Audio watermarking for live performance

AudioWatermarkingforLivePerformanceRyukiTachibanaTokyoResearchLab oratory,IBMJapanABSTRACTAudio watermarking has b een used mainly for digitally stored content.Using real-time watermark emb edding,its coverage can b e extended to live broadcasts and live p erformances.In general, a conentional emb eddingalgorithm receivesahostsignal (HS)and outputs thesummation of the HSandawatermark signal (WS).However, when applied to real-time emb edding, there are to problems:(1) delay of the HS, and (2) p ossibleinterruption of thebroadcast.Tosolve theseproblems,wepropose awatermark generation algorithm thatoutputsonlyaWS,andsystemcomp ositionmetho dinwhichmixeroutsidethecomputermixesWSgeneratedbythealgorithmandHS.Inaddition,weprop oseanewcomp ositionmetho d"sonicwatermarking".Inthiscomp ositionmetho d,thesoundofHSandWSareplayedseparately bytwospeakers, and the sounds are mixed in the air.Using this comp osition metho d, it would b ep ossible to generate a watermarking sound in a concerto hall so that the watermark could b e detected fromcontent recorded by audience memb ers who have recording devices at their seats.We rep ort on the results ofexp eriments and discuss the merits and aws of various real-time watermarking comp osition metho ds.Keywords:Audio watermarking, real-time emb edding, sonic watermarking1.INTRODUCTIONA digital audio watermark has b een prop osed as a means to identify the owner or distributor of digital audiodata.1{4Prop osed applications of audio watermark are copyright management, annotation, authentication,broadcast monitoring, and tamp er-pro o ng.2For these purp oses, transparency,datapayload, reliability,androbustnessofaudiowatermarkingtechnologieshaveb eenimproedbyanumberresearchers.Recently,severalaudiowatermarkingtechniquesthatorkbymo difyingmagnitudesinthefrequencydomainereprop osed to achieve robustness against distortions such as time-scale mo di cation and pitch shifting.5{7Ofthevariousapplications,primarydrivingforcesofaudiowatermarkingresearchhaeb eencopycontrol of digital music and searching for illegally copied music.8, 9In these usages, it is natural to considerthatan original musicsample,whichis thetarget ofwatermark emb edding,existsas a lestoreddigitallyona computer.Forcreatingawatermarked DVD-Audiodisc,whenmostofthecreation pro cess includingrecording,mixing,mastering,etc.is nished,copyingthe nishedsongtoacomputerandemb eddinganaudio watermark in the music les on the computer is p ossible.In the scenario of SDMI, an audio watermarkmaybe emb edded in a music le prepared for Internet distribution.Though it is true that these purp oses have greatly encouraged audio watermarking researchso far, audiowatermarking is not a technology useful only for digitally stored music.Of course, music is p erformed, created,stored, and listened to in many di erentways, and it is much more common that music is not stored as a digital le on a computer.When applying audio watermarking technology in various musical environments,real-timewatermarkembeddingisapreferredapproach.Forexample,inmusicmasteringstudios,byemb eddingwatermark in real time in a sound b eing played, the watermarked sound could b e instantly checked withoutsavingitasa leoncomputer.Forbroadcastingofwatermarkedsound,ouldb ecomep ossibletoembed a watermark in real time and instantly broadcast the sound of a live p erformance b eing p erformed ina studio, or the voice of a newscaster or a talk show.Further author information:E-mail: ryuki@jp.ibm.com, Address: 1623-14, Shimotsuruma, Yamato-shi, Kanagawa-ken, Japan 242-8502