Watermark-enabled value added services to broadcast audio

Digital watermarking is a method for embedding secret data into digital signals. We present a novel service that uses watermarking to add metadata into radio broadcast music. A user can record the music with a mobile phone from radio loudspeakers and extract the watermark. The watermark can contain, for example value adding metadata about the song or a link to an external server that can provide the user a possibility to buy a CD with the song in question, or a ticket to the artistpsilas next concert. This solution offers a new channel for mobile commerce. The method is tested against sampling rate changes and DA/AD conversion in noisy environment, where the audio is played through loudspeakers and recorded using a mobile phone. The success ratio of the message extraction was 83 % in the experiments, while the subjective quality was graded on average as perceptible but not annoying.