A2DP Absence: What's The Defense?

Back in late January, I listed 10 feature omissions and other shortcomings of the upcoming (and now here) Apple iPhone that I found disappointing, particularly considering the device’s hefty $500-$600 plus-2-year-contract pricetag. When the unit’s full feature set was unveiled last Friday, I discovered another deficiency: an extremely limited Bluetooth capabilities list that (at least currently) only comprehends monophonic speaker-plus-microphone headsets.

Some of the iPhone’s missing Bluetooth capabilities are, although disappointing, not terribly surprising. Carriers have long insisted that their phone provider partners disable Bluetooth file transfer capabilities, for example, so that folks can’t easily pull camera phone-captured images off the device or upload new ring tones or audio tracks to it. Instead, customers are supposed to use the carriers’ proprietary (translation=fiscally lucrative to carrier) cellular-based music, photo and ring tone services. At least, with the iPhone, you can copy AAC and MP3 music files (along with eventually, it’s rumoured, track-derived ring tones) to the unit via iTunes and a wired connection, along with using OS X-only iPhoto and a cable tether to access the iPhone camera’s 2 Mpixel photos (hmmm….will iPhoto be the next Apple application ported to Windows?).

The iPhone is also incapable of being used as a wireless modem when mated to a PC via either a Bluetooth or wired connection. Again, this limitation is disappointing albeit not surprising; it’s another common carrier requirement that serves to limit the use of your phone’s ‘unlimited data’ plan. But what really surprises me about the iPhone is that it doesn’t support Bluetooth’s A2DP profile, which enables wireless dual-channel (aka ’stereo’) audio streaming to a compatible Plantronics Pulsar or other manufacturer’s headset. I’ve also encountered this omission with Nokia’s two Internet Tablets (which seems particularly silly given that they support RealNetworks’ Rhapsody music service), and many Windows Mobile 5 AKUs (adaptation kit upgrades) also left out A2DP support. And the A2DP omission is particularly acute in the iPhone case because the device’s recessed audio jack supports (intentionally, I suspect) only a short list of 3^rd-party wired headphones (including, ironically, those from Microsoft’s Zune).

Design engineers out there, I’m curious; what’s the most common root cause for (and reasoning behind) missing A2DP support? Is the fundamental limiter the Bluetooth transceiver and, if so, were you just unwilling to shoulder the additional cost burden of an A2DP-inclusive IC? Or is the Bluetooth transceiver A2DP-cognizent but your preferred software stack doesn’t exploit the full silicon potential? Speaking as a consumer, I’ve used Bluetooth ’stereo’ headsets on several occasions and, although to date most models are somewhat bulky, the lack of cable tether is also quite liberating. Plus, if I was Plantronics or another headset supplier, I’d be unenthused with all the inevitable customer support backlash from consumers who buy a ’stereo’ headset assuming it’ll work with their mobile multimedia player, only to be disappointed when the two devices refuse to fully pair.

Readers, I welcome your thoughts.