<title>Noninvertible watermarking methods for MPEG-encoded audio</title>

Abstract

Nowadays the multimedia technology in distributed environments becomes realistic and the multimedia copyright protection issue becomes more and more important. Various digital watermarking techniques have been proposed in recent years as the methods to protect the copyright of multimedia data. Although, conceptually, these techniques can be easily extended for protecting digital audio data, it is challenging to apply these techniques to MPEG Audio streams because we need to design the watermarking schemes working directly in the compressed data domain.In this paper, we present watermarking methods which will embed the watermark directly into the MPEG audio bit streams rather than going through expensive decoding/encoding process in order to apply watermarking schemes in uncompressed data domain. Among the two presented schemes, one embeds the watermark into the Scale Factors of the MPEG audio streams and another one embeds the watermark into the MPEG encoded samples. Our experimental results show that both methods perform well and the distortion could be controlled at the minimal level. While we use MPEG Audio Layer II streams in our experimental tests, the proposed schemes can be applied to MPEG Audio Layer I and III. Furthermore, by enforcing creation of the watermark through a standard encryption function such as DES, the proposed schemes will be successful in resolving rightful ownership of watermarked MPEG audio.

Robust AVS audio watermarking

“…For example in [5], due to the lossy quantization, scale factors tend to change in the re-coding causing the watermark to be damaged. In MP3Stego, bit allocation is not done according to the MPEG audio standard but mandatorily controlled by the embedding algorithm for the bits embedding.…”

“…But the robustness performance is poor. In [5] the watermark bits were embedded into the scaling factors. But they were not robust to decoding/reencoding.…”

AC-3 bit stream watermarking

“…Conversely, the watermarking operations can be integrated into the bit stream decoding process [5] taking the bit stream as input and PCM samples as output. For embedding, scale factors for frequency subbands can be modified, where each watermark chip after spreading is embedded in an AAC-block rather than in a single scale factor as in [8].…”

Robust and efficient content-based digital audio watermarking

“…The embedded watermark information can be removed by decompressing the bit stream and then recompressing it. Qiao [15] proposes a watermarking scheme to embed watermarks in the compressed domain, but the original audio stream must be presented in the verification process. So far there is no any watermarking method for WT synthesis audio.…”