WASAPI Bridge

A low-latency C++ tool to route audio from a WASAPI loopback device (such as "CABLE Input" from VB-Audio) to a target WASAPI playback device (DAC/Sound Card) using the internal capabilities of the miniaudio library.

Features

• Device Routing: Route real-time audio from a Source Audio Device to a Target Audio Device.
• Channel Mapping: Automatically maps source channels matching target channels by position. Excellent for downmixing highly-channelled APOs (like HeSuVi taking 7.1 and converting it directly down to Stereo).
• Format Integrity: Everything runs seamlessly using 32-bit floating point calculations avoiding integer overflow crackles.
• Peak Handling: Hard clamping avoids harsh audio clipping distortion and safeguards output drivers.
• WASAPI Modes: Supports configurable target output logic using either Shared Mode or Exclusive Mode.
• Real-Time Configuration: Prompts the user smoothly for Source Device, Target Device, Latency offsets, and limits.
• Optimized: Compile with native LTO & static linking ensuring blazing-fast execution speeds without overhead.
• GUI + Terminal-Aware: Native Win32 GUI with three tabs (Bridge / Log / About). Launching from a terminal attaches to the parent console so logs flow back into the shell that started it; launching from Explorer just shows the GUI.
• Tray Integration: Optional minimize-to-tray with right-click Open/Exit menu and live-state tooltip.

Setup Requirements

• Windows 7 or later
• Visual Studio / GCC / LLVM Toolchain
• CMake

Building the Project

This repo uses git submodules to gather miniaudio. Clone the project recursively:

git clone --recurse-submodules https://github.com/DevonTM/wasapi-bridge.git
cd wasapi-bridge

Then generate and build the executable using CMake and Ninja:

mkdir build
cd build
cmake -G Ninja -DCMAKE_BUILD_TYPE=Release ..
ninja

Usage

Run wasapi-bridge.exe. The GUI opens with three tabs:

• Bridge — pick the Source loopback device and the Target playback device, choose Shared or Exclusive mode, set latency in ms (defaults: 10 for Shared, 5 for Exclusive), and click Start Bridge. The button toggles to Stop Bridge while running and inputs lock until you stop. Use Rescan after plugging or unplugging audio devices.
• Log — live log mirroring everything the bridge prints. Toggle auto-scroll, export to a UTF-8 file, or clear.
• About — version, license link, and a button to open the GitHub repo.

Tick Minimize to tray (default on) to send the window to the notification area on minimize. The tray icon shows a tooltip with the current bridge state and offers Open/Exit on right-click.

When launched from a terminal (.\wasapi-bridge.exe from cmd or PowerShell), the app attaches to the parent console and mirrors log output there. Launched from Explorer it just shows the GUI without opening a console.

License

This project is licensed under the MIT License.

miniaudio is dual-licensed under the MIT No Attribution (MIT-0) and Public Domain (Unlicense).