In this paper, we define a framework for media resources manipulation in an adaptive content delivery system. We discuss the media resources manipulation in an adaptation and negotiation architecture in terms of binary relationship definition using a so-called "related resources" approach, resources extraction, adaptation and delivery. We show how differentresources can be related by predefined semantic relationships in order to help structural adaptation and content negotiation tasks. We give a simple recursive algorithm to extract media resources form an input tree structure. The media description is specified using an extensible CC/PP profile. In order to show the benefits of our approach, we give a practical application of media manipulation: an automatic adaptation of XHTML documents for mobile phones. We propose also a general mechanism for the content servers in order to deliver media resources according to client constraints or profile. The influence of media selection in the delivery of multimedia services is also described using evaluation formulae and measured with some experimentations.