CS4953xx Data Sheet

32-bit Audio Decoder DSP Family

DS705PP2

®Copyright 2008 Cirrus Logic, Inc.

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3. Code Overlays

The suite of software available for the CS4953xx family consists of an operating system (OS) and a library of

overlays. The overlays have been divided into three main groups called Decoders, Mid-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.

decoding/processing algorithms listed below require delivery of PCM or IEC61937-packed, compressed data

3. Mid-processors - Any module that processes audio I/O buffer PCM data in-place before the Post-

processors. Generally speaking, these modules alter the number of valid channels in the audio I/O buffer

through processes like Virtualization (n 2 channels) or Matrix Decoding (2 n channels). Examples are Dolby

ProLogic IIx and DTS Neo:6.

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

Examples are Bass Management, Audio Manager, Tone Control, EQ, Delay, Customer-specific Effects, Dolby

Headphone/Virtual Speaker, etc.

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 example,

when a new decoder is selected, the OS, mid-, and post-processors do not need to be reloaded — only the

new decoder (the same is true for the other overlays).

Table 2 below lists the firmware available based on device selection. Please refer AN288 CS4953xx Firmware