Patent ID: 6148082
Filing Date: 2000-11-14
Classification: H04N

Abstract:
A method for descrambling transport packets of a transport stream, said transport packets containing elementary stream data of one or more video programs, said method comprising the steps of:(a) defining a sequence of one or more processing steps to be performed on each transport packet and ordering the step of descrambling processing within said sequence,(b) allocating one unique descriptor of a queue for each transport packet, each allocated descriptor containing a pointer to a memory location for storing said transport packet for which said descriptor is allocated, one or more processing indications and a control word information field,(c) storing control word information associated with contents of said transport packet in said control word information field of selected ones of said allocated descriptors,(d) setting said one or more of said processing indications to indicate that the next step of processing of said sequence may be performed on each of said allocated descriptors,(e) sequentially accessing each allocated descriptor, and(f) for each accessed descriptor pointing to a memory location for storing a to-be-descrambled transport packet, descrambling said transport packet stored in said memory location pointed to by said accessed descriptor using said control word information in said accessed descriptor, only if said one or more processing indications of said accessed descriptor are set to indicate that descrambling processing may be performed on said accessed descriptor and transport packet stored in said memory location to which said accessed descriptor points.