Decoding

You can decode audio data independently, without creating an AudioContext, using the exported functions decodeAudioData, decodePCMInBase64, and getAudioDuration.

If you already have an audio context, you can decode audio data directly using its decodeAudioData function; the decoded audio will then be automatically resampled to match the context's sampleRate.

caution

Supported file formats:

• flac
• mp3
• ogg
• opus
• wav
• aac
• m4a
• mp4
• aif
• aiff
• caf (ios)

Methods

decodeAudioData

Decodes audio data from a file path, an ArrayBuffer, or a bundled app asset (a number module id returned by require('./audio.mp3')). The optional sampleRate parameter lets you resample the decoded audio; if not provided, the original sample rate from the file is used.

Parameter	Type	Description
input	ArrayBuffer	ArrayBuffer with encoded audio data.
	string	Path to a remote or local audio file.
	number Mobile only	React Native asset module id (for example, the value returned by require('./audio.mp3')).
sampleRate Optional	number	Target sample rate for the decoded audio.
fetchOptions Optional	RequestInit	Additional fetch options when input is a remote URL (for example, auth headers).

caution

If you pass a number as input, decoding resolves the bundled asset through React Native's Image component. By default, only .mp3, .wav, .mp4, .m4a, and .aac assets are supported. To use other formats, see static non-image resources.

Returns: Promise<AudioBuffer>

Example decoding remote URL

import { decodeAudioData } from 'react-native-audio-api';

const url = ... // url to an audio

const buffer = await decodeAudioData(url);

getAudioDuration

Reads the duration of an audio source without decoding the full file into an AudioBuffer. Use this when you only need the encoded file duration. Use decodeAudioData when you need sample data for playback or processing.

On mobile, duration is read from file metadata via the native decoder. Local paths, file:// URIs, remote http(s): URLs, and ArrayBuffer input are supported. Remote URL probing requires FFmpeg in the native build — see Runtime flags. Asset module ids, base64 data URLs, and blob URLs are rejected explicitly.

On web, this API uses browser audio metadata loading and supports sources the browser can load, such as remote URLs, relative URLs, blob URLs, and data URLs.

There is no sampleRate option because the returned duration belongs to the encoded source and does not depend on a caller-selected output sample rate.

Parameter	Type	Description
input	ArrayBuffer	Encoded audio bytes (mobile only).
	string	Local path, file:// URI, or remote URL.
fetchOptions Optional	RequestInit	Additional fetch options when input is a remote URL (for example, auth headers).

Returns Promise<number> with the duration in seconds.

Throws an error when duration metadata is unavailable or when the input type is not supported.

Example reading local file duration

import { getAudioDuration } from 'react-native-audio-api';

const duration = await getAudioDuration('file:///tmp/recording.wav');

Example reading remote URL duration

import { getAudioDuration } from 'react-native-audio-api';

const duration = await getAudioDuration('https://example.com/audio.mp3', {
  headers: { Authorization: 'Bearer token' },
});

decodePCMInBase64

Decodes base64-encoded PCM audio data.

Parameter	Type	Description
base64String	string	Base64-encoded PCM audio data.
inputSampleRate	number	Sample rate of the input PCM data.
inputChannelCount	number	Number of channels in the input PCM data.
isInterleaved Optional	boolean	Whether the PCM data is interleaved. Defaults to true.

Returns Promise<AudioBuffer>

Example decoding with data in base64 format

const data = ... // data encoded in base64 string
// data is interleaved (Channel1, Channel2, Channel1, Channel2, ...)
const buffer = await decodeAudioData(data, 4800, 2, true);