**9. References**

38 Advances in Wavelet Theory and Their Applications in Engineering, Physics and Technology

Fig. 12. The ME/MC results on the 17th frame of the "Tennis" sequence. (a) The original image. The estimated image: (b) ME/MC in the DCT domain, (c) ME/MC in the DWT

Video coding has received an increased interest because of the big growth in the quantity of the video data. That is why a big interest has been made for developing an efficient video coding system and improving the motion estimation part which represents the most important part since it consumes most computation time and most resources used for video coding. Making the motion estimation a fast and efficient process was the goal of many researchers. But, unfortunately, that was not reached in the spatial domain. That's why, new ME systems have been conducted in other domain such as the frequency and the multiresolution domain. That is why many studies have been made to improve and simplify the ME methods. In this chapter, we have studied the wavelet as a domain for ME and we have proposed a multiresolution motion estimation and compensation method based on block matching applying in the wavelet coefficients. Because of some problems presented in this chapter, we have integrated some improvements techniques to ameliorate our ME system. As a future works, we will reinforce our method with others techniques such as the spatial segmentation which makes the estimation more accurate by trying to identify real

domain, (d) with our method.

objects in the predicted moving zones.

**7. Conclusion** 


**3** 

*Iraq* 

**Speech Scrambling** 

Sattar Sadkhan and Nidaa Abbas

*University of Babylon* 

**Based on Wavelet Transform** 

The increased interest in analog speech scrambling techniques are due to the increased visibility and publicity given to the vulnerability of communication systems to eavesdropping of unauthorized remote access (Gersho & Steele, 1984). In wireless communications, including High Frequency (H.F) and satellite communications, it is almost impossible to prevent unauthorized people from eavesdropping unless speech scramblers may be used to protect privacy. Among speech scramblers, analog scramblers are attractive and wide applicable. The conventional analog scramblers manipulate speech signal in the frequency or time domain or both. A typical frequency domain scrambler is the band splitting scrambler, which breaks the speech signal into several sub bands and permutes them. A typical time domain scrambler is the time division scrambler, which breaks the speech signal into short time segments and permutes them within a block of several segments(Sakurai et al., 1984). These conventional analog scramblers cannot provide sufficient security against cryptanalysis because the number of permutable elements in these scramblers is not large enough to provide an adequate number of different permutations

To strengthen security, a two-dimensional scrambler which manipulates the speech signal both in the frequency domain and in the time domain was proposed. Regarding other types of scramblers, which can attain a high degree of security, the transform domain scrambler

In 1979, Wyner proposed a method, in which the orthogonal transform called a Prolate Spheroidal transform (PSD) was executed on a set of the sampled speech signal. A mathematical basis for using both band splitting and time division, at the same time was presented by F. Pichler in 1983. He showed how an operation which realizes band splitting and time division can be designed, and pointed out that such an operation can be realized by a fast algorithm. The mathematical background is the theory of group-character for finite Abelian Groups and the theory of the General Fast Fourier Transform (GFFT) (Pichler, 1983). Also in 1984 Lin-Shan et. al., presented frequency domain scrambling algorithm, which is an extension of the Discrete Fourier Transform (DFT) scrambler previously proposed. The use of short-time Fourier analysis and filter bank techniques lead to the special feature that the original speech could be correctly recovered while the frame synchronization is completely

**1. Introduction** 

was proposed.

due to hardware limitation and processing delays.

