The Ishce Audio Watermark was invented at the Central Research Laboratories (CRL) of EMI and patented in 1987. Subsequently CRL formed part of a management buyout from EMI and became part of Scipher Plc in 1995. In 2000 CRL submitted the audio watermark technology to the Secure Digital Music Initiative (SDMI) for consideration as its "Phase 2 screen". SDMI was ultimately unable to reach a consensus on how to successfully deploy its planned technology and essentially disbanded in 2001. However, while SDMI was active, it submitted the candidate technologies, including CRL's Audio Watermark, to a battery of tests, including:

  • Audibility

Many listening experts "Golden Ears" at several studios around the world were given the opportunity to listen to watermarked music and to the unmarked originals. The conclusion of these tests was that the CRL watermark is inaudible in all practical situations.

  • Robustness

SDMI configured many ways to test the extent that the watermark would survive many different audio processes, including MP3 compression, WMA compression, Time-scale adjustment, Noise addition, and many others. The CRL watermark achieved extremely high scores in these tests.

  • Compression Detection

Part of the SDMI requirement was to detect unauthorized compression. The CRL watermark was the only technology submitted that reliably detected compression in the appropriate circumstances.

After SDMI the focus shifted from protection to added value and the "Xaudio" concept was created. This envisaged using the watermark to add value to broadcast audio, such that listeners would be able to use portable mobile devices such as mobile phones to extract the watermark and use it to access web-based interactive applications specifically tailored to the audio being heard. Thus creating interactive audio broadcasts. This was developed within CRL as a proof of concept demonstrator and a successful application was made for a EC supported project Xaudio.





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