According to Yong Xiang, associate professor at Deakin, the process doesn't affect the user's listening experience. “Watermarking technology can be used to prove copyright ownership, trace the source of illegal distribution, and verify the authenticity of files," said Mr Xiang, the lead researcher on the project. Publishers typically apply watermarks to content that is being distributed in advance of an official release date, such as DVDs of films being given out to review, but they can also be applied to content being consumed more widely. By tracing the origins of a watermark, Fox Productions reportedly concluded that a pirated copy of the Ben Stiller film The Secret Life of Walter Mitty had originally leaked from The Ellen Degeneres Show. Typically, a watermark's effectiveness can be diluted by changes to the original song file, including copying; recording at a faster or slower speed; increased or decreased amplification; compressing the file; or applying a filter to remove certain frequency components. Pirates can modify the audio file in such a way to damage the watermark while preserving the listening experience.

Deakin's watermark was nearly 100 per cent resistant to the most common manipulations, Mr Xiang said. A secret key, composed of a sequence of randomly generated numbers, also encrypts the data to ensure that only the content owner, or police, can access the information. "When a leak is discovered or suspected, the watermark data can be recovered from the leaked copy to identify the source of leaked contents, which provides irrefutable evidence of content misuse in support of legal action," he said. "As a result, it will deter the misuse of controlled contents either maliciously or unintentionally." IT security researcher Troy Hunt said that capturing a user's credit card details would open a can of worms. Financial information needs to be handled in a way that is compliant with PCI standards, he said - a requirement content owners could very easily breach. "The implicit collection and distribution of user data is always risky," Mr Hunt said. "There are a lot of legitimate uses of distribution of media within the copyright laws. For example, if I want to email the file to myself, for use at another location, am I starting to email around my credit card details as well?" However, NSW policeman-turned-copyright investigator, Michael Speck, said watermarks were "absolutely no impediment to the consumer".

"Watermarking has not worked in the past and cleverer watermarks are not going to change that fact," Mr Speck said. The only way to change the habits of the "criminals, challengers, and middlemen" driving the piracy industry was by disrupting the business model that supports the infrastructure underpinning their trade: the ISPs and search engines. "Middlemen provide access to networks and are not going to be discouraged by watermarks. Criminals use the watermark to guarantee to customers that they've pirated the real thing; and the challengers' imperative is to break those watermarks to push their new technology into the market," Mr Speck said. Mr Speck advised technology and content companies to develop anti-piracy measures which reward ISPs for encouraging potential pirates to purchase content legitimately. He pointed to a database such as the Global File Registry, which catalogues millions of infringing files. ISPs could use this database to catch users in the act of illegally downloading copyright material and then direct them towards official channels through which to purchase the files. In this case, the ISP would earn a commission on every sale.

"ISPs and search engines ... represent the entirety of the opportunity to access digital content," he said. "Until they fundamentally change their business practices, pirate content is largely going to continue unabated." While pirates have enjoyed a golden age of illegally downloading with impunity, he said technology and commercial imperatives were now closing the gap. "The tech and market is evolving only now. There's a saturation of ISPs in the marketplace and a realisation by consumers that search engines aren't delivering a free internet. There's a cost in legitmate or illegitimate content that search engines offer freely."