@loqalabs/loqa-audio-bridge

Production-grade Expo native module for real-time audio streaming with Voice Activity Detection and battery optimization

Features

• Real-time Audio Streaming - Capture audio at 8kHz-48kHz with configurable buffer sizes
• Voice Activity Detection (VAD) - Automatic silence detection for battery optimization
• Cross-Platform - Unified API for iOS (AVAudioEngine) and Android (AudioRecord)
• TypeScript Support - Full type definitions with strict typing
• Zero Configuration - Autolinking works out-of-the-box with Expo

Installation

npx expo install @loqalabs/loqa-audio-bridge

That's it! Autolinking handles the rest.

Quick Start

import { startAudioStream, addAudioSampleListener } from '@loqalabs/loqa-audio-bridge';

// Start streaming
await startAudioStream({ sampleRate: 16000, bufferSize: 2048 });

// Listen for audio samples
const subscription = addAudioSampleListener((event) => {
  console.log('RMS:', event.rms); // Volume level
  // Access audio samples: event.samples (number[])
});

// Clean up when done
subscription.remove();

Documentation

• Integration Guide - Step-by-step integration instructions
• API Reference - Complete API documentation
• Example App - Working Expo app demonstrating usage

Platform Requirements

• iOS 13.4+
• Android API 24+
• Expo 52+
• React Native 0.72+

Key Capabilities

Audio Configuration

Configure sample rate, buffer size, channels, and enable VAD for your use case:

await startAudioStream({
  sampleRate: 16000, // 8000, 16000, 32000, 44100, 48000
  bufferSize: 2048, // 512-8192 samples
  channels: 1, // 1 (mono) or 2 (stereo)
  vadEnabled: true, // Voice Activity Detection
});

Event-Driven Architecture

Subscribe to audio samples, status changes, and errors:

import {
  addAudioSampleListener,
  addStreamStatusListener,
  addStreamErrorListener,
} from '@loqalabs/loqa-audio-bridge';

// Audio samples (~8 Hz at 16kHz/2048 buffer)
const audioSub = addAudioSampleListener((event) => {
  const samples = event.samples; // number[] of audio data
  const rms = event.rms; // Volume level (0.0-1.0)
});

// Stream status changes
const statusSub = addStreamStatusListener((event) => {
  console.log('Status:', event.status); // "streaming" | "stopped" | "paused"
});

// Stream errors
const errorSub = addStreamErrorListener((event) => {
  console.error('Error:', event.error, event.message);
});

React Hook

Use the useAudioStreaming hook for automatic lifecycle management:

import { useAudioStreaming } from '@loqalabs/loqa-audio-bridge';

function MyComponent() {
  const { startStream, stopStream, isStreaming, rmsLevel } = useAudioStreaming({
    sampleRate: 16000,
    bufferSize: 2048,
  });

  return (
    <View>
      <Button title="Start" onPress={startStream} />
      <Button title="Stop" onPress={stopStream} />
      <Text>RMS: {rmsLevel}</Text>
    </View>
  );
}

Permissions

iOS

Add microphone permission to your app.json:

{
  "expo": {
    "ios": {
      "infoPlist": {
        "NSMicrophoneUsageDescription": "This app needs microphone access for audio recording."
      }
    }
  }
}

Android

Add microphone permission to your app.json:

{
  "expo": {
    "android": {
      "permissions": ["RECORD_AUDIO"]
    }
  }
}

Request permission at runtime using expo-av or similar:

import { Audio } from 'expo-av';

const { status } = await Audio.requestPermissionsAsync();
if (status === 'granted') {
  // Start streaming
}

Performance

• CPU Usage: 2-5% during active streaming
• Battery Impact: 3-8% per hour with VAD enabled (30-50% reduction vs. continuous)
• Event Rate: ~8 Hz at 16kHz/2048 buffer (configurable via buffer size)

Common Use Cases

• Speech Recognition: 16kHz sample rate for optimal accuracy
• Voice Communication: 8kHz-16kHz with VAD for battery efficiency
• Audio Analysis: 44.1kHz-48kHz for high-fidelity capture
• Environmental Monitoring: VAD-enabled streaming with low sample rates

EAS Build Compatibility

This package works seamlessly with Expo Application Services (EAS) Build for cloud-based iOS and Android builds. No special configuration required.

Quick Setup

1. Install the package:

   npx expo install @loqalabs/loqa-audio-bridge

2. Configure EAS Build (if not already done):

   npx eas build:configure

3. Build your app:

   # iOS
   eas build --platform ios --profile development
   
   # Android
   eas build --platform android --profile development

Standard Configuration

The package works with a standard eas.json:

{
  "build": {
    "development": {
      "developmentClient": true,
      "distribution": "internal"
    },
    "production": {
      "distribution": "store"
    }
  }
}

No custom plugins, build hooks, or special environment variables required. The module autolinks identically in cloud builds as it does in local builds.

Verification

Once your EAS build completes:

1. Download the .ipa (iOS) or .apk (Android) from the EAS dashboard
2. Install on a physical device
3. The audio streaming functionality works identically to local builds

For detailed EAS Build setup and troubleshooting, see the Integration Guide.

License

MIT

Contributing

This package is part of the Loqa monorepo. See the repository for contribution guidelines.

Support

• GitHub Issues
• Example App - Working reference implementation