A system and process for providing progressively higher quality versions of an audio and/or video program over a client-server based network. In response to a user command to view a particular program, the client requests layered data associated with the program from the server. The client also specifies how many consecutive layers are to be transmitted based on the bandwidth available on the network. The client then receives the data from the server, caches it, renders it as it is received, and presents it to the viewer. Upon a request from the user for a higher quality version of the program, the client requests as many enhancement layers associated with the program as possible given the available bandwidth. The client receives the requested data, combines it with the previously stored lower-level layer data, renders the higher quality version of the program, and presents the new version to the user.