For the consumer electronics titans, the new systems are not just digitally enhanced VCRs but represent an important beachhead in their plans to build a networked home-entertainment environment independent of the PC. For the drive makers, the audiovisual hard-disk drive (AV-HDD) is pushing them toward new command sets and interfaces, such as 1394, as well as generating new demand for ultra-high-capacity platters.

Leading U.S. drive vendors, including Quantum Corp. (Milpitas, Calif.), Western Digital Corp. (Irvine, Calif.) and Seagate Technology Inc. (Scotts Valley, Calif.), said that consumer products built around the technology will feature new functions such as live-broadcast pause: The consumer can hit the pause button, go to the fridge for a beer, then pick up the broadcast where it left off, as the system simultaneously records multiple streams of audio, video and data.

But many consumer vendors see AV-HDD as more than just a gimmick for delivering new features. By tucking a storage device into all manner of digital appliances, from satellite decoders to TV receivers, they hope to gradually build a distributed repository for media streams at home, if not offering a central home server outright, said an executive at a leading consumer electronics company who spoke on the condition of anonymity. In building that infrastructure, vendors hope to control and architect a comprehensive home network system that doesn't rest on the shoulders of the PC.

However, analysts are divided about whether the disk-driven recorders — which will be delivered in a variety of set-top designs — will be a market success.

Stuck in no-growth markets like TVs and VCRs, consumer OEMs "are so hungry for new products and desperate to restart the engine," said Jim Porter, president of Disk/Trend Inc. (Mountain View, Calif.). Yet Porter remained skeptical about AV-HDD's prospects. "There are so many variables in this market," he said, including "how couch potatoes might respond to potentially interactive features."

Baby steps

Kevin Hause, analyst at International Data Corp. (IDC), predicted that 300,000 units of the AV-HDDs will ship in the United States this year — a drop in the buck next to the 100 million-unit PC market. However, Hause expects the technology to become a mainstream consumer item within a year, selling 1 million units in 2000 as consumers catch on and HDD prices drop. IDC sees the market growing to 13 million units in the United States alone in 2005.

"The consumer market won't start to pick up until HDD manufacturers begin to produce in volume drives with 10 Gbytes per platter," said Porter. Hard drives used in desktop PCs today pack 6.8 Gbytes/platter. Quantum and Fujitsu only announced drives with a little over 8 Gbytes per platter earlier this month, Porter said.

Charlie Leeson, vice president of sales and marketing for AV products at Western Digital, acknowledged that the emerging AV-HDD demand has "reinvigorated the push for capacity."

Besides demanding beefy platters at an affordable price, the AV-HDD thrust puts the onus on drive makers to deliver the accompanying standards and interfaces to make these systems perform as advertised. Among solutions yet to be engineered are standard protocols and command sets for AV-HDDs featuring the IEEE 1394 interface.

Another challenge lies in handling streaming media. Seagate in August will propose its solution, called SeaStream, at the upcoming meeting of the T13 committee in Boulder, Colo. T13 is a technical committee of the National Committee on Information Technology Standards, accredited by the American National Standards Institute.

SeaStream, documented in T13/D99123r0, consists of new subcommands and modifications to Read and Write DMA commands for audio and video streaming. Bob Teal, vice president of consumer solutions at Seagate, called the scheme "a superset of ATA interfaces" that makes minimum changes to the existing standards. "If pioneering work done by companies like Quantum enabled AV streaming, our proposal has really optimized it," claimed Teal.

Among the three leading HDD vendors, Quantum zeroed in on HDD's role on the consumer front three years ago, dedicating a small team to explore non-PC hard-drive applications. "We are the first to take HDD out of the PC and to turn it into a recorder," said Bentley Nelson, manager of strategic and technical marketing at Quantum.

The company's head start clearly helped it land two major design wins. Quantum is now the sole supplier of hard-disk drives to both TiVo (Sunnyvale, Calif.) and Replay Networks (Palo Alto, Calif.), two startups providing unique television services that allow viewers to watch what they want, when they want.

Western Digital and Seagate, each armed with its own set of consumer partners, said in recent interviews that they have also completed the engineering work to tailor their disk drives for entertainment applications.

Western Digital, which has forged strategic partnerships with Sony Corp., has mainly focused on developing mechanical and electronic components and firmware for the AV-HDD, leaving the interface, architecture and protocols for AV applications to Sony.

Seagate, meanwhile, is the only company so far to propose a set of audio-video extensions for drives based on the ATA interface as a shared, open interface spec. "While most disk-drive vendors don't have a lot of interest in standards at the moment, the pressure is really coming from CE [consumer electronics] OEMs looking for multiple sources," said Seagate's Teal.

There are a number of somewhat trivial differences between drives designed for computers and those for consumer products. A primary one is that losing a single bit is critical for, say, a spreadsheet, but inconsequential in a large color display. That means some of the error correction can be scaled back in order to make certain that a constant video stream is supplied.

Files are stored sequentially so the heads do not have to search around as they do in today's PCs, further aiding in the continuous video stream. Handling two or three data streams is not a major problem, since a drive's relatively quick access time makes it possible to retrieve data in the time available.

Each vendor has taken a slightly different design approach to outfitting its disk drives to handle multiple media streams uninterrupted, while also tweaking them for use in a noise-sensitive living room. Most of the alterations have focused on software and firmware, rather than changes in basic hardware architecture.

A common goal was building a hard drive that can function as an embedded file system without using a host computer. The AV-HDD needs enough built-in intelligence to open, share, delete and attribute files, while letting consumers play, record, pause, stop and rewind both streaming media and Internet-based content.

Though disk-drive manufacturers have gone ahead with proprietary implementations of protocols and command sets for ATA interfaces, consumer and drive vendors alike see IEEE 1394 quickly moving to center stage as the preferred solution for linking AV-HDDs with other consumer devices.

Interface support

A 1394 solution does not make sense just yet, when a majority of consumer electronics systems on the market — be they DVD players, satellite decoders or TVs — do not sport a 1394 link. But the AV-HDD will feature a 1394 interface "by midyear 2000," predicted Russell Kraph, vice president of the AV products group at Western Digital.

The final command sets necessary for 1394-based AV-HDD are being thrashed out within the 1394 Trade Association's AV Working Group. Among drive vendors, Quantum is taking the lead as an editor and a contributor to this standards effort. The work is expected to be completed by October.

In inventing AV-HDDs, drive vendors agreed on three major areas where they've focused most of their engineering efforts: tuning acoustic features; managing multiple streams simultaneously, uninterrupted; and developing appropriate error/recovery algorithms for both isochronous and asynchronous data.

"We've taken a system-level approach to improve the acoustic performance of the AV-HDD," said Vipul Mehta, marketing manager of Western Digital's AV products. "A lot of noise is generated when a motor is running in its seek mode," he explained. "We optimized not only mechanical design but also the drive's firmware to minimize that problem."

Timely delivery

Managing multiple streams of isochronous and asynchronous data was also an important design goal. "How well you do error recovery to maintain the data integrity is essential for most PC applications, such as spreadsheets," said Quantum's Nelson, but "timely delivery of data becomes the number one priority" in streaming multimedia. Quantum claims it has developed internal algorithms that separate audiovisual data from text as they come in, coding them accordingly as they go into the hard drive and applying different error/recovery methods on the fly.

In mixing streaming media and text data in the storage device, Seagate's SeaStreams technology has the host send "start" or "end" subcommands — or both — to control AV partition-set features. (This is defined as a sequential collection of sectors within a disk drive, for the purpose of storing AV data.) When the drive is reading the AV streams, it can quit numerous retries for error correction, so that it can promptly transfer data on time without dropping frames.

Asked about Seagate's SeaStream proposal, Quantum's Nelson declined to comment.

Consumer electronics companies hold high hopes for expanding their product lines by exploiting AV-HDDs.

They could, for example, architect a home networking system by running a middleware layer such as HAVi on top of a variety of 1394-based digital consumer appliances. While the 1394 interface will allow each device to execute basic command sets such as play, record, pause, stop and rewind, the HAVi architecture could help tie together digital appliances by letting each one register its presence, discover other devices and communicate with them.

A storage device incorporated in consumer appliances could invoke a dramatic shift in the balance of power between the service operators and system OEMs. In an effort to subsidize the HDD cost, "We are beginning to see some system operators setting aside a portion of the HDD real estate for revenue-producing applications," rather than leaving the entire storage space under the consumer's control, said Andy Fischer, director of marketing at MbTV Networks, a division of Metabyte Inc. (Fremont, Calif.) that develops software for interactive TV products.

A case in point is a recent business arrangement between TiVo and Philips. Philips is an equity investor in TiVo and the first consumer OEM signed to license, manufacture and deliver video recorders for TiVo service.

TiVo's filing with the Securities and Exchange Commission earlier this month disclosed that Philips will not only receive a manufacturing subsidy from TiVo, but also a fixed payment per month for each Philips-branded video recorder owned by an active TiVo service subscriber.

— Terry Costlow contributed to this report