So far we've been focusing on sound as the main type of data within our DAW. But there's a separate kind of data that's called MIDI-data which is also very important in a contemporary music production. And it, it's important to understand the fundamentals of MIDI if we want to really work well with a contemporary DAW. Now MIDI is not a direct representation of sound, like our digital audio is. Instead, it's more like the score that a musician would read. But instead of a musician reading it directly, some sort of synthesizer or sampler receives this data. And performs it or realizes it as audio which we can actually hear. MIDI stands for Musical Instrument Digital Interface and it's what we call a serial protocol in that one bit of information is sent at a time. Now it's being sent very fast, so if we do play a chord, it can sound like it's chord, but really one bit of information is sent at a time. And it's important to know what kind of information is sent with each MIDI message. A MIDI message includes a channel number and there are 16 possible channels in the MIDI specification. You can think of it like TV channels. And it would allow me to play a single keyboard and access 16 different sound sources which would be synthesizers or samplers. After the channel, the type of message is sent and there are a variety of different types of MIDI messages. One of them is a note message, so we can have a note on or a note off message. you might have noticed on many keyboards there are a bunch of knobs. Well, most of those send control change messages. And there's also one special knob that changes the pitch of the synthesizer or sampler patch, and that's called a pitch bend. So those are the types of messages. And then there's going to be two data words. And these gives us the parameters of those messages. So let's think about a note on a message. I hold the key down on my keyboard. And it sends a note on message on a particular channel. Along with that is going to be one data word that tells us which note it is. Is it middle C is it the C above that. And then there is another message that sends the velocity. Now velocity really is how hard you hit the key, we just happen to call it velocity. But really is just how hard you hit the key. Now, both data words are 7 bit numbers, and as we heard earlier, if we want to know how many values there are in a word. We take 2 to the power of the length of the word, and we get the number. So, these are 7 bit words, so we get messages from 0 to 127. And you're going to see those kind of numbers all over the place. Now a message is sent when you hold down the key. When I release the key, a second message is sent which is a note off message. That will also include the channel and the which note it is as a specific number. And it also includes a velocity which is a release velocity, how fast you let go of the key. Now, not all controllers send release velocity. Many do, kind of the more expensive ones usually. And not many synthesizer patches, or sampler patches really respond to it. It'd be tough to come up with a, a parameter of sound that would change with how fast you release the key. But some synthesizers and sampler do respond to that. Now it's important to know that two different messages are sent. Because there are times when you're working with the DAW or the controller that you find that a note just hangs on forever. You call it a hungnote. And that's the instance where the receiving synth had received the note on message, but didn't receive the note off so it just keeps the note playing. The solution to that is just to hit all the keys on your keyboard and so it gets one of those note offs, or use some kind of MIDI panic function. And panic means to send all notes off which will stop everything from playing. Now there's a couple other things that are done with MIDI data. You'll find that you have sustain pedals on keyboards. Well, a sustain pedal sends a control change message. You might have a bunch of knobs on your keyboards. Those also send control change messages. In fact, anytime you want to change a parameter of a note over the course of a note, usually there will be a control change message. There's also one other important type of message which is channel pressure. And again some keyboards have this, some don't. But that's a measurement of how hard your pushing down on the keyboard. So, with many synthesizer pads you can play the note and then push on the keyboard harder and it will change the quality of the sound in some way. Now that's an important thing to think about. In that we have this kind of consistent protocol, the MIDI message protocol. But it's really up to the receiving synthesizer or sampler on how to respond to that. And while there are some kind of standardized ways for a synthesizer and sampler to respond, like velocity control and volume. It doesn't always have to respond that way. So, one of the tricky things about MIDI, is you're really not so sure, when you send a MIDI message, exactly how the synthesizer or sampler will respond. Sometimes it will just ignore velocity messages. You had pulled up a patch that was, say, an organ sound or a harpsichord. It might do nothing with velocity, because those instruments them selves don't respond to how hard the key was hit. So, it's just important to understand that there is a kind of sending machine. Right? A track might send MIDI data somehow and there might be another device that receives it. And that receiving device really determines what happens with that data. [UNKNOWN] One thing to just also be, just kind of thinking about is that everything you define with MIDI data. That's equivalent to a score, it's instructions to a performer on how to work with that information. If you want something that's more for the engineer, that might be information that you would do, say in the DAW intself and not send to the synthesizer. So when we talk about automation, we're going to be talking about something that's not sent to MIDI data, but is directed towards the DAW. It will look a lot like MIDI control change messages. You'll have lines, you'll kind of draw, draw shapes and create variations in sound. But if it's going directly to the DAW, that will be automation, and if it's going to one of the MIDI synthesizers, that will be a control change message. Now throughout the discussion, I use two terms, Sampler and Synthesizer, kind of repeatedly. And I'd like to make a, you know just, just a point as to what those two things are. These going to be, these are going to be our two main sound sources, synthesizers and samplers. And they function in a similar way. They receive MIDI data and they output an audio signal. How they create that audio signal is a little bit different from each other. A synthesizer will have kind of a geometric waveform or a formula for creating sound. Hear your typical synthesizer sounds and it might start with a square wave or a solid tooth wave form. And we're going to talk about synthesizers in great depth later in the course. A sampler is going to play back previously recorded audio files, which makes sense, right? Sampling, we talked about, is a copy or taking a little bit of audio and using it repeatedly. Samplers are going to be great for recreating real instrument sounds. So, a sampled violin say, really [INAUDIBLE] had a person that played every note on a violin one by one. Recorded each one of those audio files and then mapped it across the keyboard. So now it's an instrument that can be played, a sample instrument that can be played across the keyboard. So, they can very accurately represent real instruments while synthesizers are great at creating synthesizer sounds. Kind of not real sounds perfect for dance and electronic types of music.
