DISSCO: A Unified Approach to Sound Synthesis and Composition

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DISSCO A Unified Approach to Sound Synthesis
and Composition

• Hans G. Kaper Sever Tipei
• Argonne National Laboratory Computer
  Music Project
• National Science Foundation School of
  Music
• University of Illinois
  University of Illinois

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Digital Instrument for Sound Synthesis and
Composition

• Components
• LASS - Library for Additive Sound Synthesis
  written in C
• CMOD - Composition MODule
• written in C
• LASSIE - Graphic User Interface
• written in JAVA creates C script
• Open-source software
• Release 1.0 available from http//dissco.sourcefor
  ge.net

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DISSCO - main features

• Unified approach
• CMOD and LASS share
• a common formalism
• similar tools
• Comprehensive
• delivers a final product (event) that
• does not require further processing
• a black box
• takes user provided data
• produces a finished object

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LASS

• a piece is a collection of sounds and
• each sound is a collection of partials
• STL Containers and Iterators
• reflects previous work with DIASS and DISCO
  but
• no longer a MusicN program
• no instruments
• no score (XML file as record only, not input)
• no oscillators and wavetables - function
  evaluations
• partials are the building blocks
• sine waves
• any other kind of waves (not implemented
  yet)
• white noise

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LASS - features functionality

• Sounds and partials have static and dynamic
  attributes (parameters) which are associated with
  enums.
• Sound parameters are shared by all partials
• s.setParam(FREQUENCY, 440)
• Individual partials may get specific assignments
• s.get(2).setPartialParam(FREQUENCY,1234)
• Frequency may be modified in different ways
• FREQUENCY_DEVIATION, DETUNE, GLISS

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Envelopes (functions of time)

• ADSR envelope
• 5
• 0.00 0.00 EXPONENTIAL FIXED
• 0.10 1.00 LINEAR FLEXIBLE
• 0.20 0.80 LINEAR FLEXIBLE
• 0.80 0.80 EXPONENTIAL FIXED
• 1.00 0.00

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LASS - perceived loudness

• Non-linear function of the amplitude of
  constituent partials
• LASS uses the ISO equal-loudness contours and a
  number of critical bands
• (see our paper at the 2004 ICMC, Miami)
• LASS allows detailed control of an arbitrary
  number of partials through envelopes
• An infinite variety of spectra can be produced
• Crescendo / diminuendo effects can be obtained by
  multiplying envelopes

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LASS - modifiers (1)

• (applied to entire sound or individual partials)
• Vibrato (FM)
• magnitude (amplitude) - of basic frequency (Hz)
• rate (Hz)
• Tremolo (AM)
• magnitude - of max. amplitude
• rate (Hz)
• Frequency and amplitude transients
• magnitude
• rate (frequency of occurance)
• width of spike (normally 0.025 sec.)

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LASS - modifiers (2)

• (applied to the entire sound or individual
  partial)
• Reverberator (from F. Richard Moore - Computer
  Music)
• three options / constructors
• room size
• reverb vs. direct sound, hi low ratio, all-pass
  gain, and delay
• low-pass gain and comb filter gains in stead of
  hi/low
• Spatializer
• Pan - 2 channels
• MultiPan - arbitrary number of channels
• each channel receives a of the total sound
• polar coordinates to specify the position in
  space

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LASS - rendering

• clipping management
• CLIP values above threshold clipped
• SCALE sample values scaled by 1/ampmax of score
• CHANNEL_SCALE same applied per channel
• ANTICLIP sample value above threshold at scaled
  by at / ampmax
• CHANNEL_ANTICLIP same applied per channel
• AuWriter (use sox if other formats are
  desired)
• XML file generated as record - not needed to
  generate sounds

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CMOD

• LASS, a library, requires another piece of
  software or LASSIE to drive it
• CMOD also involves collections whose members
  could be themselves collections of objects
• creates objects in any (temporal) order
• consists of classes and a number of utilities
• has inherited from DISCO and uses LASS features
• (eg. Envelope class)

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CMOD - the EVENT class (1)

• abstract class, other classes are derived from
  it.
• an object may contain
• an arbitrary number of layers
• each layer may contain
• an arbitrary number of objects of various types
• an object may be an event containing other
  objects.
• all objects have
• name
• start time
• duration
• type

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CMOD - the EVENT class (2)

• Methods shared by all derived classes
• Build determines the number of
• layers
• types
• objects
• CreateNewObjects is a loop
• one pass for each object
• Selects (continuous or discrete method - Matrix
  in DISCO)
• start time
• duration
• type of new object
• SelectNextEvent calls the constructor for the new
  object

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CMOD - floating hierarchies
Herbert Brün

• Strict hierarchical structure ?
• collections of objects that are themselves
  collections of lower level objects (named TOP,
  HIGH, LOW, BOTTOM)
• CMOD has a main
• Floating
• the hierarchy is unstable, not stationary
• levels may be skipped or added
• objects do not have to be ordered in time
• connections established between objects of
  different levels (buddies).
• the main as a benign administrator /
  facilitator

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CMOD - implementation

• BOTTOMImplement provides instructions for
  LASS.
• Sound s //create sound object
• s.setParam(START_TIME, sTimeSec)
• s.setParam(DURATION, duration)
• Similar statements for frequency, loudness,
  modifiers, reverberation, and spatialization
• Many options for static or dynamic parameters by
  using
• LASS
• Envelope class (also part of LASS)
• Utility file

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CMOD - choosing a frequency brief example

• selected from
• a continuum
• a list of discrete values
• using
• well-temperate scales
• overtones of a common fundamental
• arbitrary tunings
• class Patter
• pre-defined sequence, tone-row
• pre-defined set and transformations
• constant value or dynamic envelope

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CMOD - utilities

• Utility file
• ReadCompute
• Stochos (stochastic distributions)
• Sequence (reads in order)
• random random within boundaries
• envelope making
• FitEnvelope (gets and scales envelopes)
• SegmentBuilder (builds envelope from scratch)
• misc. (GS, sieves, Weights,SoundsPerSecond, etc.)
• linkList
• DataIn - a class (file handling, I/O formats)

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CMOD - Input/Output (1)

• each object associated with an input file
• identifying tags and enums
• BottomAssignFreq
• method1 WELL_TEMPERED
• method2 SEQUENCE
• offset OBJNUM
• freq_ReadComputeInt
• step 4 58 64 68 32
• offset ZERO
• loud_ReadComputeFloat
• method COMPUTE
• loud_Stochos
• method RANGE_DISTRIB
• numEnv 3
• freqEnvs 29 29 107
• sones 11.31 22.62 1.00

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CMOD - Input / Output (2)

• Example log file
• TOP LEVEL daria.dat
• 
  
• HIGH 1 H/E0
• StartTime 0 units 0 sec
• Duration 17 units 17 sec
  
• --------------------------------------------------
  ---
• BOTTOM 1 B/sEpercus
• StartTime 0 units 0 sec
• Duration 17.5 units 17.5 sec
• ---------------------------------------------
  -------
• Sound 1 start time 16 duration 0.333333
  type 0
• has 5 partials frequency349.228
  sones254.153
• --------------------------------------------
  -------
• Sound 2 start time 1.75 duration 0.333333
  type 0
• has 4 partials frequency3520
  sones253.643

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DISSCO - results and future work

• LASS used
• to produce a piece, dARIA other works in
  progress
• hands-on in the teaching of
• Computer Music courses for 4 semesters
• theory courses dealing with late 20th century
  music
• Music, Science Technology, for non music
  majors
• CMOD
• used to produce two pieces, works in progress
• further development
• generating instrumental / vocal scores
• LASSIE
• presently only a GUI for LASS
• extend it to CMOD

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Aknowledgments

• Braden Kowitz designed and implemented the basic
  features of LASS
• the students of the Advanced Computer Music
  seminar contributed between 2002-2005 to further
  development of LASS
• The work of Hans Kaper was supported by the
  Mathematical, Information, and Computer Sciences
  Division subprogram of the Office of Advanced
  Scientific Computing Research, Office of Science,
  US Department of Energy, under Contract
  W-31-109-Eng-38.