Audio Watermarking Based on PCM Technique

igital 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. Digital Water mark technology paid much attention to solve the problem of illegal distribution & duplication when the digital contents are spread over electronic media. In this paper, we focus on a sound synthesized process in digital instruments, and propose a audio watermarking based on wavetable switching 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. In this study, we focused on digital instrument to solve this problem. Digital instrument (like electronic piano, electric drum and so on) has been used for musical performances in practice, and digital instrument has a characteristic structure in its sound synthesis process. Additionally it was considered that characteristics of the synthesis could be used for real-time watermarking. The purpose of this study is to achieve a real-time watermarking technology with another approach for musical performance with digital instruments. In the proposed method, watermarks are embedded in the wavetable of digital instruments, and embedded data are extracted from the playback acoustic signal of digital instrument. Therefore, watermarks can be embedded in the output acoustic signal that is synthesized from the wavetable in real-time musical performance, and it can be useful for the copyrights protection of real-time generated acoustic media.