SAN JOSE, Calif. — Intel Corp. kicked off an effort to define a next-generation audio standard for both PCs and consumer electronics devices Thursday (Feb. 20). The so-called Azalia specification ultimately aims to replace both AC '97 codecs in PCs and I2S codecs used in DVD players and other consumer systems.
Observers expect the initiative will be a slam dunk in PCs where Intel will build Azalia controllers into its chip sets starting with its ICH-6 south bridge that will ship with its Tejas-class next-generation desktop Pentium CPUs in mid-2004. However, some sound-chip makers expressed skepticism the spec would replace low-cost I2S chips, and others voiced fears that Intel's implementation plans, which have yet to be disclosed, might unfairly favor other chip makers.
Intel's aim is to bust through some of the shortcomings of today's AC '97 parts while providing support for new capabilities such as multiple simultaneous audio streams to and from different sources. By creating an audio subsystem that ties an independent direct memory access (DMA) engine to each audio stream, Intel hopes to create the plumbing for running DVD-Audio, Dolby Digital and THX Surround EX sound on consumer PCs as well as improved voice-over-IP and voice recognition using array microphones on business desktops.
Intel hopes to create a spec that would be compelling for consumer systems, opening the door to a larger and more robust market for high-quality audio codecs than exists today. The microprocessor giant also aims to create a model where ultimately one software driver from Microsoft could serve an entire market of audio chips, reducing system development and support costs.
"We want to unite the PC and CE worlds under one audio model," said Abdul Jarrar, an Intel platform architect who helped unveil parts of the Azalia spec for the first time in a technical session at the Intel Developer Forum here.
"There are ten different AC '97 implementations today. They all have different DMA engines and their codecs have different streaming rates, widths and formats. We would like to standardize a next-generation audio controller to allow for better PC deployment," said Jarrar.
Intel is concerned the quality of PC audio codecs is deteriorating as margins from the products have ebbed and support costs have risen due to issues with a small jungle of software drivers.
Azalia is intended as an end-to-end audio spec that will define everything from a new and simpler software model, controller, link and codec down to the audio I/O jacks. The spec, which will not be backward compatible with AC '97, is currently in an early 0.5 revision draft with a final version not expected until early 2004.
Companies including Analog Devices Inc., Microsoft, RealTek (Taipei), SigmaTel Inc. and Yamaha are believed to be working under the NDA effort. Intel and Sony are also said to in discussions about the spec.
"We are working with most of the key audio chip and codec companies under NDA," said Devon Worrell, a senior Intel engineering manager. "This is a third generation of PC audio beyond ISA SoundBlaster and AC '97. This spec will take us through the end of this decade," he added.
How it works
Azalia can handle up to 15 simultaneous audio streams. Each stream is associated with its own DMA channel. Thus each stream can run using different formats and rates as needed.
Rather than employing registers and programmed I/O, Azalia's DMA engines communicate in a packet-like fashion using 32-bit words as commands and responses between the DMA engines and memory buffers. Intel claims the method will save power and cost while improving performance.
Codecs may include optional programming nodes that can provide functions such as equalization. The nodes also may contain a mechanism for supporting universal audio jacks that can recognize a peripheral and have it's I/O device automatically routed to the correct part of the codec.
Azalia codecs sit on a dedicated bus that links to dedicated audio, telephony or communications devices. The bus runs at a selectable 3.3-1V. It supports 24 Mbit/second audio inputs and "double-pumped" 48 Mbit/second audio output.
"We've targeted this to be able to support high-end solutions," said Worrell.
Synchronization is handled at the system, controller and individual stream levels. Azalia will also make use of PCI Express' isochronous virtual channel capability when that is supported in Longhorn, Microsoft's next iteration of Windows, expected in 2005.
A standard codec package and pinout for mainstream PCs is in the works. Designers may not specify pinouts for high-end implementations.
Azalia is expected to support real-time audio capabilities with latencies that could be as low as 500 microseconds. That would open the door to playing virtual digital instruments on Azalia systems.
Intel is expected to build into Azalia some low-level support for copy protection schemes such as 4C and CPPM. The company may also be working with Microsoft and other companies on providing supporting for digital-rights management software in Azalia.
"There are other features we hope to put in Azalia that we are not talking about yet because they would depend on features of a next-generation OS," said Worrell in a veiled reference to Microsoft's Longhorn.
At the IDF presentation, Dale Gulick, a senior technical staff member for Advanced Micro Devices Inc. expressed concerns about how Intel will handle interoperability testing for Azalia. Chip partners who provided reference implementations for some past PC specs have reaped the advantage of becoming the de facto standard while other chip makers had to rev their parts to come into compliance, Gulick noted.
"All I am saying is you should use the model set by the USB Implementers Forum," he said.
Peter Frith, a vice president of new product development for Wolfson Microelectronics (Edinburgh, U.K.) said his company will make Azalia codecs for handheld PCs and may make them for desktops as well. However, he expressed doubts relatively complex Azalia device would replace in DVD players the I2S codecs that cost less than 50 cents.
Wolfson considered making AC '97 codecs for desktops. However, it pulled back from those plans after it watched codec prices fall to commodity levels while costs for supporting separate software drivers for each PC chip set skyrocketed. "We are a small company and can't support all those different PC drivers," Frith said.
Intel's Worrell said he thinks Azalia could replace AC '97 in all PCs by 2006. Replacing I2S codecs in consumer gear would take longer, he added.
