SYNOPSYS

gramophone2 [-c|-d] sourcefile [midifile]

OPTIONS

-c

is an option allowing you to control the syntax of the source without generating music.

-d

is an option allowing you to activate debug mode, with video output of the composition and player parameters plus the generated notes.

DESCRIPTION

In GRAMophone, the music is generated using two kinds of formal grammar: Chomsky's regular grammar (or Type 3) for a TOP DOWN approach to the composition and a reduced version of Lindenmayer grammar for a BOTTOM UP approach.

BASIC CONCEPT OF GRAMophone

GRAMophone is partly based on an idea of Jon McCormack's, who invented the idea of a virtual player (virtual musician). The player in question is associated with a MIDI track, and interprets instructions telling it what to do. Generally, they say play notes (send MIDI messages). GRAMophone's players together make up an orchestra, which plays a composition.

Any number of players can play a composition, but in practice the hardware used might impose an upper limit.

In general every player plays an instrument and each has a different set of grammar rules. An individual player is characterised by a set of parameters which are shared by the whole orchestra and/or a personal parameter set.

The orchestra's parameters consist of:

the kind of grammar used (Chomsky or Lindenmayer);

the metronome;

the measure;

the number of iterations used in the production process.

Each individual player's parameters consist of:

the kind of grammar used (Chomsky or Lindenmayer);

the instrument;

the MIDI channel associated with the player;

the number of iterations used in the production process;

A player's notes have a current state consisting of:

octave

volume

duration

release

These characteristics can be controlled parametrically by a player declaring its associated variables. GRAMophone, then, allows for the non-deterministic generation of music, using either Chomsky or Lindenmayer grammar.

GUIDE TO GRAMophone

"Give Me A" (The "Hello, World!" for GRAMophone")

To introduce you to the basic ideas, here is the simplest algorithmic composition that can be generated with GRAMophone: this composition simply generates the note A and is presented through both the Chomsky and Lindenmayer methods.

composition "Give Me A" of "Schroeder" {
  //this composition generates the A note with the Chomsky grammar
  grammar chomsky
  tempo 120
  time_signature 4/4
  %
  player Schroeder {
    instrument 0
    %
    @composition->A[,,,];
  }
}
composition "Give Me A" of "Schroeder" {
  //this composition generates the A note with the Lindenmayer grammar
  grammar lindenmayer
  tempo 120
  time_signature 4/4
  %
  player Schroeder {
    instrument 0
    %
    axiom->A[,,,];
  }
}

THE KEYWORDS composition E of

All compositions must begin with the keyword composition followed by a string (in inverted commas) containing the name of the composition. This must be followed by the keyword of then another string containing the copyright of the piece.

THE COMPOSITION BLOCK

The composition block is placed in brackets. It is subdivided into three sections: one section defines parameters of the composition, one declares and initiates any global variables and an orchestra section where the players who will 'play' the piece are defined. The first two sections are separated by the % symbol.

THE player KEYWORD

Each player is defined with the keyword player, followed by an identifier.

THE player BLOCK

The player block is placed in brackets and is divided into three sections: one section defines the parameters of the track associated with the player, one declares any local variables for the player and one is for the formal rules. The first two sections are separated by the % symbol.

COMMENTS

In GRAMophone, comments are C-like: they must begin with the character pair '/*' and end with the character pair '*/.' There must be no space between the asterisk and the slash. Everything between these pairs of symbols will be ignored by the GRAMophone parser. Whole lines of comments may also be included. Lines of comments begin with the symbol // and end at the end of the line, as in the two initial examples.

Section defining the composition's parameters

The parameters shared by all the orchestra's players are declared here. The parameters that may be declared are:

grammar

resolution

iterations

tempo

time_signature

This section must end with the % symbol.

grammar

This parameter is obligatory and defines the kind of grammar to be used in the generation. This can be either chomsky or lindenmayer.

resolution

This parameter defines the number of time units of 1/4 duration. If omitted, the default value 480 will be used.

iterations

This parameter defines the number of iterations contained in the generation. Its meaning depends on the kind of grammar chosen, as explained below. If omitted, the default value 1 will be used.

tempo

This parameter defines the composition's rhythm. If omitted, the default value 120 will be used.

time_signature

This parameter defines the composition's measure. If omitted, the default value 4/4 will be used.

Section declaring the composition's global variables

The variables control the parameters of a note's attributes, as explained below.

Section defining the player's parameters

Each player's personal parameters and variables are declared here. The personal parameters that may be declared are:

instrument

channel

iterations

This section must end with the % symbol.

instrument

This parameter indicates the player's instrument type. GRAMophone's instrument set is the same as that of General MIDI. The acceptable range of values is 0 to 127; there are therefore 128 instruments to choose from. A table showing the instrument codes appears below:

0 Piano

1 Brite Piano

2 HammerPiano

3 Honkey Tonk

4 New Tines

5 Digital Piano

6 Harpsichord

7 Clavi

8 Celesta

9 Glocken

10 Music Box

11 Vibes

12 Marimba

13 Xylophon

14 Tubular Bell

15 Santur

16 Full Organ

17 Percussive Organ

18 BX-3 Organ

19 Church Organ

20 Positive

21 Musette

22 Harmonica

23 Tango

24 Classic Guitar

25 Acoustic Guitar

26 Jazz Guitar

27 Clean Guitar

28 Mute Guitar

29 Overdrive Guitar

30 Distorted Guitar

31 Harmonics

32 Jazz Bass

33 Deep Bass

34 Pick Bass

35 Fretless Bass

36 Slap Bass 1

37 Slap Bass 2

38 Syntethized Bass 1

39 Syntethized Bass 2

40 Violin

41 Viola

42 Cello

43 Contra Bass

44 Tremolo String

45 Pizzicato

46 Harp

47 Timpani

48 Marcato

49 Slow String

50 Analog Pad

51 String Pad

52 Choir

53 Doo Voice

54 Voices

55 Orchestra Hit

56 Trumpet

57 Trombone

58 Tuba

59 Mute Trumpet

60 French Horn

61 Brass Section

62 Synthetized Brass 1

63 Synthetized Brass 2

64 Soprano Sax

65 Alto Sax

66 Tenor Sax

67 Baritone Sax

68 Sweet Oboe

69 English Horn

70 Bassoon Oboe

71 Clarinet

72 Piccolo

73 Flute

74 Recorder

75 Pan Flute

76 Bottle

77 Shakhukuhachi

78 Whistle

79 Ocarina

80 Square Lead

81 Saw Lead

82 Caliope Lead

83 Chiff Lead

84 Charang Lead

85 Air Chorus

86 Rezzo4ths

87 Bass & Lead

88 Fantasia

89 Warm Pad

90 Poly Synth Pad

91 Ghost Pad

92 Bowed Pad

93 Metal Pad

94 Halo Pad

95 Sweep Pad

96 Ice Rain

97 Soundtrack

98 Crystal

99 Atmosphere

100 Brightness

101 Goblin

102 Echo Drop

103 Star Theme

104 Sitar

105 Banjo

106 Shamisen

107 Koto

108 Kalimba

109 Scotland

110 Fiddle

111 Shanai

112 Metal Bell

113 Agogo

114 Steel Drums

115 Wood Blok

116 Taiko Drum

117 Melodic Tom

118 Synth Tom

119 Reverse Cymbal

120 Fret Noise

121 Noise Chiff

122 Seashore

123 Birds

124 Telephone

125 Helicopter

126 Stadium!!

127 Gunshot

If omitted, the default instrument value 0 is used.

channel

This parameter defines which Midi channel will be associated with the player. There are 16 possible channels. Channel 10 is reserved for percussion instruments. If omitted, the default channel value 1 is used.

iterations

This parameter defines the number of iterations in the generation. Its meaning depends on the kind of grammar chosen, as explained below. If the iterations parameter has been included in the composition declarations, the latter declaration will be ignored.

Section declaring the player's local variables

The variables control the parameters of a note's attributes, as explained below.

Notes in GRAMophone

HOW NOTES ARE WRITTEN DOWN IN GRAMophone

Notes are the first category of terminal symbols GRAMophone.

GRAMophone uses the English notation for notes:

        A B C D E F G

The names of notes must be written in capital letters. The flat and sharp symbols are represented by 'b' and '#' respectively; no space should appear between these symbols and the name of the note: A#, Gb, etc.

NOTE ATTRIBUTES

Notes can have four attributes in GRAMophone: octave, velocity, duration and release. The octave attribute varies between -2 and 8, while the velocity and release attributes vary from 0 to 127. If the note is written without attributes, then the following default values are used: 3 for octave, 64 for velocity and release. The current default value for duration is a crotchet. In the example, "Give me A" is written simply as A[,,,]. This means that an A is generated at the third octave, with a duration of 1/4 and a velocity and release of 64.

DEFINING THE ATTRIBUTES OF A NOTE

The attributes of a note are defined by writing them inside the square brackets which follow the name of the note, without spaces. A note can have four attributes at most and each attribute type may have only one value.

The attributes must be defined in the following order:

octave

velocity

duration

release

If all three attributes are not defined, the default value is used for the missing ones.

Here are some examples of notes with attributes:

C[2, 50+60/2, 240*4,] - plays a C at the second octave, with a velocity of 80, duration of 960 (minim with a resolution of 480) and a release of 64 (default value);

Db[4,,,] - plays a D flat at the fourth octave, using the default values for velocity, duration and release;

F#[,,,] - use the default values for all the attributes;

Incorrect examples are:

Db[3, 127, 960, 64, x] - too many attributes (x is a variable).

PAUSE

Pauses are another category of terminal symbol in GRAMophone. They are indicated by the letter R and only take a duration type attribute. If unspecified, the default resolution value is used. Attributes are defined in the same way as for notes.

Here are some examples of pauses:

R[480/2] - pause with a duration of 240;

R[] - use the default value for the attribute of type duration.

CHORDS

Chords are the final category of terminal symbol used in GRAMophone. A chord is a series of notes played simultaneously. In GRAMophone, notes played in a chord are enclosed between two '^' symbols.

Here are some examples of chords:

^C[,,,]E[,,,]G[,,,]^ - plays a C major chord, using each note's default values.

^A[2,80,240,]C[2,,240,]E[2,,240,]^ - plays an A minor chord with duration 1/8, with all notes at the second octave and velocity 64 (default value), with the first note of the chord played with a velocity of 80 and the remaining two at a velocity of 64 (default value).

THE ROLE OF R IN COMPLEX CHORDS

        The notes of a chord do not always have the same duration. For example it is possible that, while the note C[2,,1920,] of duration 4/4 is playing, the musician has to play four crotchets in the following order: C[,,,], E[,,,], G[,,,], Bb[,,,]. There has to be a way of telling GRAMophone that the notes C[2,,1920,] and C[,,,] must start at the same time, that E[,,,] must begin after a pause of 1/4, G[,,,] after 2/4 and Bb[,,,] after 3/4. In GRAMophone this is written as follows:

^C[2,,1920,]C[,,,]R[]E[,,,]R[960]G[,,,]R[1440]Bb[,,,]^

In other words, every note in the chord can be preceded by a pause definition representing the time to wait before playing the note.         It does not matter which order you write the notes down in a chord. The chord in the example above can also be written:

^R[]E[,,,]C[2,,1920,]R[1440]Bb[,,,]C[,,,]R[960]G[,,,]^

IDENTIFIERS

Some of GRAMophone's language entities, variables, macros and non-terminal symbols in Chomsky grammar for example, must have names by which they can be identified. These names are called identifiers and are chosen by the composer. GRAMophone's identifiers follow the system of identifiers used in the programming language Pascal. In fact an identifier is made up of a letter followed by a sequence of letters or digits. GRAMophone's identifiers must also be written in lower case.

Chomsky Grammar

NON-TERMINAL SYMBOLS

In Chomsky grammar non-terminal symbols are used to give a structure or 'style' to the musical composition. They are written with an '@' immediately followed by an identifier. The Chomsky grammar used by GRAMophone is context free so the head of the production can only be a non-terminal.

THE NON-TERMINAL SYMBOL @composition

This non-terminal symbol, which corresponds to the final composition of a single player, is obligatory.

PRODUCTION OPERATOR

This is defined by the character sequence '->' and separates the head of the production from the body.

BODY OF THE PRODUCTION

This may contain sequences of terminal (notes, pauses and chords) and non-terminal symbols. Each production must end with a semi-colon.

| (OR) OPERATOR

A production may be non-deterministic: in other words it may present two or more choices during generation. The body of a non-deterministic production is made up of the various choices separated by the | operator. For example

@non_det->A[,,,]B[,,,]@Seq1|^A[,,,]B[,,,]C[,,,]^@Seq2R[]C[,,,];

is a non-deterministic production.

MEANING OF ITERATION IN CHOMSKY GRAMMAR

In Chomsky grammar a production may include cycles, i.e. production bodies containing non-terminal symbols that refer to the production actually being produced. For example:

@Sequenza1->B[,,,]A[,,,]C[,,,]@Sequenza1;

To avoid an infinite loop during generation, the non-terminal symbol @Sequenza1 is processed an equal number of times to the iterations parameter.

Lindenmayer Grammar

Lindenmayer grammar only deals with terminal symbols and GRAMophone's version can be context-free or work in a polyphonic context. Therefore, single notes or chords can appear at the head of the production. All productions are separated by a semi-colon.

AXIOM

This is the initial production from which generation begins. It is obligatory. PRODUCTION OPERATOR

This is defined by the character sequence '->' and separates the head of the production from the body.

| (OR) OPERATOR

A production may be non-deterministic: in other words it may present two or more choices during generation. The body of a non-deterministic production is made up of the various choices separated by the | operator. For example

A[,,,]->A[,,,]B[,,,]|C[,,,]D[,,,];

is a non-deterministic production.

MEANING OF ITERATIONS IN LINDENMAYER GRAMMAR

At each step all the grammar's productions are simultaneously applied to the note string. In this case the iterations parameter represents the number of steps to be carried out.

Use of variables

DECLARATION AND INITIALISATION OF VARIABLES

GRAMophone is able to control the attributes of a note parametrically through the use of variables. These variables are declared in the player's declaration section and may be of the following types: octave, velocity, duration and msb. A variable is declared by writing its type followed by one or more identifiers separated by a comma. The declaration must end with a semi-colon. A player's identifier must be declared only once.

The following are correct declarations:

velocity x, y;

octave oct, z;

duration w;

The following are incorrect declarations:

velocity x, x;

octave z;

duration z;

Following the declaration section and before the grammar it is possible to initialise variables by means of the = operator.

The following is an example of declaration and initialisation:

velocity x;

x=0;

USING VARIABLES WITH NOTES

Variables are used in note attribute expressions. GRAMophone controls the types within expressions, so it is not possible to add an octave variable to a velocity variable, for example.

The following is an example of a note variable:

velocity x;

duration z, w;

A[4,x,z+w,].

EXAMPLE

composition "Crescendo" of "Schroeder" {
  //this composition generates 64 A notes with a growing velocity
  grammar chomsky
  tempo 120
  time_signature 4/4
  iterations 64
  %
  player Schroeder {
    instrument 40
    %
    velocity x=0;
    @composition->A[,x=x+1,,]@composition;
  }
}

CONDITIONS

In both Chomsky and Lindenmayer grammars it is possible to define conditions for the variables in the production body. If the condition is true, the production is executed; otherwise it is not. A condition is defined immediately after the name of the production by means of the '?' symbol, followed by one or more Boolean expressions.

The Boolean operators are:

!               not

&&              and

||              or

The relational operators are:

==              uguale

!=              diverso

<               minore

>               maggiore

<=              minore o uguale

>=              maggiore o uguale

The following is an example of a conditional production.

@battuta?x!=0->A[,x=x-10,,]@battuta;

which means: while x is not equal to zero, generate the @battuta production; otherwise do not.

Discography, GRAMophone's library

GRAMophone is able to include external libraries, called discographies. To include a discography in a source file, use the keyword discography followed by its file name. A discography can be included at any point in the source file, as long as its contents match the position of the source where it has been included.

Macros

Macros can be defined using the keyword define, followed by a lower-case identifier and a string placed in inverted commas. Macros must be defined at the beginning of the source composition, before the composition keyword. For example, in order to simply write a instead of A[,,,], the following macro must be defined: define a "A[,,,]"

Functions in GRAMophone

THE repeat() FUNCTION

The repeat() function takes an msb type value plus a Chomsky or Lindenmayer sequence. It enables the included sequence to be repeated a number of times that is equal to the msb type value.

THE rand() FUNCTION

The rand() function takes an expression and returns a random value which is less than the value of the expression.

Melodic operators in GRAMophone

transpose()

The transpose() operator takes an msb type value plus a Chomsky or Lindenmayer sequence. It generates a sequence in which all the notes in the relevant sequence are transposed by a number of semitones equal to the msb type value.

inversion()

The inversion() operator takes a Chomsky or Lindenmayer sequence. It generates a sequence in which the intervals between the first and the other notes in the sequence taken are calculated in reverse.

retrograde()

The retrograde() operator takes a Chomsky or Lindenmayer sequence. It generates a sequence which is the contrary of the sequence inserted.

AUTHOR

Giovanni Ferranti <giovanni_at_giovanniferranti_dot_it>