Abstract: A packet-based data network including: an audio/video network including a packet-switched network over which data including audio and/or video data packets can be carried; at least one data source connected to the network and operable to assemble packetized data comprising audio/video data at a first resolution and at a second resolution greater than the first resolution, and to transmit data packets carrying multiple audio/video streams at the first resolution by multicast network transmission; and at least one client connected to the network, being a data handling device for handling packetized audio/video data and being arranged to join the multicast group to receive the multiple audio/video streams at the first resolution. The client is associated with a graphical user interface configured in conjunction with a processor to select an audio/video stream.

Abstract: A packet-based data network including: an audio/video network including a packet-switched network over which data including audio and/or video data packets can be carried; at least one data source connected to the network and operable to assemble packetised data comprising audio/video data at a first resolution and at a second resolution greater than the first resolution, and to transmit data packets carrying multiple audio/video streams at the first resolution by multicast network transmission; and at least one client connected to the network, being a data handling device for handling packetised audio/video data and being arranged to join the multicast group to receive the multiple audio/video streams at the first resolution. The client is associated with a graphical user interface configured in conjunction with a processor to select an audio/video stream.

Abstract: A packet-based data network including: an audio/video network comprising: a packet-switched network over which data including audio and/or video data packets can be carried; at least one data source connected to the network and operable to assemble packetised data comprising audio/video data at a first resolution and at a second resolution greater than the first resolution, and to transmit data packets carrying multiple audio/video streams at the first resolution by multicast network transmission; at least one client connected to the network, being a data handling device for handling packetised audio/video data and being arranged to join the multicast group to receive the multiple audio/video streams at the first resolution, wherein the client is associated with a graphical user interface configured in conjunction with a processor to select an audio/video stream, and the processor is arranged to issue a unicast command to cause transmission of a selected audio/video stream at the second resolution from the

Abstract: A packet-based data network including: an audio/video network comprising: a packet-switched network over which data including audio and/or video data packets can be carried; at least one data source connected to the network and operable to assemble packetised data comprising audio/video data at a first resolution and at a second resolution greater than the first resolution, and to transmit data packets carrying multiple audio/video streams at the first resolution by multicast network transmission; at least one client connected to the network, being a data handling device for handling packetised audio/video data and being arranged to join the multicast group to receive the multiple audio/video streams at the first resolution, wherein the client is associated with a graphical user interface configured in conjunction with a processor to select an audio/video stream, and the processor is arranged to issue a unicast command to cause transmission of a selected audio/video stream at the second resolution from the

Abstract: A packet-based data network includes a packet-based network switch, and a plurality of packetised data sources coupled to the network, where the packetised data includes at least one of audio data or video data. The data network further includes at least one destination, being a data handling device for handling packetised data sources, coupled to the network, and a network control arrangement coupled to the network, the network arrangement being arranged to provide virtual circuit-switched connections for transfer of packetised data from sources to destinations via the network switch by assigning multicast group identifiers to the sources, so that the sources launch packetised data onto the network as multicast data packets identified by the multicast group identifiers, and instructing a destination to issue a request to the network switch to join the multicast group of a source so as to receive data packets from that source.