A2DP Windows Bridge (A2DPWB)
Bluetooth A2DP audio streaming for Windows with the codecs Windows lacks: LDAC, aptX HD, aptX Low Latency, LHDC V5 and more, through a dedicated USB Bluetooth adapter in WinUSB mode — no kernel driver or test signing required.
Download (installer -setup.exe or -portable.zip) | Documentation
Codecs
| Codec | Bitrate | Sample rate | Bit depth | Windows built-in | A2DPWB |
|---|
| LDAC | 330/660/990 kbps | 44.1–96 kHz | 16/24/32 bit | ❌ | ✅ |
| LHDC V5 | 400–1000 kbps, ABR 160–400 | 44.1–192 kHz | 16/24 bit | ❌ | ✅ |
| aptX HD | 576 kbps | 44.1/48 kHz | 24 bit | ❌ | 🧪 |
| aptX Low Latency | 352 kbps | 44.1/48 kHz | 16 bit | ❌ | 🧪 |
| aptX | 352/384 kbps | 44.1/48 kHz | 16 bit | ✅ | ✅ |
| AAC | 128/192/256 kbps | 44.1/48 kHz | 16 bit | Windows 11 | ✅ |
| SBC XQ | up to 552 kbps | 44.1/48 kHz | 16 bit | ❌ | ✅ |
| SBC | up to ~345 kbps | 44.1/48 kHz | 16 bit | ✅ | ✅ |
| FastStream | 198/216 kbps | 44.1/48 kHz | 16 bit | ❌ | 🧪 ¹ |
| Opus (Android) | 128/192/256 kbps | 48 kHz | 16 bit | ❌ | 🧪 |
| Opus 05 (PipeWire) | 128/192/256 kbps | 48 kHz | 16 bit | ❌ | 🧪 ¹ ² |
| aptX Adaptive | | | | ❌ | ❌ ³ |
✅ supported · 🧪 experimental: passes the encoder tests and the end-to-end test against a virtual Bluetooth sink, but not yet confirmed with real headphones that use it (reports welcome) · ❌ not supported
¹ Auto never picks it; choose it in a profile. ² Only PipeWire (Linux) receivers implement it. ³ No open-source encoder exists; headphones that also offer classic aptX get aptX.
Auto picks LDAC > aptX HD > aptX LL > aptX > LHDC V5 > Opus > AAC > SBC XQ > SBC. Per-codec details, the Ubuntu / PipeWire comparison and the verified hardware are on the documentation home.
Requirements
- Windows 10 (22H2) or 11, x64 or ARM64 (ARM64 and Windows 10 not yet tried on real hardware)
- A dedicated USB Bluetooth adapter, separate from the PC's built-in Bluetooth. Verified: TP-Link UB500 (Realtek RTL8761BU) with a Sony WH-1000XM4. See Recommended Adapters
Why a dedicated adapter?
Windows 10 / 11 load only kernel drivers signed through Microsoft, which needs an EV code signing certificate (several hundred US dollars a year, normally for companies only). A2DPWB therefore takes a whole USB adapter away from Windows with the Microsoft-signed WinUSB driver and runs the Bluetooth stack itself, in user mode. If you just want something simple, commercial software with a signed driver works with the built-in Bluetooth.
Setup
- Install: run
A2DPWB-<version>-win64-setup.exe (per user, no administrator rights), or extract the portable zip and run a2dpwb.exe. Installing over v1 removes v1 and keeps its settings, pairings and firmware.
- Plug in the dedicated adapter.
- Follow the first-run setup: choose the adapter, Assign WinUSB (Windows asks for administrator permission), add the firmware files for Realtek adapters, pair the headphones, then choose what to send and connect.
- Connect from Home, or from the tray icon.
Warning: While WinUSB is assigned, Windows' own Bluetooth no longer sees the adapter. Never assign WinUSB to your PC's built-in Bluetooth adapter. Adapter > Restore driver gives the adapter back to Windows at any time, and the uninstaller offers it too.
Realtek adapters need firmware files such as rtl8761bu_fw.bin and rtl8761bu_config.bin from linux-firmware (proprietary, not included). The Adapter screen shows which files are needed and opens the download page and the settings folder. See the Setup guide.
Usage
The resident core streams and owns the tray icon; the window only shows its state, so closing it does not stop the audio. Left-click the tray icon for the flyout, right-click it for the menu (profiles, Disconnect, Exit).
The core also runs from the command line (quit A2DPWB first: only one program can use the adapter):
a2dpwb-core.exe --cli -d AA:BB:CC:DD:EE:FF # Auto codec
a2dpwb-core.exe --cli -d AA:BB:CC:DD:EE:FF -c ldac -q hq -a # LDAC 990 kbps with ABR
a2dpwb-core.exe --cli --scan # Find nearby devices
a2dpwb-core.exe --cli -h # All options
To stream LDAC at 96 kHz, set the playback device's format to 96 kHz in Windows Sound settings. Everything else — profiles, capture modes, volume sync, link quality and AFH, diagnostics, start with Windows, troubleshooting — is in the Usage guide.
Features
- Codecs: LDAC, LHDC V5, the aptX family, AAC, SBC XQ / SBC and experimental Opus, with automatic choice and ABR (LDAC, LHDC V5)
- Capture: all system audio, a virtual audio device (e.g. VB-CABLE), or one application
- Resident core with tray: streams with the window closed; reconnects after link loss and after sleep
- WinUSB in the app: assigns and restores the adapter's driver, no Zadig needed
- Headphone controls: volume sync and play / pause / next / previous (AVRCP)
- Diagnostics: link quality, AFH (avoids your Wi-Fi channels), connection flow, log, HCI capture
- Updates: daily check, in-app update of the installed version
- 8 languages: English, Japanese, Chinese (Simplified / Traditional), Korean, German, French, Spanish
- LE Audio (experimental): LC3 to LE Audio headphones and earbuds, tested only against the Bluetooth emulator (details)
Building
Requirements: Rust 1.90+, Visual Studio 2022+ with the C++ desktop workload, Node.js 22 with pnpm (corepack enable), Git, PowerShell 7.
git clone --recursive https://github.com/SeiyaFunaokaJP/A2DP-Windows-Bridge.git
cd A2DP-Windows-Bridge
pwsh ./build.ps1
build.ps1 builds the window's page and the three programs into target/release/ (a2dpwb-core.exe, a2dpwb.exe, a2dpwb-driver.exe); double-clicking build.bat runs the same. Switches: -Test (formatting, lints, tests), -Emu (end-to-end test against a virtual sink), -Release -Arch x64|arm64 (installer, portable zip). See Building for the steps one by one, the tests and the release packages, and Architecture for how the programs fit together.
License
The A2DPWB source code is dual-licensed under the Apache License 2.0 (LICENSE-APACHE) or the MIT License (LICENSE-MIT), at your option. See LICENSE.
Important: The distributed programs include BTstack, whose license allows use and redistribution only for personal, non-commercial purposes ("solely for personal benefit and not for any commercial purpose or for monetary gain"). Commercial licenses are available from BlueKitchen GmbH.
Third-party libraries (BTstack, libldac, libopenaptx, fdk-aac, the LHDC V5 encoder, libopus, Tauri, SolidJS and others) are used under their own licenses: see THIRD_PARTY_LICENSES.md.
