Audio Watermark May Be DRM Watershed

Audio watermarking is the process of encoding information into audio that will uniquely identify that recording. A successful audio watermark must be robust, inaudible and unique – a difficult set of criteria to achieve, but that is exactly what Activated Content have done. Their watermarks are effectively undetectable by ear, remain unaffected by compression or re-recording of the source, and each recording can have its own identifier…

How They Track Your Tunes

The technical aspect of such watermarking is very challenging: low/high band modulation techniques that encode information into unused portions of the spectrum won’t work, as compression (such as radio transmission or format encoding) will damage or remove this information. Frequency notching can be used to encode data into a signal by selecting a small slice (or several slices) of the spectrum least likely to be noticed by the ear and placing the watermark into these. However, this method is still vulnerable to digital compression and can be adversely affected by time and frequency shifts.

The solution employed by Activated Content uses psychoacoustic analysis to determine locations within the signal that can be used to insert the watermark. The effect of audio masking means that the watermark data can sit safely within the signal without being distinguishable from natural artifacts of the recording, but remaining immune to compression or low-fidelity reproduction. One report stated that the watermark was still detectable in a recording made of a track using a budget microphone ‘air-to-air’ from a loudspeaker. This white paper provides more details on the technical aspects of the technology.

Microsoft have recently begun to license audio watermarking technology developed by its Redmond research labs to Activated Content Corp. Eric Silberstein, CEO of Activated Content, had this to say about their partnership:

“Working with Microsoft and being able to combine our existing assets with their innovative technologies and vast intellectual property portfolio was a unique opportunity for us…(we) can now be in the forefront, providing a digital link in the multibillion-dollar mobile advertising marketplace and enabling aggregators to link advertising and consumers with user-generated content.”

Such watermarking can be used to track recordings exactly; although it would be possible to then track piracy at an individual level, there could be far greater benefit to using this as a marketing opportunity. This is in fact already happening on a small scale; watermarked advertising (for example, bundled with a video download) allows advertisers to gather valuable data about consumer behaviour and the effectiveness of their campaigns. Also, unlike DRM, there is no risk that your legally-owned media won’t play in your favourite player.


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