A perceptible watermarking algorithm for audio signals

This paper proposes an unconventional method for removable audible watermarking system based on the requirements of a promising application .Given an audio file, the system makes some part of file available for preview and perceptual watermarking on the remaining portion. The watermark is embedded into selected DCT coefficients of host audio signal so that the signal to noise ratio is maintained at a level which is audibly annoying to human auditory system. An issue that arises here is generating huge number of copies of the audio file which are audibly similar and numerically different. Once the audio file is decoded using the secret key a new watermark is embedded in the audio that is perceptually transparent to the human auditory system. Hence this double watermarking i.e. imperceptible and perceptible watermarking provides a novel prototype for digital right management control. The subjective quality tests and robustness tests indicate that the audio quality is excellent and is robust to signal processing attacks.