1. Creating Simple Music By Keith Lynn
Field Trip #20
Creating Simple Music
By Keith Lynn

2. Midi Midi stands for Musical Instrument Digital Interface
It is an interface that allows a variety of instruments to connect and communicate with each other
A single midi link can carry up to 16 channels of information
We can connect a channel to a different device

3. Midi cont'd A Midi Event message carries information about Pitch
Notation
Velocity
Volume
etc

4. Instrument
An instrument is represented by an integer between 0 and 255
You can find a list of instruments at nstruments

5. Creating the Midi
In order to create the midi, we will create a Sequencer
After we create the Sequencer, we open it
We create a Sequence
The Sequence is made of Tracks
The Tracks are made up of MidiEvents
The MidiEvent is composted of a MidiMessage and a tick. The tick indicates the time in the sequence where the event fires

6. MidiMessage In this app, we will create a simple message
A ShortMessage contains two bytes of information
To create the ShortMessage, we specify four things
A Midi command
A channel
The first data byte
The second data byte

7. Midi Commands
The ShortMessage class contains constants that represent Midi commands
Some of the most common are
Note on – Start Playing
Note off – Stop Playing
Program change – Specify what instrument is on a channel

8. Playing Notes The third parameter to create the ShortMessage is a note
Middle C is 60
The fourth parameter is the velocity
Typically we can use 100

9. Playing the sound
In order to play the Midi sound, we create the ShortMessages and create a MidiEvent
The MidiEvent specifies the ShortMessage and the tick
The tick is the time when the event fires

10. Creating the Midi Player
In our app, we allow the user to specify through Java components, the values to create a ShortMessage
These ShortMessages appear in a Jpanel
When we are ready to play, we click Play and each of the MidiMessages are put into a track, and the track put in a sequence, and the sequence put in the sequencer

11. Storing MidiEvents
In our app, we create a Jpanel called a MidiMessagePanel
This class is declared to be Serialiazable
This means that instances of the class can be written to a file
Later we can read them back in
In order to write the objects, we use an ObjectOutputStream, and in order to read the objects, we use an ObjectInputStream