MIDIMUSIC.ORG.UK Computer Processed Music

  1. Index
  2. Technical Articles
  3. Midi File Specification

Standard MIDI-File Format Spec. 1.1, updated

Abstract.

A detailed Specification of the Standard MIDI file format

Table of Contents

Acknowledgement:

This document was originally distributed in text format by The International MIDI Association. I have updated it and added new Appendices.
© Copyright 1999 David Back.
EMail:
Web: http://www.midimusic.org.uk
This document may be freely copied in whole or in part provided the copy contains this Acknowledgement.

0 - Introduction

This document details the structure of MIDI Files. The purpose of MIDI Files is to provide a way of interchanging time-stamped MIDI data between different programs on the same or different computers. One of the primary design goals is compact representation, which makes it very appropriate for disk-based file format, but which might make it inappropriate for storing in memory for quick access by a sequencer program.

MIDI Files contain one or more MIDI streams, with time information for each event. Song, sequence, and track structures, tempo and time signature information, are all supported. Track names and other descriptive information may be stored with the MIDI data. This format supports multiple tracks and multiple sequences so that if the user of a program which supports multiple tracks intends to move a file to another one, this format can allow that to happen.

The specification defines the 8-bit binary data stream used in the file. The data can be stored in a binary file, nibbilized, 7-bit-ized for efficient MIDI transmission, converted to Hex ASCII, or translated symbolically to a printable text file. This spec addresses what's in the 8-bit stream. It does not address how a MIDI File will be transmitted over MIDI.

1 - Sequences, Tracks, Chunks: File Block Structure

In this document, bit 0 means the least significant bit of a byte, and bit 7 is the most significant.

1.1 - Variable Length Quantity

Some numbers in MIDI Files are represented in a form called VARIABLE-LENGTH QUANTITY. These numbers are represented 7 bits per byte, most significant bits first. All bytes except the last have bit 7 set, and the last byte has bit 7 clear. If the number is between 0 and 127, it is thus represented exactly as one byte.

Some examples of numbers represented as variable-length quantities:

00000000 00
00000040 40
0000007F 7F
00000080 81 00
00002000 C0 00
00003FFF FF 7F
00004000 81 80 00
00100000 C0 80 00
001FFFFF FF FF 7F
00200000 81 80 80 00
08000000 C0 80 80 00
0FFFFFFF FF FF FF 7F

The largest number which is allowed is 0FFFFFFF so that the variable-length representations must fit in 32 bits in a routine to write variable-length numbers. Theoretically, larger numbers are possible, but 2 x 108 96ths of a beat at a fast tempo of 500 beats per minute is four days, long enough for any delta-time!

1.2 - Files

To any file system, a MIDI File is simply a series of 8-bit bytes. On the Macintosh, this byte stream is stored in the data fork of a file (with file type 'MIDI'), or on the Clipboard (with data type 'MIDI'). Most other computers store 8-bit byte streams in files.

1.3 - Chunks

MIDI Files are made up of -chunks-. Each chunk has a 4-character type and a 32-bit length, which is the number of bytes in the chunk. This structure allows future chunk types to be designed which may be easily be ignored if encountered by a program written before the chunk type is introduced. Your programs should EXPECT alien chunks and treat them as if they weren't there.

Each chunk begins with a 4-character ASCII type. It is followed by a 32-bit length, most significant byte first (a length of 6 is stored as 00 00 00 06). This length refers to the number of bytes of data which follow: the eight bytes of type and length are not included. Therefore, a chunk with a length of 6 would actually occupy 14 bytes in the disk file.

This chunk architecture is similar to that used by Electronic Arts' IFF format, and the chunks described herein could easily be placed in an IFF file. The MIDI File itself is not an IFF file: it contains no nested chunks, and chunks are not constrained to be an even number of bytes long. Converting it to an IFF file is as easy as padding odd length chunks, and sticking the whole thing inside a FORM chunk.

1.4 - Chunk Types

MIDI Files contain two types of chunks: header chunks and track chunks. A -header- chunk provides a minimal amount of information pertaining to the entire MIDI file. A -track- chunk contains a sequential stream of MIDI data which may contain information for up to 16 MIDI channels. The concepts of multiple tracks, multiple MIDI outputs, patterns, sequences, and songs may all be implemented using several track chunks.

A MIDI File always starts with a header chunk, and is followed by one or more track chunks.

MThd <length of header data>
<header data>
MTrk <length of track data>
<track data>
MTrk <length of track data>
<track data>
. . .

2 - Chunk Descriptions

2.1 - Header Chunks

The header chunk at the beginning of the file specifies some basic information about the data in the file. Here's the syntax of the complete chunk:

<Header Chunk> = <chunk type><length><format><ntrks><division>

As described above, <chunk type> is the four ASCII characters 'MThd'; <length> is a 32-bit representation of the number 6 (high byte first).

The data section contains three 16-bit words, stored most-significant byte first.

The first word, <format>, specifies the overall organisation of the file. Only three values of <format> are specified:

0-the file contains a single multi-channel track
1-the file contains one or more simultaneous tracks (or MIDI outputs) of a sequence
2-the file contains one or more sequentially independent single-track patterns

More information about these formats is provided below.

The next word, <ntrks>, is the number of track chunks in the file. It will always be 1 for a format 0 file.

The third word, <division>, specifies the meaning of the delta-times. It has two formats, one for metrical time, and one for time-code-based time:

bit 15 bits 14 thru 8bits 7 thru 0
0 ticks per quarter-note
1 negative SMPTE format ticks per frame

If bit 15 of <division> is zero, the bits 14 thru 0 represent the number of delta time "ticks" which make up a quarter-note. For instance, if division is 96, then a time interval of an eighth-note between two events in the file would be 48.

If bit 15 of <division> is a one, delta times in a file correspond to subdivisions of a second, in a way consistent with SMPTE and MIDI Time Code. Bits 14 thru 8 contain one of the four values -24, -25, -29, or -30, corresponding to the four standard SMPTE and MIDI Time Code formats (-29 corresponds to 30 drop frame), and represents the number of frames per second. These negative numbers are stored in two's compliment form. The second byte (stored positive) is the resolution within a frame: typical values may be 4 (MIDI Time Code resolution), 8, 10, 80 (bit resolution), or 100. This stream allows exact specifications of time-code-based tracks, but also allows millisecond-based tracks by specifying 25 frames/sec and a resolution of 40 units per frame. If the events in a file are stored with a bit resolution of thirty-frame time code, the division word would be E250 hex.

2.2 - MIDI File Formats 0,1 and 2

A Format 0 file has a header chunk followed by one track chunk. It is the most interchangeable representation of data. It is very useful for a simple single-track player in a program which needs to make synthesisers make sounds, but which is primarily concerned with something else such as mixers or sound effect boxes. It is very desirable to be able to produce such a format, even if your program is track-based, in order to work with these simple programs.

A Format 1 or 2 file has a header chunk followed by one or more track chunks. programs which support several simultaneous tracks should be able to save and read data in format 1, a vertically one dimensional form, that is, as a collection of tracks. Programs which support several independent patterns should be able to save and read data in format 2, a horizontally one dimensional form. Providing these minimum capabilities will ensure maximum interchangeability.

In a MIDI system with a computer and a SMPTE synchroniser which uses Song Pointer and Timing Clock, tempo maps (which describe the tempo throughout the track, and may also include time signature information, so that the bar number may be derived) are generally created on the computer. To use them with the synchroniser, it is necessary to transfer them from the computer. To make it easy for the synchroniser to extract this data from a MIDI File, tempo information should always be stored in the first MTrk chunk. For a format 0 file, the tempo will be scattered through the track and the tempo map reader should ignore the intervening events; for a format 1 file, the tempo map must be stored as the first track. It is polite to a tempo map reader to offer your user the ability to make a format 0 file with just the tempo, unless you can use format 1.

All MIDI Files should specify tempo and time signature. If they don't, the time signature is assumed to be 4/4, and the tempo 120 beats per minute. In format 0, these meta-events should occur at least at the beginning of the single multi-channel track. In format 1, these meta-events should be contained in the first track. In format 2, each of the temporally independent patterns should contain at least initial time signature and tempo information.

Format IDs to support other structures may be defined in the future. A program encountering an unknown format ID may still read other MTrk chunks it finds from the file, as format 1 or 2, if its user can make sense of them and arrange them into some other structure if appropriate. Also, more parameters may be added to the MThd chunk in the future: it is important to read and honour the length, even if it is longer than 6.

2.3 - Track Chunks

The track chunks (type MTrk) are where actual song data is stored. Each track chunk is simply a stream of MIDI events (and non-MIDI events), preceded by delta-time values. The format for Track Chunks (described below) is exactly the same for all three formats (0, 1, and 2: see "Header Chunk" above) of MIDI Files.

Here is the syntax of an MTrk chunk (the + means "one or more": at least one MTrk event must be present):

<Track Chunk> = <chunk type><length><MTrk event>+

The syntax of an MTrk event is very simple:

<MTrk event> = <delta-time><event>

<delta-time> is stored as a variable-length quantity. It represents the amount of time before the following event. If the first event in a track occurs at the very beginning of a track, or if two events occur simultaneously, a delta-time of zero is used. Delta-times are always present. (Not storing delta-times of 0 requires at least two bytes for any other value, and most delta-times aren't zero.) Delta-time is in some fraction of a beat (or a second, for recording a track with SMPTE times), as specified in the header chunk.

<event> = <MIDI event> | <sysex event> | <meta-event>

<MIDI event> is any MIDI channel message See Appendix 1 - MIDI Messages. Running status is used: status bytes of MIDI channel messages may be omitted if the preceding event is a MIDI channel message with the same status. The first event in each MTrk chunk must specify status. Delta-time is not considered an event itself: it is an integral part of the syntax for an MTrk event. Notice that running status occurs across delta-times.

<sysex event> is used to specify a MIDI system exclusive message, either as one unit or in packets, or as an "escape" to specify any arbitrary bytes to be transmitted. See Appendix 1 - MIDI Messages. A normal complete system exclusive message is stored in a MIDI File in this way:

F0 <length> <bytes to be transmitted after F0>

The length is stored as a variable-length quantity. It specifies the number of bytes which follow it, not including the F0 or the length itself. For instance, the transmitted message F0 43 12 00 07 F7 would be stored in a MIDI File as F0 05 43 12 00 07 F7. It is required to include the F7 at the end so that the reader of the MIDI File knows that it has read the entire message.

Another form of sysex event is provided which does not imply that an F0 should be transmitted. This may be used as an "escape" to provide for the transmission of things which would not otherwise be legal, including system realtime messages, song pointer or select, MIDI Time Code, etc. This uses the F7 code:

F7 <length> <all bytes to be transmitted>

Unfortunately, some synthesiser manufacturers specify that their system exclusive messages are to be transmitted as little packets. Each packet is only part of an entire syntactical system exclusive message, but the times they are transmitted are important. Examples of this are the bytes sent in a CZ patch dump, or the FB-01's "system exclusive mode" in which microtonal data can be transmitted. The F0 and F7 sysex events may be used together to break up syntactically complete system exclusive messages into timed packets.

An F0 sysex event is used for the first packet in a series -- it is a message in which the F0 should be transmitted. An F7 sysex event is used for the remainder of the packets, which do not begin with F0. (Of course, the F7 is not considered part of the system exclusive message).

A syntactic system exclusive message must always end with an F7, even if the real-life device didn't send one, so that you know when you've reached the end of an entire sysex message without looking ahead to the next event in the MIDI File. If it's stored in one complete F0 sysex event, the last byte must be an F7. There also must not be any transmittable MIDI events in between the packets of a multi-packet system exclusive message. This principle is illustrated in the paragraph below.

Here is a MIDI File of a multi-packet system exclusive message: suppose the bytes F0 43 12 00 were to be sent, followed by a 200-tick delay, followed by the bytes 43 12 00 43 12 00, followed by a 100-tick delay, followed by the bytes 43 12 00 F7, this would be in the MIDI File:

F0 03 43 12 00 
81 48 200-tick delta time
F7 06 43 12 00 43 12 00 
64 100-tick delta time
F7 04 43 12 00 F7 

When reading a MIDI File, and an F7 sysex event is encountered without a preceding F0 sysex event to start a multi-packet system exclusive message sequence, it should be presumed that the F7 event is being used as an "escape". In this case, it is not necessary that it end with an F7, unless it is desired that the F7 be transmitted.

<meta-event> specifies non-MIDI information useful to this format or to sequencers, with this syntax:

FF <type> <length> <bytes>

All meta-events begin with FF, then have an event type byte (which is always less than 128), and then have the length of the data stored as a variable-length quantity, and then the data itself. If there is no data, the length is 0. As with chunks, future meta-events may be designed which may not be known to existing programs, so programs must properly ignore meta-events which they do not recognise, and indeed should expect to see them. Programs must never ignore the length of a meta-event which they do not recognise, and they shouldn't be surprised if it's bigger than expected. If so, they must ignore everything past what they know about. However, they must not add anything of their own to the end of the meta- event. Sysex events and meta events cancel any running status which was in effect. Running status does not apply to and may not be used for these messages.

3 - Meta-Events

A few meta-events are defined herein. It is not required for every program to support every meta-event.

In the syntax descriptions for each of the meta-events a set of conventions is used to describe parameters of the events. The FF which begins each event, the type of each event, and the lengths of events which do not have a variable amount of data are given directly in hexadecimal. A notation such as dd or se, which consists of two lower-case letters, mnemonically represents an 8-bit value. Four identical lower-case letters such as wwww mnemonically refer to a 16-bit value, stored most-significant-byte first. Six identical lower-case letters such as tttttt refer to a 24-bit value, stored most-significant-byte first. The notation len refers to the length portion of the meta-event syntax, that is, a number, stored as a variable- length quantity, which specifies how many bytes (possibly text) data were just specified by the length.

In general, meta-events in a track which occur at the same time may occur in any order. If a copyright event is used, it should be placed as early as possible in the file, so it will be noticed easily. Sequence Number and Sequence/Track Name events, if present, must appear at time 0. An end-of- track event must occur as the last event in the track.

3.1 - Meta-Event Definitions

FF 00 02 Sequence Number
This optional event, which must occur at the beginning of a track, before any nonzero delta-times, and before any transmittable MIDI events, specifies the number of a sequence. In a format 2 MIDI File, it is used to identify each "pattern" so that a "song" sequence using the Cue message can refer to the patterns. If the ID numbers are omitted, the sequences' locations in order in the file are used as defaults. In a format 0 or 1 MIDI File, which only contain one sequence, this number should be contained in the first (or only) track. If transfer of several multitrack sequences is required, this must be done as a group of format 1 files, each with a different sequence number.

FF 01 len text Text Event
Any amount of text describing anything. It is a good idea to put a text event right at the beginning of a track, with the name of the track, a description of its intended orchestration, and any other information which the user wants to put there. Text events may also occur at other times in a track, to be used as lyrics, or descriptions of cue points. The text in this event should be printable ASCII characters for maximum interchange. However, other character codes using the high-order bit may be used for interchange of files between different programs on the same computer which supports an extended character set. Programs on a computer which does not support non-ASCII characters should ignore those characters.

Meta-event types 01 through 0F are reserved for various types of text events, each of which meets the specification of text events (above) but is used for a different purpose:

FF 02 len text Copyright Notice
Contains a copyright notice as printable ASCII text. The notice should contain the characters (C), the year of the copyright, and the owner of the copyright. If several pieces of music are in the same MIDI File, all of the copyright notices should be placed together in this event so that it will be at the beginning of the file. This event should be the first event in the track chunk, at time 0.

FF 03 len text Sequence/Track Name
If in a format 0 track, or the first track in a format 1 file, the name of the sequence. Otherwise, the name of the track.

FF 04 len text Instrument Name
A description of the type of instrumentation to be used in that track. May be used with the MIDI Prefix meta-event to specify which MIDI channel the description applies to, or the channel may be specified as text in the event itself.

FF 05 len text Lyric
A lyric to be sung. Generally, each syllable will be a separate lyric event which begins at the event's time.

FF 06 len text Marker
Normally in a format 0 track, or the first track in a format 1 file. The name of that point in the sequence, such as a rehearsal letter or section name ("First Verse", etc.)

FF 07 len text Cue Point
A description of something happening on a film or video screen or stage at that point in the musical score ("Car crashes into house", "curtain opens", "she slaps his face", etc.)

FF 20 01 cc MIDI Channel Prefix
The MIDI channel (0-15) contained in this event may be used to associate a MIDI channel with all events which follow, including System exclusive and meta-events. This channel is "effective" until the next normal MIDI event (which contains a channel) or the next MIDI Channel Prefix meta-event. If MIDI channels refer to "tracks", this message may be put into a format 0 file, keeping their non-MIDI data associated with a track. This capability is also present in Yamaha's ESEQ file format.

FF 2F 00 End of Track
This event is not optional. It is included so that an exact ending point may be specified for the track, so that an exact length is defined, which is necessary for tracks which are looped or concatenated.

FF 51 03 tttttt Set Tempo (in microseconds per MIDI quarter-note)
This event indicates a tempo change. Another way of putting "microseconds per quarter-note" is "24ths of a microsecond per MIDI clock". Representing tempos as time per beat instead of beat per time allows absolutely exact long-term synchronisation with a time-based sync protocol such as SMPTE time code or MIDI time code. The amount of accuracy provided by this tempo resolution allows a four-minute piece at 120 beats per minute to be accurate within 500 usec at the end of the piece. Ideally, these events should only occur where MIDI clocks would be located -- this convention is intended to guarantee, or at least increase the likelihood, of compatibility with other synchronisation devices so that a time signature/tempo map stored in this format may easily be transferred to another device.

FF 54 05 hr mn se fr ff SMPTE Offset
This event, if present, designates the SMPTE time at which the track chunk is supposed to start. It should be present at the beginning of the track, that is, before any nonzero delta-times, and before any transmittable MIDI events. the hour must be encoded with the SMPTE format, just as it is in MIDI Time Code. In a format 1 file, the SMPTE Offset must be stored with the tempo map, and has no meaning in any of the other tracks. The ff field contains fractional frames, in 100ths of a frame, even in SMPTE-based tracks which specify a different frame subdivision for delta-times.

FF 58 04 nn dd cc bb Time Signature
The time signature is expressed as four numbers. nn and dd represent the numerator and denominator of the time signature as it would be notated. The denominator is a negative power of two: 2 represents a quarter-note, 3 represents an eighth-note, etc. The cc parameter expresses the number of MIDI clocks in a metronome click. The bb parameter expresses the number of notated 32nd-notes in a MIDI quarter-note (24 MIDI clocks). This was added because there are already multiple programs which allow a user to specify that what MIDI thinks of as a quarter-note (24 clocks) is to be notated as, or related to in terms of, something else.

Therefore, the complete event for 6/8 time, where the metronome clicks every three eighth-notes, but there are 24 clocks per quarter-note, 72 to the bar, would be (in hex):

FF 58 04 06 03 24 08

That is, 6/8 time (8 is 2 to the 3rd power, so this is 06 03), 36 MIDI clocks per dotted-quarter (24 hex!), and eight notated 32nd-notes per quarter-note.

FF 59 02 sf mi Key Signature
sf = -7: 7 flats
sf = -1: 1 flat
sf = 0: key of C
sf = 1: 1 sharp
sf = 7: 7 sharps

mi = 0: major key
mi = 1: minor key

FF 7F len data Sequencer Specific Meta-Event
Special requirements for particular sequencers may use this event type: the first byte or bytes of data is a manufacturer ID (these are one byte, or if the first byte is 00, three bytes). As with MIDI System Exclusive, manufacturers who define something using this meta-event should publish it so that others may be used by a sequencer which elects to use this as its only file format; sequencers with their established feature-specific formats should probably stick to the standard features when using this format.

See Appendix 2 - Program Fragments and Example MIDI Files for an example midi file.


Appendix 1 - MIDI Messages

A MIDI message is made up of an eight-bit status byte which is generally followed by one or two data bytes. There are a number of different types of MIDI messages. At the highest level, MIDI messages are classified as being either Channel Messages or System Messages. Channel messages are those which apply to a specific Channel, and the Channel number is included in the status byte for these messages. System messages are not Channel specific, and no Channel number is indicated in their status bytes.

Channel Messages may be further classified as being either Channel Voice Messages, or Mode Messages. Channel Voice Messages carry musical performance data, and these messages comprise most of the traffic in a typical MIDI data stream. Channel Mode messages affect the way a receiving instrument will respond to the Channel Voice messages.

MIDI System Messages are classified as being System Common Messages, System Real Time Messages, or System Exclusive Messages. System Common messages are intended for all receivers in the system. System Real Time messages are used for synchronisation between clock-based MIDI components. System Exclusive messages include a Manufacturer's Identification (ID) code, and are used to transfer any number of data bytes in a format specified by the referenced manufacturer.

Appendix 1.1 - Table of Major MIDI Messages

Channel Voice Messages
Status
D7----D0
nnnn is the MIDI channel no.
Data Byte(s)
D7----D0
Description
1000nnnn0kkkkkkk
0vvvvvvv
Note Off event.
This message is sent when a note is released (ended).
(kkkkkkk) is the key (note) number.
(vvvvvvv) is the velocity.
1001nnnn0kkkkkkk
0vvvvvvv
Note On event.
This message is sent when a note is depressed (start).
(kkkkkkk) is the key (note) number.
(vvvvvvv) is the velocity.
1010nnnn0kkkkkkk
0vvvvvvv
Polyphonic Key Pressure (Aftertouch).
This message is most often sent by pressing down on the key after it "bottoms out".
(kkkkkkk) is the key (note) number.
(vvvvvvv) is the pressure value.
1011nnnn0ccccccc
0vvvvvvv
Control Change.
This message is sent when a controller value changes. Controllers include devices such as pedals and levers. Certain controller numbers are reserved for specific purposes. See Channel Mode Messages.
(ccccccc) is the controller number.
(vvvvvvv) is the new value.
1100nnnn0pppppppProgram Change.
This message sent when the patch number changes.
(ppppppp) is the new program number.
1101nnnn0vvvvvvvChannel Pressure (After-touch).
This message is most often sent by pressing down on the key after it "bottoms out". This message is different from polyphonic after-touch. Use this message to send the single greatest pressure value (of all the current depressed keys).
(vvvvvvv) is the pressure value.
1110nnnn0lllllll
0mmmmmmm
Pitch Wheel Change.
This message is sent to indicate a change in the pitch wheel. The pitch wheel is measured by a fourteen bit value. Centre (no pitch change) is 2000H. Sensitivity is a function of the transmitter.
(lllllll) are the least significant 7 bits.
(mmmmmmm) are the most significant 7 bits.
Channel Mode Messages (See also Control Change, above)
1011nnnn0ccccccc
0vvvvvvv
Channel Mode Messages.
This the same code as the Control Change (above), but implements Mode control by using reserved controller numbers. The numbers are:
Local Control.
When Local Control is Off, all devices on a given channel will respond only to data received over MIDI. Played data, etc. will be ignored. Local Control On restores the functions of the normal controllers.
c = 122, v = 0: Local Control Off
c = 122, v = 127: Local Control On

All Notes Off.
When an All Notes Off is received all oscillators will turn off.
c = 123, v = 0: All Notes Off
c = 124, v = 0: Omni Mode Off
c = 125, v = 0: Omni Mode On
c = 126, v = M: Mono Mode On (Poly Off) where M is the number of channels (Omni Off) or 0 (Omni On)
c = 127, v = 0: Poly Mode On (Mono Off) (Note: These four messages also cause All Notes Off)

System Common Messages
111100000iiiiiii
0ddddddd
..
..
0ddddddd
11110111
System Exclusive.
This message makes up for all that MIDI doesn't support. (iiiiiii) is usually a seven-bit Manufacturer's I.D. code. If the synthesiser recognises the I.D. code as its own, it will listen to the rest of the message (ddddddd). Otherwise, the message will be ignored. System Exclusive is used to send bulk dumps such as patch parameters and other non-spec data. (Note: Real-Time messages ONLY may be interleaved with a System Exclusive.) This message also is used for extensions called Universal Exclusive Messages.
11110001 Undefined.
111100100lllllll
0mmmmmmm
Song Position Pointer.
This is an internal 14 bit register that holds the number of MIDI beats (1 beat= six MIDI clocks) since the start of the song. l is the LSB, m the MSB.
111100110sssssssSong Select.
The Song Select specifies which sequence or song is to be played.
11110100 Undefined.
11110101 Undefined.
11110110 Tune Request.
Upon receiving a Tune Request, all analog synthesisers should tune their oscillators.
11110111 End of Exclusive.
Used to terminate a System Exclusive dump (see above).
System Real-Time Messages
11111000 Timing Clock.
Sent 24 times per quarter note when synchronisation is required.
11111001 Undefined.
11111010 Start.
Start the current sequence playing. (This message will be followed with Timing Clocks).
11111011 Continue.
Continue at the point the sequence was Stopped.
11111100 Stop.
Stop the current sequence.
11111101 Undefined.
11111110 Active Sensing.
Use of this message is optional. When initially sent, the receiver will expect to receive another Active Sensing message each 300ms (max), or it will be assume that the connection has been terminated. At termination, the receiver will turn off all voices and return to normal (non-active sensing) operation.
11111111 Reset.
Reset all receivers in the system to power-up status. This should be used sparingly, preferably under manual control. In particular, it should not be sent on power-up.
In a MIDI file this is used as an escape to introduce <meta events>.

Appendix 1.2 - Table of MIDI Controller Messages (Data Bytes)

The following table lists the MIDI Controller messages in numerical (binary) order.

2nd Byte ValueFunction3rd Byte
BinaryHexDec ValueUse
00000000000Bank Select0-127MSB
00000001011* Modulation wheel0-127MSB
00000010022Breath control0-127MSB
00000011033Undefined0-127MSB
00000100044Foot controller0-127MSB
00000101055Portamento time0-127MSB
00000110066Data Entry0-127MSB
00000111077* Channel Volume (formerly Main Volume)0-127MSB
00001000088Balance0-127MSB
00001001099Undefined0-127MSB
000010100A10* Pan0-127MSB
000010110B11* Expression Controller0-127MSB
000011000C12Effect control 10-127MSB
000011010D13Effect control 20-127MSB
000011100E14Undefined0-127MSB
000011110F15Undefined0-127MSB
000100001016General Purpose Controller #10-127MSB
000100011117General Purpose Controller #20-127MSB
000100101218General Purpose Controller #30-127MSB
000100111319General Purpose Controller #40-127MSB
000101001420Undefined0-127MSB
000101011521Undefined0-127MSB
000101101622Undefined0-127MSB
000101111723Undefined0-127MSB
000110001824Undefined0-127MSB
000110011925Undefined0-127MSB
000110101A26Undefined0-127MSB
000110111B27Undefined0-127MSB
000111001C28Undefined0-127MSB
000111011D29Undefined0-127MSB
000111101E30Undefined0-127MSB
000111111F31Undefined0-127MSB
001000002032Bank Select0-127LSB
001000012133Modulation wheel0-127LSB
001000102234Breath control0-127LSB
001000112335Undefined0-127LSB
001001002436Foot controller0-127LSB
001001012537Portamento time0-127LSB
001001102638Data entry0-127LSB
001001112739Channel Volume (formerly Main Volume)0-127LSB
001010002840Balance0-127LSB
001010012941Undefined0-127LSB
001010102A42Pan0-127LSB
001010112B43Expression Controller0-127LSB
001011002C44Effect control 10-127LSB
001011012D45Effect control 20-127LSB
001011102E46Undefined0-127LSB
001011112F47Undefined0-127LSB
001100003048General Purpose Controller #10-127LSB
001100013149General Purpose Controller #20-127LSB
001100103250General Purpose Controller #30-127LSB
001100113351General Purpose Controller #40-127LSB
001101003452Undefined0-127LSB
001101013553Undefined0-127LSB
001101103654Undefined0-127LSB
001101113755Undefined0-127LSB
001110003856Undefined0-127LSB
001110013957Undefined0-127LSB
001110103A58Undefined0-127LSB
001110113B59Undefined0-127LSB
001111003C60Undefined0-127LSB
001111013D61Undefined0-127LSB
001111103E62Undefined0-127LSB
001111113F63Undefined0-127LSB
010000004064* Damper pedal on/off (Sustain)<63=off>64=on
010000014165Portamento on/off<63=off>64=on
010000104266Sustenuto on/off<63=off>64=on
010000114367Soft pedal on/off<63=off>64=on
010001004468Legato Footswitch<63=off>64=on
010001014569Hold 2<63=off>64=on
010001104670Sound Controller 1 (Sound Variation)0-127LSB
010001114771Sound Controller 2 (Timbre)0-127LSB
010010004872Sound Controller 3 (Release Time)0-127LSB
010010014973Sound Controller 4 (Attack Time)0-127LSB
010010104A74Sound Controller 5 (Brightness)0-127LSB
010010114B75Sound Controller 60-127LSB
010011004C76Sound Controller 70-127LSB
010011014D77Sound Controller 80-127LSB
010011104E78Sound Controller 90-127LSB
010011114F79Sound Controller 100-127LSB
010100005080General Purpose Controller #50-127LSB
010100015181General Purpose Controller #60-127LSB
010100105282General Purpose Controller #70-127LSB
010100115383General Purpose Controller #80-127LSB
010101005484Portamento Control0-127Source Note
010101015585Undefined0-127LSB
010101105686Undefined0-127LSB
010101115787Undefined0-127LSB
010110005888Undefined0-127LSB
010110015989Undefined0-127LSB
010110105A90Undefined0-127LSB
010110115B91Effects 1 Depth0-127LSB
010111005C92Effects 2 Depth0-127LSB
010111015D93Effects 3 Depth0-127LSB
010111105E94Effects 4 Depth0-127LSB
010111115F95Effects 5 Depth0-127LSB
 
011000006096Data entry +1N/A 
011000016197Data entry -1N/A 
011000106298Non-Registered Parameter Number LSB0-127LSB
011000116399Non-Registered Parameter Number MSB0-127MSB
0110010064100* Registered Parameter Number LSB0-127LSB
0110010165101* Registered Parameter Number MSB0-127MSB
0110011066102Undefined? 
0110011167103Undefined? 
0110100068104Undefined? 
0110100169105Undefined? 
011010106A106Undefined? 
011010116B107Undefined? 
011011006C108Undefined? 
011011016D109Undefined? 
011011106E110Undefined? 
011011116F111Undefined? 
0111000070112Undefined? 
0111000171113Undefined? 
0111001072114Undefined? 
0111001173115Undefined? 
0111010074116Undefined? 
0111010175117Undefined? 
0111011076118Undefined? 
0111011177119Undefined? 
 
0111100078120All Sound Off0 
0111100179121* Reset All Controllers0 
011110107A122Local control on/off0=off127=on
011110117B123* All notes off0 
011111007C124Omni mode off (+ all notes off)0 
011111017D125Omni mode on (+ all notes off)0 
011111107E126Poly mode on/off (+ all notes off)** 
011111117F127Poly mode on (incl mono=off +all notes off)0 
* Equipment must respond in order to comply with General MIDI level 1.
** This equals the number of channels, or zero if the number of channels equals the number of voices in the receiver.

Appendix 1.3 - Table of MIDI Note Numbers

This table (Amended August 2012) lists all MIDI Note Numbers (middle C is note 60) by octave.

The absolute octave number designations are based on Middle C = C5, which is an arbitrary assignment (as used by Cakewalk).

Octave #Note Numbers
 CC#DD#EF F#GG#AA#B
001234567891011
1121314151617181920212223
2242526272829303132333435
3363738394041424344454647
4484950515253545556575859
5606162636465666768697071
6727374757677787980818283
7848586878889909192939495
896979899100101102103104105106107
9108109110111112113114115116117118119
10120121122123124125126127    

Appendix 1.4 - General MIDI Instrument Patch Map

GM Instrument Families

The General MIDI instrument sounds are grouped by families. In each family are 8 specific instruments.

PC#FamilyPC#Family
1-8Piano65-72Reed
9-16Chromatic Percussion73-80Pipe
17-24Organ81-88Synth Lead
25-32Guitar89-96Synth Pad
33-40Bass97-104Synth Effects
41-48Strings105-112Ethnic
49-56Ensemble113-120Percussive
57-64Brass121-128Sound Effects

GM Instrument Patch Map

Note: While GM does not define the actual characteristics of any sounds, the names in parentheses after each of the synth leads, pads, and sound effects are, in particular, intended only as guides.

PC#InstrumentPC#Instrument
1.Acoustic Grand Piano65.Soprano Sax
2.Bright Acoustic Piano66.Alto Sax
3.Electric Grand Piano67.Tenor Sax
4.Honky-tonk Piano68.Baritone Sax
5.Electric Piano 1 (Rhodes Piano)69.Oboe
6.Electric Piano 2 (Chorused Piano)70.English Horn
7.Harpsichord71.Bassoon
8.Clavinet72.Clarinet
9.Celesta73.Piccolo
10.Glockenspiel74.Flute
11.Music Box75.Recorder
12.Vibraphone76.Pan Flute
13.Marimba77.Blown Bottle
14.Xylophone78.Shakuhachi
15.Tubular Bells79.Whistle
16.Dulcimer (Santur)80.Ocarina
17.Drawbar Organ (Hammond)81.Lead 1 (square wave)
18.Percussive Organ82.Lead 2 (sawtooth wave)
19.Rock Organ83.Lead 3 (calliope)
20.Church Organ84.Lead 4 (chiffer)
21.Reed Organ85.Lead 5 (charang)
22.Accordion (French)86.Lead 6 (voice solo)
23.Harmonica87.Lead 7 (fifths)
24.Tango Accordion (Band neon)88.Lead 8 (bass + lead)
25.Acoustic Guitar (nylon)89.Pad 1 (new age Fantasia)
26.Acoustic Guitar (steel)90.Pad 2 (warm)
27.Electric Guitar (jazz)91.Pad 3 (polysynth)
28.Electric Guitar (clean)92.Pad 4 (choir space voice)
29.Electric Guitar (muted)93.Pad 5 (bowed glass)
30.Overdriven Guitar94.Pad 6 (metallic pro)
31.Distortion Guitar95.Pad 7 (halo)
32.Guitar harmonics96.Pad 8 (sweep)
33.Acoustic Bass97.FX 1 (rain)
34.Electric Bass (fingered)98.FX 2 (soundtrack)
35.Electric Bass (picked)99.FX 3 (crystal)
36.Fretless Bass100.FX 4 (atmosphere)
37.Slap Bass 1101.FX 5 (brightness)
38.Slap Bass 2102.FX 6 (goblins)
39.Synth Bass 1103.FX 7 (echoes, drops)
40.Synth Bass 2104.FX 8 (sci-fi, star theme)
41.Violin105.Sitar
42.Viola106.Banjo
43.Cello107.Shamisen
44.Contrabass108.Koto
45.Tremolo Strings109.Kalimba
46.Pizzicato Strings110.Bag pipe
47.Orchestral Harp111.Fiddle
48.Timpani112.Shanai
49.String Ensemble 1 (strings)113.Tinkle Bell
50.String Ensemble 2 (slow strings)114.Agogo
51.SynthStrings 1115.Steel Drums
52.SynthStrings 2116.Woodblock
53.Choir Aahs117.Taiko Drum
54.Voice Oohs118.Melodic Tom
55.Synth Voice119.Synth Drum
56.Orchestra Hit120.Reverse Cymbal
57.Trumpet121.Guitar Fret Noise
58.Trombone122.Breath Noise
59.Tuba123.Seashore
60.Muted Trumpet124.Bird Tweet
61.French Horn125.Telephone Ring
62.Brass Section126.Helicopter
63.SynthBrass 1127.Applause
64.SynthBrass 2128.Gunshot

Appendix 1.5 - General MIDI Percussion Key Map

On MIDI Channel 10, each MIDI Note number ("Key#") corresponds to a different drum sound, as shown below. GM-compatible instruments must have the sounds on the keys shown here. While many current instruments also have additional sounds above or below the range show here, and may even have additional "kits" with variations of these sounds, only these sounds are supported by General MIDI.

Key#NoteDrum SoundKey#NoteDrum Sound
35B1Acoustic Bass Drum59B3Ride Cymbal 2
36C2Bass Drum 160C4Hi Bongo
37C#2Side Stick61C#4Low Bongo
38D2Acoustic Snare62D4Mute Hi Conga
39D#2Hand Clap63D#4Open Hi Conga
40E2Electric Snare64E4Low Conga
41F2Low Floor Tom65F4High Timbale
42F#2Closed Hi Hat66F#4Low Timbale
43G2High Floor Tom67G4High Agogo
44G#2Pedal Hi-Hat68G#4Low Agogo
45A2Low Tom69A4Cabasa
46A#2Open Hi-Hat70A#4Maracas
47B2Low-Mid Tom71B4Short Whistle
48C3Hi Mid Tom72C5Long Whistle
49C#3Crash Cymbal 173C#5Short Guiro
50D3High Tom74D5Long Guiro
51D#3Ride Cymbal 175D#5Claves
52E3Chinese Cymbal76E5Hi Wood Block
53F3Ride Bell77F5Low Wood Block
54F#3Tambourine78F#5Mute Cuica
55G3Splash Cymbal79G5Open Cuica
56G#3Cowbell80G#5Mute Triangle
57A3Crash Cymbal 281A5Open Triangle
58A#3Vibraslap   

Appendix 2 - Program Fragments and Example MIDI Files

Here are some of the routines to read and write variable-length numbers in MIDI Files. These routines are in C, and use getc and putc, which read and write single 8-bit characters from/to the files infile and outfile.

WriteVarLen(value)
register long value;
{
register long buffer;

buffer = value & 0x7f;
while((value >>= 7) > 0)
 {
 buffer <<= 8;
 buffer |= 0x80;
 buffer += (value &0x7f);
 }

while (TRUE)
 {
 putc(buffer,outfile);
 if(buffer & 0x80) buffer >>= 8;
 else
 break;
 }
}

doubleword ReadVarLen()
{
register doubleword value;
register byte c;

if((value = getc(infile)) & 0x80)
 {
 value &= 0x7f;
 do
  {
  value = (value << 7) + ((c = getc(infile))) & 0x7f);
  } while (c & 0x80);
 }
return(value);
}

As an example, MIDI Files for the following excerpt are shown below. First, a format 0 file is shown, with all information intermingled; then, a format 1 file is shown with all data separated into four tracks: one for tempo and time signature, and three for the notes. A resolution of 96 "ticks" per quarter note is used. A time signature of 4/4 and a tempo of 120, though implied, are explicitly stated.
test.gif
The contents of the MIDI stream represented by this example are broken down here:

Delta-Time
(decimal)
Event-Code
(hex)
Other Bytes
(decimal)
Comment
0 FF 58 04 04 02 24 08 4 bytes; 4/4 time; 24 MIDI clocks/click, 8 32nd notes/ 24 MIDI clocks (24 MIDI clocks = 1 crotchet = 1 beat)
0 FF 51 03 500000 3 bytes: 500,000 usec/ quarter note = 120 beats/minute
0 C0 5 Ch.1 Program Change 5 = GM Patch 6 = Electric Piano 2
0 C1 46 Ch.2 Program Change 46 = GM Patch 47 = Harp
0 C2 70 Ch.3 Program Change 70 = GM Patch 71 = Bassoon
0 92 48 96 Ch.3 Note On C3, forte
0 92 60 96 Ch.3 Note On C4, forte
96 91 67 64 Ch.2 Note On G4, mezzo-forte
96 90 76 32 Ch.1 Note On E5, piano
192 82 48 64 Ch.3 Note Off C3, standard
0 82 60 64 Ch.3 Note Off C4, standard
0 81 67 64 Ch.2 Note Off G4, standard
0 80 76 64 Ch.1 Note Off E5, standard
0 FF 2F 00 Track End
The entire format 0 MIDI file contents in hex follow. First, the header chunk:
4D 54 68 64 MThd
00 00 00 06 chunk length
00 00 format 0
00 01 one track
00 60 96 per quarter-note
Then the track chunk. Its header followed by the events (notice the running status is used in places):
4D 54 72 6B MTrk
00 00 00 3B chunk length (59)
Delta-Time Event Comments
00 FF 58 04 04 02 18 08 time signature
00 FF 51 03 07 A1 20 tempo
00 C0 05  
00 C1 2E 
00 C2 46 
00 92 30 60 
00 3C 60 running status
60 91 43 40 
60 90 4C 20 
81 40 82 30 40 two-byte delta-time
00 3C 40 running status
00 81 43 40 
00 80 4C 40 
00 FF 2F 00 end of track
A format 1 representation of the file is slightly different. Its header chunk:
4D 54 68 64 MThd
00 00 00 06 chunk length
00 01 format 1
00 04 four tracks
00 60 96 per quarter note
First, the track chunk for the time signature/tempo track. Its header, followed by the events:
4D 54 72 6B MTrk
00 00 00 14 chunk length (20)
Delta-Time Event Comments
00 FF 58 04 04 02 18 08 time signature
00 FF 51 03 07 A1 20 tempo
83 00 FF 2F 00 end of track
Then, the track chunk for the first music track. The MIDI convention for note on/off running status is used in this example:
4D 54 72 6B MTrk
00 00 00 10 chunk length (16)
Delta-Time Event Comments
00 C0 05 
81 40 90 4C 20 
81 40 4C 00 Running status: note on, vel=0
00 FF 2F 00  
Then, the track chunk for the second music track:
4D 54 72 6B MTrk
00 00 00 0F chunk length (15)
Delta-Time Event Comments
00 C1 2E 
60 91 43 40 
82 20 43 00 running status
00 FF 2F 00 end of track
Then, the track chunk for the third music track:
4D 54 72 6B MTrk
00 00 00 15 chunk length (21)
Delta-Time Event Comments
00 C2 46 
00 92 30 60 
00 3C 60 running status
83 00 30 00 two-byte delta-time, running status
00 3C 00 running status
00 FF 2F 00 end of track