|
Abstract:
|
Presently different audio watermarking methods are available; most of them
inclined towards copyright protection and copy protection. This is the key
motive for the notion to develop a speaker verification scheme that guar-
antees non-repudiation services and the thesis is its outcome.
The research presented in this thesis scrutinizes the field of audio water-
marking and the outcome is a speaker verification scheme that is proficient
in addressing issues allied to non-repudiation to a great extent. This work
aimed in developing novel audio watermarking schemes utilizing the fun-
damental ideas of Fast-Fourier Transform (FFT) or Fast Walsh-Hadamard
Transform (FWHT). The Mel-Frequency Cepstral Coefficients (MFCC) the
best parametric representation of the acoustic signals along with few other
key acoustic characteristics is employed in crafting of new schemes. The au-
dio watermark created is entirely dependent to the acoustic features, hence
named as FeatureMark and is crucial in this work.
In any watermarking scheme, the quality of the extracted watermark de-
pends exclusively on the pre-processing action and in this work framing and windowing techniques are involved. The theme non-repudiation provides
immense significance in the audio watermarking schemes proposed in this
work. Modification of the signal spectrum is achieved in a variety of ways
by selecting appropriate FFT/FWHT coefficients and the watermarking
schemes were evaluated for imperceptibility, robustness and capacity char-
acteristics. The proposed schemes are unequivocally effective in terms of
maintaining the sound quality, retrieving the embedded FeatureMark and
in terms of the capacity to hold the mark bits.
Robust nature of these marking schemes is achieved with the help of syn-
chronization codes such as Barker Code with FFT based FeatureMarking
scheme and Walsh Code with FWHT based FeatureMarking scheme. An-
other important feature associated with this scheme is the employment
of an encryption scheme towards the preparation of its FeatureMark that
scrambles the signal features that helps to keep the signal features unreve-
laed.
A comparative study with the existing watermarking schemes and the ex-
periments to evaluate imperceptibility, robustness and capacity tests guar-
antee that the proposed schemes can be baselined as efficient audio water-
marking schemes. The four new digital audio watermarking algorithms in
terms of their performance are remarkable thereby opening more opportu-
nities for further research. |