I am a parser for a MIDI data stream. I support:

real-time MIDI recording,
overdubbing (recording while playing),
monitoring incoming MIDI, and
interactive MIDI performances.

Note: MIDI controllers such as pitch benders and breath controllers generate large volumes of data which consume processor time. In cases where this information is not of interest to the program using it, it is best to filter it out as soon as possible. I support various options for doing this filtering, including filtering by MIDI channel and/or by command type.

	midi filtering
	ignoreChannel: ignoreCommand: ignoreSysEx: ignoreTuneAndRealTimeCommands noFiltering recordOnlyChannels:

	midi monitor
	monitor printCmd:with:with:

	private-other
	setMIDIPort:

	private-state machine
	endSysExclusive: ignoreOne: ignoreTwo: ignoreZero: processByte: recordOne: recordTwo: recordZero: startSysExclusive: undefined:

	real-time processing
	midiDo: midiDoUntilMouseDown:

	recording
	clearBuffers processMIDIData received

	instance creation
	on:

	accessing	top
	midiPort
	midiPort: Use the given MIDI port.

	midi filtering	top
	ignoreChannel: Don't record any events arriving on the given MIDI channel (in the range 1-16).
	ignoreCommand: Don't record the given MIDI command on any channel.
	ignoreSysEx: If the argument is true, then ignore incoming system exclusive message.
	ignoreTuneAndRealTimeCommands Ignore tuning requests and real-time commands.
	noFiltering Revert to accepting all MIDI commands on all channels. This undoes any earlier request to filter the incoming MIDI stream.
	recordOnlyChannels: Record only MIDI data arriving on the given list of channel numbers (in the range 1-16).

	midi monitor	top
	monitor Print MIDI messages to the transcript until any mouse button is pressed.
	printCmd:with:with: Print the given MIDI command.

	private-other	top
	setMIDIPort: Initialize this instance for recording from the given MIDI port. Tune and real-time commands are filtered out by default; the client can send noFiltering to receive these messages.

	private-state machine	top
	endSysExclusive: Error! Received 'end system exclusive' command when not receiving system exclusive data.
	ignoreOne: Ignore a one argument command.
	ignoreTwo: Ignore a two argument command.
	ignoreZero: Ignore a zero argument command, such as tune request or a real-time message. Stay in the current and don't change active status. Note that real-time messages can arrive between data bytes without disruption.
	processByte: Process the given incoming MIDI byte and record completed commands.
	recordOne: Record a one argument command at the current time.
	recordTwo: Record a two argument command at the current time.
	recordZero: Record a zero-byte message, such as tune request or a real-time message. Don't change active status. Note that real-time messages can arrive between data bytes without disruption.
	startSysExclusive: The beginning of a variable length 'system exclusive' command.
	undefined: We have received an unexpected MIDI byte (e.g., a data byte when we were expecting a command). This should never happen.

	real-time processing	top
	midiDo: Poll the incoming MIDI stream in real time and call the given block for each complete command that has been received. The block takes one argument, which is an array of the form (<time><cmd byte>[<arg1>[<arg2>]]). The number of arguments depends on the command byte. For system exclusive commands, the argument is a ByteArray containing the system exclusive message.
	midiDoUntilMouseDown: Process the incoming MIDI stream in real time by calling midiActionBlock for each MIDI event. This block takes three arguments: the MIDI command byte and two argument bytes. One or both argument bytes may be nil, depending on the MIDI command. If not nil, evaluatue idleBlock regularly whether MIDI data is available or not. Pressing any mouse button terminates the interaction.

	recording	top
	clearBuffers Clear the MIDI record buffers. This should be called at the start of recording or real-time MIDI processing.
	processMIDIData Process all MIDI data that has arrived since the last time this method was executed. This method should be called frequently to process, filter, and timestamp MIDI data as it arrives.
	received Answer my current collection of all MIDI commands received. Items in this list have the form (<time><cmd byte>[<arg1>[<arg2>]]). Note that the real-time processing facility, midiDo:, removes items from this list as it processes them.

	class initialization	top
	initialize Build the default MIDI command-byte action table. This table maps MIDI command bytes to the action to be performed when that is received. Note that MIDI data bytes (bytes whose value is < 128) are never used to index into this table.

	instance creation	top
	on: Answer a new MIDI parser on the given port.