Over six years after development started, Bluetooth SIG’s Advanced Audio Distribution profile (A2DP) is now making its way on to wireless devices. The purpose of A2DP is to enable stereo output for wireless headphones.

A2DP is not particularly popular at the moment, but some people will begin to cotton on to the fact that if you spend all you’re hard earned cash on something like the iPhone and pair it up with a Bluetooth headset expecting the same quality as from your MP3 player, you will likely be disappointed.

Apple could effectively add A2DP at any time they desire even though most reports say the update won’t be on the software development kit (SDK).

Mark Pundsack, the president of Wi-Gear attempts to shed some light on the feature, “A2DP is for all intents and purposes a geek’s luxury at this point. Really only in the last year has A2DP been in cell phones. It’s just not that obvious,”

The majority of experts agree that the most technical obstacle is battery life. To transmit stereo audio wirelessly, regardless of the communications protocol, requires the transmitter to be switched on the entire time. A2DP output could drain talk time by around 10 percent or more, Bluetooth SIG Executive Director Mike Foley says. There are also financial reasons not to include the feature. High-end H2DP implementations often require an additional DSP chip, driving up the parts cost.

Foley targeted Apple recently in his blog, “As hard to believe as it is, the iPhone does not enable stereo headphones … Supporting stereo for headphones, car stereos, portable speakers and home stereos is a simple extension.”

“If the iPhone implements the standardized Bluetooth stereo profile, the device will work with headphones, cars, home stereos and portable speakers from any manufacturer. While this is great for the consumer, it isn’t as great for Apple’s bottom line. Apple may be under the impression that they can create an entire ecosystem of wireless peripherals for the iPhone and iPod in which they control by licensing the proprietary interface into the devices,” Foley continues. “I’ve asked Apple what the rationale was for not enabling more Bluetooth features in the iPhone, but as of yet, have not received a reply,” he says.

With industry speculation that interference between the telephone radio and Bluetooth radio holding back the rollout of A2DP 1.2, which the latest version, Foley explains that this is simply not true, “We probably have more Bluetooth devices per square foot in the country and we also run Wi-Fi and things like that, and we don’t see any issues. It’s been out there long enough. All these sorts of concerns don’t hold water any more.”

One possible solution to the A2DP power problem is Wibree. This became part of the Bluetooth portfolio last summer after being originally pushed by Nokia. Designed for low-power devices such as clock radios and wristwatches, the specification will be published in the first half of 2009.

David Favreau, senior director of product management at Qualcomm said, “In general, we found that the A2DP standard has been very well-defined for some time now. The technical challenges themselves are really not that substantial for implementing the technology. Certainly there are things from vendor to vendor that impact things such as battery life and audio quality to some degree.”