Developing Virtual Synthesizers with VCV Rack

287 Pages·2020·15.021 MB·\287

by  Leonardo Gabrielli (Author)

Developing Virtual Synthesizers
with VCV Rack
Developing Virtual Synthesizers with VCV Rack takes the reader step by step through the process of
developing synthesizer modules, beginning with the elementary and leading up to more engaging
examples. Using the intuitive VCV Rack and its open-source C++ API, this book will guide even
the most inexperienced reader to master efficient DSP coding to create oscillators, filters, and
complex modules.
Examining practical topics related to releasing plugins and managing complex graphical user
interaction, with an intuitive study of signal processing theory specifically tailored for sound
synthesis and virtual analog, this book covers everything from theory to practice. With exercises and
example patches in each chapter, the reader will build a library of synthesizer modules that they can
modify and expand.
Supplemented by a companion website, this book is recommended reading for undergraduate and
postgraduate students of audio engineering, music technology, computer science, electronics, and
related courses; audio coding and do-it-yourself enthusiasts; and professionals looking for a quick
guide to VCV Rack. VCV Rack is a free and open-source software available online.
Leonardo Gabrielli, PhD, is a research fellow at the Department of Information Engineering,
Università Politecnica delle Marche, Italy, where he lectures on music production and conducts
research on physical modeling and deep neural audio processing. He collaborates with the music
industry as a DSP developer and he is scientific director of Acusmatiq MATME.
Developing Virtual Synthesizers with VCV Rack is a great read; an informative read; an inspiring
read; an empowering read; an essential read! This fantastic textbook and comprehensive set of
applied audio coding tutorials by Gabrielli will become the basis of many college courses and foun-
dational courses of study for every electronic musician interested in knowing how things work under
the hood. With that knowledge and understanding, they can code their own software synthesizers
and DSP modules in VCV Virtual Eurorack format.
Dr. Richard Boulanger, Professor of Electronic Production and Design,
Berklee College of Music
If, like me, you enjoy creating your own music tools, this book will help you bring your ideas to life
inside the wonderful world of VCV Rack. Whether you are a beginner or an expert in DSP, you will
learn something interesting or new.
Dr. Leonardo Laguna Ruiz, Vult DSP
Developing Virtual Synthesizers
with VCV Rack
Leonardo Gabrielli
Firstpublished2020
byRoutledge
52VanderbiltAvenue,NewYork,NY10017
andbyRoutledge
2ParkSquare,MiltonPark,Abingdon,Oxon,OX144RN
RoutledgeisanimprintoftheTaylor&FrancisGroup,aninformabusiness
©2020Taylor&Francis
TherightofLeonardoGabriellitobeidentifiedasauthorofthisworkhasbeenassertedbyhimin
accordancewithsections77and78oftheCopyright,DesignsandPatentsAct1988.
Allrightsreserved.Nopartofthisbookmaybereprintedorreproducedorutilizedinanyformor
byanyelectronic,mechanical,orothermeans,nowknownorhereafterinvented,including
photocopyingandrecording,orinanyinformationstorageorretrievalsystem,withoutpermission
inwritingfromthepublishers.
Trademarknotice:Productorcorporatenamesmaybetrademarksorregisteredtrademarks,and
areusedonlyforidentificationandexplanationwithoutintenttoinfringe.
LibraryofCongressCataloging-in-PublicationData
Names:Gabrielli,Leonardo,author.
Title:DevelopingvirtualsynthesizerswithVCVRack/LeonardoGabrielli.
Description:NewYork,NY:Routledge,2020.|Includesbibliographicalreferencesandindex.
Identifiers:LCCN2019039167(print)|LCCN2019039168(ebook)|ISBN9780367077730
(paperback)|ISBN9780367077747(hardback)|ISBN9780429022760(ebook)|ISBN
9780429663321(epub)|ISBN9780429660603(mobi)|ISBN9780429666049(adobepdf)
Subjects:LCSH:VCVRack.|Softwaresynthesizers.|Computersoundprocessing.|Sound
studios–Equipmentandsupplies.
Classification:LCCML74.4.V35G3252020(print)|LCCML74.4.V35(ebook)|
DDC786.7/4134–dc23
LCrecordavailableathttps://lccn.loc.gov/2019039167
LCebookrecordavailableathttps://lccn.loc.gov/2019039168
ISBN:978-0-367-07774-7(hbk)
ISBN:978-0-367-07773-0(pbk)
ISBN:978-0-429-02276-0(ebk)
TypesetinTimesNewRoman
bySwales&Willis,Exeter,Devon,UK
Visitthecompanionwebsite:www.leonardo-gabrielli.info/vcv-book
LightbulbiconbyPettyconfromPixabay
Contents
Preface..........................................................................................................................x
Acknowledgments........................................................................................................xiii
Chapter1: ModularSynthesis:Theory..............................................................................1
1.1 WhyModularSynthesis?............................................................................................................1
1.2 AnHistoricalPerspective............................................................................................................2
1.2.1 TheEarlyElectronicandElectroacousticMusicStudios................................................2
1.2.2 TheBirthandEvolutionofModularSynthesizers..........................................................4
1.2.3 TheAdventofaStandard................................................................................................6
1.2.4 TheSoftwareShift...........................................................................................................7
1.3 ModularSynthesisBasics...........................................................................................................8
1.3.1 SoundSources..................................................................................................................8
1.3.2 TimbreModificationandSpectralProcessing...............................................................10
1.3.3 Envelope,Dynamics,Articulation.................................................................................12
1.3.4 “FireatWill,”orinShort:Sequencers..........................................................................13
1.3.5 UtilityModules..............................................................................................................15
Chapter2: ElementsofSignalProcessingforSynthesis.....................................................16
2.1 Continuous-TimeSignals........................................................................................................16
2.2 Discrete-TimeSignals.............................................................................................................18
2.3 Discrete-TimeSystems...........................................................................................................22
2.4 TheFrequencyDomain...........................................................................................................27
2.4.1 DiscreteFourierSeries................................................................................................29
2.4.2 DiscreteFourierTransform.........................................................................................32
2.4.3 PropertiesoftheDiscreteFourierTransform..............................................................35
2.4.4 AgainonLTISystems:TheFrequencyResponse......................................................36
2.4.5 ComputationalComplexityandtheFastFourierTransform.......................................36
2.4.6 Short-TimeFourierTransform....................................................................................37
2.5 OnceAgainonLTISystems:Filters.......................................................................................38
2.6 SpecialLTISystems:Discrete-TimeDifferentiatorandIntegrator........................................40
2.7 AnalogtoDigitalandBack.....................................................................................................42
2.8 SpectralContentofTypicalOscillatorWaveforms................................................................46
2.9 UnderstandingAliasing...........................................................................................................49
v
vi Contents
2.10 Filters:ThePracticalSide.......................................................................................................52
2.11 NonlinearProcessing..............................................................................................................54
2.11.1 Waveshaping..............................................................................................................54
2.11.2 AmplitudeandRingModulation...............................................................................58
2.11.3 FrequencyModulation...............................................................................................60
2.12 RandomSignals......................................................................................................................63
2.13 NumericalIssuesandHintsonCoding...................................................................................69
2.14 ConcludingRemarks...............................................................................................................71
Chapter3: VCVRackBasics.........................................................................................74
3.1 OverviewoftheSystem............................................................................................................75
3.2 AnatomyofaModule...............................................................................................................76
3.3 ContextMenus..........................................................................................................................77
3.4 CoreModules............................................................................................................................78
3.4.1 AUDIO-8andAUDIO-16.............................................................................................78
3.4.2 MIDI-CV........................................................................................................................78
3.4.3 MIDI-CC........................................................................................................................79
3.4.4 MIDI-GATE...................................................................................................................80
3.4.5 MIDI-MAP.....................................................................................................................80
3.4.6 CV-MIDI,CV-CC,CV-GATE.......................................................................................80
3.5 FundamentalModules...............................................................................................................80
3.6 QuickPatches............................................................................................................................83
3.6.1 AudioandMIDIRouting...............................................................................................83
3.6.2 EastCoastSynthesisinOneMinute..............................................................................84
3.6.3 UsingtheSCOPE...........................................................................................................85
3.6.4 ObservingAliasing........................................................................................................88
3.6.5 UsingPolyphonicCables...............................................................................................88
Chapter4: DevelopingwithVCVRack...........................................................................91
4.1 ComparisonwithOtherPlatforms............................................................................................92
4.1.1 AudioProcessing...........................................................................................................92
4.1.2 Scheduling......................................................................................................................94
4.1.3 PolyphonicCables..........................................................................................................95
4.1.4 ExpanderModules.........................................................................................................95
4.1.5 SimplicityandObject-OrientedProgramming..............................................................95
4.2 Plugins:FilesandDirectories...................................................................................................96
4.3 Plugins:SoftwareComponents.................................................................................................97
4.4 SettingUpYourSystemforCoding.........................................................................................99
4.4.1 Linux..............................................................................................................................99
4.4.2 Windows......................................................................................................................100
4.4.3 macOS..........................................................................................................................100
4.4.4 BuildingVCVRackfromSources..............................................................................100
4.5 BuildingYourFirst“HelloWorld”Module...........................................................................102
Contents vii
4.5.1 BuildandRun..............................................................................................................102
4.5.2 StructureoftheSourceFiles........................................................................................102
4.6 AdoptinganIDEforDevelopment:Eclipse...........................................................................106
4.6.1 Importinga“MakefileProject”....................................................................................107
4.6.2 BuildingtheProjectInsideEclipse..............................................................................108
Chapter5: TheGraphicalUserInterface:AQuickIntroduction.......................................110
5.1 GeneratingSVGFileswithInkscape......................................................................................110
5.1.1 CreatingthePanelandtheBackground.......................................................................111
5.1.2 CreatingthePanelandtheBackground.......................................................................112
5.2 BaseWidgetObjectsforKnobs,PortsandSwitches.............................................................113
5.2.1 AutomaticallyPlacingComponents.............................................................................115
Chapter6: Let’sStartProgramming:TheEasyOnes.....................................................119
6.1 CreatingaNewPluginfromScratch,UsingtheHelperScript..............................................119
6.2 ComparatorModule................................................................................................................120
6.3 MuxingandDemuxing...........................................................................................................125
6.4 Knobs:Displaying,Mapping,andComputingTheirValues..................................................129
6.5 ClockGenerator......................................................................................................................131
6.6 SequencerModule...................................................................................................................137
6.7 BinaryFrequencyDivider.......................................................................................................140
6.8 RandomModule......................................................................................................................143
6.9 ToRecap:ExercisePatches....................................................................................................147
6.9.1 CreatingaBernoulliDistributionandBernoulliGate.................................................147
6.9.2 Polyrhythms.................................................................................................................147
Chapter7: GettingSerious:DSP“Classroom”Modules.................................................148
7.1 HandlingPolyphonyProperly.................................................................................................148
7.2 LinearEnvelopeGenerator.....................................................................................................150
7.3 ExponentialEnvelopeGenerator............................................................................................153
7.3.1 AVirtualAnalogRCFilter..........................................................................................154
7.3.2 ImplementationoftheExponentialEnvelopeGenerator.............................................155
7.4 EnvelopeFollower..................................................................................................................158
7.4.1 ModellingaDiodeEnvelopeFollower........................................................................159
7.4.2 ImplementationoftheEnvelopeFollower..................................................................163
7.5 MultimodeState-VariableFilter.............................................................................................165
7.5.1 ADiscrete-TimeModeloftheMultimodeState-VariableFilter.................................165
7.5.2 ImplementationoftheState-VariableFilter.................................................................168
7.6 PolyphonicFilter.....................................................................................................................171
7.6.1 ToRecap:ExercisewithPatches.................................................................................173
7.6.1.1 SimpleSnareSoundGeneration.....................................................................174
7.6.1.2 Auto-WahEffect.............................................................................................174
7.6.1.3 CreatingaStepFilter......................................................................................174
7.6.1.4 TheChemist’sLab,AkaPolyphonicNoiseFilters........................................174
viii Contents
Chapter8: CrunchingNumbers:AdvancedDSPModules................................................175
8.1 ModalSynthesis......................................................................................................................175
8.1.1 ModalSynthesisPrinciples..........................................................................................176
8.1.2 AState-VariableFilterBank........................................................................................177
8.1.3 The“Modal”Module...................................................................................................177
8.1.4 AddingContextMenuOptions....................................................................................180
8.1.5 ComputationalCost......................................................................................................183
8.2 VirtualAnalogOscillatorwithLimitedAliasing...................................................................184
8.2.1 TrivialOscillators.........................................................................................................184
8.2.2 Oversampling:TheEasySolution...............................................................................186
8.2.3 ImplementingaTrivialOscillatorwithOversampling................................................188
8.2.4 DifferentiatedParabolicWaveformandItsExtensions...............................................192
8.2.5 DifferentiatedParabolicWaveformImplementation...................................................196
8.2.6 ComputationalCostandAliasing................................................................................203
8.2.7 PolyphonicOscillatorModule.....................................................................................204
8.3 Wavefolding............................................................................................................................206
8.3.1 TrivialFoldbackAlgorithm.........................................................................................208
8.3.2 AntiderivativeAnti-AliasingMethod..........................................................................208
8.3.3 WavefolderModuleImplementation...........................................................................210
8.4 ToRecap:ExercisewithPatches............................................................................................214
8.4.1 AModalSynthesisPatch.............................................................................................214
8.4.2 EastCoastClassic........................................................................................................214
8.4.3 WestCoastMonoVoice...............................................................................................215
8.4.4 JunttiWaveshaper........................................................................................................215
Chapter9: TheGraphicalUserInterface:CreatingCustomWidgets................................217
9.1 TheRenderingLibrary:NanoVG...........................................................................................217
9.2 CustomWidgetsCreation.......................................................................................................218
9.2.1 CustomKnobsandButtons.........................................................................................219
9.2.2 DrawingText................................................................................................................222
9.3 AnInteractiveWidget.............................................................................................................225
Chapter10: AdditionalTopics.....................................................................................233
10.1 DebuggingtheCode..............................................................................................................233
10.1.1 RunningaDebugSession........................................................................................234
10.1.2 DebuggingaSegmentationFault............................................................................236
10.1.3 DevelopmentMode.................................................................................................237
10.1.4 DebuggingwiththeEclipseIDE.............................................................................237
10.1.5 OtherDebuggingMethods......................................................................................239
10.2 Optimization..........................................................................................................................241
10.2.1 TableLookupforTranscendentalFunctions...........................................................242
10.2.2 SineApproximationbyTableLookup....................................................................245
10.2.3 QuadraticApproximationofSine............................................................................245
10.2.4 TheChamberlinResonatorasaSineOscillator......................................................246
Contents ix
10.2.5 ReducingtheGUIProcessingBurden.....................................................................247
10.3 DevelopingExpanderModules.............................................................................................247
10.4 AddingFactoryPresets.........................................................................................................250
10.5 StoringandRecallingModuleInformationthroughJSON..................................................251
10.5.1 StoringandRecallingJSONDataforAModalGUI................................................253
10.6 VersioningtheCodeandManagingaGitRepository..........................................................256
10.7 GettingintotheThird-PartyPluginList...............................................................................258
10.8 MakingaRevenueoutofCoding.........................................................................................259
10.8.1 TheVCVStore........................................................................................................259
10.8.2 Donations.................................................................................................................259
10.8.3 BlankPanels............................................................................................................260
Chapter11: AfterReadingThisBook...........................................................................261
11.1 ForkingtheABCCollection.................................................................................................261
11.2 LearnMoreaboutVirtualAnalogAlgorithms......................................................................262
11.3 ExperimentwithNovelDigitalAlgorithms..........................................................................262
11.4 BuildaHybridHardware/SoftwareModularRack..............................................................263
Bibliography 266
Index 270