Microboost

A Windows microphone booster that amplifies your mic for other apps (Discord, Teams, etc.) using a real-time audio pipeline through VB-CABLE — a free virtual audio cable driver that creates a pair of connected audio devices (one for input, one for output) so audio can be routed between applications.

Watch the demo on Loom

How it works

Microphone → [capture] → gain × boost → noise gate → ring buffer → [playback] → VB-CABLE
                                                                                    ↓
                                                                Discord/Teams/Zoom picks up
                                                                "CABLE Output" as microphone

The audio driver delivers mic samples via an input callback
Each sample is multiplied by the boost factor (e.g. 2.0x) and clamped to [-1, 1]
If the noise gate is calibrated, quiet samples below the learned noise floor are faded to silence
Processed samples are written to a lock-free ring buffer (a circular array using atomic operations, so the input and output callbacks never block each other)
A separate output callback reads from the ring buffer and writes to VB-CABLE's virtual input
Apps like Discord see "CABLE Output" as a microphone and receive the boosted audio

On first launch, the app will offer to download and install VB-CABLE (free) automatically.

Features

Real-time microphone boost from 0.1x to 5x (10% to 500%)
Auto-calibration: detects your voice level and sets the boost to YouTube-recommended loudness (~-16 dBFS)
Noise gate: learns your background noise and suppresses it
Live waveform visualizer: see input vs boosted output in real-time
Per-microphone profiles: saves boost and noise gate settings per device
Mic hot-plug detection: auto-switches when devices connect/disconnect
Automatic VB-CABLE setup on first run
Test recording and playback to verify your levels
Lock-free audio pipeline (96.7 dB SNR)
Native UI built with egui

Installation

Download the latest release from the Releases page.

Or build from source:

git clone https://github.com/alexeygrigorev/microboost.git
cd microboost
make build

The executable will be at target/x86_64-pc-windows-msvc/release/microboost.exe.

Note: The build requires the MSVC target (x86_64-pc-windows-msvc). The Makefile handles this automatically.

Usage

Launch Microboost. If VB-CABLE is not installed, click "Install VB-CABLE" and accept the admin prompt.
Select your microphone from the dropdown.
Click "Auto-Calibrate" to detect your voice level, or manually set the boost.
Click "Start Boost" (or "Accept & Start" after calibration).
In your other app (Discord, Teams, etc.), select "CABLE Output" as the microphone input.

Use "Record Test" and "Play" to verify the boost sounds right before going live.

Recordings are saved to %APPDATA%\Microboost\.

Requirements

Windows 10 or later
VB-CABLE (installed automatically on first launch, or get it from https://vb-audio.com/Cable/)

Development

Build

make build      # Build release (MSVC target)
make run        # Build and run
make open       # Open the built executable
make kill       # Kill running instance
make clean      # Clean build artifacts
make folder     # Open recordings folder
make rebuild    # Kill, rebuild, then run: make open

Tests

Unit tests verify the audio pipeline produces identical output at 1x boost:

cargo test --release --target x86_64-pc-windows-msvc

Tests include:

passthrough_test — verifies 1x boost is identity, 2x doubles signal, noise gate works, sample rate conversion is correct
cable_loopback — sends a sine wave through VB-CABLE and measures distortion (requires VB-CABLE installed)
deep_compare — sample-level cross-correlation comparison of pipeline output vs original (SNR, alignment)
quality_check — automated quality analysis: clipping, noise floor, smoothness, frequency balance
spectral_check — frequency band comparison across full recordings

End-to-end test tools (in src/bin/):

e2e_test — feeds a WAV through the ring buffer + CABLE and compares direct vs ring buffer output
audio_test — records simultaneously from a mic and CABLE Output for comparison
pipeline_test — feeds a WAV through the full pipeline and records from CABLE

Run the e2e test (requires VB-CABLE):

cargo run --release --target x86_64-pc-windows-msvc --bin e2e_test

Tech Stack

egui - Native GUI
cpal - Audio capture and playback
hound - WAV encoding/decoding
VB-CABLE - Virtual audio cable driver

License

MIT