X-Fi Ring Architecture

During the early investigation phase of development we identified that there are three categories of usage scenarios that have unique audio processing requirements: gaming, entertainment and audio creation. Therefore we knew that the chip architecture needed to be flexible in order to provide the best features and benefits for each usage. This meant an architecture that could essentially morph itself for each usage. This had never been attempted before and involved working out how to allow the chip to partition its features and power in the correct way for each usage (or as we call it, "mode")

We also identified that there were a number of common tasks that could be optimized, so we developed the X-Fi Audio Processor to provide very efficient special purpose processing elements for many of these common processing tasks. We also included a powerful audio DSP so that algorithms that don't map into the special purpose processors can be programmed in the DSP.

A major requirement of both the modal approach and the optimization is very flexible signal routing. For example the following image shows the typical topology of the signal flow in an audio chip today:

This is typical of the topology found in today's audio processors. There are special purpose processing elements, but the signal path routing is not flexible.

The X-Fi chip on the other hand has a very flexible signal routing architecture as follows:

This new patent pending architecture provides complete signal routing flexibility by means of the "Audio Ring". Each processing element can take audio data off the ring, process it and place it back on the ring. This allows signals to be routed from anywhere to anywhere. The Audio Ring is a pipelined, time division multiplexed bus that supports 4096 audio channels. This sounds like a lot of channels, but these channels are not just the channels corresponding to a recording studio mixing console.

Channels are also needed for the internal signal paths of the reverbs, dynamics processors, special effects processors and all the other gear found in an audio studio.

The SDRAM interface is of particular importance as it enables the X-Fi processor to use memory bandwidth beyond that which the PCI bus can provide.