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    HLS.js is a JavaScript library that implements an HTTP Live Streaming client. It relies on HTML5 video and MediaSource Extensions for playback.

    It works by transmuxing MPEG-2 Transport Stream and AAC/MP3 streams into ISO BMFF (MP4) fragments. Transmuxing is performed asynchronously using a Web Worker when available in the browser. HLS.js also supports HLS + fmp4, as announced during WWDC2016.

    HLS.js works directly on top of a standard HTML<video> element.

    HLS.js is written in ECMAScript6 (*.js) and TypeScript (*.ts) (strongly typed superset of ES6), and transpiled in ECMAScript5 using Babel and the TypeScript compiler.

    Webpack is used to build the distro bundle and serve the local development environment.


    • VOD & Live playlists
      • DVR support on Live playlists
    • Fragmented MP4 container
    • MPEG-2 TS container
      • ITU-T Rec. H.264 and ISO/IEC 14496-10 Elementary Stream
      • ISO/IEC 13818-7 ADTS AAC Elementary Stream
      • ISO/IEC 11172-3 / ISO/IEC 13818-3 (MPEG-1/2 Audio Layer III) Elementary Stream
      • Packetized metadata (ID3v2.3.0) Elementary Stream
    • AAC container (audio only streams)
    • MPEG Audio container (MPEG-1/2 Audio Layer III audio only streams)
    • Timed Metadata for HTTP Live Streaming (ID3 format carried in MPEG-2 TS, Emsg in CMAF/Fragmented MP4, and DATERANGE playlist tags)
    • AES-128 decryption
    • SAMPLE-AES decryption (only supported if using MPEG-2 TS container)
    • Encrypted media extensions (EME) support for DRM (digital rights management)
    • CEA-608/708 captions
    • WebVTT subtitles
    • Alternate Audio Track Rendition (Master Playlist with Alternative Audio) for VoD and Live playlists
    • Adaptive streaming
      • Manual & Auto Quality Switching
        • 3 Quality Switching modes are available (controllable through API means)
          • Instant switching (immediate quality switch at current video position)
          • Smooth switching (quality switch for next loaded fragment)
          • Bandwidth conservative switching (quality switch change for next loaded fragment, without flushing the buffer)
        • In Auto-Quality mode, emergency switch down in case bandwidth is suddenly dropping to minimize buffering.
    • Accurate Seeking on VoD & Live (not limited to fragment or keyframe boundary)
    • Ability to seek in buffer and back buffer without redownloading segments
    • Built-in Analytics
      • All internal events can be monitored (Network Events, Video Events)
      • Playback session metrics are also exposed
    • Resilience to errors
      • Retry mechanism embedded in the library
      • Recovery actions can be triggered fix fatal media or network errors
    • Redundant/Failover Playlists

    Supported M3U8 tags

    For details on the HLS format and these tags' meanings, see

    Manifest tags

    • #EXT-X-STREAM-INF:<attribute-list> <URI>
    • #EXT-X-MEDIA:<attribute-list>
    • #EXT-X-SESSION-DATA:<attribute-list>

    The following properties are added to their respective variants' attribute list but are not implemented in their selection and playback.

    • VIDEO-RANGE and HDCP-LEVEL (See #2489)

    Playlist tags

    • #EXTM3U
    • #EXT-X-VERSION=<n>
    • #EXTINF:<duration>,[<title>]
    • #EXT-X-BYTERANGE=<n>[@<o>]
    • #EXT-X-MAP:<attribute-list>
    • #EXT-X-KEY:<attribute-list> (METHOD=SAMPLE-AES is only supports with MPEG-2 TS segments)
    • #EXT-X-PROGRAM-DATE-TIME:<attribute-list>
    • #EXT-X-SERVER-CONTROL:<attribute-list>
    • #EXT-X-PART:<attribute-list>
    • #EXT-X-PRELOAD-HINT:<attribute-list>
    • #EXT-X-SKIP:<attribute-list>
    • #EXT-X-RENDITION-REPORT:<attribute-list>
    • #EXT-X-DATERANGE:<attribute-list>

    The following tags are added to their respective fragment's attribute list but are not implemented in streaming and playback.

    • #EXT-X-BITRATE (Not used in ABR controller)
    • #EXT-X-GAP (Not implemented. See #2940)

    Not Supported

    For a complete list of issues, see "Top priorities" in the Release Planning and Backlog project tab. Codec support is dependent on the runtime environment (for example, not all browsers on the same OS support HEVC).

    • FairPlay and PlayReady DRM ( See #3779 and issues labeled DRM)
    • Advanced variant selection based on runtime media capabilities (See issues labeled media-capabilities)
    • HLS Content Steering
    • HLS Interstitials
    • #EXT-X-DEFINE variable substitution
    • #EXT-X-GAP filling #2940
    • #EXT-X-I-FRAME-STREAM-INF I-frame Media Playlist files
    • SAMPLE-AES with fmp4, aac, mp3, vtt... segments (MPEG-2 TS only)

    Server-side-rendering (SSR) and require from a Node.js runtime

    You can safely require this library in Node and absolutely nothing will happen. A dummy object is exported so that requiring the library does not throw an error. HLS.js is not instantiable in Node.js. See #1841 for more details.

    Getting started with development

    First, checkout the repository and install the required dependencies

    git clone
    cd hls.js
    # After cloning or pulling from the repository, make sure all dependencies are up-to-date
    npm install ci
    # Run dev-server for demo page (recompiles on file-watch, but doesn't write to actual dist fs artifacts)
    npm run dev
    # After making changes run the sanity-check task to verify all checks before committing changes
    npm run sanity-check

    The dev server will host files on port 8000. Once started, the demo can be found running at http://localhost:8000/demo/.

    Before submitting a PR, please see our contribution guidelines. Join the discussion on Slack via in #hlsjs for updates and questions about development.

    Build tasks

    Build all flavors (suitable for prod-mode/CI):

    npm install ci
    npm run build

    Only debug-mode artifacts:

    npm run build:debug

    Build and watch (customized dev setups where you'll want to host through another server than webpacks' - for example in a sub-module/project)

    npm run build:watch

    Only specific flavor (known configs are: debug, dist, light, light-dist, demo):

    npm run build -- --env dist # replace "dist" by other configuration name, see above ^

    Note: The "demo" config is always built.

    NOTE: hls.light.*.js dist files do not include EME, subtitles, CMCD, or alternate-audio support. In addition, the following types are not available in the light build:

    • AudioStreamController
    • AudioTrackController
    • CuesInterface
    • EMEController
    • SubtitleStreamController
    • SubtitleTrackController
    • TimelineController
    • CmcdController

    Linter (ESlint)

    Run linter:

    npm run lint

    Run linter with auto-fix mode:

    npm run lint:fix

    Run linter with errors only (no warnings)

    npm run lint:quiet

    Formatting Code

    Run prettier to format code

    npm run prettier

    Type Check

    Run type-check to verify TypeScript types

    npm run type-check

    Automated tests (Mocha/Karma)

    Run all tests at once:

    npm test

    Run unit tests:

    npm run test:unit

    Run unit tests in watch mode:

    npm run test:unit:watch

    Run functional (integration) tests:

    npm run test:func


    An overview of this project's design, it's modules, events, and error handling can be found here.

    API docs and usage guide

    Note you can access the docs for a particular version using ""


    Latest Release


    Specific Version

    Find the commit on


    HLS.js is only compatible with browsers supporting MediaSource extensions (MSE) API with 'video/MP4' mime-type inputs.

    HLS.js is supported on:

    • Chrome 39+ for Android
    • Chrome 39+ for Desktop
    • Firefox 41+ for Android
    • Firefox 42+ for Desktop
    • Edge for Windows 10+
    • Safari 8+ for MacOS 10.10+
    • Safari for ipadOS 13+

    A Promise polyfill is required in browsers missing native promise support.

    Please note: iOS Safari on iPhone does not support the MediaSource API. This includes all browsers on iOS as well as apps using UIWebView and WKWebView.

    Safari browsers (iOS, iPadOS, and macOS) have built-in HLS support through the plain video "tag" source URL. See the example below (Using HLS.js) to run appropriate feature detection and choose between using HLS.js or natively built-in HLS support.

    When a platform has neither MediaSource nor native HLS support, the browser cannot play HLS.

    Keep in mind that if the intention is to support HLS on multiple platforms, beyond those compatible with HLS.js, the HLS streams need to strictly follow the specifications of RFC8216, especially if apps, smart TVs, and set-top boxes are to be supported.

    Find a support matrix of the MediaSource API here:

    Using HLS.js


    Prepackaged builds are included with each release. Or install the hls.js as a dependency of your project:

    npm install --save hls.js

    A canary channel is also available if you prefer to work off the development branch (master):

    npm install hls.js@canary

    Embedding HLS.js

    Directly include dist/hls.js or dist/hls.min.js in a script tag on the page. This setup prioritizes HLS.js MSE playback over native browser support for HLS playback in HTMLMediaElements:

    <script src=""></script>
    <!-- Or if you want the latest version from the main branch -->
    <!-- <script src=""></script> -->
    <video id="video"></video>
      var video = document.getElementById('video');
      var videoSrc = '';
      if (Hls.isSupported()) {
        var hls = new Hls();
      // HLS.js is not supported on platforms that do not have Media Source
      // Extensions (MSE) enabled.
      // When the browser has built-in HLS support (check using `canPlayType`),
      // we can provide an HLS manifest (i.e. .m3u8 URL) directly to the video
      // element through the `src` property. This is using the built-in support
      // of the plain video element, without using HLS.js.
      // Note: it would be more normal to wait on the 'canplay' event below however
      // on Safari (where you are most likely to find built-in HLS support) the
      // video.src URL must be on the user-driven white-list before a 'canplay'
      // event will be emitted; the last video event that can be reliably
      // listened-for when the URL is not on the white-list is 'loadedmetadata'.
      else if (video.canPlayType('application/')) {
        video.src = videoSrc;

    Alternative setup

    To check for native browser support first and then fallback to HLS.js, swap these conditionals. See this comment to understand some of the tradeoffs.

    <script src=""></script>
    <!-- Or if you want the latest version from the main branch -->
    <!-- <script src=""></script> -->
    <video id="video"></video>
      var video = document.getElementById('video');
      var videoSrc = '';
      // First check for native browser HLS support
      if (video.canPlayType('application/')) {
        video.src = videoSrc;
        // If no native HLS support, check if HLS.js is supported
      } else if (Hls.isSupported()) {
        var hls = new Hls();

    For more embed and API examples see docs/


    All HLS resources must be delivered with CORS headers permitting GET requests.

    Video Control

    Video is controlled through HTML <video> element HTMLVideoElement methods, events and optional UI controls (<video controls>).

    Player Integration

    The following players integrate HLS.js for HLS playback:

    They use HLS.js in production!


    Chrome/Firefox integration

    made by gramk, plays hls from address bar and m3u8 links


    HLS.js is released under Apache 2.0 License




    npm i hls.js@1.2.4-0.canary.8621





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    • robwalch
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