- 02-15-2013, 03:53 AM #1
I have a 2012 Volvo V70 with the premium sound system, and I cant seem to get a high bitrate out of the 920 when connected over bluetooth,
It pairs and works just fine (with the portico update), but the audio quality is not as good as our ipads or androids phones over bluetooth.
I've tried syncing high bitrate mp3s (320kbps) from my computer, Spotify with high quality, WiMP with high quality and Xbox Music. It sounds great on the headphones or connected to the cars AUX socket. But on bluetooth the sound quality is more like < 100kbps, and is painfull to listen to.
I used to have a HTC Mozart (WP7) phone that had even worse bluetooth issues, but this was fixable it you got into the registry and flicked some keys related to bluethooth bitrates/bitpool/jointstereo etc.
My guess is that there are some settings in 920 that should be fixed to improve audio quality over bluetooth? Any one else not getting the audio performance that a flagship should provide?
- 02-18-2013, 08:55 AM #4
Well, now I've done some rudimentary tests with a tone generator app on both my Ipad and my 920. Both connected to my MY12 Volvo via bluetooth (not at the same time obviously).
One very interesting issue occured:
* On the ipad, tones from 40Hz to 18kHz were clearly audible without noticable distortion.
* With the 920, there were a lot of artifacts produced in both deep bass and high treble. The artifacts were strange almost clicking /thumping sounds, and all kinds of harmonics.
Then I tested with the aux plug. This time, no artifacts. Hmmmm?
This triggers the need for some further investigation. Since the tone generator app were not the same, the artifacts could stem from the app? I think, buy making a test audio track in reasonable bitrate (e.g. 320kbps mp3), and load this into ipad and phone to see if the same artifacts occur.
More to com
- 02-20-2013, 08:12 AM #5
I now tested with a frequency sweep .mp3 file (320kbps). No difference between ipad and 920, neither deep bass or high treble. This means is that the audio quality issues could be related to the music app being used and the format it uses.'
I'll try different formats than .mp3 to see if there are problems with formats.
03-29-2013, 07:33 PM #6
- 73 Posts
I'm pretty sure the Bluetooth issue has to do with the bitpool setting. The stereo is probably reporting a value of 32, which correlates to 128kbps, and thus the phone is sending data at that rate. If the stereo supports EDR then it should be able to support a bitpool value of 51+, which would be equivalent to 320kbps. If we could get into the windows phone 8 registry we could change the bitpool value to 51+ and force a high quality output, but as of yet there is no way into the windows phone 8 registry. I've got the same issue, and its present with most, but not all Bluetooth stereos. Until someone figures out a way into the registry, we're going to have to live with the little bit of scratchiness in the audio.
BTW I have an 8x and it's the same issue as the 920. Should be 100% software based which means there will be a way to fix it at some point, hopefully.
03-30-2013, 02:37 AM #8
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