react-native-nitro-realtime-audio

A high-performance real-time audio streaming library for React Native, powered by Nitro Modules.

It captures microphone audio with ultra-low latency and streams raw 16-bit Linear PCM audio directly to JavaScript as standard ArrayBuffer objects.

Designed for modern real-time audio applications such as:

• 🤖 AI Voice Assistants (OpenAI Realtime, Gemini Live)
• 🗣️ Speech-to-Text
• 🌐 WebRTC & VoIP
• 📈 Audio Visualizers
• 🎛️ Digital Signal Processing (DSP)
• 🎤 Voice Activity Detection (VAD)

Unlike traditional recording libraries that primarily save audio files, this library is built for real-time audio streaming, allowing every audio chunk to be processed immediately in JavaScript.

Works with Expo Development Builds, EAS Build, and React Native CLI projects.

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Features

• ⚡ Powered by Nitro Modules for extremely low-overhead native-to-JS communication
• 🎙️ Real-time microphone audio streaming
• 📦 Streams raw 16-bit PCM audio as standard ArrayBuffer
• 🔄 Automatic native audio resampling
• 🎚️ Configurable sample rate, channels, and chunk duration
• 📱 Native support for Android and iOS
• 🚀 Compatible with Expo Development Builds and React Native CLI
• 🧩 Ideal for AI, WebRTC, DSP, speech processing, and custom audio pipelines

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Architecture

Microphone
      │
      ▼
Native Audio Recorder
      │
      ▼
Chunk Accumulator
      │
      ▼
PCM16 AudioChunk
      │
      ▼
ArrayBuffer
      │
      ▼
JavaScript Callback

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Why ArrayBuffer?

The library streams raw PCM audio as ArrayBuffer instead of Base64 strings or temporary audio files.

This provides:

• Lower memory overhead
• Lower latency
• No encoding/decoding overhead
• Standard JavaScript binary format
• Easy interoperability with AI SDKs, WebRTC, DSP libraries, and custom processing pipelines

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Installation

Install the library together with its required peer dependency:

npm install @mindinventory/react-native-nitro-realtime-audio react-native-nitro-modules

or

yarn add @mindinventory/react-native-nitro-realtime-audio react-native-nitro-modules

or for Expo:

npx expo install @mindinventory/react-native-nitro-realtime-audio react-native-nitro-modules

Note

react-native-nitro-modules is a required peer dependency.

Install iOS dependencies:

```bash
cd ios
pod install

Note

react-native-nitro-modules is required as a peer dependency.

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Expo Support

This library is fully compatible with:

• ✅ Expo Development Build
• ✅ Expo Prebuild
• ✅ Expo Bare Workflow
• ✅ React Native CLI
• ✅ EAS Build

Important

Since this library contains native code, it cannot run inside Expo Go.

Use an Expo Development Build or EAS Build instead.

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iOS Setup

Add the microphone usage description to your Info.plist

<key>NSMicrophoneUsageDescription</key>
<string>This app requires access to the microphone to record audio.</string>

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Android Setup

Add microphone permission to:

android/app/src/main/AndroidManifest.xml

<uses-permission android:name="android.permission.RECORD_AUDIO" />

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API Reference

Permissions & Device Information

getPlatformName(): string

Returns the current platform.

'iOS';
'Android';

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getNativeSampleRate(): number

Returns the device's native hardware sample rate.

Example:

48000
44100

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getMicrophonePermissionStatus(): MicrophonePermissionStatus

Returns one of:

'granted';
'denied';
'undetermined';

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requestMicrophonePermission(): Promise<MicrophonePermissionStatus>

Requests microphone permission from the user.

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Recording

startRecording(config: AudioRecordingConfig): void

Starts recording microphone audio.

startRecording({
  sampleRate: 24000,
  channels: 1,
  chunkDurationMs: 100,
});

Property	Description
sampleRate	Target output sample rate. Native audio is automatically resampled if required.
channels	1 = Mono, 2 = Stereo
chunkDurationMs	Duration of each emitted audio chunk in milliseconds

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stopRecording(): void

Stops recording and stops streaming audio chunks.

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isRecording(): boolean

Returns true if the native recorder is actively capturing audio.

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getCapturedBufferCount(): number

Returns the number of audio chunks captured during the current recording session.

Useful for debugging and validating streaming behaviour.

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onAudioChunk(callback)

Registers a callback that receives every PCM audio chunk.

onAudioChunk((buffer: ArrayBuffer) => {
  // buffer contains signed 16-bit PCM samples
});

The callback is invoked whenever a chunk is completed by the native recorder.

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Recommended Configurations

Use Case	Sample Rate	Channels	Chunk Duration
Voice AI	24000	Mono	100 ms
Whisper	16000	Mono	100 ms
WebRTC	48000	Mono	20 ms
General Recording	Native	Stereo	100 ms

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Usage Example

import React, { useEffect, useRef, useState } from 'react';
import { View, Text, Button } from 'react-native';

import {
  getMicrophonePermissionStatus,
  requestMicrophonePermission,
  startRecording,
  stopRecording,
  onAudioChunk,
  isRecording,
} from '@mindinventory/react-native-nitro-realtime-audio';

export default function AudioRecorder() {
  const [recording, setRecording] = useState(false);
  const [chunksReceived, setChunksReceived] = useState(0);

  const recordedPcmChunks = useRef<Uint8Array[]>([]);

  useEffect(() => {
    onAudioChunk((buffer) => {
      recordedPcmChunks.current.push(new Uint8Array(buffer));

      setChunksReceived((count) => count + 1);

      const samples = new Int16Array(buffer);

      // Send to AI
      // websocket.send(buffer);

      // Visualize waveform

      // Apply DSP

      console.log(samples.length);
    });
  }, []);

  const start = async () => {
    let permission = getMicrophonePermissionStatus();

    if (permission !== 'granted') {
      permission = await requestMicrophonePermission();

      if (permission !== 'granted') {
        return;
      }
    }

    recordedPcmChunks.current = [];
    setChunksReceived(0);

    startRecording({
      sampleRate: 24000,
      channels: 1,
      chunkDurationMs: 100,
    });

    setRecording(isRecording());
  };

  const stop = () => {
    stopRecording();
    setRecording(isRecording());

    console.log(`Captured ${recordedPcmChunks.current.length} chunks`);
  };

  return (
    <View>
      <Text>{recording ? 'Recording...' : 'Stopped'}</Text>

      <Text>Chunks Received: {chunksReceived}</Text>

      <Button title="Start" onPress={start} disabled={recording} />

      <Button title="Stop" onPress={stop} disabled={!recording} />
    </View>
  );
}

---

Example Application

The example application included in this repository demonstrates:

• 🎙️ Real-time microphone recording
• 📈 Live waveform visualization
• 📊 Live chunk statistics
• 📦 Raw PCM streaming
• 💾 WAV generation
• ▶️ Audio playback
• 📋 Recording summaries

It serves as both a demo application and a reference implementation for integrating the library.

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Notes

• Audio chunks contain signed 16-bit Linear PCM samples.
• Samples are stored in little-endian format.
• Audio is streamed as standard JavaScript ArrayBuffer.
• Recording does not automatically save audio files.
• Generate WAV files or encode MP3/AAC yourself using the streamed PCM data.
• Chunk size depends on the configured sample rate, channel count, and chunk duration.

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Best Practices

The example application stores every PCM chunk in memory so it can generate a WAV file after recording.

For production applications such as AI assistants, speech recognition, or WebRTC, process each chunk immediately instead of storing them all in memory.

Example:

onAudioChunk((buffer) => {
  websocket.send(buffer);
});

Streaming chunks immediately keeps memory usage low even during long recording sessions.

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Roadmap

• ✅ Real-time PCM recording
• ✅ Configurable recording
• ✅ Native audio resampling
• ✅ Real-time PCM streaming
• ⏳ PCM playback
• ⏳ Audio session configuration
• ⏳ Voice Activity Detection (VAD)
• ⏳ Echo cancellation
• ⏳ Noise suppression
• ⏳ Automatic Gain Control (AGC)

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Contributing

Contributions, bug reports, and feature requests are welcome.

Please read the Contributing Guide before opening a pull request.

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License

MIT

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Let us know

If you use our open-source libraries in your project, please make sure to credit us and Give a star to www.mindinventory.com

Please feel free to use this component and Let us know if you are interested to building Apps or Designing Products.

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Built with ❤️ using React Native Builder Bob (create-react-native-library).