Abstract: A relay system has a router and multiple relay servers with specific network addresses on a first network. The router and servers are mutually connected by a second network. The router receives a relay-service request from a source on the first network, addressed to an address distinct from the relay servers' specific addresses. It forwards the request to the relay servers. Each relay server instructs the source to issue a relay-service request to its specific address. The server that receives the request provides the service. Two routers may be connected to different respective sub-networks of the first network and be connected to each other by the second network. The routers announce a common destination network address on the first network. The first network is configured such that only one of the routers receives a data packet addressed to the common address, which it forwards onto the second network.

Abstract: A data distribution system comprises a plurality of processing devices (8) connected by a packet-based transport network (2), and a session manager (12). The session manager (12) is configured to manage a distribution session by (i) associating two or more of the processing devices (8) with a multicast group on the transport network, (ii) storing and/or accessing a mapping between a session identifier for the distribution session and the multicast group address, and (iii) configuring the transport network (2) and/or the processing devices (8) so that data output to the multicast group by any one of the processing devices in the group is received by all the other processing devices in the group. Each of the processing devices (8) can receive data from a respective node (16) located on an external network, and send the received data, or data derived therefrom, over the transport network (2) to a multicast group.

Abstract: A data distribution system comprises a plurality of processing devices (8) connected by a packet-based transport network (2), and a session manager (12). The session manager (12) is configured to manage a distribution session by (i) associating two or more of the processing devices (8) with a multicast group on the transport network, (ii) storing and/or accessing a mapping between a session identifier for the distribution session and the multicast group address, and (iii) configuring the transport network (2) and/or the processing devices (8) so that data output to the multicast group by any one of the processing devices in the group is received by all the other processing devices in the group. Each of the processing devices (8) can receive data from a respective node (16) located on an external network, and send the received data, or data derived therefrom, over the transport network (2) to a multicast group.

Abstract: In the field of IP telephony, a video conference call is established between a calling node and a called node. Identification information relating to a calling party is transmitted to a connection server, which accesses a database of information relating to one or more parties and links between the parties. It uses the links to determine a set of parties depending on the identity of the calling party. It transmits identification information relating to the set of parties, and receives a selection from a user of a party from said set. It interrogates a database to determine a network address for one of the nodes and initiates a call with one of the nodes. It sends a call-transfer instruction to that node, which instructs the node to cease the call with the connection server and to transfer the call to the other node.

Abstract: A relay system has a router and multiple relay servers with specific network addresses on a first network. The router and servers are mutually connected by a second network. The router receives a relay-service request from a source on the first network, addressed to an address distinct from the relay servers' specific addresses. It forwards the request to the relay servers. Each relay server instructs the source to issue a relay-service request to its specific address. The server that receives the request provides the service. Two routers may be connected to different respective sub-networks of the first network and be connected to each other by the second network. The routers announce a common destination network address on the first network. The first network is configured such that only one of the routers receives a data packet addressed to the common address, which it forwards onto the second network.

Abstract: The present invention relates to a method of copy protecting optical discs, such as CDs or DVDs. Instead of encoding data onto the CD-ROMs in a conventional manner which ensures balanced dc content, for copy protection the digital data is encoded and recorded onto the optical disc such that it is arranged to give some of the recorded digital data highly unbalanced dc content. Thus, for example, the DSV (digital sum value) value of the encoded data is recorded so that the DSV value changes continuously once 50 frames of data or more.

Abstract: The ability of a data reader to access, extract, or otherwise read the data on a CD-DA provides a problem for the music industry. A user can use his CD-ROM drive to read the data from an audio disc into a computer file, and then that data can be copied. Therefore, errors are deliberately introduced into the encoded data, these errors being of a type which are generally transparent to an audio player but which will interfere with the extraction or reading of the audio data by a data reader. The data on a CD is encoded into frames by EFM (eight to fourteen modulation), and each frame includes 24 bytes of audio data. There are 8 sub-code bits contained in every frame which enable 8 different subchannels, P to W, to be formed. The P- and Q-subchannels incorporate timing and navigation data for the tracks on the disc, and generally are the only subchannels utilised on an audio disc.