CS48AU2B Data Sheet

Dedicated 32-bit Audio DSP for Audyssey Laboratories Technology

6

Copyright 2009 Cirrus Logic

DS876F3

CONFIDENTIAL

3. Code Overlays

The suite of software available for the CS48AU2B consists of an operating system (OS) and a library

of overlays. The overlays have been divided into three main groups called Matrix-processors,

Virtualizer-processors, and Post-processors. All software components are defined below:

1. OS/Kernel - Encompasses all non-audio processing tasks, including loading data from external

memory, processing host messages, calling audio-processing subroutines, error concealment,

etc.

2. Matrix-processor- Any Module that performs a matrix decode on PCM data to produce more

output channels than input channels (2 n channels). Generally speaking, these modules

increase the number of valid channels in the audio I/O buffer.

3. Virtualizer-processor - Any module that encodes PCM data into fewer output channels than

input channels (n 2 channels) with the effect of providing “phantom” speakers to represent the

physical audio channels that were eliminated. Generally speaking, these modules reduce the

number of valid channels in the audio I/O buffer.

4. Post-processors - Any module that processes audio I/O buffer PCM data in-place after the

matrix- or virtualizer-processors. Examples are bass management, audio manager, tone control,

Audyssey Dynamic Volume, Audyssey Dynamic EQ, Audyssey EQ, Audyssey BassXT, delay, &

customer-specific effects, etc.

The certified DSP firmware or application codes provided by Cirrus Logic (under a licensed to you

from Audyssey Laboratories) may enable some or all of the Audyssey Laboratories algorithms.

These licensed processing blocks can be used in combination with a host standard post-processing

signal blocks (tone control, Bass Management, delays, etc.) or lower level primitives such as a filter

or math function.

A product-specific signal flow is generated by the designer using DSP Composer.

Once all of the custom coefficient files supplied by Audyssey Laboratories have been loaded and the

signal flow has been set, the user can perform a “generate deliverables” inside DSP Composer.

This generates a collection of files that can be easily converted to .c or .h files by the designer for

storage inside the host controller OR can be converted into a small image that can either be stored in

port.

The overlay structure reduces the time required to reconfigure the DSP when a processing change is

requested. Each overlay can be reloaded independently without disturbing the other overlays. For

need to be reloaded — only the new matrix-processor (the same is true for the other overlays).

Table 2 below lists the firmware available based on device selection. Please refer to AN298,

modules available.