Increasing robustness of an audio watermark using turbo codes

Standard spread spectrum audio watermarking algorithms offer BER unacceptable for reliable transmission of data. Causes of unreliable watermark detection are often attacks that distort the watermarked audio in fading-like manner, disabling the correlation-based detectors to extract data. In this paper, consideration of capacity of the audio watermark channel in the presence of fading-like distortion is performed. It is shown that turbo codes offer convenient trade-off between capacity of the watermark channel and BER due to large coding gain in fading environment. Test results proved a large advantage of the proposed algorithm over standard detection as robustness is significantly increased for a given watermark data rate.