Codec cranks for wireless stereo headsets

SAN JOSE, Calif. — The promise of affordable, high quality Bluetooth stereo headsets appears to be getting closer, thanks to better hardware and software on the horizon.

Today most MP3 players and even an increasing number of cellphones that build in music capabilities typically use wired headsets. Even the much hyped Apple iPhone today only supports monophonic Bluetooth headsets.

The lag is due to the fact wireless stereo headsets have generally either been low in quality or cost as much as $300. Pushing the shift to wireless stereo forward, Open Interface North America (OINA; Seattle) is rolling out a lossless audio codec that provides better performance than its competitors without requiring new hardware.

“We are very early into what could be a market for billions of Bluetooth stereo headsets and adapters, so the game is on,” said Richard Doherty, principal of market watcher Envisioneering (Seaford, NY).

The SoundAbout Lossless codec provides a near real time performance with latency between 2-10 milliseconds. By contrast, the Apple Lossless Audio Codec (ALAC) has latency of about 100 ms, and an open source alternative called the Free Lossless Audio Codec (FLAC) can be tuned to about 25-50 ms, said Tom Nault, OINA's chairman and chief executive.

In addition, the new codec is symmetric. That means it takes about the same amount of processing power—roughly 20 Mips—to encode or decode an audio stream. ALAC and FLAC generally take significantly more time to encode an audio stream than decode one.

The codec also supports the relatively new 2.0 version of Bluetooth which provides affective throughput of about 2.1 Mbits/second. That compares to about 750 Kbits/s for the previous version of the short-range wireless standard.

The software supports multi-channel streaming and is independent of any sampling frequency. It can also be used for source material other than audio and networks other than Bluetooth.

OINA has demo software for the new codec up and running. It expects a production version of the code could ship to partners in time for them to build prototype headsets to demonstrate at the Consumer Electronics Show in January.

The code is based on the Advanced Audio Distribution Profile (A2DP), part of the Bluetooth spec that defines wireless stereo audio. Many handsets, including the Apple iPhone, still do not support A2DP.

A2DP includes a basic lossy codec called the sub-band codec (SBC) for stereo audio. OINA developed a proprietary extension of that codec that it uses in its current products.

OINA licenses its software for both to headset makers directly and to chip makers who integrate it into their firmware. The company has licensed lossy Bluetooth stereo codecs to companies such as Samsung, Sony, STMicroelectroncs and Qualcomm.

Bluetooth hardware is maturing, a fact that should help nudge the market for stereo headsets forward. “The first generation products for wireless audio did not meet the quality and power consumption requirements, but the current generation devices is where we will see some uptake,” Nault said.

Those chips typically support Bluetooth 2.0. They also tend to integrate enough memory and analog/digital conversion circuitry to lower costs to bolster stereo audio processing and drive headset costs to about $100, Nault said.

The software is available on the x86 and ARM7 TDMI chips. It is also being ported to the Broadcom’s BCM2047 and Cambridge Silicon Radio's BlueCore5-Multimedia which supports Bluetooth 2.0.

CSR is the dominant supplier of Bluetooth silicon. Its existing BlueCore3-Multimeida part is one of the most widely sold Bluetooth parts today, said Nault.

License fees for the codec are based on volume sales. The company would not provide any price information.

OINA, focused on software for Bluetooth, was formed in 2000 when it spun off from its parent company in Japan. “We want to take Bluetooth into new areas,” said Nault

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