11Audio Audio W a t e r m a r k in gW a t e r m a r k in gAdam BrickmanAdam [email protected]@mail.utexas.eduDepartment of Electrical & Computer EngineeringDepartment of Electrical & Computer EngineeringThe University of Texas at AustinThe University of Texas at AustinMarch 5, 2003March 5, 200322What is Audio What is Audio Wate r m ar k in g ?Wate r m ar k in g ?WhatWhatInsertion of information into an Insertion of information into an audio fileaudio fileMay be done May be done audiblyaudiblyor or inaudiblyinaudiblyMay be done in time or frequencyMay be done in time or frequencyWhyWhyCopyright protectionCopyright protectionControl or hidden descriptionControl or hidden descriptionCovert communicationsCovert communicationsChallengeChallenge: Ear sensitivity: Ear sensitivity33Basic MethodBasic MethodAAfAW'(,)=+InsertionExtractionsim w wwwww( , *)'''=⋅⋅Compare to threshold T44P r e v ious M e thod # 1P r e v ious M e thod # 1Independent Multiband Phase Independent Multiband Phase Modulation [Kuo Modulation [Kuo et alet al, 2002], 2002]Alter phase in limited amountAlter phase in limited amountCovert (nonCovert (non--blind)blind)Intellectual property protectionIntellectual property protection55P r e v ious M e thod # 1P r e v ious M e thod # 1Insertion in Insertion in timetime, , Modulation in Modulation in frequencyfrequencyTime WindowTime Windowwin nnNn N( ) sin(.),=+≤ ≤ −π0501ddbφ< °30φπ( ) sin( ),bbb=+− ≤ ≤21211Φk iiIb a b i b I( ) ( ),= − ≤ ≤=∑φ01Phase Window Phase Window Phase modulationPhase modulation66P r e v ious M e thod # 2P r e v ious M e thod # 2mm--Sequences and Temporal Sequences and Temporal Masking [Cvejic Masking [Cvejic et alet al, 2001], 2001]Can work in realCan work in real--time (fast time (fast algorithm)algorithm)Attack resistantAttack resistantEmploys temporal maskingEmploys temporal maskingWatermark bits spread in timeWatermark bits spread in timeModulation through pseudoModulation through pseudo--noise noise sequencesequenceMM--sequencesequence77P r e v ious M e thod # 2P r e v ious M e thod # 2Temporal AnalysisTemporal AnalysisHelps determine level of power for watermark sequenceHelps determine level of power for watermark sequenceAudio frames Audio frames ≈≈7.6 ms in length7.6 ms in lengthFrequency AnalysisFrequency AnalysisVia zeroVia zero--crossingscrossingsComputes information about audio spectrumComputes information about audio spectrumHigher Higher b(nb(n) values where host audio has higher frequency) values where host audio has higher frequencyynxnanbnwn()()()()()=+⋅⋅88P r e v ious M e thod # 3P r e v ious M e thod # 3Video Watermarking CrossVideo Watermarking Cross--Correlation Correlation [Dittmann, Mukherjee, and Steinebach, [Dittmann, Mukherjee, and Steinebach, 2000]2000]“Content“Content--fragile” watermarkingfragile” watermarkingMPEG files MPEG files ––image + audioimage + audioFile integrityFile integrityWatermark images via audio informationWatermark images via audio informationWatermark audio via image informationWatermark audio via image information99P r e v ious M e thod # 3P r e v ious M e thod # 3Video DomainVideo DomainExtract an imageExtract an imagePattern from audio featuresPattern from audio featuresApply pattern to luminanceApply pattern to luminanceAudio DomainAudio DomainExtract a frameExtract a framePattern from image edge characteristicsPattern from image edge characteristicsApply pattern to audio scale factorsApply pattern to audio scale factors1010C on c l usionC on c l usionInaudibility possible by exploiting characteristics Inaudibility possible by exploiting characteristics of Human Auditory Systemof Human Auditory SystemType of watermark to use dependent on Type of watermark to use dependent on applicationapplicationRobustness vs. CapacityRobustness vs. CapacitySecuritySecurityTransparency (audibility)Transparency (audibility)Future work will build upon crossFuture work will build upon cross--correlation method applied correlation method applied toward stereo (multitoward stereo (multi--channel) audio fileschannel) audio filesGoal is to produce an inaudible watermarkGoal is to produce an inaudible
View Full Document
Unlocking...