Bluetooth Headsets and A2DP

[Guest ghm101]

Actually the volume on these is fine, just me failing to deal with three separate volume controls on the headset, the phone and in the media player :rolleyes:

[Guest nowimboard]

Any one else having problems with pitch when playing tracks?

I have a paid of Sony DR-BT30Q's and every so often the pitch goes up and down on tracks. Not sure if its the headphones, the phone, media player, file transfer/conversion into WMA or bluetooth transmitting! :S

[Guest Menneisyys]

Any one else having problems with pitch when playing tracks?

I have a paid of Sony DR-BT30Q's and every so often the pitch goes up and down on tracks. Not sure if its the headphones, the phone, media player, file transfer/conversion into WMA or bluetooth transmitting! :S

Unfortunately, while the new 2.0/EDR-based WM6, with the hacks outlined above, indeed delivers MUCH superior sound quality compared to WM5/BT 1.2-based solutions (even hacked), the sound quality is STILL worse than with the Widcomm BT stack.

This is a very common problem and I've published a LOT of articles on it. See for example http://www.pocketpcmag.com/blogs/index.php...p;tb=1&pb=1 . Note that the article is pre-BT 2.0 / EDR; the Vox (which has 2.0 / EDR) delivers definitely better (but in no way flawless - it's still worse than that of Widcomm) sound quality.

Incidentally, I REALLY recommend my article to anyone wanting to know more about A2DP, the different headphones etc.

[Guest Phrak]

Thanks Menneisyys, your article got me searching again for better sound :rolleyes:

d7oad's settings improved the sound quality over the default settings, but in my searching I came across hardcore and Sleuth255's testing for WM6 optimum settings for bluetooth A2DP:

http://forum.xda-developers.com/showthread.php?t=308752

These are applicable to the newer releases of WM6.

Finding #1:

ADD/CHANGE the following values from the registry at HKLM\Software\Microsoft\Bluetooth\A2DP\Settings :

Name: UseJointStereo

Value (DWORD): 1

What this does is enable Joint-Stereo for the SBC codec, which is important and makes the biggest significant change to improve sound quality. (Note: In earlier versions of WM5 and WM6, Joint-Stereo was broken and resulted in a mono-output. This is not the case anymore with the newer WM6 ROMS.)

Further note: Sleuth255 found that some of his A2DP headsets could not work with JS turned on. In that case, you have to set the value to 0 to disable JS (resulting in poorer quality sound with more "hissing").

Finding #2:

REMOVE the following values from the registry at HKLM\Software\Microsoft\Bluetooth\A2DP\Settings if they are present:

- BitPool

- MaxSupportedBitPool

These values are used to manually set limits for the BT stack for the A2DP SBC codec. Previously, it was thought that these values should be set between 38 to 86. But if the values are removed, I think that the BT stack automatically chooses the best BitPool values for maximum quality. I've tried removing these values and the sound quality either improved or at least stayed the same.

[ SUMMARY ]

At this point, you should have only one value in the registry at HKLM\Software\Microsoft\Bluetooth\A2DP\Settings:

UseJointStereo = 1

Your A2DP audio should be very good at this point - almost indistinguishable from a wired headset. However, if you are still unsatisfied with the sound (you may notice some very slight "hissing" or "swishing" sounds on high frequencies of certain songs), you may want to try the optional setting below.

[ OPTIONAL ]

Finding #3:

This is optional, and a matter of preference.

ADD the following value to the registry at HKLM\Software\Microsoft\Bluetooth\A2DP\Settings:

Name: SampleRate

Value (DWORD): 48000 (decimal)

This forces the A2DP stack to send the audio to the headset at 48000Hz instead of the default 44100Hz. For some reason, I find that the 48Khz value makes the "hissing" sounds less obvious. Your findings may vary, as some people may prefer the slightly more forward sound of the original setting. But if you are game, give this a try - one thing for sure is that it definitely changes the sound quality.

To reverse the change, just remove the SampleRate value.

If you make this 3rd optional change, you should have the following values in the registry at HKLM\Software\Microsoft\Bluetooth\A2DP\Settings:

UseJointStereo = 1

SampleRate = 48000

[ Note - Quick tip on registry editing ]

Of course, every registry change needs a soft-reset to take effect. And please take the usual proper care when editing the registry or risk damaging your device.

Find that your settings dont "stick" after a reset?

Make sure you reset the phone like this: After making changes to the registry, exit your registry editor. Then push the power button of your phone (putting it into standby, with the screen off). Wait for about 10 seconds (the phone will be saving the data to disk during this time), and only after that push the reset button.

These settings SIGNIFICANTLY improved the audio quality again. I tried both default and tweaked SampleRates and kept the setting as 48000. There's no hissing or crackling at all with my HBH-DS970 'phones.

The audio quality is still not perfect though. It's lacking somewhat in the low-end and the mid-ranges are a little washed-out, but without an equiliser for the HTC Audio Manager I don't know if there's much I can do about that...

Thanks to hardcore and Sleuth255 if this helps you too :P

Tim

[Guest Menneisyys]

Thanks Menneisyys, your article got me searching again for better sound :rolleyes:

d7oad's settings improved the sound quality over the default settings, but in my searching I came across hardcore and Sleuth255's testing for WM6 optimum settings for bluetooth A2DP:

http://forum.xda-developers.com/showthread.php?t=308752

These settings SIGNIFICANTLY improved the audio quality again. I tried both default and tweaked SampleRates and kept the setting as 48000. There's no hissing or crackling at all with my HBH-DS970 'phones.

The audio quality is still not perfect though. It's lacking somewhat in the low-end and the mid-ranges are a little washed-out, but without an equiliser for the HTC Audio Manager I don't know if there's much I can do about that...

Thanks to hardcore and Sleuth255 if this helps you too :P

Tim

Thanks for the link; checked it out. On my Plantronics 590A, there is no real difference between the older hacks and the newer ones - that is, there is still distortion (as opposed to using the same headphones with the Widcomm BT stack).

It's acceptable but I think I'll stick with my HP iPAQ hx4700 (Widcomm) in the future too - even if it's a brick, it delivers flawess, really wired-like sound quality.

[Guest GarFie]

The only annoyance is when listening to MP3's via MediaPlayer or TCPMP and a call comes in, I have to restart the app after the call to enable playback via bluetooth, though this could be related to the lack of Headset profile on the E650.

What about WMP? On my VOX, WMP while playing freeze the phone when a call comes in. No music, no ring, can't even answer. Not happening, when BT headphones are disconnected. Did anybody suffer the same?