Patent ID: 7969972

Claim:
A system comprising: at least one transport stream interface for receiving a plurality of packet streams from a plurality of sources, each of the plurality of packet streams being received from a corresponding source of the plurality of sources, a first packet stream of the plurality of packet streams comprising a plurality of packets for providing audio, video, private data and/or associated information; and at least one output for sending at least one packet of said plurality of packets to circuitry arranged to provide an output stream, wherein: each packet in the plurality of packets is associated with one of a plurality of programs, each packet comprising a program identifier tag identifying the program associated with the packet; the system is arranged to provide a source identifier tag for the at least one packet, the source identifier tag being different from the program identifier tag and indicative of the source of the at least one packet; said at least one output sends said at least one packet to said circuitry via a first communication line; said system is arranged to provide the source identifier tag to said circuitry separately from said at least one packet, on a second communication line separate from said first communication line; the at least one transport stream interface comprises a software input port arranged to receive at least one of the plurality of packet streams from a memory; and the value of the source identifier tag provided for a first packet received by said software input port is determined by adding an offset to one or more bits of an address of the source of said first packet.