This volume contains the full and short papers of SAMT 2009, the 4th Int- national Conference on Semantic and Digital Media Technologies 2009 held in Graz, Austria. SAMT brings together researchers dealing with a broad range of research topics related to semantic multimedia and a great diversity of application - eas. The current research shows that adding and using semantics of multimedia content is broadening its scope from search and retrieval to the complete media life cycle, from content creation to distribution and consumption, thus lever- ing new possibilities in creating, sharing and reusing multimedia content. While some of the contributions present improvements in automatic analysis and - notation methods, there is increasingly more work dealing with visualization, user interaction and collaboration. We can also observe ongoing standardization activities related to semantic multimedia in both W3C and MPEG, forming a solid basis for a wide adoption. Theconferencereceived41submissionsthisyear,ofwhichtheProgramC- mittee selected 13 full papers for oral presentation and 8 short papers for poster presentation. In addition to the scienti?c papers, the conference program - cluded two invited talks by Ricardo Baeza-Yates and Stefan Rug er and a demo session showing results from three European projects. The day before the main conference o?ered an industry day with presen- tions and demos that showed the growing importance of semantic technologies in real-world applications as well as the research challenges coming from them.