music-metadata

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music-metadata

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Key features:

The music-metadata module is ideal for developers working on media applications, music players, or any project that requires access to detailed audio file metadata.

Compatibility

Module: version 8 migrated from CommonJS to pure ECMAScript Module (ESM). The distributed JavaScript codebase targets ECMAScript 2023 (14th Edition).

[!NOTE] See also CommonJS backward Compatibility

This module requires a Node.js ≥ 22 engine. It can also be used in a browser environment when bundled with a module bundler.

Support the Project

If you find this project useful and would like to support its development, consider sponsoring or contributing:

Features

Support for audio file types

Audio format Description Logo
AIFF / AIFF-C Audio Interchange File Format Apple rainbow logo
AAC ADTS / Advanced Audio Coding AAC logo
APE Monkey’s Audio Monkey's Audio logo
ASF Advanced Systems Format  
BWF Extended WAV format for broadcast and archiving  
CAF Core Audio File Format Apple rainbow logo
DSDIFF Philips DSDIFF DSD logo
DSF Sony’s DSD Stream File DSD logo
FLAC Free Lossless Audio Codec FLAC logo
MP2 MPEG-1 Audio Layer II (predecessor to MP3)  
Matroska Matroska (EBML), mka, mkv Matroska logo
MP3 MPEG-1 / MPEG-2 Audio Layer III MP3 logo
MPC Musepack SV7 musepack logo
MPEG 4 mp4, m4a, m4v mpeg 4 logo
Ogg Open container format Ogg logo
Opus Low-latency, high-quality codec for speech and music Opus logo
Speex Open-source speech codec optimized for VoIP Speex logo
Theora Open video compression format (typically paired with Ogg) Theora logo
Vorbis Vorbis audio compression Vorbis logo
WAV Uncompressed PCM audio in RIFF container  
WebM WebM Matroska logo
WV WavPack WavPack logo
WMA Windows Media Audio Windows Media logo

Supported tag headers

Following tag header formats are supported:

Following lyric formats are supported:

Support for MusicBrainz tags as written by Picard. ReplayGain tags are supported.

Audio format & encoding details

Support for encoding / format details:

Online demo’s

Used by around 50k+ GitHub projects.

Usage

Installation

Install using npm:

npm install music-metadata

or using yarn:

yarn add music-metadata

API Documentation

Overview

Node.js specific functions to read an audio file or stream:

  1. File Parsing: Parse audio files directly from the filesystem using the parseFile function
  2. Stream Parsing: Parse audio metadata from a Node.js Readable stream using the parseStream function.

Cross-platform functions available to read an audio file or stream:

There are multiple ways to parse (read) audio tracks:

  1. Web Stream Parsing: Parse audio data from a web-compatible ReadableStream using the parseWebStream function.
  2. Blob Parsing: Parse audio metadata from a (Web API) Blob or File using the parseBlob function.
  3. Buffer Parsing: Parse audio metadata from a Uint8Array or Buffer using the parseBuffer function.
  4. Tokenizer Parsing: Use a custom or third-party strtok3 ITokenizer to parse using the parseFromTokenizer function.

[!NOTE] Direct file access in Node.js is generally faster because it can ‘jump’ to various parts of the file without reading intermediate data.

Node.js specific functions

These functions use Node.js-specific APIs, making them incompatible with browser-based JavaScript engines.

parseFile function

The parseFile function is intended for extracting metadata from audio files on the local filesystem in a Node.js environment. It reads the specified file, parses its audio metadata, and returns a promise that resolves with this information.

Syntax
parseFile(filePath: string, options?: IOptions): Promise<IAudioMetadata>
Parameters
Returns
Usage Notes
Example:

The following example demonstrates how to use the parseFile function to read metadata from an audio file:

import { parseFile } from 'music-metadata';
import { inspect } from 'node:util';

(async () => {
  try {
    const filePath = 'test/samples/MusicBrainz - Beth Hart - Sinner\'s Prayer [id3v2.3].V2.mp3';
    const metadata = await parseFile(filePath);

    // Output the parsed metadata to the console in a readable format
    console.log(inspect(metadata, { showHidden: false, depth: null }));
  } catch (error) {
    console.error('Error parsing metadata:', error.message);
  }
})();

parseStream function

The parseStream function is used to parse metadata from an audio track provided as a Node.js Readable stream. This is particularly useful for processing audio data that is being streamed or piped from another source, such as a web server or file system.

Syntax:
parseStream(stream: Readable, fileInfo?: IFileInfo | string, options?: IOptions): Promise<IAudioMetadata>
Parameters:
Returns
Usage Notes
Example:

The following example demonstrates how to use the parseStream function to read metadata from an audio stream:

import { parseStream } from 'music-metadata';
import { createReadStream } from 'fs';

(async () => {
  try {
    // Create a readable stream from a file
    const audioStream = createReadStream('path/to/audio/file.mp3');

    // Parse the metadata from the stream
    const metadata = await parseStream(audioStream, { mimeType: 'audio/mpeg'});

    // Log the parsed metadata
    console.log(metadata);
  } catch (error) {
    console.error('Error parsing metadata:', error.message);
  }
})();

Cross-platform functions

These functions are designed to be cross-platform, meaning they can be used in both Node.js and web browsers.

parseWebStream function

The parseWebStream function is used to extract metadata from an audio track provided as a web-compatible ReadableStream. This function is ideal for applications running in web environments, such as browsers, where audio data is streamed over the network or read from other web-based sources.

Syntax
parseWebStream(webStream: ReadableStream<Uint8Array>, fileInfo?: IFileInfo | string, options?: IOptions): Promise<IAudioMetadata>
Parameters
Returns
Example

Here’s an example of how to use the parseWebStream function to extract metadata from an audio stream in a web application:

import { parseWebStream } from 'music-metadata';

(async () => {
  try {
    // Fetch the audio file
    const response = await fetch('https://github.com/Borewit/test-audio/raw/refs/heads/master/Various%20Artists%20-%202008%20-%20netBloc%20Vol%2013%20-%20Color%20in%20a%20World%20of%20Monochrome%20%5BAAC-40%5D/1.02.%20Solid%20Ground.m4a');

    // Extract the Content-Length header and convert it to a number
    const contentLength = response.headers.get('Content-Length');
    const size = contentLength ? parseInt(contentLength, 10) : undefined;

    // Parse the metadata from the web stream
    const metadata = await parseWebStream(response.body, {
      mimeType: response.headers.get('Content-Type'),
      size // Important to pass the content-length
    });

    console.log(metadata);
  } catch (error) {
    console.error('Error parsing metadata:', error.message);
  }
})();

The example uses the fetch API to retrieve an audio file from a URL. The response.body provides a ReadableStream that is then passed to parseWebStream.

parseBlob function

Parses metadata from an audio file represented as a Blob. This function reads slices of the Blob and supports both browser File objects and Node.js Blob objects.

Syntax
parseBlob(blob: Blob, options?: IOptions): Promise<IAudioMetadata>
Parameters
Returns
Example
import { parseBlob } from 'music-metadata';

(async () => {
  const fileInput = document.querySelector('input[type="file"]');
  const file = fileInput.files[0];
  
  try {
    const metadata = await parseBlob(file);
    console.log(metadata);
  } catch (error) {
    console.error('Error parsing metadata:', error.message);
  }
})();

parseBuffer function

Parses metadata from an audio file where the audio data is held in a Uint8Array or Buffer. This function is particularly useful when you already have audio data in memory.

Syntax
parseBuffer(uint8Array: Uint8Array, fileInfo?: IFileInfo | string, options?: IOptions): Promise<IAudioMetadata>
Parameters
Returns
Example
import { parseBuffer } from 'music-metadata';
import fs from 'fs';

(async () => {
  const buffer = fs.readFileSync('path/to/audio/file.mp3');

  try {
    const metadata = await parseBuffer(buffer, { mimeType: 'audio/mpeg' });
    console.log(metadata);
  } catch (error) {
    console.error('Error parsing metadata:', error.message);
  }
})();

parseFromTokenizer function

Parses metadata from an audio source that implements the strtok3 ITokenizer interface. This is a low-level function that provides flexibility for advanced use cases, such as parsing metadata from streaming audio or custom data sources.

This also enables special read modules like:

Syntax
parseFromTokenizer(tokenizer: ITokenizer, options?: IOptions): Promise<IAudioMetadata>
Parameters
Returns
Example
import { fromNodeProviderChain } from '@aws-sdk/credential-providers';
import { S3Client } from '@aws-sdk/client-s3';
import { makeTokenizer } from '@tokenizer/s3';
import { parseFromTokenizer as mmParseFromTokenizer } from 'music-metadata';

// Configure the S3 client
const s3 = new S3Client({
  region: 'eu-west-2',
  credentials: fromNodeProviderChain(),
});

// Helper function to create a tokenizer for S3 objects
async function makeS3TestDataTokenizer(key, options) {
  return await makeTokenizer(s3, {
    Bucket: 'music-metadata',
    Key: key,
  }, options);
}

// Function to read and log metadata from an S3 object
async function readMetadata() {
  try {
    // Create a tokenizer for the specified S3 object
    const tokenizer = await makeS3TestDataTokenizer('path/to/audio/file.mp3', { disableChunked: false });

    // Parse the metadata from the tokenizer
    const metadata = await mmParseFromTokenizer(tokenizer);

    // Log the retrieved metadata
    console.log(metadata);
  } catch (error) {
    console.error('Error parsing metadata:', error.message);
  }
}

// Execute the metadata reading function
readMetadata();
Additional Resources

Handling Parse Errors

music-metadata exports custom error classes that extend JavaScript Error. Parsing can also reject with other errors, such as filesystem, stream, or tokenizer errors. Handle caught values as unknown in TypeScript and narrow them before accessing error properties.

Union of Parse Errors

The UnionOfParseErrors type groups the following library error classes; it does not describe every possible rejection:

export type UnionOfParseErrors =
  | CouldNotDetermineFileTypeError
  | UnsupportedFileTypeError
  | UnexpectedFileContentError
  | FieldDecodingError
  | InternalParserError;

Error Types

Other functions

orderTags function

Converts an array of native tags to a dictionary keyed by tag identifier. Each value is an array of tag values.

orderTags(nativeTags: ITag[]): INativeTagDict

import { parseFile, orderTags } from 'music-metadata';
import { inspect } from 'util';

(async () => {
  try {
    const metadata = await parseFile('../test/samples/MusicBrainz - Beth Hart - Sinner\'s Prayer [id3v2.3].V2.mp3');
    const orderedTags = orderTags(metadata.native['ID3v2.3']);
    console.log(inspect(orderedTags, { showHidden: false, depth: null }));
  } catch (error) {
    console.error(error.message);
  }
})();

ratingToStars function

Can be used to convert the normalized rating value to the 0..5 stars, where 0 an undefined rating, 1 the star the lowest rating and 5 the highest rating.

   ratingToStars(rating: number | undefined): number

selectCover function

Select cover image based on image type field, otherwise the first picture in file.

export function selectCover(pictures?: IPicture[]): IPicture | null

import { parseFile, selectCover } from 'music-metadata';

(async () => {
  const {common} = await parseFile(filePath);
  const cover = selectCover(common.picture); // pick the cover image
}
)();

getSupportedMimeTypes function

Returns a list of supported MIME-types. This may include some MIME-types which are not formally recognized.

IOptions Interface

[!NOTE]

IAudioMetadata interface

If the returned promise resolves, the metadata (TypeScript IAudioMetadata interface) contains:

metadata.format

The questionmark ? indicates the property is optional.

Audio format information. Defined in the TypeScript IFormat interface:

metadata.format.trackInfo

metadata.format.trackInfo provides the same track abstraction for single-stream audio files and multi-track containers (MPEG-4, Matroska, ASF, and Ogg). Tracks can carry audio, video, subtitles, or metadata. Import TrackType from music-metadata to select tracks without knowing the container:

import { parseFile, TrackType } from 'music-metadata';

const { format } = await parseFile('movie.mp4', { duration: true });
const audioTracks = format.trackInfo.filter(track => track.type === TrackType.audio);
const videoTracks = format.trackInfo.filter(track => track.type === TrackType.video);
for (const track of videoTracks) {
  console.log(track.duration, track.bitrate, track.video?.pixelWidth, track.video?.pixelHeight);
  console.log(track.video?.frameRate);
}
console.log(format.containerDuration, format.overallBitrate);

Each entry describes one discovered track. The order follows container discovery and does not identify a preferred track; use type, container flags, and language to choose one. In MPEG-4, the codec and media properties describe the first sample description, even when the track has multiple sample descriptions. In Ogg, entries describe logical media streams; Skeleton headers do not create media tracks. Single-stream audio parsers map their format properties to one audio track after parsing.

Properties are optional when unavailable and are not copied between tracks. In particular, a container or summary bitrate is not a per-track bitrate. The existing format.duration and format.bitrate fields retain their summary semantics. Use containerDuration for the complete presentation and overallBitrate for the actual file size multiplied by eight and divided by that duration. These statistics remain unset when timing is unavailable; overallBitrate also requires a known input size.

MPEG-4 derives audio and video timing from media headers, sample tables, and fragments, including fragment defaults and decode timestamps. Track bitrates use sample sizes and duration; video properties include encoded dimensions, display dimensions, and average frame rate. ASF supplies stream dimensions, stream bitrates, and extended stream timing and frame rate when present. Standalone and nested Stream Properties Objects describe actual streams; Codec List entries supply names without creating unused tracks.

Matroska applies specified defaults for flags, language, channels, and sample rate, and prefers IETF language tags when present. Track statistics tags provide duration, bitrate, and frame count; without these tags, per-track timing may be unavailable even when segment duration is known. Media clusters are not scanned to calculate missing track statistics.

Ogg/Theora duration comes from granule positions. Set duration: true to allow scanning beyond the initial metadata pages. Once a video stream has been fully read, its average bitrate uses that logical stream’s payload bytes, including codec headers and excluding Ogg framing and other streams. Resolution and frame rate are available from the identification header. Audio streams retain their own codec bitrate semantics.

For Ogg/Opus, the per-track average bitrate uses the logical stream’s payload bytes, including codec headers and excluding Ogg framing and other streams. It requires the logical stream’s end-of-stream (EOS) page and a known duration; reaching input EOF alone is insufficient. Set duration: true to allow scanning when needed. The summary format.bitrate retains its existing file-size estimate and can differ from the per-track bitrate. Vorbis and Speex use nominal bitrates when their headers provide them.

metadata.format.trackInfo is an array of trackInfo objects, empty when no track information is available.

trackInfo

Individual track information. Defined in the TypeScript ITrackInfo interface:

trackInfo.audio
trackInfo.video

metadata.common

Common tag documentation is automatically generated.

Examples

In order to read the duration of a stream (with the exception of file streams), in some cases you should pass the size of the file in bytes.

import { parseStream } from 'music-metadata';
import { inspect } from 'util';

(async () => {
    const metadata = await parseStream(someReadStream, {mimeType: 'audio/mpeg', size: 26838}, {duration: true});
    console.log(inspect(metadata, {showHidden: false, depth: null}));
    someReadStream.close();
  }
)();

Access cover art

Via metadata.common.picture you can access an array of cover art if present. Each picture has this interface:

/**
 * Attached picture, typically used for cover art
 */
export interface IPicture {
  /**
   * Image mime type
   */
  format: string;
  /**
   * Image data
   */
  data: Uint8Array;
  /**
   * Optional description
   */
  description?: string;
  /**
   * Picture type
   */
  type?: string;
}

To assign img HTML-object you can do something like:

import {uint8ArrayToBase64} from 'uint8array-extras';

img.src = `data:${picture.format};base64,${uint8ArrayToBase64(picture.data)}`;

Dependencies

Dependency diagram:

graph TD;
    MMN("music-metadata (Node.js entry point)")-->MMP
    MMN-->FTN
    MMP("music-metadata (primary entry point)")-->S(strtok3)
    MMP-->TY(token-types)
    MMP-->FTP
    MMP-->UAE
    FTN("file-type (Node.js entry point)")-->FTP
    FTP("file-type (primary entry point)")-->S
    S(strtok3)-->TO("@tokenizer/token")
    TY(token-types)-->TO
    TY-->IE("ieee754")
    FTP-->TY
    NS("node:stream")
    FTN-->NS
    FTP-->UAE(uint8array-extras)
    style NS fill:#F88,stroke:#A44
    style IE fill:#CCC,stroke:#888
    style FTN fill:#FAA,stroke:#A44
    style MMN fill:#FAA,stroke:#A44

Dependency list:

CommonJS backward compatibility

Using Node.js ≥ 22, which is support loading ESM module via require

const mm = require('music-metadata');

Alternatively, dynamically import music-metadata:

(async () => {
  // Dynamically loads the ESM module in a CommonJS project
  const mm = await import('music-metadata');
})();

For CommonJS TypeScript projects, I recommend to avoid using commonjs for the TypeScript compiler module option, and either use node16 or nodenext, which enable utilizing dynamic import.

If you do want to use the classic commonjs option, this is how you can get the dynamic import to work.

import {loadEsm} from 'load-esm';

(async () => {
  // Dynamically loads the ESM module in a CommonJS project
  const mm = await loadEsm<typeof import('music-metadata')>('music-metadata');
})();

When you use Node.js version ≥ 22, which supports loading ESM modules via require, this compensates for that issue.

Frequently Asked Questions

How can I traverse (a long) list of files?

What is important that file parsing should be done in a sequential manner. In a plain loop, due to the asynchronous character (like most JavaScript functions), it would cause all the files to run in parallel which is will cause your application to hang in no time. There are multiple ways of achieving this:

  1. Using recursion

    import { parseFile } from 'music-metadata';

function parseFiles(audioFiles) {

  const audioFile = audioFiles.shift();

  if (audioFile) {
    return parseFile(audioFile).then(metadata => {
      // Do great things with the metadata
      return parseFiles(audioFiles); // process rest of the files AFTER we are finished
    })
  }
}

  2. Use async/await

    Use async/await

    import { parseFile } from 'music-metadata';

// it is required to declare the function 'async' to allow the use of await
async function parseFiles(audioFiles) {

    for (const audioFile of audioFiles) {

        // await will ensure the metadata parsing is completed before we move on to the next file
        const metadata = await parseFile(audioFile);
        // Do great things with the metadata
    }
}

Using music-metadata with TypeScript and module-resolution set to bundler.

If the TypeScript compiler option moduleResolution is set to "bundler", it does not set the ECMAScript "node" condition, causing the Node specific function fail to import.

This is the case using Next.js. See issue #2370 how to resolve that.

Licence

This project is licensed under the MIT License. Feel free to use, modify, and distribute as needed.

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