Real-Time Audio Watermarking Based on Characteristics of PCM in Digital Instrument

Musical performance with digital instruments has become a common practice today, and many digital instruments come to be used in Desk Top Music (DTM), live performance, etc. These performances are recorded as digital contents, and circulated actively through network and electronic media. However, the spread of digital contents causes a problem of illegal duplication and distribution, so that digital watermark has recently attracted much attention as a technology to solve this problem. In this paper, we focus on a sound synthesized process in digital instruments, and propose a real-time watermark method. Certain watermarks are embedded in wavetables that are included in our digital instruments, and the insertion of secret messages is actualized with wavetable switching. Additionally, embedded watermarks can be extracted from the acoustic signal. The proposed method is able to achieve a real-time watermark, i.e., both musical performance and the insertion of watermark can be actualized.