Midi Parser

A robust MIDI parser which can parse and validate any MIDI files.

How to use in your project

The easiest way to use this library is to clone the repo and put the jar file in your local Maven repository using the command

./gradlew publishToMavenLocal

Next, you can easily include the project in Gradle with

repositories {
    mavenLocal()
}

dependencies {
    implementation("com.ejrp.midi:MidiParser:1.0")
}

or in Maven with

<dependency>
    <groupId>com.ejrp.midi</groupId>
    <artifactId>MidiParser</artifactId>
    <version>1.0</version>
</dependency>

Parsing MIDI files

To parse a MIDI file, use the StandardMidiFileClass

val file = File("input.mid")
val midiFile = StandardMidiFile.fromInputStream(file.inputStream())

Error handling

Different exceptions will be thrown if the structure of the MIDI file is invalid. Look inside the MidiExceptions.kt file for possible exceptions thrown by the parser.

Writing MIDI files

To write a MIDI file, create a StandardMidiFileClass using its constructor. You will be working directly with header/tracks chunks and MIDI events to make your MIDI file. Check out the links below to read more about the MIDI specs if you have never worked with it.

Warning: You can create invalid MIDI files this way

Here is an example of a basic MIDI file which plays a C-Major chord

val midiFile = StandardMidiFile(
    HeaderChunk(0u, 1u, TicksPerQuarterNoteDivision(96u)),
    MidiSequence(listOf(
        TrackChunk(listof(
            NoteOn(
                VariableLengthQuantity(0u), 0, MidiKey.C4, MidiVelocity.Forte
            ),
            NoteOn(
                VariableLengthQuantity(0u), 0, MidiKey.E4, MidiVelocity.Forte
            ),
            NoteOn(
                VariableLengthQuantity(0u), 0, MidiKey.G4, MidiVelocity.Forte
            ),
            // a delta-time of 96 is a quarter note since there are 96 ticks per quarter note
            NoteOn(
                VariableLengthQuantity(96u), 0, MidiKey.C4, MidiVelocity.Niente
            ),
            NoteOn(
                VariableLengthQuantity(96u), 0, MidiKey.E4, MidiVelocity.Niente
            ),
            NoteOn(
                VariableLengthQuantity(96u), 0, MidiKey.G4, MidiVelocity.Niente
            ),
            EndOfTrack(VariableLengthQuantity(0u))
        ))
    ))
)

To write the MIDI file to a file:

val file = File("output.mid")
midiFile.toOutputStream(file.outputStream())

Notes Regarding the parser

Despite what the MIDI specification says, this parser does not support MIDI file formats other than 0, 1, and 2. It also will not parse the file if the track chunk has any length other than 6. This means that if you are using an extended specification of the MIDI file format, this parser will need to be modified to support it.

Links

Official MIDI specs: https://www.midi.org/specifications
Old MIDI File Format Tutorial Page: http://www.music.mcgill.ca/~ich/classes/mumt306/StandardMIDIfileformat.html#BM2_3