This book constitutes the refereed proceedings of the 4th European Conference on Multimedia Applications, Services and Techniques, ECMAST'99, held in Madrid, Spain in May 1999. The 37 revised full papers presented were carefully reviewed and selected from a total of 71 submissions. The book is divided in sections on services and applications, multimedia terminals, content creation, physical broadcast infrastructure, multimedia over the Internet, metadata, 3D imaging, multicast protocols, security and protection, and mobility.