The value of forensic marks, often simply referred to as watermarks, is that they can identify where the content last was. If a pirated copy is captured, its marks will show where the content was last viewed. So to be useful, the marks must survive brutal captures, such as that from a low-resolution camcorder tucked between seats in a theatre.
Content gets marked more than once. It’s usually marked before leaving the post facility where it was post-produced. It then gets marked at least once again while being screened to an audience. Generally, a Verance mark is applied at the post house, and a Thomson or Philips watermark is applied in real-time during screenings in the theatre. When digital cinema was first introduced, only the image was marked in-theatre. Today, most movies have audio marking turned on.
Due to its relative newness on the scene, the audio watermark hasn’t received much attention. But the technology isn’t as new as that, having undergone plenty of listening tests. The concept of a good mark, whether image or audio, is that it cannot be perceived by the audience, but it can be picked up by capable equipment from the lousiest of unlawful recordings. A bad mark can be picked up by humans.
As you might think from all of this rambling, there’s a problem. Audio watermarks can be heard. Studio sound mixers abhor them. And with two sets of marks, one applied in post and one applied in the theatre, there’s apparently plenty to hear.
Dolby, who would seem to be the perfect company to pursue quality marking technologies, decided that the potential rewards weren’t worth the effort, and abandoned its work in this area several years ago. The marking industry is so challenging that the two remaining competitors — Philips and Thomson — merged into one company: Netherlands-based Civolution.
With companies secretive about their methods, it’ll be difficult to get Verance and Civolution to work together on complementary marking schemes that have the least impact on the quality of sound. It is more likely that willing studios will begin to analyze the use case more closely, and apply the marks only where the value is. For example, marking only dialog tracks might make more sense than marking all six (or more) channels of sound, most of which carry music and effects that are more sensitive to marking.
D-Box, the motion seat company, says that it has succeeded in convincing DCI to exclude its audio-recorded control tracks from being watermarked, as the marks interfere with the control signals to the seats. Now all we need is for someone to convince DCI that sound tracks carry more valued information than seat controls.