Improvement of the Embedding Capacity for Audio Watermarking Method Using Non-negative Matrix Factorization

Abstract

We propose a watermarking method using nonnegative matrix factorization (NMF) for audio signals. NMF is applied to the host signal, and the amplitude spectrogram of the host signal is factorized into the basis matrix and the activation matrix, which are nonnegative matrices. The notes are estimated from the activation matrix, and the estimated notes are regarded as root notes. In the existing method, one-bit watermark is embedded into the dominant note corresponding to the root note. However, it is difficult to say that the embedding capacity is enough. Hence, in the proposed method, watermarks are embedded into the mediant and leading notes in addition to the dominant note. Up to three-bit watermarks can be embedded into one note while maintaining a detection accuracy.