Lossless and secure watermarking scheme in MP3 audio by modifying redundant bit in the frames

This paper expounds the encoding method and the frame structure of MP3 audio in detail and presents a digital watermarking scheme without changing the host audio data. The private bit in the bitstream of the host MP3 frame header is used as an indicator to show the consistency between watermark and maindata. Since the maindata are unchanged, the watermark does not introduce any distortion to the host audio. Secret information is encrypted by Arnold transform before embedding to improve the system security. Furthermore, under the circumstance of packet loss during web transmission, a synchronic symbol is inserted to the watermark to enhance the reconstruction quality of the watermark. Experimental results prove the imperceptibility of the proposed method. Additionally, low processing time makes it a real-time method for streaming media applications.