Now, audio trick to catch movie pirates in cinema halls

London, Mar 10 (ANI): As video piracy continues to plague the film industry, scientists have now developed a new audio trick that can allow authorities to keep a check on video pirates that make illegal camcorder copies in cinema halls.

Digital watermarks built into movies now make it possible to identify the seat a video pirate was sitting in when they made an illegal camcorder copy.

The audio watermarks can identify how far the pirate is from the cinema's speakers, and can even locate the seat on which he or she is sitting.

Noboru Babaguchi of Osaka University in Japan and colleagues have claimed that if you know which cinema a pirate operates from, you can locate where they were sitting by adding an audio watermark into the movie's soundtrack.

The technique is introduced during the mixing of the soundtrack by slightly varying the waveform of music and speech at regular intervals.

Babaguchi created an audio watermark with a specific signal for each separate "channel" of a soundtrack, broadcast from different loudspeakers in the cinema.

The team analysed the recorded audio from a camcorder copy and tried to find out how far away the camera's microphone was from each of the loudspeakers, pinning it down to a specific seat.

"This is a brand new application of the digital watermarking technique," New Scientist quoted the authors as saying.

The study is published in IEEE Transactions on Multimedia. (ANI)