![]() By placing these echoes regularly in an audio track, it is possible to detect the watermark in any clipped segment. Verance's scheme involved echoes with delays varying between 0.5 ms and 1.75 ms, rendering them indecipherable to the human ear. In fact, only echoes with a time difference of 100 ms or more become annoying. Note that the human ear is not sensitive to echoes involving speech and music where the delay is less than 50 ms. In short, Verance's watermarking scheme involved frequency domain modifications, hiding multiple time-varying echoes. Readers interested in the full technical details of Felten's attack in the SDMI challenge can peruse this paper presented at the 10th USENIX Security Symposium. Edward Felten was threatened with legal action if he wanted to discuss how Verance's DVD-A watermark scheme (along with a host of other audio protection schemes) was deciphered and overcome. In fact, Verance was one of the companies involved in the infamous Felten-SDMI Challenge case, where Prof. Robust watermarks can't be destroyed by digital-to-analog conversion, re-encoding or addition of small amounts of noise to the track. Audio watermarks can be robust or fragile, and Verance's DVD-A watermarking scheme as well as Cinavia belong to the former category. DVD-Audio adopted their technology in the late 90s. Verance is no newcomer to the audio watermarking market. What exactly is the Cinavia watermark? How is it embedded in a soundtrack? When does a consumer encounter the watermark? What is the result when the encounter happens? These are some of the questions we will try to answer in this section. ![]() In particular, owners of the PS3 have been vocal enough to warrant the appearance of sites dedicated to bypassing the Cinavia triggers on the PS3. ![]() ![]() Cinavia, from Verance, is an audio watermarking scheme which has ended up inconveniencing a number of consumers. We briefly discussed watermarking schemes in the previous section. ![]()
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