WM6 & Microsoft Bluetooth A2DP quality: Light at the End of the Tunnel?

[Menneisyys]

Everyone into A2DP and stereo, wireless Bluetooth headphones knows the Microsoft Bluetooth stack, quality-wise, used to be WAY worse than that of competing products (Widcomm / Broadcom on Windows Mobile; Nokia and other products on other platforms). I’ve thoroughly elaborated on this issue in the Comparison & thorough compliance report of three stereo Bluetooth headphones: Nokia HS-12W, Plantronics Pulsar 590 and 260 (http://www.pocketpcmag.com/blogs/index.php?blog=3&p=1744&more=1&c=1&tb=1&pb=1) and previous articles. Note that you WILL want to read at least this article - it may answer a LOT of your A2DP-related questions.

Fortunately, there IS light at the end of the tunnel. Upon seeing THIS (http://forum.xda-developers.com/showthread.php?p=1295190) XDA-Dev thread (linked from THIS (http://www.modaco.com/index.php?showtopic=254179) thread at MoDaCo), I’ve made some very thorough tests with the new, WM6 Bluetooth implementation and was VERY pleased with the results.

Yes, the new WM6 (as far as REAL, official WM6 versions are concerned and NOT illegal, “cooked” ROM’s, some of which still having the pre-WM6, low-quality A2DP implementation) indeed delivers a vast quality increase.

Listening to any music with singing was pretty much impossible with the MS BT stack back in the WM5 days (with an incompatible pair of headphones; don’t forget that, as has also been pointed out in my already-linked article (http://www.pocketpcmag.com/blogs/index.php?blog=3&p=1744&more=1&c=1&tb=1&pb=1), the A2DP implementation of WM5 delivers excellent results with already compatible A2DP headphones like the Nokia HS-12W); now, with WM6, the sound quality is pretty much close to that of the Widcomm (Broadcom) BT stack. It’s only audiophiles (like me) that will notice the VERY slightly lower sound quality with the new, WM6 implementation; ordinary people not really.

Again, the sound quality of the new A2DP implementation is orders of magnitude better (again, I only speak about incompatible headphones, NOT about compatible ones like the already-mentioned Nokia HS-12W! Keep this in mind when I speak about the bad sound quality of pre-WM6 A2DP implementation) than that of ANY WM5-based Pocket PC’s or Smartphones. This means you can, finally, dump Widcomm hacks or Widcomm-based handhelds in favor of new, WM6-based phones.

What about pre-WM6 Windows Mobile models?

After Microsoft introduced A2DP support in January 2006 with WM5 AKU2, the vast majority (exceptions include, for example, the HTC Wizard, which has never officially received any A2DP support) of new models (and operating system upgrades for existing ones) coming with the Microsoft BT stack (that is, all WM5 models except for Acer’s and HP’s models and the Fujitsu-Siemens T830 phone) have been released with A2DP support.

The A2DP sound quality of WM5 AKU2 devices was terrible. It was only with VERY few headphones models (for example, the already-mentioned Nokia HS-12W) that it delivered good sound quality. The vast majority of existing A2DP stereo headphones models (for example, the Plantronics Pulsar 590 and 260) were plain useless with the stack.

While Microsoft (vaguely) promised A2DP quality increase with the Autumn 2006 release of WM5 AKU3, real upgrades / devices didn’t deliver ANY increased sound quality. I’ve tested this with MANY WM5 AKU3 devices; both Pocket PC’s and MS Smartphones natively delivered with AKU3; for example, the HTC Oxygen (aka S310; a WM5 AKU3.0 MS Smartphone) and the HTC Trinity (aka P3600; a WM5 AKU3.3 Pocket PC).

This means it’s only with WM6 that you can expect (almost) flawless A2DP sound quality. With ANYTHING earlier, you will have MUCH worse sound quality – unless, again, you have one of the very few compatible headphones (Nokia HS-12W etc).

Also note that, should you use a “cooked” WM6 ROM, you may still have pre-WM6 A2DP support because these ROM’s may use components from older operating system versions. As cooked ROMs are not really legal, I am not allowed to provide you more information on the affected models or ROM versions - sorry. However, the next section explaining the Joint Stereo mode will be of great help to decide whether your cooked WM6 version already has the latest A2DP support, or still an old, WM5-based one.

Affected ROM versions – of which ROM’s can you expect good A2DP quality?

As a rule of thumb, if a given ROM version supports Joint Stereo, then, it’s capable of delivering pretty good A2DP quality. That is, if, in the Registry, the value HKLM\Software\ Microsoft\Bluetooth\ A2DP\Settings\ UseJointStereo (note that HKLM, as usual, stands for HKEY_LOCAL_MACHINE) is 1 , meaning enabled (NOT 0, meaning disabled) and the sound is (still) stereo, then, you have the new, WM6-based, high-quality A2DP implementation.

If you get mono sound (as is the case with ALL pre-WM6 models I’ve ever tested, despite what some say; and, again, some cooked WM6 ROM’s also belong to this category), then, you have the old (low-quality) MS BT stack, which can’t really be “hacked” – it’ll always deliver sub-par sound quality with most headphones, except for some select headphones models like the Nokia HS-12W (but, according to this XDA-Dev thread (http://forum.xda-developers.com/showthread.php?p=1295190), not necessarily other Nokia headphones).

To make sure your (WM6) device has a new BT stack (or an old one), get a registry editor. If you’re unsure, read the Registry Editor Bible (http://www.pocketpcmag.com/blogs/menneisyys/UltimateRoundupOfRegistryEditors.asp) for a roundup; I recommend the registry editor in Resco File Explorer (http://www.resco.net/pocketpc/explorer/default.asp) the most. It runs great on both regular Pocket PC’s and MS Smartphones. Note that many recommend (for example, in THIS (http://forum.xda-developers.com/showthread.php?t=285344) thread) Breaksoft’s Mobile Registry Editor. You won’t want to use it because it isn’t able to modify the HKLM branch (only for seeing what’s in there it’s sufficient, though).

The same may stand for the, mostly for MS Smartphone users, highly recommended RegEditSTG on some WM5+ Smartphone models – it’s been signed by HTC’s certificate, which has been put on the ban list in at least Orange-branded phones released since Feb. 2006. That is, this registry editor won’t run for example on the SPV C100 (the Orange rebranded HTC Oxygen / S310), not even on a completely (application) unlocked phone. This isn’t the case with Resco’s editor: it’ll work just great on (app) unlocked new Orange Smartphones.

Yeah, I have a new, legal, official WM6 device, I still have VERY bad sound quality!

People that DO have a legal and official WM6 model (for example, the HTC Vox (s710) smartphone) still MUST hack the Registry to get rid of two registry values really degrading sound quality: the "MaxSupportedBitPool" and the "BitPool" values under HKLM\Software\ Microsoft\Bluetooth \A2DP\Settings. These both have a very low (with the Vox, 30) default value, resulting in VERY bad sound quality. I just don’t understand why Microsoft and HTC have left these values in there – all they do is completely degrading sound quality, without fixing anything / making more A2DP headphones compatible.

Just remove these two registry values and shut down / restart Bluetooth (or, if you choose so, reset the device – you won’t need this for the changes to be heard).

Note that if you have a Smartphone (and not a Pocket PC), make sure you application unlock your device before modifying the Registry; otherwise, you won’t have edit access to the Registry. To unlock your phone, you will want to read THIS (http://www.modaco.com/Remove-S710-application-lock-install-prompt-t254325.html) (if you have a Vox or a similar, new, mostly WM6 device) or THIS (http://forum.xda-developers.com/showthread.php?t=285344) (if you have an older WM5 device like the Oxygen – while these models still have the old, low-quality A2DP implementations, you may still want to either remove these values or increase their value too slightly increase the A2DP quality. You will still have bad sound quality compared to the WM6 one - or that of the Widcomm stack).

You may also want to create a SampleRate DWORD value with the value of 48000. Many have reported subsequent quality increase (I haven’t noticed this with my HTC Vox + Plantronics Pulsar 590A duo but this doesn’t necessarily mean with other models you won’t hear an increase in the sound quality.) If you’re unsure, just import this registry script (http://www.winmobiletech.com/sekalaiset/WM6A2DPSoundQualityIncrease.reg) – it’ll increase the sampling frequency and also makes sure the Joint Stereo mode is enabled, should you or some tweaker tools have messed with it.

[Menneisyys]

Don’t forget than in pre-WM6 times you HAD to disable the Joint Stereo mode; therefore, if you have ever run automatised sound quality enhancer tweaks (for example, with the excellent HTweakC tool; see THIS (http://www.pocketpcmag.com/blogs/index.php?blog=3&p=1697&more=1&c=1&tb=1&pb=1) for more info) , they may have already set this to 0 (which isn’t recommended any more).

Incidentally, this registry import file, which works on both MS Smartphone and Pocket PC models, has another value, HKLM\Software\Microsoft\ Bluetooth\AudioGateway\ Capability, which makes it possible for the phone to play the ringtone in the connected A2DP headphones and not in the phone itself. If you don’t want this to be changed, just remove the two related rows before importing the script.

Note that as you can’t delete anything from a registry import file, you’ll still need to manually remove the Public Enemy Number One: that is, the "MaxSupportedBitPool" and the "BitPool" values under HKLM\Software\ Microsoft\Bluetooth\A2DP\ Settings.

Verdict

WM6, as opposed to ALL versions of the previous, WM5 operating system, has vastly enhanced A2DP support already available for legal WM6 users ready to do some registry editing (most importantly, removing two registry values). If you’re, on the other hand, a user with a “cooked” WM6 ROM, you may still have the old, low-quality A2DP implementation.

Don’t forget to remove the two registry values if you have a legal WM6 device and you’re still encountering bad sound quality – it’ll REALLY work.

[lie_ui]

i read through your article. Thanks.
I have been experiencing everything you described above since WM5 and its various AKU and never experienced a good A2DP yet.
The only time I experienced something wow with Bluetooth music is when I run MSI Blue Player with the itech R35 headset which is MSI compatible headset, and the quality is superior, I could not differenciate it with the wired sound quality.

So, for us with WM5 devices, what we can do. From the description, its a matter of software, new BT implementation in the WM6.
How could we port out this piece to run in WM5 or self cooked WM6?

[CWKJ]

You missed out the Sony Ericsson A2DP BT Stereo headset which has not too bad result except for the bass is a little coloured. The bass is too strong for my taste.

Anyway I like my Nokia HS-12W.

I seems to experience (with the registry hack) a better sound quality with AKU2.0 than in AKU3.x. I have not tried the any WM6 for A2DP.

[Menneisyys]

i read through your article. Thanks.
I have been experiencing everything you described above since WM5 and its various AKU and never experienced a good A2DP yet.
The only time I experienced something wow with Bluetooth music is when I run MSI Blue Player with the itech R35 headset which is MSI compatible headset, and the quality is superior, I could not differenciate it with the wired sound quality.

So, for us with WM5 devices, what we can do. From the description, its a matter of software, new BT implementation in the WM6.
How could we port out this piece to run in WM5 or self cooked WM6?

The best way is installing the Widcomm BT stack (if there's a working hack for your particular model - what's it?) - it'll deliver the best quality.

Or, wait for a working and really up-to-date WM6 version to appear, let it be either an official upgrade or an unofficial, cooked ROM version. Unfortunately, I may not elaborate on the latter more - a simple forum search can do wonders ;-)

[lie_ui]

I have a Prophet running unofficial WM6.
Everything runs pretty stable. I checked the registry setting for Bluetooth A2DP and it does not have any folder named Settings under Bluetooth A2DP. So, there is nothing like JointStereo, BitPool, etc.

A2DP sound quality is just the same like the AKU 2.x and AKU 3.x

From your article, its implied indeed it has the old/WM5 Bt stack.

Hmmm, they just launched the T-Mobile Wing which is officially running WM6. I was thinking to upgrade before, but cancelling it, because from my current Prophet to the new T-Mobile Wing, there is no significant upgrades besides the keyboard. I will lose infrared, normal audio port, full size SD Card, in exchange of getting exactly same size device, same hardware with only addition: the keyboard.

But now, you pointed out the proper and good A2DP quality... which should be part of the new T-Mobile Wing according to your article... =)

[Dishe]

For those of us stuck with WM5 devices for now, we need someone to extract the a2dp drivers for the current "fixed" WM6 installations.

We've had a2dp drivers floating around ever since the original Tornado a2dp hack, leading up to versions from AKU 3.2, 3.5, and even the beta WM6's (which were terrible). It shouldn't be difficult for anyone to do the same with these new "fixed" drivers, however as far as I can tell, no one has bothered yet.

If anyone out there knows how to do this, you would be doing a great service to your fellow WM fans!

[Menneisyys]

I have a Prophet running unofficial WM6.
Everything runs pretty stable. I checked the registry setting for Bluetooth A2DP and it does not have any folder named Settings under Bluetooth A2DP. So, there is nothing like JointStereo, BitPool, etc.

A2DP sound quality is just the same like the AKU 2.x and AKU 3.x

From your article, its implied indeed it has the old/WM5 Bt stack.

Hmmm, they just launched the T-Mobile Wing which is officially running WM6. I was thinking to upgrade before, but cancelling it, because from my current Prophet to the new T-Mobile Wing, there is no significant upgrades besides the keyboard. I will lose infrared, normal audio port, full size SD Card, in exchange of getting exactly same size device, same hardware with only addition: the keyboard.

But now, you pointed out the proper and good A2DP quality... which should be part of the new T-Mobile Wing according to your article... =)

Hope it is also part of the Wing and it's not based on an older / beta A2DP. I could only test this with my HTC Vox.

[Menneisyys]

For those of us stuck with WM5 devices for now, we need someone to extract the a2dp drivers for the current "fixed" WM6 installations.

We've had a2dp drivers floating around ever since the original Tornado a2dp hack, leading up to versions from AKU 3.2, 3.5, and even the beta WM6's (which were terrible). It shouldn't be difficult for anyone to do the same with these new "fixed" drivers, however as far as I can tell, no one has bothered yet.

If anyone out there knows how to do this, you would be doing a great service to your fellow WM fans!

While I'm not allowed to post direct links, I'll definitely report on whenever someone "somewhere" manages to do this.

[bjrmd]

BTW--nice paper going over the meaning of joint stereo and bandwidth issues
http://www.impulsesoft.com/home/download/btaudioguide.pdf

[Dishe]

Oh hey, that explains joint stereo! I though it was something Microsoft made up...

[arnste]

Menneinsyys,

Clearly you are a man who knows a lot about A2DP. Unfortunately I can't say the same for myself. I wonder if I could pick your brain for a minute...

I own a treo 700wx and have just bought a pair of Sony DR-BT21G headphones but was disappointed to discover I had no A2DP. I'm having troubles wth my earphone jack which makes me doubly interested in getting Bluetooth to work. My carrier is (unfortunately) Bell Canada. That means no WM6 update and no AKU3 or other update. I have been looking around for an A2DP patch and have already tried installing one from Hannip at TreoCentral and another from Sheehan but neither have worked.

From what I have read from you, I should ideally upgrade to WM6 before trying to add on an A2DP patch (correct me if I am wrong). That begs the question whether there is a way to upgrade to WM6 despite your carrier - any suggestions?

Then comes the question of A2DP - what would the best route be for me to take? (carefull, I'm a real neophyte in all of this). Knowing my situation, what do you think of my chances to sovle this ?

Much obliged for your time.

Arnste

[Menneisyys]

Menneinsyys,

Clearly you are a man who knows a lot about A2DP. Unfortunately I can't say the same for myself. I wonder if I could pick your brain for a minute...

I own a treo 700wx and have just bought a pair of Sony DR-BT21G headphones but was disappointed to discover I had no A2DP. I'm having troubles wth my earphone jack which makes me doubly interested in getting Bluetooth to work. My carrier is (unfortunately) Bell Canada. That means no WM6 update and no AKU3 or other update. I have been looking around for an A2DP patch and have already tried installing one from Hannip at TreoCentral and another from Sheehan but neither have worked.

From what I have read from you, I should ideally upgrade to WM6 before trying to add on an A2DP patch (correct me if I am wrong). That begs the question whether there is a way to upgrade to WM6 despite your carrier - any suggestions?

Then comes the question of A2DP - what would the best route be for me to take? (carefull, I'm a real neophyte in all of this). Knowing my situation, what do you think of my chances to sovle this ?

Much obliged for your time.

Arnste


It seems it's working. See http://discussion.treocentral.com/showthread.php?t=112637

(if it's not accessible, use http://209.85.135.104/search?q=cache:umaPm8U_vQwJ:discussion.treocentral .com/showthread.php%3Ft%3D112637 instead)

[joecruz]

Hi, first off I give my hats off to ur very detailed and informative article about a2dp.

However, I think (i'm not sure about this but based on experience), a2dp registry settings vary by model. I previously owned a Wizard and use to search for all kinds of threads regarding improving a2dp. I even searched in other devices' threads (universal, hermes, etc). Although I was using pre-official wm6 (cooked one) and in the other devices' threads that I've read, they were also using the same type of roms (but for their device).

I've noticed that the registry settings that people in the universal forums were using, did not give me the best results for my wizard. The same results were obtained from using the registry settings that were suggested in the hermes forums. Although the people in those threads swear by the improvement and excellent results with their device, I was getting constant skipping and mono-type sound. I then stuck to the suggested registry settings in my own device's forum (wizard) and I did get pretty decent,skip-free music.

Now I'm using a hermes and I tried using the registry settings that I used in my wizard but I did not get the same results in comparison to using the registry settings suggested in the hermes forums.

The validity of my statements may not be accurate but these are my findings based on experience and it could be something to ponder on when it comes to achieving the best a2dp experience

[dbrotzen]

Thank you! This is great news! I own a pair of 590a's and not being able to use them on the X7500 was a dealbreaker. Now that they ought to work in WM6, I'm one step closer to getting that X7500. BTW your previous BT article was brilliant!

[Menneisyys]

BTW your previous BT article was brilliant!



Thanks :)

[Menneisyys]

Hi, first off I give my hats off to ur very detailed and informative article about a2dp.

However, I think (i'm not sure about this but based on experience), a2dp registry settings vary by model. I previously owned a Wizard and use to search for all kinds of threads regarding improving a2dp. I even searched in other devices' threads (universal, hermes, etc). Although I was using pre-official wm6 (cooked one) and in the other devices' threads that I've read, they were also using the same type of roms (but for their device).

I've noticed that the registry settings that people in the universal forums were using, did not give me the best results for my wizard. The same results were obtained from using the registry settings that were suggested in the hermes forums. Although the people in those threads swear by the improvement and excellent results with their device, I was getting constant skipping and mono-type sound. I then stuck to the suggested registry settings in my own device's forum (wizard) and I did get pretty decent,skip-free music.

Now I'm using a hermes and I tried using the registry settings that I used in my wizard but I did not get the same results in comparison to using the registry settings suggested in the hermes forums.

The validity of my statements may not be accurate but these are my findings based on experience and it could be something to ponder on when it comes to achieving the best a2dp experience



Yup, they vary on both the handheld and the headphones model.

Note that, however, the WM5 / WM6 versions you've tested are all cooked ROM's. I didn't have really good results with the (early; dunno if current ROM's are better in this respect) WM6 Universal cooked ROM's either - it delivers MUCH worse sound quality than my natively WM6 HTC Vox.

[joecruz]

Hi Menneinsyys,now that the official wm6 roms are out, chefs are cooking their own versions and saying that they kept the bluetooth stuff of the official wm6 rom but they still "optimize" them for "best" quality (by some registry tweaks). You may not have the answer to this but, in ur own opinion (for the hermes specifically), do u think the chefs are really keeping the BT stuff from the original wm6 rom?

[Menneisyys]

Hi Menneinsyys,now that the official wm6 roms are out, chefs are cooking their own versions and saying that they kept the bluetooth stuff of the official wm6 rom but they still "optimize" them for "best" quality (by some registry tweaks). You may not have the answer to this but, in ur own opinion (for the hermes specifically), do u think the chefs are really keeping the BT stuff from the original wm6 rom?

Dunno, haven't tested the latest WM6 cooked ROM's as yet - my Universal still runs one of the earliest WM6 builds and haven't flashed it to anything newer as yet. As soon as I have some time, I flash them onto my PDA's and, A2DP-quality-wise, I test them.

[joe_dude]

<Original message deleted>

Ah, I understand the situation now. Sorry, I've been away for awhile. There's still hope for WM5 devices, I think. :)

[Dishe]

Ah guys, if you want to improve your WM5 A2DP quality, please check out my old post from this thread:

http://forum.xda-developers.com/showthread.php?t=284344&page=6

Message #59. Works for Wizard and Prophet. If only I had remembered to try the UseJointStereo months ago....

I tried that one- I think that was based on the "older" beta version of WM6. The a2dp fixes weren't apparent until the final release!

Correct me if I'm wrong, I don't recall that one being any better... and I played with all the settings...

[joe_dude]

Ah, I see... time to go back to the kitchen. Stay tuned, folks.... :)

[joe_dude]

Sorry guys, the new WM6 files are quite different than the old ones. I can't get them to work on WM5. So I guess it's WM6 ROM or no dice. :(

[bsw11]

When I turn off my phone after being paired to a stereo headset or receiver (I have 4 different devices - they all have the same problem), it does not reconnect the stereo mode automatically - is there a fix for this issue?
I am using an ATT-Tilt with Dutty ATT beta2 ROM right now. The BTLink makes it a bit easier, but I still have to put the device in discover mode to get the stereo connection to work.

Does anyone else notice this problem?

[Menneisyys]

When I turn off my phone after being paired to a stereo headset or receiver (I have 4 different devices - they all have the same problem), it does not reconnect the stereo mode automatically - is there a fix for this issue?
I am using an ATT-Tilt with Dutty ATT beta2 ROM right now. The BTLink makes it a bit easier, but I still have to put the device in discover mode to get the stereo connection to work.

Does anyone else notice this problem?

Definitely a ROM problem as I've never encountered similar probs on any of my WinMo devices. Repost your Q to the Kaiser forums.

[gambit07]

Hey! Great informative information in here, however I have a slight problem. I have a legal version of wm6 on a samsung sch-i760, and I use sktools for registry editing. However when I go to a2dp under localmachine/software/microsoft/bluetooth all I get is a registry key called address. No settings where I can edit jointstereo or anything like that. Any suggestions?!

[keithwwalker]

Menneisyys,

I checked my registry and I was wondering what the value should be to make the phone play the ringtonw to the headset and not the phone?

Currently my Capability setting is at DWORD Data: 37

Thanks
Keith Walker

Incidentally, this registry import file, which works on both MS Smartphone and Pocket PC models, has another value, HKLM\Software\Microsoft\ Bluetooth\AudioGateway\ Capability, which makes it possible for the phone to play the ringtone in the connected A2DP headphones and not in the phone itself.

[Menneisyys]

Hey! Great informative information in here, however I have a slight problem. I have a legal version of wm6 on a samsung sch-i760, and I use sktools for registry editing. However when I go to a2dp under localmachine/software/microsoft/bluetooth all I get is a registry key called address. No settings where I can edit jointstereo or anything like that. Any suggestions?!


just create them. I think I've also provided some readily-importable reg import scrripts that do this.

[austinbrady]

Everyone into A2DP and stereo, wireless Bluetooth headphones knows the Microsoft Bluetooth stack, quality-wise, used to be WAY worse than that of competing products (Widcomm / Broadcom on Windows Mobile; Nokia and other products on other platforms). I’ve thoroughly elaborated on this issue in the Comparison & thorough compliance report of three stereo Bluetooth headphones: Nokia HS-12W, Plantronics Pulsar 590 and 260 (http://www.pocketpcmag.com/blogs/index.php?blog=3&p=1744&more=1&c=1&tb=1&pb=1) and previous articles. Note that you WILL want to read at least this article - it may answer a LOT of your A2DP-related questions.

Fortunately, there IS light at the end of the tunnel. Upon seeing THIS (http://forum.xda-developers.com/showthread.php?p=1295190) XDA-Dev thread (linked from THIS (http://www.modaco.com/index.php?showtopic=254179) thread at MoDaCo), I’ve made some very thorough tests with the new, WM6 Bluetooth implementation and was VERY pleased with the results.

Yes, the new WM6 (as far as REAL, official WM6 versions are concerned and NOT illegal, “cooked” ROM’s, some of which still having the pre-WM6, low-quality A2DP implementation) indeed delivers a vast quality increase.

Listening to any music with singing was pretty much impossible with the MS BT stack back in the WM5 days (with an incompatible pair of headphones; don’t forget that, as has also been pointed out in my already-linked article (http://www.pocketpcmag.com/blogs/index.php?blog=3&p=1744&more=1&c=1&tb=1&pb=1), the A2DP implementation of WM5 delivers excellent results with already compatible A2DP headphones like the Nokia HS-12W); now, with WM6, the sound quality is pretty much close to that of the Widcomm (Broadcom) BT stack. It’s only audiophiles (like me) that will notice the VERY slightly lower sound quality with the new, WM6 implementation; ordinary people not really.

Again, the sound quality of the new A2DP implementation is orders of magnitude better (again, I only speak about incompatible headphones, NOT about compatible ones like the already-mentioned Nokia HS-12W! Keep this in mind when I speak about the bad sound quality of pre-WM6 A2DP implementation) than that of ANY WM5-based Pocket PC’s or Smartphones. This means you can, finally, dump Widcomm hacks or Widcomm-based handhelds in favor of new, WM6-based phones.

What about pre-WM6 Windows Mobile models?

After Microsoft introduced A2DP support in January 2006 with WM5 AKU2, the vast majority (exceptions include, for example, the HTC Wizard, which has never officially received any A2DP support) of new models (and operating system upgrades for existing ones) coming with the Microsoft BT stack (that is, all WM5 models except for Acer’s and HP’s models and the Fujitsu-Siemens T830 phone) have been released with A2DP support.

The A2DP sound quality of WM5 AKU2 devices was terrible. It was only with VERY few headphones models (for example, the already-mentioned Nokia HS-12W) that it delivered good sound quality. The vast majority of existing A2DP stereo headphones models (for example, the Plantronics Pulsar 590 and 260) were plain useless with the stack.

While Microsoft (vaguely) promised A2DP quality increase with the Autumn 2006 release of WM5 AKU3, real upgrades / devices didn’t deliver ANY increased sound quality. I’ve tested this with MANY WM5 AKU3 devices; both Pocket PC’s and MS Smartphones natively delivered with AKU3; for example, the HTC Oxygen (aka S310; a WM5 AKU3.0 MS Smartphone) and the HTC Trinity (aka P3600; a WM5 AKU3.3 Pocket PC).

This means it’s only with WM6 that you can expect (almost) flawless A2DP sound quality. With ANYTHING earlier, you will have MUCH worse sound quality – unless, again, you have one of the very few compatible headphones (Nokia HS-12W etc).

Also note that, should you use a “cooked” WM6 ROM, you may still have pre-WM6 A2DP support because these ROM’s may use components from older operating system versions. As cooked ROMs are not really legal, I am not allowed to provide you more information on the affected models or ROM versions - sorry. However, the next section explaining the Joint Stereo mode will be of great help to decide whether your cooked WM6 version already has the latest A2DP support, or still an old, WM5-based one.

Affected ROM versions – of which ROM’s can you expect good A2DP quality?

As a rule of thumb, if a given ROM version supports Joint Stereo, then, it’s capable of delivering pretty good A2DP quality. That is, if, in the Registry, the value HKLM\Software\ Microsoft\Bluetooth\ A2DP\Settings\ UseJointStereo (note that HKLM, as usual, stands for HKEY_LOCAL_MACHINE) is 1 , meaning enabled (NOT 0, meaning disabled) and the sound is (still) stereo, then, you have the new, WM6-based, high-quality A2DP implementation.

If you get mono sound (as is the case with ALL pre-WM6 models I’ve ever tested, despite what some say; and, again, some cooked WM6 ROM’s also belong to this category), then, you have the old (low-quality) MS BT stack, which can’t really be “hacked” – it’ll always deliver sub-par sound quality with most headphones, except for some select headphones models like the Nokia HS-12W (but, according to this XDA-Dev thread (http://forum.xda-developers.com/showthread.php?p=1295190), not necessarily other Nokia headphones).

To make sure your (WM6) device has a new BT stack (or an old one), get a registry editor. If you’re unsure, read the Registry Editor Bible (http://www.pocketpcmag.com/blogs/menneisyys/UltimateRoundupOfRegistryEditors.asp) for a roundup; I recommend the registry editor in Resco File Explorer (http://www.resco.net/pocketpc/explorer/default.asp) the most. It runs great on both regular Pocket PC’s and MS Smartphones. Note that many recommend (for example, in THIS (http://forum.xda-developers.com/showthread.php?t=285344) thread) Breaksoft’s Mobile Registry Editor. You won’t want to use it because it isn’t able to modify the HKLM branch (only for seeing what’s in there it’s sufficient, though).

The same may stand for the, mostly for MS Smartphone users, highly recommended RegEditSTG on some WM5+ Smartphone models – it’s been signed by HTC’s certificate, which has been put on the ban list in at least Orange-branded phones released since Feb. 2006. That is, this registry editor won’t run for example on the SPV C100 (the Orange rebranded HTC Oxygen / S310), not even on a completely (application) unlocked phone. This isn’t the case with Resco’s editor: it’ll work just great on (app) unlocked new Orange Smartphones.

Yeah, I have a new, legal, official WM6 device, I still have VERY bad sound quality!

People that DO have a legal and official WM6 model (for example, the HTC Vox (s710) smartphone) still MUST hack the Registry to get rid of two registry values really degrading sound quality: the "MaxSupportedBitPool" and the "BitPool" values under HKLM\Software\ Microsoft\Bluetooth \A2DP\Settings. These both have a very low (with the Vox, 30) default value, resulting in VERY bad sound quality. I just don’t understand why Microsoft and HTC have left these values in there – all they do is completely degrading sound quality, without fixing anything / making more A2DP headphones compatible.

Just remove these two registry values and shut down / restart Bluetooth (or, if you choose so, reset the device – you won’t need this for the changes to be heard).

Note that if you have a Smartphone (and not a Pocket PC), make sure you application unlock your device before modifying the Registry; otherwise, you won’t have edit access to the Registry. To unlock your phone, you will want to read THIS (http://www.modaco.com/Remove-S710-application-lock-install-prompt-t254325.html) (if you have a Vox or a similar, new, mostly WM6 device) or THIS (http://forum.xda-developers.com/showthread.php?t=285344) (if you have an older WM5 device like the Oxygen – while these models still have the old, low-quality A2DP implementations, you may still want to either remove these values or increase their value too slightly increase the A2DP quality. You will still have bad sound quality compared to the WM6 one - or that of the Widcomm stack).

You may also want to create a SampleRate DWORD value with the value of 48000. Many have reported subsequent quality increase (I haven’t noticed this with my HTC Vox + Plantronics Pulsar 590A duo but this doesn’t necessarily mean with other models you won’t hear an increase in the sound quality.) If you’re unsure, just import this registry script (http://www.winmobiletech.com/sekalaiset/WM6A2DPSoundQualityIncrease.reg) – it’ll increase the sampling frequency and also makes sure the Joint Stereo mode is enabled, should you or some tweaker tools have messed with it.

Thanks for a very informative and useful post :).

[cly_evo]

If i'm not mistaken, in a2dp the data is streamed digitally in compressed form into the headphones bluetooth receiver. This means that the mp3 files is converted into digital data of unknown format to me and is actually played in the bluetooth receiver itself and not the mobile phone. So the sound quality is actually very very dependent on the bluetooth headphone chip quality. But, there are several factors from the mobile phone itself: like the cpu power which is needed to compressed the digital audio data and the bluetooth transmitter build quality and the bluetooth version. Bluetooth 2 is better than bluetooth 1.2 and edr (enhanced data rate) is slightly even better. One of the best SnR (signal to noise ratio) in stereo bluetooth headphones i've seen is on these models: Motorola s605 (-85db) and iTech D-Radio (-90db), both supports external headphone/earphone with 3.5mm jack, Please point out if i'm wrong as my knowledge of a2dp is somewhat limited...

[Menneisyys]

If i'm not mistaken, in a2dp the data is streamed digitally in compressed form into the headphones bluetooth receiver. This means that the mp3 files is converted into digital data of unknown format to me and is actually played in the bluetooth receiver itself and not the mobile phone. So the sound quality is actually very very dependent on the bluetooth headphone chip quality. But, there are several factors from the mobile phone itself: like the cpu power which is needed to compressed the digital audio data and the bluetooth transmitter build quality and the bluetooth version. Bluetooth 2 is better than bluetooth 1.2 and edr (enhanced data rate) is slightly even better. One of the best SnR (signal to noise ratio) in stereo bluetooth headphones i've seen is on these models: Motorola s605 (-85db) and iTech D-Radio (-90db), both supports external headphone/earphone with 3.5mm jack, Please point out if i'm wrong as my knowledge of a2dp is somewhat limited...

sure it's limited - otherwise, it'd be impossible to transfer stereo 16 bit 44 kHz sound.

[cly_evo]

sure it's limited - otherwise, it'd be impossible to transfer stereo 16 bit 44 kHz sound.
Come to think of it, 16 bit in 44khz is cd quality format and in uncompressed format it is roughly 10mb file per minute which is 1.35Mbit/second of data to be played in real time. It is actually achievable through bluetooth v2 with edr that have 2.1Mbit/second maximum transfer rate. So what is the need of the compression in the first place? Or is it not compressed afterall. I couldnt find an article that describe a2dp in detail, but from reading about it here and there i get the impression that the audio data is compressed and stream digitally.

And one more thing that i m curious to know is if the audio is stream digitally and the sound quality is bottlenecked by the bluetooth receiver of the headphones, i dont see the buying point of bluetooth mp3 players. Especially if you have an a2dp compatible windows mobile phone. Most of them are equipped with bluetooth v2 anyways. Or do they have any other advantages?? Just wondering.... :)

[cly_evo]

I found some really good info on codec usage in A2DP:
http://www.soundexpert.info/jblog/blog/se_official/Audio+quality/2008/06/29/Bluetooth-audio-quality-A2DP
This is an alternative codec which suppose to provide good SQ:
http://www.aptx.com/default.asp?page=198

However, windows, widcomm, toshiba bluetooth stack only support SBC codec streaming. That answers my previous question: portable audio players with bluetooth a2dp supports streaming data in MP3 and AAC to bluetooth headphones that support the format which is definitely better quality sound. Now, if anyone can enable mp3 or aac streaming in bluetooth stack on windows mobile 6 that would be great!!

I just found that someguys here tried but i guess they are unsuccessful in doing so:
http://forum.xda-developers.com/showthread.php?t=388475

[actasci]

i need help, i have htc hd2 with latest "turkcell carrier" official rom, latest radio, latest everything but i wasn't have A2DP file under Bluetooth; so just some people said i created Bluetooth key, under Settings key and in that UseJointStereo dword value and i set "1" into it. But i got nothing, i really upset about this phone's a2dp issues. iphone was like this too, but users force apple to fix that, so they fixed it in the 2.1 version, and that was work like magical. but what the hell is this? i can sell this phone just because a2dp bullsh.t.

sorry about replying old thread, but i already tried every single thing to fix this one.

[Dishe]

TP2 uses Widcomm stack. The majority of threads here are discussing the older tried-and-true MS stack. Different software.

[mazak23]

Old thread but help to my WM 6.5 and HTC TP2 Rhodium.
My Stereo bluetooth HTC BH S100 had hiccup sometimes.
I am listening to internet radio mainly and it was terrible sometimes.
When WLAN or HSDPA connection is turned off and listening to MP3 from Storage Card there is no problem at all. So found no hiccup when listening to internet radio thru speaker phone.

I delete "MaxSupportedBitPool" and "BitPool" from registry.
Changed "LineSpeed" from 320 to 256.

It is better now, but sometimes no sound from headphones like once in 5 minutes for about 1-2 seconds, before was plenty of it in one minute.

Anybody have same set?
I am looking for perfect settings.