AudioDataEvent

The AudioDataEvent type represents audio data streamed at the configured interval. The data format depends on the streamFormat setting in your RecordingConfig.

Type Definition

AudioDataEvent is a discriminated union of two variants:

// Common fields shared by both variants
interface AudioDataEventBase {
    position: number        // Position in the recording (seconds)
    fileUri: string         // URI of the audio file being written
    eventDataSize: number   // Size of this chunk in bytes
    totalSize: number       // Total recorded bytes so far
}

// Default mode (streamFormat: 'raw' or unset)
interface AudioDataEventRaw extends AudioDataEventBase {
    data: string | Float32Array | Int16Array
    streamFormat?: undefined | 'raw'
}

// Float32 mode (streamFormat: 'float32')
interface AudioDataEventFloat32 extends AudioDataEventBase {
    data: Float32Array
    streamFormat: 'float32'
}

type AudioDataEvent = AudioDataEventRaw | AudioDataEventFloat32

Data Field

The type of data depends on the streamFormat setting:

streamFormat	Native (Android/iOS)	Web
'raw' (default)	base64-encoded string	Float32Array
'float32'	Float32Array	Float32Array

With streamFormat: 'float32', data is guaranteed to be Float32Array on all platforms — no manual base64 decoding or type checking needed.

Example Usage

import { useAudioRecorder, type AudioDataEvent } from '@siteed/expo-audio-studio';

const { startRecording } = useAudioRecorder({ debug: true });

await startRecording({
    sampleRate: 16000,
    channels: 1,
    streamFormat: 'float32',
    onAudioStream: async (event: AudioDataEvent) => {
        // With streamFormat: 'float32', data is always Float32Array
        const samples = event.data as Float32Array;
        console.log(`Received ${samples.length} samples at position ${event.position}s`);
    },
});