csc475 music information retrieval - symbolic music...
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CSC475 Music Information RetrievalSymbolic Music Representations
George Tzanetakis
University of Victoria
2014
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Table of Contents I
1 Western Common Music Notation
2 Digital Formats for Symbolic Representations
3 Tools for Symbolic Representations
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Introduction
Music notation and theory are complex topics that cantake many years to master
This presentation barely scratches the surface of thesubject
The main goal is to provide enough background forstudents with no formal music training to be able to readand understand MIR papers that use terminology frommusic notation and theory
It is never too late to get some formal music training
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History of Music Notation
Earliest known form of music notation in cuneiformSumerian tablet around 2000 BC.
Initially a mnemonic aid to oral instruction, performanceand transmission it evolved into a codified set ofconventions that transformed how music was created,distributed and consumed across time and space.
Notation can be viewed as a visual representation ofinstructions for how to perform an instrument. Tablaturenotation for example is specific to stringed instruments.
Primary focus of traditional musicology
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Western Common Music Notation
Originally used inEuropean Classical Musicis currently used in manygenres around the world
Mainly encodes pitch andtiming (to a certaindegree designed forkeyboard instruments)
Considerable freedom ininterpretation
Five staff lines
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Notating rhythm
Symbols indicate relative durations in terms of multiples(or fractions) of underlying regular pulse
If tempo is specified then exact durations can becomputed (for example the first symbol would last 60seconds / 85 BPM = 0.706 seconds)
A different set of symbols is used to indicate rests
Numbers under symbols indicate the duration in terms ofeighth notes. Each measure is subdivded into 2 halfnotes, 4 quarter notes, 8 eighth notes.
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Time signature and measures
Measure (or bar) lines indicate regular groupings of notes
Time signature shows the rhythmic content of eachmeasure
Compound rhythms consists of smaller rhythmic units
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Notating pitches
Clef sign anchors the five staff lines to a particular pitch
Note symbols are either placed on staff lines or betweenstaff lines.
Successive note symbols (one between lines followed byone on a staff line or the other way around) correspond tosuccessive white notes on a keyboard.
Invisible staff lines extend above and below
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Notating pitches
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Repeat signs and structure
Repeat signs and other notation conventions can bethought of as a “proto” programming language providinglooping constructs and goto statements
Hierarchical structure is common i.e ABAA form
Structure = segmentation + similarity
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Structure of Naima by J. Coltrane
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Intervals
Intervals are pairs of pitches
Melodic when the pitches are played in succession
Harmonic when the pitches are played simultaneously
Uniquely characterized by number of semitones (althoughtypically named using a more complex system)(microtuning also possible)
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Naming of intervals
The most common naming convention for intervals uses twoattributes to describe them: quality and number.
Quality
Quality: perfect, major, minor, augmented, diminished.
Number
Number: unison, second, third, fifth, sixth, seventh, octaveand is based on counting staff positions
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Scales and Modes
A scale is a sequence of intervals typically consisting of wholetones and semitones and spanning an octave. Diatonic scalesare the ones that can be played using only the white keys on apiano. They are called modes and have ancient greek names.
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Major/Minor Scales
The scales used in composed Western classical music areprimarily the major and minor scales. The harmonic minorscale has an augmented second (A) that occurs between the6th and 7th tone.
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Enharmonic Spelling
The naming of intervals (and absolute pitches) is not uniquemeaning that the same exact note can have two differentnames as in C# and Db. Similarly the same interval can be aminor third or an augmented second. The spelling comes fromthe role an interval plays as part of a scale as well as thehistorical tuning practice of having different frequency ratiosfor enharmonic intervals.
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Chords
A chord is a set of two or more notes that soundsimultaneously. A chord label can also be applied to a musicexcerpt (typically a measure) by inferring, using various rulesof harmony, what theoretical chord would sound “good” withthe underlying music material. The basis of the westernclassical and pop music chord system is the triad consisting ofthree notes. Different naming schemes are used for chords.Jazz and Pop music frequently use naming based on triad withadditional modifiers for the non-triad notes.
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Root, Inversions, Voicings
The lowest note of a chord in its “default” position is calledthe root. Inversions occur when the lowest note of a chord isdifferent than the root. Voicings are different arrangementsof the chord notes that can include repeated notes as well asoctaves.
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Chord Progressions and Harmony
Sequences of chords are called chord progressions. Certainprogressions are more common than others and also indicatethe key of a piece. Frequently chords are constructed fromsubsets of notes from a particular scale. The root of the scaleis called the tonic and defines the key of the piece. Forexample a piece in C Major will mostly consist of chordsformed by the notes of the C major scale. Modulation refersto a change in key. Chords have specific qualities andfunctions which are studied in Harmonic analysis.
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Jazz Lead Sheets
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TuneDex
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Pianoroll
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Table of Contents I
1 Western Common Music Notation
2 Digital Formats for Symbolic Representations
3 Tools for Symbolic Representations
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MIDI
Musical Instrument Digital Interface
MIDI is both a communication protocol (and associated fileformat) as well as a hardware connector specification thatallows the exchange of information between electronic musicalinstruments and computers. It was developed in the early 80sand was mostly designed with keyboard instruments in mind.Essentially piano-roll representation of music.
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Lilypond
Music engraving program
Text language for input that is complied
Encodes much more than just notes and duration in orderto produce a visual musical score
Produces beautiful looking scores and is free
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Music XML
Extensible MarkupLanguage (XML) formatfor interchanginginformation about scores
Supported by more than a170 notation, scorewriting applications
Proprietary but openspecification
Hard to read butcomprehensive
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Table of Contents I
1 Western Common Music Notation
2 Digital Formats for Symbolic Representations
3 Tools for Symbolic Representations
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jSymbolic - jMIR
Software in Java for extractinghigh level musical features fromsymbolic music representations,specifically MIDI files
Features capture aspects ofinstrumentation, texture,rhythm, dynamics, pitchstatistics, melody, and chords
Part of jMIR a more generalpackage for MIR including audio,lyrics, web feature extraction aswell as a classification engine
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music21
Set of tools written in Python for computer aidedmusicology
Corpora included is a great feature
Works with MusicXML, MIDI
Example: add german name (i.e., B=B, B=H, A= Ais)under each note of a Bach chorale
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music 21 pitch/duration distribution
Distribution of pitches and note duration for a ChopinMazurka using music21.
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