SyncWave

SyncWave is a local-first live audio streaming app. Android can host system audio with MediaProjection and AudioPlaybackCapture, and listeners can join from a browser on the same Wi-Fi/hotspot. Optional internet mode uses a self-hosted FastAPI WebSocket server.

• Version: 1.1.4
• Android package/application ID: io.github.opencodequark.syncwave
• Source: https://github.com/OpenCodeQuark/syncwave

Features

• LAN browser listening through GET /stream/join and WS /stream/audio.
• Optional WAN rooms through the FastAPI signaling/relay server.
• Explicit LAN, Internet, or LAN + Internet broadcast choice when both are ready.
• Active broadcast banner with Return and Stop actions.
• Room PIN: optional, exactly 6 digits.
• Server Connection PIN: optional, exactly 8 digits for protected host/relay actions.
• Mobile-first Material 3 app UI and refreshed browser listener page.

App Setup

cd apps
flutter pub get
dart run build_runner build --delete-conflicting-outputs
flutter analyze
flutter test
flutter build apk --debug

Release validation:

cd apps
flutter build apk --release

Android hosting needs a physical Android 10+ device. Emulators do not fully validate system-audio capture.

Server Setup

cd server
python -m venv .venv
.venv/bin/python -m pip install --upgrade pip
.venv/bin/python -m pip install -r requirements.txt
.venv/bin/python -m pip install ruff
.venv/bin/python -m uvicorn app.main:app --host 0.0.0.0 --port 8000

Main server routes: GET /, GET /health, GET /status, POST /rooms, GET /stream/join, and WS /ws.

For GitHub Releases, the workflow uses GITHUB_TOKEN with contents: write. Also verify: Repo -> Settings -> Actions -> General -> Workflow permissions -> Read and write permissions.

Usage

For LAN, connect the host and listener to the same Wi-Fi or Android hotspot, start a broadcast, choose LAN, approve Android capture prompts, then open the shown /stream/join URL on another device.

For internet mode, deploy the server over HTTPS/WSS, enable Internet Streaming in app Settings, test/connect the server, then choose Internet or LAN + Internet when starting a broadcast.

PINs

• Room PIN protects a room. Normal listeners only need this 6-digit PIN when the room is protected.
• Server Connection PIN protects host/server actions such as WAN room creation and relay startup.
• /stream/join never asks normal listeners for the Server Connection PIN.

Tests

cd apps
dart format --output=none --set-exit-if-changed lib test
flutter analyze
flutter test
flutter build apk --debug

cd ../server
.venv/bin/python -m ruff check app tests
.venv/bin/python -m pytest

Known Limitations

• Audio transport is still PCM16 mono JSON/base64 over WebSocket. Opus/WebRTC remains future work.
• Android is the supported host platform; other platforms are listener/control surfaces for now.
• In-app listener playback is not implemented; listener flows open or copy the browser listener link.
• Android OS-level syncwave:// intent-filter launch handling is pending.
• Redis is optional but not yet shared room state across multiple server instances.

Made with love by R. Jha