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orca/mobile/packages/expo-two-way-audio/README.md
2026-05-14 14:36:44 -07:00

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# Orca Two Way Audio
Vendored Expo module for capturing and playing PCM audio data in the Orca mobile app (iOS and Android).
The aim of the module is to facilitate creating real-time conversational apps. The following features are provided:
- Request audio recording permissions
- Get clean (applying Acoustic Echo Cancelling) microphone samples in PCM format (1 channel 16 bit at 16kHz)
- Play audio samples in PCM format (1 channel 16 bit at 16kHz). Playback happens through main speaker unless external audio sources are connected.
- Provide volume level both for the input and output samples. Float between 0 and 1.
- [iOS only] Get microphone mode and prompt user to select a microphone mode.
## Installation
```
npm i @orca/expo-two-way-audio
```
## Usage
1. Request permissions for recording audio
```JSX
import {useMicrophonePermissions} from "@orca/expo-two-way-audio";
const [micPermission, requestMicPermission] = useMicrophonePermissions();
console.log(micPermission);
```
1. Initialize the module before calling any audio functionality.
```JSX
useEffect(() => {
const initializeAudio = async () => {
await initialize();
};
initializeAudio();
}, []);
```
1. Play audio
> [!NOTE]
> The sample below uses the `buffer` module:
> `npm install buffer`
```JSX
import { Buffer } from "buffer";
// As an example, play pcm data hardcoded in a variable.
const audioChunk = "SOME PCM DATA BASE64 ENCODED HERE"
const buffer = Buffer.from(audioChunk, "base64");
const pcmData = new Uint8Array(buffer);
playPCMData(pcmData);
```
1. Get microphone samples
```JSX
// Set up a function to deal with microphone sample events.
// In this case just print the data in the console.
useExpoTwoWayAudioEventListener(
"onMicrophoneData",
useCallback<MicrophoneDataCallback>((event) => {
console.log(`MIC DATA: ${event.data}`);
}, []),
);
// Unmute the microphone to get microphone data events
toggleRecording(true);
```
## Notes
Some audio features of expo-two-way-audio like Acoustic Echo Cancelling, noise reduction or microphone modes (iOS) don't work on simulator. Run the Orca mobile app on a real device to test these features.
```bash
# iOS
npx expo run:ios --device --configuration Release
# Android
npx expo run:android --device --variant release
```
For Android, the following permissions are needed: `RECORD_AUDIO`, `MODIFY_AUDIO_SETTINGS`. In Expo apps they can bee added in your `app.json` file:
```javascript
expo.android.permissions: ["RECORD_AUDIO", "MODIFY_AUDIO_SETTINGS"]
```