Portability	GHC (at least generalized newtype deriving)
Stability	unstable
Maintainer	Stephen Tetley <stephen.tetley@gmail.com>
Safe Haskell	None

ZMidi.Core.Datatypes

Contents

MidiFile syntax.

Description

Concrete syntax tree for MIDI files.

Values are sometimes not interpreted. This means that the the data types do not fully represent the sematics of the data, but all the data is either stored in the tree or synthesizeable.

readFile >>= writeFile will produce an identical binary [1].

[1] Or it should, failure indicates a bug...

Synopsis

MidiFile syntax.

data DeltaTime Source

All time values in a MIDI track are represented as a delta from the previous event rather than an absolute time.

DeltaTime is a newtype wrapper over Word32, note that in MIDI files it is represented as a varlen to save space rather than a four byte number.

Instances

Enum DeltaTime
Eq DeltaTime
Integral DeltaTime
Num DeltaTime
Ord DeltaTime
Real DeltaTime
Show DeltaTime

type TagByte = Word8 Source

TagByte is an alias to Word8.

data MidiFile Source

MidiFile : header * tracks

Constructors

MidiFile
Fields mf_header :: MidiHeader mf_tracks :: [MidiTrack]

Instances

Eq MidiFile
Show MidiFile

data MidiHeader Source

Header : format * num_tracks * time_division

TimeDivision is often 384 or 480 ticks per beat.

The header is the start of a MIDI file, it is indicated by the 4 character marker MThd.

Constructors

MidiHeader
Fields hdr_format :: MidiFormat num_tracks :: Word16 time_division :: MidiTimeDivision

Instances

Eq MidiHeader
Show MidiHeader

newtype MidiTrack Source

Track : [message]

In MIDI files, the start of a track is indicated by the 4 character marker MTrk.

Constructors

MidiTrack
Fields getTrackMessages :: [MidiMessage]

Instances

Eq MidiTrack
Show MidiTrack

data MidiFormat Source

The file format - in a MIDI file this is a big-endian word16 with 0,1 or 2 being the only valid values.

Constructors

MF0	Format 0 file - single multi-channel track.
MF1	Format 1 file - 1 or more tracks, played simultaneously.
MF2	Format 2 file - 1 or more independent tracks.

Instances

Enum MidiFormat
Eq MidiFormat
Show MidiFormat

type MidiMessage = (DeltaTime, MidiEvent)Source

MIDI messages are pairs of DeltaTime and Event wrapped in a newtype.

Sequential messages with delta time 0 are played simultaneously.

data MidiEvent Source

Recognised event types - some types (DataEvent and SysEx) are not interpreted.

Constructors

DataEvent MidiDataEvent	Data event - just initial tag byte, uninterpreted
VoiceEvent MidiVoiceEvent	Voice event (e.g `note-on`, `note-off`) are relayed to specific channels.
SysExEvent MidiSysExEvent	SysEx - system exclusive event. Usually synthesizer specific, not interpreted.
SysCommonEvent MidiSysCommonEvent	SysCommon - system common event.
SysRealTimeEvent MidiSysRealTimeEvent	SysRealTime - system realtime event.
MetaEvent MidiMetaEvent	Meta event - interpreted (e.g. `end-of-track`, `set-tempo`).

Instances

Eq MidiEvent
Ord MidiEvent
Show MidiEvent

newtype MidiDataEvent Source

Data events are events with tags from 0x00 to 0x7F.

Data events have no payload - they are represented only by the tag byte.

Constructors

MidiDataEvent
Fields getTagByte :: TagByte

Instances

Eq MidiDataEvent
Ord MidiDataEvent
Show MidiDataEvent

data MidiVoiceEvent Source

Voice events control the output of the synthesizer.

Note - the constructors are not in the the same order as their byte values. Controller and ProgramChange are higher than they naturally occur so the will come first after a comparison or sort.

When generating MIDI, Controller and ProgramChange events should be signalled before NoteOn or NoteOff events at the same delta-time. Changing the order of the constructors helps to sort for this.

Constructors

Controller Word8 Word8 Word8	channel * controller_number * value Controller change, e.g. by a footswitch.
ProgramChange Word8 Word8	`channel * program_number` - change the instrument playing on the specified channel. For playback on computers (rather than synthesizers) the program numbers will correspond to the General MIDI instrument numbers.
NoteOff Word8 Word8 Word8	channel * note * velocity Turn off a sounding note.
NoteOn Word8 Word8 Word8	channel * note * velocity Start playing a note.
NoteAftertouch Word8 Word8 Word8	channel * note * pressure_value Change of pressure applied to the synthesizer key.
ChanAftertouch Word8 Word8	channel * pressure_value
PitchBend Word8 Word16	channel * value Change the pitch of a sounding note. Often used to approximate microtonal tunings. NOTE - currently value is uninterpreted.

Instances

Eq MidiVoiceEvent
Ord MidiVoiceEvent
Show MidiVoiceEvent

data MidiSysExEvent Source

SysEx - system exclusive event.

Constructors

SysEx Word32 [Word8]

 length * data

An uninterpreted sys-ex event.

Instances

Eq MidiSysExEvent
Ord MidiSysExEvent
Show MidiSysExEvent

data MidiSysCommonEvent Source

System common event.

Common information for all channels in a system.

These events may not be pertinent to MIDI files generated on a computer (as opposed to MIDI generated by a synthesizer or sequencer).

Constructors

QuarterFrame Word8	Time code quarter frame. Note the payload is really a byte split into two 4-bit values, however here it is uninterpreted.
SongPosPointer Word8 Word8	Song position pointer.
SongSelect Word8	song_number Song number should be in the range 0..127.
Common_undefined TagByte	Tag should be limited to 0xF4 or 0xF5. Other values would indicate either a badly formed MIDI file or a failure with the parser.
TuneRequest	Tune request message for analogue synthesizers.
EOX	End-of-system-exclusive message.

Instances

Eq MidiSysCommonEvent
Ord MidiSysCommonEvent
Show MidiSysCommonEvent

data MidiSysRealTimeEvent Source

System real-time event.

These events may not be pertinent to MIDI files generated on a computer (as opposed to MIDI generated by a synthesizer or sequencer).

Constructors

TimingClock	Timing signal.
RT_undefined TagByte	Tag should be limited to either 0xF9 or 0xFD. Other values would indicate either a badly formed MIDI file or a failure with the parser.
StartSequence	Start playing a sequence.
ContinueSequence	Continue playing a stopped sequence.
StopSequence	Stop playing a sequence.
ActiveSensing	Synchronization pulse...
SystemReset	Reset to power-up status.

Instances

Eq MidiSysRealTimeEvent
Ord MidiSysRealTimeEvent
Show MidiSysRealTimeEvent

data MidiMetaEvent Source

Meta event

In Format 1 files general events (e.g. text events) should only appear in track 1. Certain events (e.g. end-of-track) can appear in any track where necessary.

Constructors

TextEvent MidiTextType String	Text / copywright etc. FF * text_type * contents Free text field (e.g. copyright statement). The contents can notionally be any length.
SequenceNumber Word16	Sequence Number FF 00 02 * value Format 1 files - only track 1 should have a sequence number. Format 2 files - a sequence number should identify each track. The sequence number event should occur at the start of a track, before any non-zero time events.
ChannelPrefix Word8 Word8	Channel prefix FF 20 01 * channel Relay all meta and sys-ex events to the given channel. The first byte should always be 1.
MidiPort Word8	Midi port FF 21 01 * port Midi port number - used to workaround 16 channel limit...
EndOfTrack	End-of-track event. FF 2F 00
SetTempo Word32	Set tempo FF 51 03 * microseconds_per_quarter_note
SMPTEOffset Word8 Word8 Word8 Word8 Word8	SMPTE offest FF 54 05 * hour * minute * second * frac * subfrac The SMPTE time when a track should start. This event should occur at the start of a track, before any non-zero time events.
TimeSignature Word8 Word8 Word8 Word8	Time signature FF 58 04 * numerator * denominator * metro * num_32nd_notes
KeySignature Int8 MidiScaleType	Key signature FF 59 02 * key_type * scale_type `key_type` is the number of sharps (postive numbers) or flats (negative numbers), e.g. (-1) is 1 flat. `scale_type` indicates major or minor.
SSME Word32 [Word8]	SSME FF 7F * length * data Sequencer specific meta-event - uninterpreted.
MetaOther Word8 Word32 [Word8]	Unrecognized Meta Event FF * type * length * data

Instances

Eq MidiMetaEvent
Ord MidiMetaEvent
Show MidiMetaEvent

data MidiTimeDivision Source

Default unit of time in the MIDI file.

Constructors

FPS Word16	Frames-per-second.
TPB Word16	Ticks-per-beat, i.e. the number of units for a quarter note.

Instances

Eq MidiTimeDivision
Show MidiTimeDivision

data MidiTextType Source

Enumeration of the text meta event types.

Constructors

GENERIC_TEXT
COPYRIGHT_NOTICE
SEQUENCE_NAME
INSTRUMENT_NAME
LYRICS
MARKER
CUE_POINT

Instances

Enum MidiTextType
Eq MidiTextType
Ord MidiTextType
Show MidiTextType

data MidiScaleType Source

Scale type - major or minor or SCALE_OTHER.

SCALE_OTHER represents a parse error.

Constructors

MAJOR
MINOR
SCALE_OTHER Word8

Instances

Eq MidiScaleType
Ord MidiScaleType
Show MidiScaleType