What to Expect: Stereo Bluetooth & iPhone 3G with iPhone OS 3.0 | iLounge Article


What to Expect: Stereo Bluetooth & iPhone 3G with iPhone OS 3.0

Though a number of competing mobile “musicphones” have offered Bluetooth wireless stereo audio streaming for years, the 2007 iPhone conspicuously left that feature out, as did the 2008 iPhone 3G—surprising given Apple’s music-heavy marketing focus, and both iPhones’ inclusion of Bluetooth 2.0 hardware that could be used for monaural wireless handsfree phone calls. Some thought the company was planning its own proprietary wireless music accessory standard for the iPhone; other possibilities included battery drain associated with streaming stereo Bluetooth audio, or problems getting the feature to work reliably given everything else the iPhone had to do in the foreground and background.

Yet whatever the issue or issues may have been, Apple seems to have mostly resolved them in iPhone OS 3.0—at least, for the iPhone 3G. While the original iPhone is stuck with monaural Bluetooth telephone calling support, the iPhone 3G and iPhone 3G S gain stereo Bluetooth streaming and control capabilities with A2DP, a widely used Bluetooth protocol that instantly expands the universe of wireless accessories that users can choose from.

But will they work properly? Or with limitations? We have the answers: here is what users can expect when using stereo Bluetooth accessories with the iPhone 3.0 software.

* Wide compatibility. Stereo-capable A2DP Bluetooth 2.0 accessories have been around for years, and though there will likely be some exceptions, the iPhone 3G appears to pair with and stream to virtually everything without complaint. Pairing is handled through the same buried Settings > General > Bluetooth menu as before, with no differentiation between monaural and stereo devices.

* Near-flawless stereo music and app audio streaming from an actively used iPhone. The iPhone 3G sends a properly separated left- and right-channel audio signal to accessories, with apparent audio quality more often constrained by the speakers or headphones than the signal. Do not expect lossless-quality audio, but rather, very listenable wireless sound. The iPhone 3G will continue to stream iPod mode music even when an app is running, or stream the app’s audio, which means that apps such as Slacker Radio can perform through wireless speakers and headphones. Streaming will continue even when transitions are made from iPod mode to in-app audio, and in-app audio can overlap iPod mode music, as well.

* Seemingly flawless switching between stereo and monaural modes when interrupting music or apps to take phone calls. As with prior accessories, the iPhone fades out its music or other audio to play the ringing sound and then the phone call, complete with microphone support for the phone call.

* Small audio hiccups when apps launch, and infrequently mid-run. Very brief, split-second interruptions can sometimes be heard in playback when audio is streaming while an app is loading; iPod audio continues to be almost perfect when running even device-taxing games, but there are occasionally similarly brief interruptions. This will depend on the app.

* Small audio hiccups when toggling between multiple stereo Bluetooth devices. As with virtually every past iPhone-compatible Bluetooth accessory, switching between two different devices results in a brief audio stutter, but ultimately a working connection to the new device. The iPhone pauses audio playback—when possible, even in apps—when the connection with the original device is cut off, and the new connection is stable from the point you press play.

* Greater potential for audio problems after the iPhone 3G turns off its screen. Bluetooth streaming continues for several minutes without any issues, but sometimes will start stuttering for unknown reasons—possibly just a bug, or the iPhone trying to enter power-conserving deep sleep despite the audio playback. This doesn’t always happen and may be an accessory-specific bug.

* Limited accessory control of music playback. Accessories can include a play-pause button that works to stop and start iPod music—surprisingly even controlling iPod music when an app has its own audio—but their track controls do not appear to work, and they must include their own volume controls for non-calling purposes. The iPhone’s volume controls are disabled in stereo Bluetooth streaming mode, but remain in monaural Bluetooth calling mode; the iPhone’s on-screen track controls remain in stereo Bluetooth mode.


* Odd conflicts between Wi-Fi and monaural Bluetooth functionality. For reasons that aren’t yet clear, iPhone 3G Wi-Fi signal strength drops to 2 of 3 bars when in stereo Bluetooth streaming mode and becomes unpredictable if not unusable for Wi-Fi gaming, and drops to 1 of 3 bars when in monaural Bluetooth phone mode, becoming unusable for web browsing in Wi-Fi mode. This is the most serious set of issues with the new Bluetooth functionality, and it is unclear whether these are just bugs that need to be worked out, or consequences of trying to use Bluetooth and Wi-Fi capabilities at the same time. Notably, switching the iPhone 3G off of Wi-Fi and into 3G restores web browsing capabilities to the device.

* Monaural stays monaural, stereo stays stereo. The iPhone 3G will not send music to monaural devices such as calling headsets, or enable the typical “handsfree car kit” to function as a music player. It will enable AD2P stereo devices to play music for sure, as well as handling monaural calls if they have the microphone hardware to do so.

iPhone 3G S performance will likely vary from the iPhone 3G due to differences in both processing capabilities and Bluetooth chips; the second-generation iPod touch will also gain stereo Bluetooth functionality for the first time. We’ll have more to share on this in the near future.

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Will the enhanced Bluetooth functionality allow a portable Bluetooth keyboard to be used with the iPhone?

This would be really useful if it did.

Posted by BigTram in East Amherst, NY, USA on June 11, 2009 at 1:27 PM (CDT)


While it would be theoretically possible for developers to write their own specific apps that use a Bluetooth keyboard by directly accessing the Bluetooth hardware from within their app, the iPhone itself does not look like it will support any keyboard drivers in the Bluetooth profile.

Posted by Jesse Hollington in East Amherst, NY, USA on June 11, 2009 at 1:31 PM (CDT)


Has anyone verified that this 3.0 update does allow A2DP protocol and not some off the wall apple so called stereo bluetooth that will require one of thier products? In the 3G S specs it states Bluetooth 2.1 + EDR
and no A2DP protocol.

Posted by Nurc Diver in East Amherst, NY, USA on June 11, 2009 at 1:48 PM (CDT)


#3: See above. That’s your verification right there.

Posted by Jeremy Horwitz in East Amherst, NY, USA on June 11, 2009 at 2:34 PM (CDT)


I recently had a chance to test out an iphone using the 3.0 gold dev release update. I cant seem to get the radio bluetooh to work in my car’s bluetooth hands free kid. I purchased the kit directly from Toyota last year and had them install it.

In the past, if i was playing music and it was interupted by a call, there was a chance that my music would end up playing over the bluetooth speakers. It pretty much showed that this was possible, but there just wasnt the option to manually select it.

Well so far with 3.0 gold release the option to select a paired bluetooth device doesnt appear at all.

Does this mean that radio bluetooh wont work with my bluetooth kit or anyone thats current in the market or is there something else im not seeing?

Posted by blkmagik in East Amherst, NY, USA on June 11, 2009 at 2:51 PM (CDT)


droping signal with BT and WiFi is normal - both technologies share the same chip, antenna and radio frequency 2,4GHz

Posted by Tomáš Kapler in East Amherst, NY, USA on June 11, 2009 at 2:56 PM (CDT)


#3 I have Motorola S9’s and they work great, with some limitations. I wrote a review of my experience with them under the main Ipod Touch forums.

Posted by Esoy in East Amherst, NY, USA on June 11, 2009 at 3:05 PM (CDT)


With Globalsat BTH-820 track control doesn’t work.

So, it’s useless having a bluetooth receiver when you can’t skip forward o backward songs, you only can play/pause

Posted by Gwydion in East Amherst, NY, USA on June 11, 2009 at 5:20 PM (CDT)


So, it has no AVRCP, only A2DP profile.

I can’t understand Apple

Posted by Gwydion in East Amherst, NY, USA on June 11, 2009 at 5:24 PM (CDT)


I think Im missing the point about the car kits? Can someone help me? Will Music from the iphone 3gs play through my built in bluetooth car player?
Please help me!!

Posted by Belinda Morrison in East Amherst, NY, USA on June 11, 2009 at 11:39 PM (CDT)


Jeremy, thanks for the info. 

i’m assuming that you’ve tested this on the gold master?  if thats the case and AVRCP is not in the software…  i will not be a happy camper.

Posted by cantankerous in East Amherst, NY, USA on June 12, 2009 at 12:43 PM (CDT)


I’m looking for an answer to that question on he interner for 3 days, unsucessfully…
Is the new iphone software application abble to send a contact with bluetooth, as most of cell phones?
It would be great for me to get that response

Posted by Claude in East Amherst, NY, USA on June 13, 2009 at 5:51 AM (CDT)


I have a Kenwood KCA-BT200 bluetooth box that talks to my Kenwood KVT-514 DVD head unit.  Currently in iPhone 3G 2.2.1 firmware there is only bluetooth HFP, and no A2DP (as we know).  There is no ability to access the iPhone contacts or SMS functionality from my head unit…  These functions, however, work perfectly with my wife’s 3 year old Razr phone.  I think the Phone Book Access Profile (PBAP) and maybe the Object Push Profile (OPP) are required for this to work.  Any idea if these profiles will be included with iPhone OS 3.0?  I’ll be extremely disappointed if it won’t, as my Kenwood allows the storage of only 6 numbers.  There is no phone book built, but a bluetooth-transmitted phone book accepts 1000 numbers per paired phone (max 5 phones)...

Posted by David Arthurs in East Amherst, NY, USA on June 14, 2009 at 11:42 AM (CDT)


Thank you for the info, Jeremy. No wonder I visit iLounge every single day of my life.

Posted by iLly in East Amherst, NY, USA on June 14, 2009 at 1:44 PM (CDT)


Thanks for the info!  You might want to fix the typo at the end, where you call it “AD2P”.  At the beginning of the article, you have it correctly as “A2DP”.  I was unfamiliar with this term, so was confused when I did a Google search on “AD2P”.

Posted by Mike in East Amherst, NY, USA on June 15, 2009 at 1:19 PM (CDT)


Hi Jeremy,
I’ve some complicated scenarios on the audio output using A2DP, 3.5mm, and iPod Dock. May I know if you can tell me all of the results?  I’m planning to explore on that once I get my iPhone 3GS 2 weeks after launch due to sold-out stock in AT&T;.  I will make a detail review specifically on A2DP on YouTube.

1st: a 3.5mm headphone is plugged in, the audio comes out of the headphone. Next, connect your A2DP device to the iPhone. Will the audio come out to both 3.5mm headphone and A2DP device?  Can I connect a mono Bluetooth headset at the same time as the A2DP is connected?

2nd: Similar to 1st Scenario, but reverse the process by connecting the A2DP first then plug in the 3.5mm headphone, which device outputs audio?
Again, can I connect a mono BT headset at the same time.

3rd: Connect the iPhone via the iPod dock to a stereo system.  Play the music.  While the music is playing, connect the 3.5mm stereo headphone to the iPhone and play the music again.  Where does the audio output?  After that, connect the A2DP device, where does the audio output now?

Can we random access the audio output device among: A2DP, 3.5mm headphone, Speaker, iPod Dock?  If do where do we change the audio output?

I really need to know this because when I’m driving, my iPhone is connected to a FM transmitter via iPod Dock, so the audio must be output to the iPod Dock and not the A2DP nor 3.5mm headphones.  But when I’m at home, I want to randomly access the 3.5mm, A2DP, and iPod Dock for home stereo.

Does the new software support Bluetooth contact, calender sharing?
Does it support Bluetooth keyboard and mouse?

Thanks Jeremy!

Posted by squarejp in East Amherst, NY, USA on June 16, 2009 at 12:31 AM (CDT)


Re Monaural stays monaural, stereo stays stereo.

Mono Headset For Mono/Stereo.
There are some ‘mono headsets’ with support for both headset and A2DP profiles, e.g. Jabra BT530. I use this ‘mono headset’ with Sony Ericsson W890i. It allows me to make phone calls on phone and also I can listen to the ‘stereo mp3 files’ with the ‘same headset’. This is my preferred option as I drive a lot so wearing a ‘stereo headset’ is not an option. (Note, I listen to stereo mp3 when I am not driving the car as I have a decent car radio!). I know that there are other mono headset models also available that offer this feature.

Not the ideal solution for all but more convenient than carrying a ‘full blown stereo headset’, (with microphone support for phone calls), for to listen to the occasional music track.

Have not tried this headset with iphone but would expect that it would work the same as for W890i.

Posted by AN in East Amherst, NY, USA on June 16, 2009 at 2:33 PM (CDT)


The cause of the Bluetooth/WiFi issues is likely the fact that they’re both in unlicensed 2.4GHz spectrum, and on a device as small as the iPhone, it’s simply impossible to put in enough shielding and achieve enough path separation to prevent interference.  I’ve seen this with Nokia phones, as well.

It can even show up using Bluetooth and WiFi on a MacBook, so it’s unsurprising, and I doubt there’s much Apple or anyone else can do about it, given the form-factor of a phone.

The supposed lack of AVRCP is surprising; AVRCP works just fine with my iPhone 3G when I use the (unsupported for iPhone) Brandon Bluetooth dongle with it, interestingly enough.

My guess is that the keyboard profile isn’t supported because an iPhone 3G(s) would be a viable laptop replacement for a lot of folks who only do email, light Web surfing, and light IM.  A snap-on hardware keyboard via the dock connector would be ideal, however, if Apple allow someone to make one.

Posted by Roland Dobbins in East Amherst, NY, USA on June 17, 2009 at 5:01 AM (CDT)


Has anyone had luck with A2DP headphones on the iPod touch 2G?  If so, what headphones?  My Logitech headphones, which work fine on my Mac, don’t show up in the list on my iPod touch.

Posted by Nicholas Riley in East Amherst, NY, USA on June 17, 2009 at 5:17 PM (CDT)


I installed the Gold Master yesterday and tried it on my bluetooth car stereo… music plays great through AD2P.

I can pause it from my stereo, but not fast fwd or rewind… I’d say AVRCP is busted!

Posted by mmmmok in East Amherst, NY, USA on June 17, 2009 at 7:46 PM (CDT)

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