PC, consumer engineers play different tunes on road to wireless music
By Rick Merritt
EE Times
December 11, 2003 (10:17 a.m. ET)
SAN JOSE, Calif. — PC and consumer engineers are taking separate paths to audio over Bluetooth, raising the possibility of incompatible wireless MP3 players, headsets and speakers. Word of the split comes as Bluetooth is gaining traction in its core market of cellular handsets and marshalling its forces for a next-generation spec that could deliver megabit data rates and multimedia capabilities.
A handful of top consumer companies, including Matsushita, Philips, Sony and Toshiba, have defined in a Bluetooth Special Interest Group working group a low cost means for streaming audio to Bluetooth headsets with plans to roll out products in 2004. For its part, Microsoft and a group of unnamed OEMs are hammering out a different approach to implement on the PC based on Internet Protocol over Bluetooth.
"We may see multiple standards existing," said J. Eric Janson, vice president of marketing for Cambridge Silicon Radio (CSR, Cambridge, England), one of the top Bluetooth chip suppliers. "I'd sooner everyone go in one direction so we can optimize around that and take the cost out of it, but I'm not sure that's realistic at this point," Janson added.
In contrast to Microsoft's IP approach, the SIG's consumer audio/video working group has defined a mechanism for streaming audio over Bluetooth using the Real Time Protocol defined by the Internet Engineering Task Force.
"At this point there is a controversy as to whether IP is cost effective for simple devices like headphones. So far we haven't found a need for an IP address on such devices," said Tsuyoshi Okada, a staff engineer in the wireless group at Matsushita Electric Industrial Co. Ltd. (Osaka).
Matsushita and other companies in the SIG's A/V working group are preparing MP3 players, headsets and speakers using the current 723 Kbit/s Bluetooth version 1.2 spec and an advanced audio distribution profile (A2DP) defined by the SIG in May. Some of the companies are in talks with Microsoft to find ways to bridge the two efforts.
"We want to make sure our headsets interoperate with PCs," said Okada.
The issue for Microsoft is audio quality, particularly in an environment where there might be multiple Bluetooth devices. Wireless keyboards, mice and other 2.4 GHz devices could generate interference that could result in crackling speakers when PCs stream audio over Bluetooth. A2DP is essentially a point-to-point spec that doesn't take that scenario into account, said Mike Foley, a wireless architect at Microsoft.
"We're working with OEMs to come up with a solution...it's a very important issue," Foley said.
It's not clear whether the PC effort is part of an existing personal-area network group in the SIG or a separate ad hoc collaboration often favored by Microsoft. Foley would not name companies involved in the effort or say when the work will be finished.
"There are a lot of consumer companies that want to get products out, and if they wait for Microsoft it will delay them," said Jennifer Bray who tracks standards for CSR.
Microsoft elected not ship native support for Bluetooth in its Windows XP, though the company did ship in September an add-on pack with a Bluetooth application programming interface. Going forward, the company has kicked off an effort to define an umbrella set of APIs under its Winsock framework. Under the framework, that will probably be built into Longhorn, the next generation of Windows, developers would write to Winsock and Windows would determine what services are passed over what networks.
Apple Computer has taken a different approach, building Bluetooth support into its OS X and into its current series of Powerbook notebooks. David Russell, director of product marketing for wireless and notebooks at Apple, made a pitch to developers at the Bluetooth Americas conference here Wednesday (Dec. 10) to accelerate adoption by making Bluetooth easier to set up and use.
Russell would not comment on widespread reports at the conference that the next version of Apple's iPod MP3 player will use Bluetooth. He poured cold water on the idea of using Bluetooth to download music to the device that currently uses USB or Firewire interfaces for that function.
At the conference, consumer audio devices were seen as the next likely target for Bluetooth, for which some 75 million chip sets will ship this year, mostly for GSM phones in Europe and Asia.
In separate presentations, chip and software vendors indicated several challenges to delivering music over Bluetooth. Systems will need sub-band coding to efficiently move MP3, Windows Media or other codec files in a simple way to a headset or speaker. Headsets should have 80 milliseconds or less latency to stay in synch with video from a TV. A Broadcom manager said upcoming megabit versions of Bluetooth will be required to eliminate the need in wireless headsets for large and expensive buffers.
Janson of CSR noted that vendors also will have to work out ways to protect copyright for wireless music traveling between a device and a headset, another thorny issue.
The audio debate comes as the Bluetooth SIG is setting up a new road map committee to provide broad market input on directions and timing for the next revs of the short range wireless link. The committee could help the SIG get under control an expanding list of applications and software profiles to go with them as well as proposals for low- and high-end versions of spec that could clash with 802.11, ultrawideband and Zigbee networks.
"The SIG has become a dumping ground for profiles," said Seamus McAteer, an analyst with Zelos Group (San Francisco) who follows Bluetooth.
The SIG has already queued up work on a number of advancements for the technology that could be in a next major release of Bluetooth.
