The unprecedented growth in the range of multimedia services offered these days by modern telecommunication systems has been made possible only because of the advancements in signal processing technologies and algorithms. In the area of telecommunications, application of signal processing allows for new generations of systems to achieve performance close to theoretical limits, while in the area of multimedia, signal processing the underlying technology making possible realization of such applications that not so long ago were considered just a science fiction or were not even dreamed about. We all learnt to adopt those achievements very quickly, but often the research enabling their introduction takes many years and a lot of efforts. This book presents a group of invited contributions, some of which have been based on the papers presented at the International Symposium on DSP for Communication Systems held in Coolangatta on the Gold Coast, Australia, in December 2003. Part 1 of the book deals with applications of signal processing to transform what we hear or see to the form that is most suitable for transmission or storage for a future retrieval. The first three chapters in this part are devoted to processing of speech and other audio signals. The next two chapters consider image coding and compression, while the last chapter of this part describes classification of video sequences in the MPEG domain.