Direct memory access execution engine with indirect addressing of circular queues in addition to direct memory addressing

Abstract

A method for enhancing transport packet demultiplexing and distribution in a digital transport demultiplexing system that inputs a stream of digital multimedia transport packets is provided. Each of the transport packets includes a packet identifier (PID) to identify the digital program or elementary stream to which it corresponds. Local packet information is generated for each of the transport packets, which is used in identifying and distributing the transport packets. A local header is created that includes the generated local packet information, and the local header is linked to its corresponding transport packet to create a modified transport packet. In this manner, each of the modified transport packets represents a self-contained digital transport packet having local distribution information contained therein. A transport stream demultiplexing apparatus for use in a digital transmission system capable of providing a plurality of digital transport packets to a digital program presentation device is provided. The demulitplexing apparatus performs the demultiplexing operation by creating a set of direct memory access (DMA) instructions for a DMA engine to execute when transferring the transport packets to one or more output queues. The DMA engine is also configured to descramble the contents of the transport packets while the DMA operation occurs.