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review.blissroms.org / platform_system_bt / f9cc2e98e0f33bc0a60fa678c71e7d429711522a
commitf9cc2e98e0f33bc0a60fa678c71e7d429711522a[log] [tgz]
authorValdikSS <iam@valdikss.org.ru>Mon Sep 17 18:48:42 2018 +0300
committerrohan <purohit.rohan@gmail.com>Sat Jul 18 01:21:08 2020 -0400
tree0fdb15f8c67888852c0d36e83d5123fc6b83eb1f
parent170b53bc47a45f044a7c9100e82b4948c9724a2f [diff]
Explicit SBC Dual Channel (SBC HD) support

Overwhelming majority of Bluetooth audio devices have SBC maximum bitpool value
limited to 53, which prevents bitrates higher than 328 kbit/s to be used with
the most common 44.1 kHz Joint Stereo, 8 subbands, 16 blocks profile. This
limitation could be circumvented on any existing device to achieve higher audio
quality, by using Dual Channel mode.
Dual Channel encodes channels separately, using the entire bitpool for each
channel. Forcing the device to use Dual Channel instead of Joint Stereo almost
doubles maximum possible bitrate for the same bitpool value.

A2DP specification v1.2, which was active from 2007 to 2015, requires all
decoders to work correctly with bitrates up to 512 kbps. Newer specification
does not have the limit at all. It is assumed that most modern headphones with
EDR support can handle any SBC profile with maximum bitpool value, regardless
of resulting bitrate.

This commit defines optimal Dual Channel bitrate profiles:
EDR 2mbit/s - 452 kbit/s for 44.1 kHz, 492 kbit/s for 48 kHz (bitpool 38,
4 audio frames, 10.7 ms, 6 wasted bytes per packet)
EDR 3mbit/s - 551.3 kbit/s for 44.1 kHz, 600 kbit/s for 48 kHz (bitpool 47,
5 audio frames, 13.4 ms, 4 wasted bytes per packet)

With 452 kbit/s, SBC outperforms aptX, with 551.3 kbit/s, on par or close to
aptX HD.

53 out of 57 tested headphones, receivers and automotive head units were able
to correctly receive and decode high bitrate Dual Channel audio.
SBC HD is disabled by default and could be activated in Bluetooth device menu,
per device.

Change-Id: Ic002851882900476019d70a9e3cb0c0bab3de290
11 files changed
tree: 0fdb15f8c67888852c0d36e83d5123fc6b83eb1f
  1. audio_a2dp_hw/
  2. audio_bluetooth_hw/
  3. audio_hal_interface/
  4. audio_hearing_aid_hw/
  5. binder/
  6. bta/
  7. btcore/
  8. btif/
  9. build/
  10. common/
  11. conf/
  12. device/
  13. doc/
  14. embdrv/
  15. gd/
  16. hci/
  17. include/
  18. internal_include/
  19. linux_include/
  20. main/
  21. osi/
  22. packet/
  23. profile/
  24. proto/
  25. service/
  26. stack/
  27. test/
  28. tools/
  29. types/
  30. udrv/
  31. utils/
  32. vendor_libs/
  33. vnd/
  34. .clang-format
  35. .gitignore
  36. .gn
  37. Android.bp
  38. AndroidTestTemplate.xml
  39. BUILD.gn
  40. CleanSpec.mk
  41. EventLogTags.logtags
  42. MODULE_LICENSE_APACHE2
  43. NOTICE
  44. OWNERS
  45. PREUPLOAD.cfg
  46. README.md
  47. TEST_MAPPING
README.md

Fluoride Bluetooth stack

Building and running on AOSP

Just build AOSP - Fluoride is there by default.

Building and running on Linux

Instructions for Ubuntu, tested on 14.04 with Clang 3.5.0 and 16.10 with Clang 3.8.0

Download source

mkdir ~/fluoride
cd ~/fluoride
git clone https://android.googlesource.com/platform/system/bt

Install dependencies (require sudo access):

cd ~/fluoride/bt
build/install_deps.sh

Then fetch third party dependencies:

cd ~/fluoride/bt
mkdir third_party
cd third_party
git clone https://github.com/google/googletest.git
git clone https://android.googlesource.com/platform/external/aac
git clone https://android.googlesource.com/platform/external/libchrome
git clone https://android.googlesource.com/platform/external/libldac
git clone https://android.googlesource.com/platform/external/modp_b64
git clone https://android.googlesource.com/platform/external/tinyxml2

And third party dependencies of third party dependencies:

cd fluoride/bt/third_party/libchrome/base/third_party
mkdir valgrind
cd valgrind
curl https://chromium.googlesource.com/chromium/src/base/+/master/third_party/valgrind/valgrind.h?format=TEXT | base64 -d > valgrind.h
curl https://chromium.googlesource.com/chromium/src/base/+/master/third_party/valgrind/memcheck.h?format=TEXT | base64 -d > memcheck.h

NOTE: If system/bt is checked out under AOSP, then create symbolic links instead of downloading sources

cd system/bt
mkdir third_party
cd third_party
ln -s ../../../external/aac aac
ln -s ../../../external/libchrome libchrome
ln -s ../../../external/libldac libldac
ln -s ../../../external/modp_b64 modp_b64
ln -s ../../../external/tinyxml2 tinyxml2
ln -s ../../../external/googletest googletest

Generate your build files

cd ~/fluoride/bt
gn gen out/Default

Build

cd ~/fluoride/bt
ninja -C out/Default all

This will build all targets (the shared library, executables, tests, etc) and put them in out/Default. To build an individual target, replace "all" with the target of your choice, e.g. ninja -C out/Default net_test_osi.

Run

cd ~/fluoride/bt/out/Default
LD_LIBRARY_PATH=./ ./bluetoothtbd -create-ipc-socket=fluoride

Eclipse IDE Support

  1. Follows the Chromium project Eclipse Setup Instructions until "Optional: Building inside Eclipse" section (don't do that section, we will set it up differently)

  2. Generate Eclipse settings:

cd system/bt
gn gen --ide=eclipse out/Default

  1. In Eclipse, do File->Import->C/C++->C/C++ Project Settings, choose the XML location under system/bt/out/Default

  2. Right click on the project. Go to Preferences->C/C++ Build->Builder Settings. Uncheck "Use default build command", but instead using "ninja -C out/Default"

  3. Goto Behaviour tab, change clean command to "-t clean"