Dolby Digital™ AC-3 Audio Decoder
ZSP Application Software
OVERVIEW
APPLICATIONS
Dolby Digital™ (AC-3) is the perceptual coding technology used for DVD
and HDTV audio compression. The ongoing transition to digital media delivery
systems for pre-recorded media like DVD-video and Digital Television
programming via cable, terrestrial and satellite, has created the need for high
quality, digital coding techniques. The advent of multi-channel surround sound
in feature films and movie-like theatre reproduction for the living-room can only
be achieved by effective audio compression technologies.
• Home Entertainment Systems
DOLBY DIGITAL (AC-3)
• 32-bit audio precision
Dolby Digital was first developed for film and HDTV broadcast delivery
of 5.1 channel audio. The consumer version covers the range of mono to 5.1
channel audio, and data rates from 32 kbps to 640 kbps. For DVD-video,
AC-3 multi-channel audio supports bit rates up to 448 kbps and a sampling
frequency of 48kHz. Although the specification allows for competing
technologies like DTS and MPEG-multi-channel, the majority of DVD-video titles
use Dolby Digital. Since feature films and DVD-movies are a key element of
broadcast programming, support for Dolby Digital decoding in DTV and Set-top
boxes worldwide is vital.
AC-3 is a flexible audio data compression technology, capable of
encoding a variety of audio channel formats into a single low-rate bit stream.
Eight channel configurations are supported, ranging from mono or stereo to a
surround format with six discrete channels (left, center, right, left-surround, rightsurround and subwoofer).
AC-3 Frame Synchronization Error Detection
Frame De-Formatting
Bit
Allocation
Spectral
Envelope Decoding
Figure 1. Decoder Block Diagram
• AV-Receivers
• DVD-players
FEATURES
• Fully optimized for ZSP platforms
• Low MCPS and memory requirements
• 6-channel surround sound
• 32 kbits/s to 640 kbits/s compressed
audio bit rates
• 16 kHz to 48 kHz sampling rates
• Supports all 8 channel coding modes
• Fully compliance tested
• Hardware test and development board
available
BENEFITS
• Dolby A grade tested
• High-end audio quality
• High performance while the low MCPS
requirements leave headroom for
additional DSP tasks
• Easy-to-use and hassle free system
integration
DeQuantization
Synthesis
Filter Bank
• Digital Television
• ZOpen® compliant
THE DOLBY DIGITAL CODING SYSTEM
AC-3
Bit Stream
• Set-top Boxes
Delay
Buffer
PCM
Samples
Down Mix
Buffer
Window
Overlap
PCM Output
Buffer
Dolby Digital™ AC-3 Audio Decoder ZSP Application Software
ITEM
ZSP400 RESOURCE (5.1)
Program Memory
10.5 kW
Table Memory
3.7 kW
Data Memory
3 kW
Maximum Cycles/Sec
27.5 MCPS
Note: wordlength=16bit; I/O buffering not included
(I/O buffering for 5.1 configuration: 5 kW)
For more information please call:
LSI Logic Corporation
North American Headquarters
Milpitas, CA
Tel: 866 574 5741
LSI Logic Europe Ltd.
European Headquarters
United Kingdom
MCPS (Million Cycles Per Second) is used rather than MIPS, since multiple
instructions per cycle will be executed.
Tel: 44 1344 426544
Note on Dolby Digital Licensing
The implementation is provided subject to the terms and conditions of the
Dolby Laboratories Licensing Corporation and requires certification of the
end-product
LSI Logic KK Headquarters
As the subwoofer channel only contains the Low Frequency Elements (LFE),
the required bandwidth required is only one-tenth of the others; therefore the
LFE channels is referred to as the “.1” channel.
DOLBY DIGITAL ON ZSP
The ZSP software implementation is designed with effectiveness and cost
efficiency in mind while maintaining superb audio quality and resolution.
The implementation uses 32-bit word width throughout the signal path and
signal fidelity is maintained at 24-bits or more. Prior to re-quantization
(application of exponents to mantissas) all information is maintained in 16-bits.
The software is delivered within the ZOpen® test environment which
verifies bit-exact operation under the ZOpen test conditions for easy software
integration with other software components.
Fax: 44 1344 481039
Tokyo, Japan
Tel: 81 3 5463 7165
Fax: 81 3 5463 7820
LSI Logic web site
www.lsilogic.com
LSI Logic logo design, ZOpen and ZSP are
trademarks or registered trademarks of LSI Logic
Corporation. Dolby Digital and the Dolby Digital
logo are registered trademarks of Dolby Digital Inc.
All other brand names and product names may be
trademarks of their respective companies.
LSI Logic Corporation reserves the right to make
changes to any products and services herein at any
time with out notice. LSI Logic does not assume any
responsibility or liability arising out of the
application or use of any product or service
described herein, except as expressly agreed to in
writing by LSI Logic; nor the purchase, lease, or use
of a product or service from LSI Logic convey a
license under any patent, copyright, trademark
rights, or any other of the intellectual property
rights of LSI Logic or of third parties.
Copyright ©2002 by LSI Logic Corporation.
All rights reserved.
Order No. R20067
1202.1K.SR.IK - Printed in USA
ZSP Application Development Partners