Bluetooth SBC bitpool 35 on H850 V20b resulting bad audio quality - LG G5 Questions & Answers

Hi, people of internet! Here some research, to prove that im not gone mad or having a nocebo effect, since I was very disappointed in bt audio quality of h850 running 7.0 (V20b) compared to lg g2 running cm13. The regression that I didn't expect.
So, even without root on g5, in the devel options we can enable bt log dump:
{
"lightbox_close": "Close",
"lightbox_next": "Next",
"lightbox_previous": "Previous",
"lightbox_error": "The requested content cannot be loaded. Please try again later.",
"lightbox_start_slideshow": "Start slideshow",
"lightbox_stop_slideshow": "Stop slideshow",
"lightbox_full_screen": "Full screen",
"lightbox_thumbnails": "Thumbnails",
"lightbox_download": "Download",
"lightbox_share": "Share",
"lightbox_zoom": "Zoom",
"lightbox_new_window": "New window",
"lightbox_toggle_sidebar": "Toggle sidebar"
}
1. Dasable bluetooth.
2. Turn logging on.
3. Enable bluetooth and connect a device.
4. Play your lovely tunes in any audio player for ~5 seconds.
5. Disable bluetooth, turn off logging.
The log file named btsnoop_hci.log will appear on /sdcard.
Delete or rename this file every test.
Do not forget to turn the logging option off, otherwise it will flood your storage.
And analyze these files in Wireshark:
Lets compare the two. The testing device is JBL Reflect bt mini (also tested with Plantronics M70 with same result).
LG G2, requesting capabilities of device (useful to check which codec(s) your device supports)
And getting reply that only SBC (not aptx, mp3 or aac, we are talking sbc only here) codec is supported, giving the command to use it with bitpool (quality) from 2 to 53, as reported.
Later in the log we see actual sbc packets transmitted, each carrying music itself, so to say, at maximum bitpool of 53. Also note the packet size.
And the music sounds good, well, for sbc at least.
Now lets look at LG G5
Results are, negotiating quality and settings with the device, is same, but when we take a single sbc packet.. Actual sbc bitpool is 35.
Why, LG? So, if you guys test it for yourself and report back here, it would be great.
To me it looks like an android bug, maybe closed long time ago in the mainstream and lg was just unlucky to snapshot it. Dunno.
Further actions may be waiting for 7.1 or rooting and trying to find if bitpool 35 is indeed hardcoded and where.
Update: Well, frack me sideways. Problem fixed itself by hard resetting again (3rd time for the phone) and then re-pairing headphones. Go figure. Thank you for your attention.

---

Similar behavior
Greetings from late 2018. I am seeing similar behavior. My G5 drops from bitpool of 53 to 25. In my case, this happens whenever there is BLE advertising which happens every 15 seconds or so for about 10 seconds. This makes listening to audio sources that only support sbc unlistenable. This started happening about a year after I bought it so I am thinking that an update broke it.
I'll probably try what you did (hard resets) and see what happens.
If you or anyone have a suggestion, please let me know.
Thanks!

---

TRANKA2010 said:
Greetings from late 2018. I am seeing similar behavior. My G5 drops from bitpool of 53 to 25. In my case, this happens whenever there is BLE advertising which happens every 15 seconds or so for about 10 seconds. This makes listening to audio sources that only support sbc unlistenable. This started happening about a year after I bought it so I am thinking that an update broke it.
I'll probably try what you did (hard resets) and see what happens.
If you or anyone have a suggestion, please let me know.
Thanks!
Click to expand...
Click to collapse
Yes, that..
Since then, bt was behaving well.
I would suggest also resetting network settings (found in "Backup & Reset") without a full system reset, then pairing BLE and regular bt devices in some order or another, like good old "jiggle the handle" method untill its working :b
For me, I have a pocophone f1 now running a custom rom (Sybiria) which includes so called SBC HD, (take a look at this commit for explaination review.lineageos.org/c/LineageOS/android_system_bt/+/229125 ) tl;dr aptx-like quality on nearly any sbc device.