Multimedia Transcoding in Wireless and Mobile Networks

This chapter presents a keyless self-encrypting/decrypting system to be used in various communications systems. In the world of vast communications systems, data flow through various kinds of media, including free air. Thus the information transmitted is free to anyone who can peer it, which means that there should be a guarding mechanism so the information is transmitted securely over the medium from the sender to the intended receiver, who is supposed to get it in the first place and deter the others from getting the information sent. Many encryption systems have been devised for this purpose, but most of them are built around Public Key Infrastructure (PKI) wherein public key cryptography, a public and private key, is created simultaneously using the same algorithm (a popular one is known as RSA) by a certificate authority (CA). The private key is given only to the requesting party, and the public key is made publicly available (as part of a digital certificate) in a directory that all parties can access. The private key is never shared with anyone or sent across the medium. All of the commonly used encryption systems exchange keys that need to be generated using complex mathematical operations that take noticeable time, which is sometimes done once, and exchanged openly over unsecured medium. We are proposing an expandable keyless self-encrypting/decrypting system, which does not require the use of keys in order o minimize the chances of breaching data exchange security and enhance the data security of everyday communications devices that are otherwise insecured.

Modality Conversion

Content adaptation currently appears to be the key solution to support the quality of service (QoS) for multimedia services over heterogeneous environments. In this chapter, we study modality conversion as an important adaptation method. We point out two main challenging issues of the problem of modality conversion: (1) the quantification of the content value (quality) when contents are drastically scaled and/or converted to other modalities and (2) the method to accurately decide the modality and content value for each object given that quantification. Accordingly, we will present in detail the solutions as well as the open questions to these two issues. Moreover, we discuss the benefits and obstacles as well as future trends of modality conversion in realizing the goal of universal multimedia access.

Getting the Big Picture on Small Screens

This chapter provides an overview of the key factors that influence the quality of experience (QoE) of mobile TV services. It compiles the current knowledge from empirical studies and recommendations on four key requirements for the uptake of mobile TV services: (1) handset usability and its acceptance by the user, (2) the technical performance and reliability of the service, (3) the usability of the mobile TV service (depending on the delivery of content), and (4) the satisfaction with the content. It illustrates a number of factors that contribute to these requirements ranging from the context of use to the size of the display and the displayed content. The chapter highlights the interdependencies between these factors during the delivery of content in mobile TV services to a heterogeneous set of low resolution devices.

Semantic Multimedia Information Analysis for Retrieval Applications

Most of the research in multimedia retrieval applications has focused on retrieval by content or retrieval by example. Since the classical review by Smeulders, Worring, Santini, Gupta, and Jain (2000), a new interest has grown immensely in the multimedia information retrieval community: retrieval by semantics. This exciting new research area arises as a combination of multimedia understanding, information extraction, information retrieval, and digital libraries. This chapter presents a comprehensive review of analysis algorithms in order to extract semantic information from multimedia content. We discuss statistical approaches to analyze images and video content and conclude with a discussion regarding the described methods.

An H.264/AVC Error Detection Algorithm Based on Syntax Analysis

In this chapter, we present the possibility of detecting errors in H.264/AVC encoded video streams. Standard methods usually discard the damaged received packet. Since they can still contain valid information, the localization of the corrupted information elements prevents discarding of the error-free data. The proposed error detection method exploits the set of entropy coded words as well as range and significance of the H.264/AVC information elements. The performance evaluation of the presented technique is performed for various bit error probabilities. The results are compared to the typical packet discard approach. Particular focus is given on low-rate video sequences.

Extreme Rate Distributed Video Transcoding System

This chapter provides a comprehensive awareness and understanding of research efforts in the field of extreme rate-distributed video transcoding. The basic concepts and theories of rate control methods such as requantization, temporal resolution reduction, spatial resolution reduction, and object-based transcoding are introduced. We will identify each rate control scheme’s strengths and weaknesses and provide a distributed video transcoding system architecture that uses multiple transcoding techniques in the creation of an extreme rate video. Experimental results show that the appropriate use of multiple transcoding schemes retains a better quality video in an extreme rate control. At the end of this chapter, we will identify unsolved problems and related issues and will offer suggestions for future research directions.

Multimedia Transcoding in Mobile and Wireless Networks

Secure multimedia transcoding is a challenge that operates the encrypted multimedia content directly. For example, the encrypted multimedia data’s bit rate is changed directly in order to adapt a narrow channel. However, since it avoids the triple operations decryption-transcoding-re-encryption, it is suitable for the application scenarios requiring low cost operations, such as wireless or mobile multimedia communication. In this chapter, the secure transcoding scheme for scalable video coding is proposed and analyzed, together with the introduction to scalable video coding and multimedia encryption, the overview of existing secure transcoding schemes, and some open issues in this field. The chapter is expected to provide researchers or engineers valuable information on secure multimedia transcoding and communication.

Image Watermarking Algorithms Based on the Discrete Wavelet Transform

In the last decade, many digital image watermarking algorithms have been proposed and implemented; however, algorithms based on the discrete wavelet transform (DWT) have been widely recognized to be more prevalent than the others. This is due to the wavelets’ excellent spatial localization, frequency spread, and multiresolution characteristics, which are similar to the theoretical models of the human visual system. In this chapter, we describe three DWT-based digital image watermarking algorithms. The first algorithm watermarks a given image in the DWT domain, while the second and third algorithms improve the basic algorithm by combining DWT with two powerful transforms. The second algorithm is a hybrid algorithm in which DWT and the discrete cosine transform (DCT) are combined. The third algorithm is also a hybrid algorithm in which DWT and the singular value decomposition transform (SVD) are combined. Performance evaluation results show that combining DWT with DCT or SVD improved the imperceptibility and robustness performance of the basic DWT-based digital watermarking algorithm. Finally, the ideas described in the chapter can be easily extended to watermarking multimedia objects that include audio and video data contents.

Adaptation and Personalization of Web-Based Multimedia Content

A traditional multimedia system presents the same static content and suggests the same next page to all users, even though they might have widely differing knowledge of the subject. Such a system suffers from an inability to be all things to all people, especially when the user population is relatively diverse. The rapid growth of mobile and wireless communication allowed service providers to develop new ways of interactions, enabling users to become accustomed to new means of multimedia-based service consumption in an anytime, anywhere, and anyhow manner. This chapter investigates the new multichannel constraints and opportunities emerged by these technologies, as well as the new user-demanding requirements that arise. It further examines the relationship between the adaptation and personalization research considerations, and proposes a three-layer architecture for adaptation and personalization of Web-based multimedia content based on the “new” user profile, with visual, emotional, and cognitive processing parameters incorporated.

Multimedia Essentials and Challenges

This chapter introduces multimedia and multimedia elements and technology that are influencing and will continue to influence much of the exchanged data over the Internet today. It presents all the elements of multimedia with an emphasis on the basic building block of each element and how it integrates with the other elements to achieve a better multimedia content. This chapter also presents the close relation between advancements in multimedia technology and the immense use of the Internet. In addition, various popular image, audio, and video standards are presented with more emphasis on compression standards that are influencing multimedia use. Furthermore, we hope the inclusion of a section dealing with copyrights, ownership, and cross-platform issues will shed light on the challenges facing multimedia producers and owners alike. Finally, the chapter includes some of the future challenges and issues facing the research community for the advancement of multimedia uses.