eme-01b-polyfill

Unprefixed EME (navigator.requestMediaKeySystemAccess(), MediaKeys, MediaKeySession) on top of the webkit-prefixed EME v0.1b API, for browsers that only have the latter: Chrome 38-41 and the Smart TV engines based on them.

Players such as hls.js only use unprefixed EME. With this polyfill installed, they can play DRM-protected streams on those devices. Shaka Player ships its own set of polyfills; this one is inspired by Shaka's EME v0.1b polyfill, and works without Shaka.

Install

npm install eme-01b-polyfill

The package is an ES2015 module. Chrome 38-41 need ES5, so compile it along with the rest of your app. Setups that skip node_modules when compiling, such as the common babel-loader exclude: /node_modules/, must include this package, or it fails to parse on those devices.

Usage with hls.js

hls.js reads navigator.requestMediaKeySystemAccess once, when it loads. Install the polyfill in a module that is imported before hls.js:

// polyfills.ts
import { install } from 'eme-01b-polyfill';

install();

// main.ts
import './polyfills';
import Hls from 'hls.js';

const video = document.querySelector('video') as HTMLVideoElement;
const hls = new Hls({
  emeEnabled: true,
  drmSystems: {
    'com.widevine.alpha': { licenseUrl: 'https://license.example.com/widevine' },
  },
});
hls.attachMedia(video);
hls.loadSource('https://cdn.example.com/stream.m3u8');

Or pass the polyfilled function to hls.js, which works regardless of load order:

import Hls from 'hls.js';
import { install, requestMediaKeySystemAccess } from 'eme-01b-polyfill';

install();

const hls = new Hls({
  emeEnabled: true,
  requestMediaKeySystemAccessFunc: requestMediaKeySystemAccess,
  drmSystems: {
    'org.w3.clearkey': { licenseUrl: 'https://license.example.com/clearkey' },
  },
});

install() returns true once installed. On platforms with native unprefixed EME, or without EME v0.1b, it does nothing and returns false.

Required polyfills

The polyfill uses these APIs, which Chrome 38-41 lack. Load them first, for example from core-js:

import 'core-js/modules/es.promise.with-resolvers'; // Chrome 119
import 'core-js/modules/es.typed-array.slice'; // Chrome 45
import 'core-js/modules/es.uint8-array.from-base64'; // Chrome 140
import 'core-js/modules/es.uint8-array.from-hex'; // Chrome 140
import 'core-js/modules/es.uint8-array.to-base64'; // Chrome 140
import 'core-js/modules/es.uint8-array.to-hex'; // Chrome 140
import 'core-js/modules/web.dom-exception.constructor'; // Chrome 46

Limitations

• EME v0.1b reports no key statuses. The polyfill reports one status for all keys of a session, under the key IDs it finds in the init data (Widevine and PlayReady PSSH boxes, keyids). When it finds none, every key ID matches, and hls.js only picks up the status after its 1 second key status timeout.
• Only temporary sessions: configurations that require persistent state or other session types are rejected.
• setServerCertificate() resolves with false, as v0.1b has no server certificates.
• v0.1b keys live in the media pipeline, so they may not survive hls.js' detachMedia().
• event.target of session events is an internal object, not the session.

Development

npm run build      # ES2015 module and type declarations
npm test
npm run typecheck
npm run check      # Biome lint and format check; `npm run format` fixes

License

Apache-2.0