A study of audio watermarking method using nonharmonic note as watermark signal

A digital watermark is a technique to embed another digital data into digital contents such as music, image and movie. For audio signals, it is required that the sound quality of stego signal is not deteriorated. In existing methods, the high sound quality means that the difference between host signal and stego signal is small. On the other hand, in this paper, there is no problem even if a different sound from host signal is perceived as long as stego signal is maintained as music. Accordingly, we make a countermelody based on counterpoint and we propose a watermarking method that the countermelody is added to host signal as watermark signal. In this paper, we introduce not only chord tone but also nonharmonic note as an effective musical accent to watermark signal. Moreover, multiple notes can be arranged in one note of host signal, and it is expected to increase the embedding capacity of watermarks.