Improve Bluetooth audio quality on headphones without aptX or LDAC

268 posts
Thanks Meter: 197
By ValdikSS, Senior Member on 22nd August 2018, 06:13 PM
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5th May 2020, 08:19 PM |#281  
Senior Member
Thanks Meter: 100
Is this possible to use on stock with a pixel 3a?
18th May 2020, 03:35 PM |#282  
Thanks Meter: 6
I try the music play on JBL Bar 3.1 with the "HD sound: SBC" codec (Xperia Z3C, Lineage 16) but the sound is distorted. From post
@grandgreed shows that my soundbar works with a maximum of 482 kbps. How to edit the bluetooth library to reduce the sound to 482 kbps?

  bc:6e:64:bc:ad:2b (Xperia Z3 Compact) → 88:d0:39:07:20:2f (JBL Bar 3.1)

Supported codecs:
  Audio SBC (16000 32000 44100 48000 | Mono DualChannel Stereo JointStereo | block: 4 8 12 16 | subbands: 4 8 | allocation: SNR Loudness | bitpool: 2..53)

Used for audio:
  Audio SBC (44100 | JointStereo | block: 16 | subbands: 8 | allocation: Loudness | bitpool: 2..53)
  Audio SBC (44100 | DualChannel | block: 16 | subbands: 8 | allocation: Loudness | bitpool: 2..53)

Latest SBC Bitpool value: 38
20th May 2020, 08:33 AM |#283  
Junior Member
Thanks Meter: 0
Maximizing the audio quality of bluetooth
I have enjoyed SBC XQ on TWS earphones very much and find a mod to maximize the audio quality by reducing jitters.

DISCLAIMER: I am not responsible for any damage that may occur to your device, it is your own choice to attempt this mod.

1. No battery optimizations of apps
music players, licensing apps, bluetooth (system app), magisk, keyboard
app, etc.

2. No bluetooth absolute volume and setting -6dB gain
In developer options, you can disable bluetooth absolute volume.
Reduce the sender side volume to -6dB gain level to avoid distortion of the
receiver side DAC. (DACs on portable devices are easily distorted by loudly
compressed music)

3. DRC disabled
In /vendor/etc/audio_policy_configuration.xml, there may be a line containing 'speaker_drc_enabled="true"'. This means that all audio output on your device is deeply compressed. Edit the line to replace "true" with "false" and reboot. Then, the DRC go away.
(Note: Pie GSI roms may have a bug that cannot disable DRC on bluetooth audio output.)

4. Using kernel adiutor to modify kernel settings
Change CPU governors to "performance". Change I/O schedulers to
"deadline" and set their parameters like:
fifo_batch:15, front_merge:1, read_expire:0, write_expire:460,
writes_starved:1, RQ_Affinity:2, read ahead buffer size:640kB
Change the 'Laptop mode' on in the virtual memory section. If there are core
control or CPU hotplug (MPDecision), set the controls off.

5. for MediaTek CPUs
MediaTek is using the EAS+ scheduler that affects CPU governors. To let
really performance mode, edit /vendor/etc/init/hw/ to replace
a line
'write /proc/cpufreq/cpufreq_sched_disable 0' with
'write /proc/cpufreq/cpufreq_sched_disable 1' .

6. Remove effects
In /vendor/etc/audio_effects.xml, remove effects relating to equalizing (reverb, base boost, virtualizer, etc.) and visualizer.

7. Reducing wifi jitter for streaming servcies and DLNA play
settings put global wifi_suspend_optimizations_enabled 0

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