1 Computational Methods for the Alignment and Score-Informed Transcription of Piano Music By Siying WANG Submittedinpartialfulfilmentoftherequirements oftheDegreeofDoctorofPhilosophy London,UK November6,2017 AUTHOR’S DECLARATION I,SiyingWang,confirmthattheresearchincludedwithinthisthesisismyown workorthatwhereithasbeencarriedoutincollaborationwith,orsupported by others, that this is duly acknowledged below and my contribution indi- cated.Previouslypublishedmaterialisalsoacknowledgedbelow. IattestthatIhaveexercisedreasonablecaretoensurethattheworkisorig- inal, and does not to the best of my knowledge break any UK law, infringe anythirdparty’scopyrightorotherIntellectualPropertyRight,orcontainany confidentialmaterial. IacceptthattheCollegehastherighttouseplagiarismdetectionsoftwareto checktheelectronicversionofthethesis. Iconfirmthatthisthesishasnotbeenpreviouslysubmittedfortheawardofa degreebythisoranyotheruniversity. The copyright of this thesis rests with the author and no quotation from it or information derived from it may be published without the prior written consentoftheauthor. SIGNATURE: .......................................... DATE: .......................................... Detailsofcollaborationandpublications:SeeSection1.3. 2 ABSTRACT Thisthesisisconcernedwithcomputationalmethodsforalignmentandscore-informed transcriptionofpianomusic. Firstly,severalmethodsareproposedtoimprovethealign- mentrobustnessandaccuracywhenvariousversionsofonepieceofmusicshowcomplex differenceswithrespecttoacousticconditionsormusicalinterpretation.Secondly,score toperformancealignmentisappliedtoenablescore-informedtranscription. Although music alignment methods have considerably improved in accuracy in re- centyears,thetaskremainschallenging. Theresearchinthisthesisaimstoimprovethe robustnessforsomecaseswheretherearesubstantialdifferencesbetweenversionsand state-of-the-artmethodsmayfailinidentifyingacorrectalignment. Thisthesisfirstex- ploitstheavailabilityofmultipleversionsofthepiecetobealigned. Byprocessingthese jointly,thealignmentprocesscanbestabilisedbyexploitingadditionalexamplesofhow asectionmightbeinterpretedorwhichacousticconditionsmayarise. Twomethodsare proposed, progressivealignmentandprofileHMM,bothadaptedfromthemultiplebi- ologicalsequencealignmenttask. Experimentsdemonstratethatthesemethodscanin- deedimprovethealignmentaccuracyandrobustnessovercomparablepairwisemethods. Secondly,thisthesispresentsascoretoperformancealignmentmethodthatcanimprove therobustnessincaseswheresomemusicalvoices,suchasthemelody,areplayedasyn- chronouslytoothers–astylisticdeviceusedinmusicalexpression.Theasynchroniesbe- tweenthemelodyandtheaccompanimentarehandledbytreatingthevoicesasseparate timelinesinamulti-dimensionalvariantofdynamictimewarping(DTW).Themethod measurably improves the alignment accuracy for pieces with asynchronous voices and preservestheaccuracyotherwise. Onceanaccuratealignmentbetweenascoreandanaudiorecordingisavailable,the scoreinformationcanbeexploitedaspriorknowledgeinautomaticmusictranscription (AMT),forscenarioswherescoreisavailable,suchasmusictutoring.Score-informeddic- tionarylearningisusedtolearnthespectralpatternofeachpitchthatdescribestheenergy distributionoftheassociatednotesintherecording.Moreprecisely,thedictionarylearn- ingprocessinnon-negativematrixfactorization(NMF)isconstrainedusingthealigned score. Thisway, byadaptingthedictionarytoagivenrecording, theproposedmethod improvestheaccuracyoverthestate-of-the-art. 3 ACKNOWLEDGEMENTS Firstandforemost,IwouldliketothankmytwowonderfulPhDsupervisors-Sebastian EwertandSimonDixon.Ihavebeenfeelingextremelyluckysincethefirstdaytheyagreed tosuperviseme. Backthen,Iwasconfusedwithmyresearchtopicandhadstrongself- doubt. I simply would not be able to accomplish the work in this thesis without their invaluableguidanceandencouragement,supportandfaithinme. Theyshapedmyun- derstandingofgoodresearchandshowedmethespiritofscientists. Iespeciallywantto thankSebastianforalwaysmakingthetimetodiscusswithme,despitebeingverybusy himself. I want to express my gratitude to Professor Elaine Chew, for being my female role model. IwasinspiredbyElaine’sattitudetowardresearchandlifeingeneralandheref- fortsingenderequality. ThefouryearsIspentinQueenMaryhavealwaysbeenenjoyable,thankstomydear friendshere. EspeciallyYading,Chunyang,ChrisandShan. Iwillneverforgetthelaugh andtearswesharetogether,thedaysandeveningswespenttogetherworkingandchat- ting.IreallyappreciatethatyouarealwaystherewheneverIneed,offeringhelpandsug- gestionsorsimplylistening. IwouldalsoliketothankMaria, Veronica, Mi, Tian, Beici, Simin,Katerina,Sid,Peter,Di,Mattias,Janis,Luwei,Matt,Eitaforbeinggreatlab-mates andfriends. ThanksforStellaSickandWernerGoeblforkindlyprovidingthedataset. Lastbutnotleast, mydeepestthanksgotomyfamilyfortheirunwaveringsupport andtrust. Thankstomyparentsforunderstandingandsupportingmeinpursuingmy dreamfarfromhome.ThankstoFranforyourenduringtrust,encouragementandcaring forme, forkeepingmephysicallyandmentallyhealthy, sometimessimplybydragging meoutfromworktoawalk,alsoforproofreadingmythesis,discussingwithmeaboutmy researchfromtimetotimeandalwaysprovidinggoodadvices. ThisworkwasfundedbytheChinaScholarshipCouncil. 4 TABLE OF CONTENTS Author’sDeclaration 2 Abstract 3 Acknowledgements 4 TableofContents 8 ListofTables 9 ListofFigures 10 ListofSymbols 13 1 Introduction 15 1.1 MotivationandGoals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 1.2 ThesisStructure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 1.3 AssociatedPublications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2 Background 22 2.1 MusicTerminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2.1.1 MusicalScore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.1.2 MusicalPerformancesandExpression . . . . . . . . . . . . . . . . . 24 2.1.3 MIDINotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.2 FeatureRepresentationinMusicAlignment. . . . . . . . . . . . . . . . . . . 25 2.2.1 Chroma-basedFeature . . . . . . . . . . . . . . . . . . . . . . . . . . 27 5 TABLEOFCONTENTS 6 2.2.2 Decaying Locally adaptive Normalised Chroma Onset (DLNCO) Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 2.3 AlignmentMethods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.3.1 DynamicProgramming . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.3.2 ProbabilisticModelling . . . . . . . . . . . . . . . . . . . . . . . . . . 37 2.3.3 Similarity between Dynamic Time Warping and Hidden Markov Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 2.3.4 OtherTechniquesusedinMusicAlignment . . . . . . . . . . . . . . 44 2.4 ExploitingScoreInformationusingAlignmentTechniquesinMIR . . . . . 44 2.4.1 Score-informedExpressiveParameterExtraction . . . . . . . . . . . 44 2.4.2 Score-informedSourceSeparation . . . . . . . . . . . . . . . . . . . 45 2.4.3 Score-informedTranscription . . . . . . . . . . . . . . . . . . . . . . 46 2.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 3 Robustjointalignmentofmultipleperformances 50 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 3.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 3.3 BackgroundonMultipleSequenceAlignment . . . . . . . . . . . . . . . . . 52 3.4 MethodsforJointMusicAlignment . . . . . . . . . . . . . . . . . . . . . . . . 55 3.4.1 ProgressiveAlignment . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3.4.2 ProbabilisticProfile . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 3.4.3 AcceleratingAlignmentsUsingMulti-ScaleDynamicProgramming 66 3.5 ComparingPairwise,ProgressiveandProfile-HMMBasedAlignment . . . 67 3.5.1 DatasetandSettings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 3.5.2 ComparisonBetweenthePairwiseandJointAlignments . . . . . . 70 3.5.3 ComparisonoftheTwoJointAlignmentMethods. . . . . . . . . . . 73 3.6 FurtherInvestigationsoftheJointAlignmentMethod . . . . . . . . . . . . . 74 3.6.1 SubsetExperiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 3.6.2 GapPenalty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 3.6.3 AlignmentOrder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 3.6.4 ViterbiTraining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 3.6.5 IterativeAlignment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 TABLEOFCONTENTS 7 3.6.6 Furtherevaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 3.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 4 Compensating For Asynchronies Between Musical Voices In Score- PerformanceAlignment 84 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 4.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 4.3 AlignmentMethod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 4.3.1 ComputingFeaturesforIndividualVoices . . . . . . . . . . . . . . . 88 4.3.2 Three-DimensionalDynamicTimeWarping. . . . . . . . . . . . . . 88 4.3.3 PathConstraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 4.4 Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 4.4.1 DataSet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 4.4.2 GroundTruthGeneration . . . . . . . . . . . . . . . . . . . . . . . . . 94 4.4.3 EvaluationMeasure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 4.4.4 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 4.5 ConclusionandFutureWork. . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 5 Identifying Missing and Extra Notes in Piano Recordings Using Score- InformedDictionaryLearning 100 5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 5.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 5.3 BaselineMethod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 5.4 AnalysisandExtensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 5.4.1 ExampleofFailureUsingtheBaselineMethod . . . . . . . . . . . . 111 5.4.2 FromSpectralTemplatestoTime-FrequencyPatterns . . . . . . . . 113 5.4.3 FromHardtoSoftConstraintRegions. . . . . . . . . . . . . . . . . . 114 5.4.4 EncouragingTemporalContinuityinA . . . . . . . . . . . . . . . . . 115 5.4.5 EncouragingEnergyDecayintheTemplateMatrix . . . . . . . . . . 116 5.4.6 ParameterEstimation . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 5.5 Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 5.5.1 Dataset&EvaluationMeasure . . . . . . . . . . . . . . . . . . . . . . 118 TABLEOFCONTENTS 8 5.5.2 InfluenceofIndividualParameters . . . . . . . . . . . . . . . . . . . 120 5.5.3 ComparisonBetweentheBaselineMethodandExtendedMethod. 124 5.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 6 Conclusion 127 6.1 SummaryofContributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 6.2 FutureDirections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 6.3 ClosingRemarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 References 133 LIST OF TABLES 2.1 AnexampleofLCSalignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.1 ChopinMazurkasandtheiridentifiersusedintheexperiments . . . . . . . . . 69 3.2 Alignmenterror(meanandstandarddeviationofaveragebeatdeviationinmil- liseconds)forfourtypesofalignmentmethodsandarandombaseline. . . . . 71 3.3 Comparing the Pairwise II alignment method (Ewert et al., 2009b)), Profile HMMandProgressiveAlignmentmethodsintermsofaveragenoteonsetde- viation(inmilliseconds) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 4.1 Experimentalresultsforthreeexcerptsplayedwithstrongasynchrony(upper) andthreepieceswithoutasynchrony(lower). Thistableshowsthenumberof performancesavailableandstatisticsofthealignmenterrorinmillisecondsfor therespectivepieces.Bothresultsforthe2D-DTW(Ewertetal.,2009b)andour 3D-DTWalignmentmethodarecomputedseparatelyforthemelody(Mel)and accompaniment(Acc). Theerrorvaluesofthesetwovoicesareaveragedover the number of notes to get the overall (OA) alignment error. The change in alignmenterrorachievedby3D-DTWisshowninparentheses. . . . . . . . . . 96 5.1 Piecesforevaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 5.2 AverageEvaluationResultsofthreeMethodsforCorrectlyPlayedNotes(C),Ex- traNotes(E)andMissingNotes(M). . . . . . . . . . . . . . . . . . . . . . . . . . 125 9 LIST OF FIGURES 2.1 Anexampleofamusicalscore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.2 Generalframeworkofmusicalignment . . . . . . . . . . . . . . . . . . . . . . . 26 2.3 SolvingtheDynamicProgrammingproblemwithalook-uptable . . . . . . . . 31 2.4 AnexampleofDTWalignmentfortwoperformanceexcerptsofChopinOp.24 No.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 2.5 MultiscaleDTW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 2.6 AnexampleofHMMmodel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 2.7 Non-NegativeMatrixFactorisation(NMF) . . . . . . . . . . . . . . . . . . . . . . 45 3.1 Areal-worldexampleofpairwisemethodfailingtocomputeracorrectalignment 51 3.2 Anexampleofprogressivealignment . . . . . . . . . . . . . . . . . . . . . . . . . 57 3.3 Anexampleofreplacingcopiesofelementswithgapsymbolsafteraligninga newsequenceX tothetemplateF,whereC(3,2)<C(2,2)andC(5,5)<C(5,4). 59 3.4 TopologyofaProfileHMM(Durbinetal.,1999),showingrowsofdeletestates(top), insertstates(middle)andmatchstates(bottom) . . . . . . . . . . . . . . . . . . . . . 60 3.5 AnexampleofProfileHMM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 3.6 ComparisonofthePairwiseIIalignmentmethod(Ewertetal.,2009b)withthe proposedprogressivealignmentmethodandprofileHMMmethod. . . . . . . 71 3.7 HistogramsofbeatdeviationusingthePairwiseIIalignmentmethod(Ewert etal.,2009b),theprogressivealignmentandprofileHMMmethod. . . . . . . . 73 3.8 Comparison between the Pairwise II alignment method (Ewert et al., 2009b) andtwojointalignmentmethodsforsubsetexperiments. . . . . . . . . . . . . 75 10
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