CIS4390 - Presentation - Java Sound API MIDI - Jon Cobb

8/16/2019 CIS4390 - Presentation - Java Sound API MIDI - Jon Cobb

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An Introduction to MIDI Programming with

The Java Sound API : Overview

Provides low level services for digital audio andmidi processing.

Is essentially an abstraction layer over the lowerlevel native services offered by the operatingsystem.Is hardware agnostic and relies on the operatingsystem to provide access to hardwareresources.The Java Sound packages were designed toprovide application programmers with aconsistent interface to resources and servicesregardless of the audio hardware configuration.

The Java Sound API : Packages

Two main packages – targeted byapplication programmers

javax.sound.sampled – provides services forcapturing, mixing, and playback of digital audiostreams.

javax.sound.midi – provides services to supportMIDI synthesis, sequencing, and eventcapture/playback.


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Devices, Transmitters, andReceivers

Transmitters generate MIDI messages andstream them to connected receivers.

MIDI Streaming vs. Sequencing Streaming – Real Time

Processing

MessagesMessage TypeChannel Number

Associated Data

Sequencing – Relative

Time Processing

EventsMessage TypeChannel Number

Associated DataRelative Time

MIDI Streaming

Can be thought of as “Live” MIDIMIDI Messages contain no timing informationand are processed immediately as they arrive.Examples:

A MIDI controller generates MIDI messages which arestreamed to capture devices (like sequencers) duringrecording or sound generators (like synthesizers)during performance.

A MIDI sequencer generates MIDI messages whichare streamed to devices which generate sound (likesynthesizers) during playback.

MIDI Sequencing

Can be thought of as “Scheduled” MIDI.MIDI Events contain MIDI Messages andassociated timing values.Examples:

Playback - A MIDI file stores a series of MIDI Eventswhich a sequencer can use to generate MIDImessages to send to sound generating devices at theappropriate time.Capture - A MIDI sequencer captures MIDI messagesfrom a MIDI controller and adds a time stamp to themessage data for storage and subsequent playback.


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MIDI Data Flow Sequences and Tracks

Sequence – stored in a MIDI File ormanaged by a MIDI Sequencer.

A Sequence can be thought of as a MIDIschedule.

Track – represents a MIDI Event schedulefor a single instrument/performer/voice.

Sequences and Tracks

A sequence can be thought of as an entire“song,” whereas a track can be thought of asa single part of the song like “the guitar part”or the “drum part.”

A sequence can, but does not necessarilyhave to, contain multiple tracks.

Sequences and Tracks

A Sequence is a collection of Tracks

A Track is a collection of MIDI Events

A MIDI Event is a MIDI Message combinedwith timing information.


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MidiDevice Interface

Interface implemented by softwarerepresentations of MIDI devices.

Can represent both software devices andhardware devices.

Implementations provide all functionalityrequired by a MIDI port (input or output).

MidiDevice Interface

open(), close(), isOpen()

getDeviceInfo()

getReceiver(), getReceivers(),getMaxReceivers()

getTransmitter(), getTransmitters(),getMaxTransmitters()

getMicrosecondPosition()

MidiDevice.Info Class

A data access class whose soleresponsibility is to provide informationdescribing a MidiDevice instance.

Clients of a MidiDevice may obtain aninstance of this class to query for informationabout the MidiDevice by calling theMidiDevice’s getDeviceInfo() method.


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MidiDevice.Info Class

getName()

getVendor()

getVersion()

getDescription()

Transmitter Interface

Interface implemented by software objectsthat transmit MIDI messages on behalf of aMidiDevice implementation.

Examples: Sequencers and MIDI Input Portsprovide Transmitters to clients.


Instances of a MidiDevice’s Transmitterimplementation can be obtained by callingthe MidiDevice’s getTransmitter() method.

Be sure to call the Transmitter instance’sclose() method when the Transmitter is nolonger needed.


setReceiver(), getReceiver()

close()


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Receiver Interface

Interface implemented by software objectsthat receive MIDI messages on behalf of aMidiDevice implementation.

Examples: Synthesizers and MIDI OutputPorts provide Receivers to clients.

Receiver Interface

Instances of a MidiDevice’s Receiverimplementation can be obtained by callingthe MidiDevice’s getReceiver() method.

Be sure to call the Receiver instance’sclose() method when the Receiver is nolonger needed.

Receiver Interface

send()

close()

MidiMessage Class

Base class for all MIDI Messageimplementations.

Provides access to the message’s statusbyte, data bytes, and total message length.

Subclasses include ShortMessage,

MetaMessage, and SysExMessage classes.


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MidiMessage Class

getStatus()

getLength()

getMessage()

ShortMessage Class

Implements data access and transport forshort messages (2 data bytes) which areusually associated with MIDI channels.

Examples: Note On and Note Off messages

ShortMessage Class

getCommand()

getChannel()

getData1(), getData2()

getDataLength()

setMessage()

ShortMessage Class

Status code byte values are provided bystatic fields on the ShortMessage class.

Examples:ShortMessage.NOTE_ONShortMessage.NOTE_OFFShortMessage.PITCH_BEND


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SysexMessage Class

Implements data access and transport forMIDI system exclusive messages.

MIDI system exclusive messages are largelyvendor specific and are variable in size.

SysexMessage Class

getData()

setMessage()

MetaMessage Class

Implements data access and transport forMIDI meta messages.

MetaMessages are used in MIDI files andSequences and are not used during livecommunication.

Contain data useful for sequencers liketempo changes, time signatures, etc.

MetaMessage Class

getType()

getData()

setMessage()


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Sequence Interface

Extends the MidiDevice Interface

Implemented by classes which representMIDI Sequencers.

Sequencer Interface

getSequence(), setSequence()

getTickLength()

getTickPosition(), setTickPosition()

start(), stop()

Sequencer Interface

startRecording(), stopRecording()

isRunning(), isRecording()

getTrackSolo(), setTrackSolo()

getTrackMute(), setTrackMute()

Sequencer Interface

addControllerEventListener()

addMetaEventListener()


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MidiEvent Class

Implements data access and transport for aMIDI Event.

Is, quite simply, a container for aMidiMessage object and an associated tickvalue.

MidiEvent Class

getTick(), setTick()

getMessage()

Event Listener Interfaces

ControllerEventListener InterfacecontrolChange()

MetaEventListener Interfacemeta()

Synthesizer Interface

Extends the MidiDevice Interface

Implemented by software objects thatrepresent MIDI Synthesizers.

Implementations of this interface are theonly objects in the Midi package that

produce audio.


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Synthesizer Interface

getChannels()

getAvailableInstruments()

getMaxPolyphony()

getLatency()

getVoiceStatus()

Instrument Class

Implements the sound synthesis algorithmsfor a specific instrument provided by aSoundbank.

To use an instance of an Instrument objectwith a Synthesizer, that Instrument and itsSoundbank must be loaded into theSynthesizer.

Instrument Class

getName()

getPatch()

Patch Class

Implementation of an Instrument’s soundpatch.

Represents the “location” at which aninstrument’s data is loaded into asynthesizer.

Provides the bank and program numbers to

a MidiChannel so the channel can use theinstrument.


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MidiSystem Class

Provides access to the system’s MIDI

resources (installed hardware and softwarebased MIDI devices, soundbanks, etc.)

Like most subsystems in the Java Libraries,the MIDI subsystem is implemented as aSingleton by exposing only static methods.

MidiSystem Class

getMidiDeviceInfo()

getMidiDevice()

getReceiver(), getTransmitter(),getSynthesizer(), getSequencer()

getSequence()

MidiSystem Class

getMidiFileTypes()

write()


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References

JavaSound API Programmer’s Guide

http://download.oracle.com/javase/1.5.0/docs/guide/sound/programmer_guide/index.html

Java SE 6 APIhttp://download.oracle.com/javase/6/docs/api/javax/sound/midi/package-summary.html

Java Sound API – Soundbankshttp://www.oracle.com/technetwork/java/soundbanks-135798.html

Documents

CIS4390 - Presentation - Java Sound API MIDI - Jon Cobb