, System Messages.
These are messages that go to all channels,
and the most basic of these,
the one that's sort of essential for everything
is the MIDI Time Code.
Right, so I can say
that there's going to be a Note On message
and I can say that it occurs at a certain moment in time
but somebody has to be keeping time.
Somebody has to be in charge of the clock.
And that's what MIDI Time Code is doing.
It's sending messages
steadily across all channels
to regulate the time
between all these different devices.
A MIDI clock, MIDI Time Code,
measures in musical time that we're familiar with,
it measures in measures.
And then, depending on the time signature beats,
it's a certain number of beats per measure,
and then a certain number of pulses.
There are 24 pulses defined per quarter note.
So, for example, 16th notes would be six pulses long,
one quarter of,
of a quarter note beat.
And then pulses are further divided into ticks.
And this depends now on the specific MIDI messages
that you're using in the specific instrument
or software that you're using,
but there can be up to 960 ticks per quarter note, okay?
So MIDI events are recorded
in traditional musical time locations.
Therefore there's also a tempo.
And if you change the MIDI tempo
everything will happen faster
if you raise the tempo,
slower if you lower the tempo.
This is in contrast, for example, to SMPTE time code.
SMPTE stands for
society of motion picture and television engineers.
And SMPTE code is measured in more like a clock time,
hours and minutes and seconds, and then frames.
So after, like, if I'm in hour one,
minute three, 12 seconds in,
then how many frames into that second
that is frames of film, right?
So the typical frame rate
for a cinema quality quality film is 24 frames per second.
There are other frame rates,
48 frames per second, 29.97 frames per second.
But SMPTE time code is measuring things
in hours, minutes, seconds, and frames.
And in your DAW, you can, in the preferences,
arrange to see the time as MIDI time,
musical time or as SMPTE time
or as straight clock time, hours, minutes
and then seconds in decimals.
And then like 1.67 seconds measuring in 100ths of a second,
and then eventually in samples.
So when you get past, usually 100ths of a second,
most programs will then show you how many samples are you
into that second there being, whatever the sample rate is,
44,000 or whatever number of samples per second.
You may be wondering why, you know,
you can have of course, over samplings on your DAW,
so many DAWs will allow you to record at
much higher sample rates, 96,000 samples per second.
They'll also allow 48,000 samples per second,
which is very close
to the standard CD rate of 44,100 samples per second.
So like, why bother?
Why have it 44.1 and then also 48,000?
The reason is because of scoring video.
So since so much film is 24 frames per second,
if you are scoring a movie
or TV advertisement, whatever,
and it's 24 frames per second
and your audio is 48,000 frames per second,
those divide into each other very tidally, right?
So you have exactly 2,000 samples per frame.
That's why that is.
Then finally, another kind of System Message
is the System Exclusive Message.
And it's called exclusive
because it's specific to one device,
one musical machine,
it's addressed to a specific machine.
So for instance, I could be sending
out a System Exclusive message,
I say this is for
machine number such and such
which means the Moog synthesizer or the Yamaha DX7,
I'm talking to a specific manufactured keyboard
or other kind of synthesizer or musical device.
And the main reason,
the main use for SysEx message
is to address something that's specific to that instrument.
Usually that means to edit the sound parameters
of that instrument.
So if you have a synthesizer where you can adjust,
let's say, the FM synthesis algorithm
to change the tone color,
or if it works the way a Hammond organ does
with additives synthesis and you can have
different strengths of different harmonics.
And these are all things that you can program
on the synthesizer itself.
You can also, instead of programming
them on the synthesizer itself,
you can address those via MIDI
by using a System Exclusive message
that's designed to talk only to that specific instrument.
Now I've been describing everything as if you were running
an old-fashioned MIDI electronic studio,
where you had multiple different devices,
all changed together and being controlled
from your master keyboard controller or from your computer.
Not many of you are likely to be working that way.
Nowadays, people much more often are using,
maybe they just have the one MIDI controller,
say a master keyboard, which is plugged into their computer,
and then, for many people, all of the MIDI music making
that they're doing is inside the computer,
inside Logic or Reason or Cubase,
where there are these software synthesizers
which are generating sounds in response
to the MIDI data that they're receiving.
So it actually works exactly the same way
as I've been describing,
except that it's all internal, it's all Logic,
say talking to itself.
So I play MIDI data or I draw in
or enter MIDI information in some way.
And then on track one, maybe that MIDI data
gets sent to Logic's flute software instrument,
and on track two, it gets sent
to the drum kit that I'm using in Logic.
But it works on exactly the same principle.
It's sending MIDI information internally
to generate sounds in response to those MIDI messages.
Now, speaking of the old days versus now,
I was gonna talk some
about MIDI hardware and connections.
I'm gonna just breeze over this really quickly,
because for 99% of you, this will not be relevant.
Nowadays, you simply take your MIDI device,
your keyboard or whatever it might be,
and it probably has a USB connector
which you can plug directly
into the USB port of your computer
and, magically, your keyboard is communicating
with your notation software, your audio software, et cetera.
There is actually something called a MIDI interface
which converts the MIDI data
into a form that can be sent via USB.
But that's all, again, under the hood nowadays,
it's happening inside the device.
However, if you are using machines that are not that old,
maybe 10, 15 years old,
you will see often that they have
actual MIDI ports on the back.
They have what's called a MIDI in and a MIDI out
and sometimes a MIDI through port,
and these do not plug directly into your computer.
In fact, if you go to our tech lab,
you'll see that there are MIDI cables
coming out of the Yamaha keyboards
and going into a little standalone interface
which is converting the information
and then sending it via USB into the computer
where you can deal with it in Logic or in Sibelius.
So there's like a whole protocol
and a whole knowledge you have to have
if you're going to be hooking up these now
somewhat old fashioned or vintage devices.
And that still happens some.
So I'm assigning some reading that will talk about that
but I will spare that for us now.
And go on and to talk about
MIDI and sound quality.
So a lot of, MIDI has this reputation
of creating not very good sound.
People are like, "Oh I don't want that lousy MIDI sound,
give me real audio.
I don't want this cheap, tinny MIDI sound."
Well, the thing about MIDI sound quality is,
there is no such thing as MIDI sound quality,
because MIDI is not audio.
Have I said that before?
MIDI is not audio, it's performance data.
It tells other instruments
to create audio,
to trigger their audio functions to create sound.
So why does MIDI have this reputation
of being tinny and cheap and inexpressive?
Well, part of the reason
is that back in the day,
in the 1980s when MIDI was invented,
remember that computers did not have
very sophisticated digital audio capabilities, right?
So as people became more familiar,
as MIDI files sort of entered the general consciousness
in the 1990s, people associated MIDI and MIDI files
with the MIDI playback of those files on their computers.
And their computers,
you know, had these cheap, as I said,
sound cards that really couldn't do very much, right.
They basically beeped.
So you could have a MIDI sound file,
or excuse me, a MIDI file that would sound fantastic
if realized on high-quality synthesis equipment,
but played back on people's computer,
it sounded cheap and tinny
like all of their computer sounds.
And the same with early video games
whether they were computer-based video games
or standalone games, like in a game arcade,
the sound quality was not very good.
And that's what people associated with MIDI.
Also low-budget soundtracks
when people couldn't afford real musicians
and they would instead use these,
not very sophisticated yet, 1980s, 1990s virtual instruments
on synthesizers, it didn't sound great.
So people thought that's what MIDI sounds like.
But, again, MIDI doesn't sound like anything.
The other thing is that MIDI files,
and we'll talk about MIDI file formats in a minute,
but MIDI files are often hard quantized.
They don't have to be, but they are often hard quantized
which means that things happen exactly on the beat
or on the eighth note of the 16,
with no expressive variation.
So people also associate MIDI
with this very mechanical, very inexpressive
sort of performance,
which might sound great for certain kinds of hip hop,
techno dance music.
But for a lot of music, it's gonna sound just
really mechanical and robotic.
But that's not MIDI,
that's just the nature of how people use MIDI
and how people realize those MIDI files
on their sound equipment.
So let's talk about file formats.
MIDI results in a standard MIDI file,
has either the .smf or the .mid format.
And these MIDI files, the intent of these MIDI files,
right, is to generate sound.
So that means that a synthesizer,
whether it's the software synthesizer inside your computer
or a standalone synthesizer,
it takes this MIDI data,
these smf or .mid files
and creates from them digital audio,
uses them to trigger the digital audio
that those instruments produce.
That's the normal direction from MIDI to digital audio.
You can also, to some degree,
can you go the other direction?
Can you go from audio to MIDI?
Can you take an audio signal
and generate MIDI data or a MIDI file from that?
Well, in the 1980s, the short answer is no.
When MIDI was invented,
this was not something you could do.
But more recently, this has become,
with certain limitations,
this has become possible.
So nowadays, there is software
that can do frequency analysis.
It can take an audio signal and say,
"Hmm, that sounds like a middle C
plus the G above it
and the F sharp below it." right?
This is all based on the same theory
that, just as all sounds are,
can be represented as a sum
of various different sine waves,
likewise even the most complex repeating sounds
can be broken down into a series of component frequencies
using something called Fast Fourier Transform.
So algorithms exist
that can take audio signals
and deduce or analyze from them
what are the component frequencies.
And then once you know the component frequencies
and when they started and stopped,
you can turn that into MIDI information.
There are limitations.
It depends how good your software is, how fast it is
and also how complex or dirty the original audio is.
So this might work very well for,
say the recording of a slow piano piece
with only one or two different parts.
But if you put in a complex symphonic sound
or something with lots of
non-harmonic sounds, like percussion,
then this won't work as well.
So MIDI, once again,
came into existence at a time when computers,
personal computers, were barely able
to do much in terms of generating and editing
digital audio, right?
There were standalone synthesizers
that did a pretty good job of this
and you could send the MIDI information to these things.
But the computers themselves not so much.
And hence MIDI was really important
as a medium of communication
between controllers or computer-based sequencers
and the instruments that would be generating the sounds
from the information, from the MIDI information.
But nowadays, computers of course, much faster,
much more sophisticated,
and even your phone can record digital audio
and process it and edit it.
So is MIDI on the way out, do we still need to have MIDI?
The answer is that MIDI is not going anywhere.
It's still enormously important, enormously useful
in any number of software applications
that are basically speaking the language of MIDI
that are entirely dependent on MIDI to do what they do.
For example, notation programs, such as Sibelius,
which we'll be learning in a little while.
Notation programs, for one thing,
you can enter information,
you can say I'm playing these notes on my keyboard
and that's usually the most efficient
and best way to enter musical data
into a score notation program.
The score notation programs
can also take the music that you've entered
and play them back by taking the MIDI information,
which is being represented as notes on a staff,
notes on a score,
but which exists behind the scenes as MIDI information,
so the notation program can play the score back
which is enormously important
in checking to see what you've written
or making sure that you haven't got some typos
or other errors in your notation, and so on.
CAI, computer aided instruction,
is often very MIDI intensive.
So there may be musicianship and ear training programs,
they play a sound and they say,
"Now you play that sound on your keyboard." right?
Or "You play the notes that you're hearing."
or "The chord progression that has just been played."
and so on, those are computer aided instruction
that's often MIDI-based.
Automated accompaniment
which has become more and more sophisticated.
So if I'm playing a violin concerto
and I want the orchestral accompaniment,
but I want it in a format
that can lead and follow, can play with me,
and that I can change the tempo
and adjust and all these things,
those are often MIDI-based accompaniments.
Likewise, if you're familiar with the program Band-in-a-Box,
which is the best of several similar programs.
You can enter a lead sheet, like a jazz lead sheet,
into Band-in-a-Box,
and it will play the rhythm section, right?
From the MIDI data,
and using MIDI to create these realizations
of the bass part and the drum part and the piano part.
And it can even make solos, right?
Generate it algorithmically, all of this is MIDI-based.
And then of course sequencers.
So when you're in your DAW workstation software,
there's audio recording and editing,
but there's also a MIDI layer
in all these DAWs where you can use MIDI
to control the software instruments
or to control external instruments
via your master file.
All of this is communication,
whether internal or external, via MIDI.
So MIDI remains important,
even as PC-based audio
has become more and more sophisticated.
But you often don't see the difference, right?
So, I mean, in other words, again,
a lot of this stuff is
invisible to the user.
You're just playing stuff and you're hearing sounds.
So the question is,
do you really need to understand much
about how MIDI works and what MIDI is,
how it is like an unlike audio files,
or is that all just
like insider information that's not necessary?
And the answer is, yes,
you definitely need to understand how MIDI works
and how it is distinguished from audio.
And to understand that,
let's look at a couple of things in Logic.
So here I am in Logic, I'm creating a new project.
Immediately, I have to decide if my track is an audio track
or a Software Instrument or an External MIDI instrument.
An audio track is just what you think it is.
I'm going to have a track where I can record
and edit digital audio information.
If I create a New External MIDI Track,
I'm creating a track where I can record MIDI information
and edit it in Logic,
but that information is intended to be sent
out from my computer
to some external MIDI sound producing device.
If I create a Software Instrument Track,
what is that?
Is that audio, is that MIDI? Yes.
Okay, a software instrument,
what that means in Logic,
is that I'm going to be recording
MIDI information into this track.
But within Logic, again, sort of under the hood, seamless,
within Logic, Logic is gonna take that MIDI information
and assign it to a synthesized
or sample instrument within Logic.
But it's still a MIDI controlled synthesizer.
It's just all happening inside your computer.
So it's going to take my MIDI information
and it's going to also interpret it.
So I'll hear whatever I hear, right?
But it's important to know which is which
and what you can and can't do
with different kinds of tracks,
and also what you do and don't want to do
with different kinds of tracks.
So, for instance, if I record Classic Electric Piano
in my Software Instrument Track,
when I'm done, I have to know,
do I want to, say send this to someone
and be sure that they're hearing exactly what I'm hearing,
in which case, I need to Bounce that file or that track,
I need to Bounce it in some audio file format,
whether it's an AIFF or a WAV file or an MP3.
On the other hand,
if my intention is to upload this to the internet
so that somebody could download it very quickly
and play it back, and I don't care
if they have exactly the right sound that I have,
or maybe I'm putting it up on the internet
because I want somebody to be able to import it
into a notation program and notate it for me,
or maybe I was recording it just as a dummy track
and actually I wanna send this to my producer
and have them play a really sick bass sound,
and I'd rather have them have the MIDI information
so that they can easily convert that into something else.
So that's sort of my rough overview, introduction to MIDI.
There are some things, again,
that may be of historical interest,
but you don't need to know,
there are other things that you might need to know
if you are a very MIDI-intensive electronic musician.
But if you're mostly thinking
about just recording and producing live audio sounds,
maybe aren't so as important to you.
And then there are things that everybody needs to know.
So if you have any questions about any of this,
you know what to do, right?
Go jump over to Yellowdig
and we can talk about things further there.