Digital Watermarking Method Based on STFT Histogram

This paper presents a digital audio watermarking method. In the method, watermark has been represented by a form of the histogram for sound power level´s distribution in time domain in certain frequency band(s). The relation of four numbers of selected bins in a histogram are changed by a rule of watermark bits assignment. To evaluate the performance of the embedding procedure in each frequency band, the robustness test against several kinds of manipulations or attacks were conducted for some instrumental music sources and harmonic complex tone. Considering the results of robustness test, the performance of multi-band embedding is discussed. Promising results of hearing tests are also presented.