TWS Noise Canceller (ANC-application)

Android application prototype for real-time Bluetooth microphone capture and playback using Kotlin + C++ (JNI) with Oboe for low-latency audio streaming.

Overview

This project demonstrates an Active Noise Cancellation pipeline scaffold for True Wireless Stereo (TWS) devices:

• Android UI to start/stop processing
• Runtime permission handling for audio and Bluetooth
• Bluetooth SCO routing for voice communication audio path
• Native audio engine using Oboe input/output streams
• DSP insertion point in native callback (currently placeholder attenuation)

Current DSP behavior is a placeholder (output = input * 0.9) and not a full ANC/noise suppression algorithm yet.

Tech Stack

• Android: Kotlin, AppCompat, ConstraintLayout
• Native: C++17, JNI
• Audio: Google Oboe (com.google.oboe:oboe:1.8.0)
• Build: Gradle Kotlin DSL, AGP 8.1.4, Kotlin 1.9.0
• CI: GitHub Actions (assembleDebug on pushes/PRs to main)

Project Structure

ANC-application/
├── app/
│   ├── build.gradle.kts
│   └── src/main/
│       ├── AndroidManifest.xml
│       ├── java/com/example/twsnoisecanceller/MainActivity.kt
│       ├── cpp/
│       │   ├── CMakeLists.txt
│       │   └── native-lib.cpp
│       └── res/
│           ├── layout/activity_main.xml
│           ├── values/{strings,themes}.xml
│           ├── xml/{backup_rules,data_extraction_rules}.xml
│           └── mipmap*/drawable* launcher assets
├── .github/workflows/android-build.yml
├── build.gradle.kts
├── settings.gradle.kts
└── gradle.properties

How It Works

1. User taps toggle in MainActivity.
2. App checks runtime permissions and requests missing ones.
3. On start:
   • Sets AudioManager.MODE_IN_COMMUNICATION
   • Starts Bluetooth SCO and enables SCO route
   • Calls native startDenoise()
4. Native engine:
   • Opens low-latency output stream with callback
   • Opens matching input stream (VoiceCommunication preset)
   • In output callback, reads mic frames from input stream
   • Runs DSP placeholder and writes to output buffer
5. On stop/destroy:
   • Stops native streams
   • Disables SCO and restores MODE_NORMAL

Permissions and Device Requirements

Manifest features

• android.hardware.microphone (required)
• android.hardware.bluetooth (required)

Runtime permissions

• RECORD_AUDIO
• MODIFY_AUDIO_SETTINGS
• Android 12+ (SDK 31+): BLUETOOTH_CONNECT
• Android 11 and below: BLUETOOTH, BLUETOOTH_ADMIN

Minimum environment

• minSdk: 26
• targetSdk / compileSdk: 34
• Android device with Bluetooth + microphone
• Preferably a TWS/Bluetooth headset supporting SCO voice path

Build and Run

Prerequisites

• JDK 17
• Android SDK / Android Studio with NDK + CMake support
• Gradle (wrapper or local install)

Build debug APK

gradle assembleDebug --no-daemon

APK output:

app/build/outputs/apk/debug/app-debug.apk

Run in Android Studio

1. Open repository in Android Studio.
2. Let Gradle sync.
3. Connect device/emulator (Bluetooth tests require real device).
4. Run app configuration.
5. Grant requested permissions, then toggle ANC on/off.

CI

Workflow: .github/workflows/android-build.yml

• Triggers on push and pull request to main
• Sets up JDK 17 + Gradle 8.4
• Runs gradle assembleDebug --no-daemon
• Uploads app-debug.apk artifact

Native DSP Integration Point

The key insertion point for ANC/noise suppression is in:

• app/src/main/cpp/native-lib.cpp inside onAudioReady(...)

Replace placeholder frame processing with:

• RNNoise integration
• Echo cancellation / adaptive filtering
• Additional gain control / filtering chain as needed

Current Limitations

• No production ANC algorithm yet (placeholder pass-through attenuation)
• Uses Thread.sleep(1000) on start while waiting for SCO (blocking UI)
• No explicit SCO state broadcast handling
• No advanced error recovery for stream interruptions/disconnects
• No automated tests currently included

Suggested Next Steps

• Replace placeholder DSP with real frame-based denoiser/ANC
• Move SCO startup flow to async state-driven handling
• Add robust Oboe error callbacks and stream restart strategy
• Add instrumentation tests for permission/routing lifecycle
• Improve UX/state feedback for Bluetooth routing and failures

License

No license file is currently included in this repository.