JS MediaTags

The next version of https://github.com/aadsm/JavaScript-ID3-Reader.

Current Support

• File Readers
  • NodeJS
  • XMLHttpRequest
  • Blob
  • File
  • Buffers/Arrays
• Tag Readers
  • ID3v1
  • ID3v2 (unsynchronisation is not supported)
  • MP4

How to use

NodeJS

Run npm install jsmediatags --save to install.

// Simple API - will fetch all tags
var jsmediatags = require("jsmediatags");

jsmediatags.read("./music-file.mp3", {
  onSuccess: function(tag) {
    console.log(tag);
  },
  onError: function(error) {
    console.log(':(', error.type, error.info);
  }
});

// Advanced API
var jsmediatags = require("jsmediatags");

new jsmediatags.Reader("http://www.example.com/music-file.mp3")
  .setTagsToRead(["title", "artist"])
  .read({
    onSuccess: function(tag) {
      console.log(tag);
    },
    onError: function(error) {
      console.log(':(', error.type, error.info);
    }
  });

Browser

Copy the dist/jsmediatags.min.js file into your web application directory and include it with a script tag. UMD will give you multiple usage options to use it:

// As a global Object
var jsmediatags = window.jsmediatags;

// As a CommonJS Module
var jsmediatags = require("jsmediatags");

It supports loading files from remote hosts, Blob and File objects:

// From remote host
jsmediatags.read("http://www.example.com/music-file.mp3", {
  onSuccess: function(tag) {
    console.log(tag);
  },
  onError: function(error) {
    console.log(error);
  }
});

// From Blob
jsmediatags.read(blob, ...);

// From File
inputTypeFile.addEventListener("change", function(event) {
  var file = event.target.files[0];
  jsmediatags.read(file, ...);
}, false);

You can find more about UMD usage options here.

Documentation

The Output

This is an example of the object passed to the jsmediatags.read's onSuccess callback.

ID3v2

{
  type: "ID3",
  version: "2.4.0",
  major: 4,
  revision: 0,
  tags: {
    artist: "Sam, The Kid",
    album: "Pratica(mente)",
    track: "12",
    TPE1: {
      id: "TPE1",
      size: 14,
      description: "Lead performer(s)/Soloist(s)",
      data: "Sam, The Kid"
    },
    TALB: {
      id: "TALB",
      size: 16,
      description: "Album/Movie/Show title",
      data: "Pratica(mente)"
    },
    TRCK: {
      id: "TRCK",
      size: 3,
      description: "Track number/Position in set",
      data: "12",
    }
  },
  size: 34423,
  flags: {
    unsynchronisation: false,
    extended_header: false,
    experimental_indicator: false,
    footer_present: false
  }
}

MP4

{
  type: "MP4",
  ftyp: "M4A",
  version: 0,
  tags: {
    "©too": {
      id: "©too",
      size: 35,
      description: 'Encoding Tool',
      data: 'Lavf53.24.2'
    }
  }
}

The tags property includes all tags that were found or specified to be read. Since each tag type (e.g.: ID3, MP4) uses different tag names for the same type of data (e.g.: the artist name) the most common tags are also available under human readable names (aka shortcuts). In this example, artist will point to TPE1.data, album to TALB.data and so forth.

The expected tag object depends on the type of tag read (ID3, MP4, etc.) but they all share a common structure:

{
  type: <the tag type: ID3, MP4, etc.>
  tags: {
    <shortcut name>: <points to a tags data>
    <tag name>: {
      id: <tag name>,
      data: <the actual tag data>
    }
  }
}

Shortcuts

These are the supported shortcuts.

• title
• artist
• album
• year
• comment
• track
• genre
• picture
• lyrics

HTTP Access Control (CORS)

When using HTTP CORS requests you need to make sure that the server is configured to receive If-Modified-Since and Range headers with the request. This can be configured by returning the Access-Control-Allow-Headers HTTP header with the OPTIONS request response.

Similarly, you should also allow for the browser to read the Content-Length and Content-Range headers. This can be configured by returning the Access-Control-Expose-Headers HTTP header.

In short, the following headers are expected:

Access-Control-Allow-Headers: If-Modified-Since, Range
Access-Control-Expose-Headers: Content-Length, Content-Range

This library still works without these options configured on the server. However it will download the entire file instead of only the necessary bytes for reading the tags.

File and Tag Readers

This library uses file readers (MediaFileReader API) to read the file itself and media tag readers (MediaTagReader API) to parse the tags in the file.

By default the library will automatically pick the most appropriate file reader depending on the file location. In the common case this will be the URL or local path where the file is located.

A similar approach is taken for the tag reader. The most appropriate tag reader will be selected depending on the tag signature found in the file.

However, you can specify exactly which file reader or tag reader to use using the advanced API.

New file and tag readers can be implemented by extending the MediaFileReader and MediaTagReader classes. Check the Development section down bellow for more information.

Reference

• jsmediatags.Reader

  • setTagsToRead(tags: Array<string>) - Specify which tags to read
  • setFileReader(fileReader: typeof MediaFileReader) - Use this particular file reader
  • setTagReader(tagReader: typeof MediaTagReader) - Use this particular tag reader
  • read({onSuccess, onError}) - Read the tags.

• jsmediatags.Config

  • addFileReader(fileReader: typeof MediaFileReader) - Add a new file reader to the automatic detection system.
  • addTagReader(tagReader: typeof MediaTagReader) - Add a new tag reader to the automatic detection system.
  • setDisallowedXhrHeaders(disallowedXhrHeaders: Array<string>) - Prevent the library from using specific http headers. This can be useful when dealing with CORS enabled servers you don't control.
  • setXhrTimeoutInSec(timeoutInSec: number) - Sets the timeout time for http requests. Set it to 0 for no timeout at all. It defaults to 30s.

Development

Source code uses Flow for type checking meaning that a compilation step is needed to remove all type annotations. When using this library with NodeJS you can use the runtime compilation that is supported by babel. It will be slightly slower but no compilation step is required.

NodeJS (With Runtime Compilation)

require('babel-core/register');

var NodeFileReader = require('./src/NodeFileReader');
var ID3v2TagReader = require('./src/ID3v2TagReader');
...

NodeJS (With Compiled Code (faster))

Run npm run build to generate proper JavaScript code into the build2 directory.

var NodeFileReader = require('./build2/NodeFileReader');
var ID3v2TagReader = require('./build2/ID3v2TagReader');
...

Run npm run watch to automatically recompile the source code whenever a file is changed.

Browser

Run npm run dist to generate a UMD version of this library that is ready to be used in a browser.

Two packages are created for the browser: dist/jsmediatags.min.js and dist/jsmediatags.js. One is a minimized version that is meant to be used in production and the other a regular version meant to be used for debugging.

Run npm run dist-watch to recompile and browserify the source code whenever a file is changed. This will only regenerate the dist/jsmediatags.js file.

New File Readers

Extend the MediaFileReader class to implement a new file reader. Methods to implement are:

• init
• loadRange
• getBytesLoaded
• getByteAt

Current Implementations:

• NodeFileReader (NodeJS)
• XhrFileReader (Browser and NodeJS)
• BlobFileReader (Blob and File)

New Tag Readers

Extend the MediaTagReader class to implement a new tag reader. Methods to implement are:

• getTagIdentifierByteRange
• canReadTagFormat
• _loadData
• _parseData

Current Implementations:

• ID3v1TagReader
• ID3v2TagReader
• MP4TagReader

Unit Testing

Jest is the framework used. Run npm test to execute all the tests.

JavaScript-ID3-Reader

If you want to migrate your project from JavaScript-ID3-Reader to jsmediatags use the following guiding examples:

All tags

JavaScript-ID3-Reader:

ID3.loadTags("filename.mp3", function() {
  var tags = ID3.getAllTags("filename.mp3");
  alert(tags.artist + " - " + tags.title + ", " + tags.album);
});

jsmediatags:

jsmediatags.read("filename.mp3", {
  onSuccess: function(tag) {
    var tags = tag.tags;
    alert(tags.artist + " - " + tags.title + ", " + tags.album);
  }
});

Specific tags

JavaScript-ID3-Reader:

ID3.loadTags("filename.mp3", function() {
  var tags = ID3.getAllTags("filename.mp3");
  alert(tags.COMM.data + " - " + tags.TCON.data + ", " + tags.WXXX.data);
},
{tags: ["COMM", "TCON", "WXXX"]});

jsmediatags:

new jsmediatags.Reader("filename.mp3")
  .setTagsToRead(["COMM", "TCON", "WXXX"])
  .read({
    onSuccess: function(tag) {
      var tags = tag.tags;
      alert(tags.COMM.data + " - " + tags.TCON.data + ", " + tags.WXXX.data);
    }
  });

Error handling

JavaScript-ID3-Reader:

ID3.loadTags("http://localhost/filename.mp3", function() {
  var tags = ID3.getAllTags("http://localhost/filename.mp3");
  alert(tags.comment + " - " + tags.track + ", " + tags.lyrics);
},
{
  tags: ["comment", "track", "lyrics"],
  onError: function(reason) {
    if (reason.error === "xhr") {
      console.log("There was a network error: ", reason.xhr);
    }
  }
});

jsmediatags:

new jsmediatags.Reader("filename.mp3")
  .setTagsToRead(["comment", "track", "lyrics"])
  .read({
    onSuccess: function(tag) {
      var tags = tag.tags;
      alert(tags.comment + " - " + tags.track + ", " + tags.lyrics);
    },
    onError: function(error) {
      if (error.type === "xhr") {
        console.log("There was a network error: ", error.xhr);
      }
    }
  });

Goals

• Improve the API of JavaScript-ID3-Reader
• Improve the source code with readable code and Flow annotated types
• Have unit tests
• Support NodeJS