In a surveillance system with a huge number of cameras, the number of videos to be transmitted and displayed is usually restricted by network bandwidth and the resource of display terminal. Given that the source video is captured at high quality, a network transcoder is used to send video with lower data rate as the default for ordinary scenes, while only extraordinary or unusual scenes are sent with higher quality. With such a scenario, it is necessary to switch from a low quality version of the video to a higher quality video with low latency and in a seamless manner. This paper presents a network transcoder that is able to change the content and the quality of videos seamlessly and with low latency. The novelty of the proposed scheme is possible to change the quality and camera in the same session. Moreover, this paper describes an RTSP enhancement that enables this dynamic transcoding function. Finally, an evaluation of the results is provided.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.