A data streaming system comprises: one or more streaming sources, one or more streaming clients, a network connecting said streaming sources and said clients, and a level of service selector able for each data stream to monitor the network, the respective streaming source and the respective streaming client to control streaming to the respective streaming client to define a level of service of the data stream. For a video stream the level of service may define the frame rate, the resolution, the overall quality or a level of masking used.