Patent ID: 7394834
Filing Date: 2008-07-01
Classification: H04N

Abstract:
1. A common interface controller for use in a digital television device having a connector for a selectively attachable conditional access module for descrambling channels of a transport stream as identified by respective PIDs, the common interface controller including: a first input interface for a first transport stream having a first channel identifiable by one or more first PIDs; a conditional access interface configured to transmit to the conditional access module transport streams having scrambled channels and receive from the conditional access module transport streams having descrambled channels; a second input interface for a second transport stream having a second channel identifiable by one or more second PIDs; a forward multiplexer configured to provide an intermediate data stream by time multiplexing at least part of the first transport stream with at least part of the second transport stream, the at least part of the first transport stream including the first channel and the at least part of the second transport stream including the second channel; a PID remapper configured to change the original values of the second PIDs to intermediate values not used by any PID of said at least part of the first transport stream such that said intermediate data stream forms an intermediate transport stream, the conditional access interface being arranged to transmit the intermediate transport stream to a conditional access module configured to descramble at least the first channel and the second channel; a return demultiplexer configured to receive from the conditional access interface the intermediate transport stream descrambled by the conditional access module and separate said at least part of the first transport stream from said at least part of the second transport stream; and a PID demapper configured to change the intermediate values of the one or more second PIDs, as received by the conditional access interface from the conditional access module, back to their original values.