A video server comprising an input port configured to receive from a user terminal requests to deliver video segments in a target representation. The server comprises an output port configured to deliver the requested video segments to the user terminal. The server comprises a data link configured to retrieve from storage capabilities, for each request from the user terminal, a video segment in at least one source representation in an Open GOP scheme. The server comprises an access to one or more video transcoding capabilities. The video server is configured to cause one or more video transcoding capabilities to transcode at least a part of the video segment in at least one source representation in an Open GOP scheme into the requested target representation in a Closed GOP scheme when the requested target representation is different from a representation previously provided to the user terminal.