A system for providing streaming services, comprising: a plurality of capture devices (12a, 12b, 12c), each for capturing data and providing a captured data stream (14a, 14b, 14c) having metadata including a prioritisation score; a server, for receiving the plurality of captured data streams and outputting output streams (18a, 18b); and a device (16a, 16b) for requesting content from the server and for receiving the output stream from the server, wherein the prioritisation score is indicative of the relevance of the captured data stream to the request for content, wherein the server is configured to: assign a timeline of priority values to each of the captured data streams (14a, 14b, 14c) in dependence on the current metadata of that data stream including the prioritisation score and in dependence on a current definition for prioritisation, each timeline of priority values indicating the priority value of a content of the captured data stream at an instant of its duration; group each captured data stream (14a, 14b, 14c); prioritise, within each group, the streams in dependence on the timeline of priority values; and determine the output stream for each group at each instant in dependence on the stream having the highest priority in that group at that instant, wherein the metadata for a captured data stream additionally includes feedback data from a device receiving the output stream from the server. a plurality of capture devices (12a, 12b, 12c), each for capturing data and providing a captured data stream (14a, 14b, 14c) having metadata including a prioritisation score; a server, for receiving the plurality of captured data streams and outputting output streams (18a, 18b); and a device (16a, 16b) for requesting content from the server and for receiving the output stream from the server, wherein the prioritisation score is indicative of the relevance of the captured data stream to the request for content, wherein the server is configured to: assign a timeline of priority values to each of the captured data streams (14a, 14b, 14c) in dependence on the current metadata of that data stream including the prioritisation score and in dependence on a current definition for prioritisation, each timeline of priority values indicating the priority value of a content of the captured data stream at an instant of its duration; group each captured data stream (14a, 14b, 14c); prioritise, within each group, the streams in dependence on the timeline of priority values; and determine the output stream for each group at each instant in dependence on the stream having the highest priority in that group at that instant, assign a timeline of priority values to each of the captured data streams (14a, 14b, 14c) in dependence on the current metadata of that data stream including the prioritisation score and in dependence on a current definition for prioritisation, each timeline of priority values indicating the priority value of a content of the captured data stream at an instant of its duration; group each captured data stream (14a, 14b, 14c); prioritise, within each group, the streams in dependence on the timeline of priority values; and determine the output stream for each group at each instant in dependence on the stream having the highest priority in that group at that instant, wherein the metadata for a captured data stream additionally includes feedback data from a device receiving the output stream from the server.