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Monitor dash.js

This guide walks through integration with dash.js to collect video performance metrics with Mux data.


The following data can be collected by the Mux Data SDK when you use the Dash.js SDK, as described below.

Supported Features:

  • Engagement metrics
  • Quality of Experience Metrics
  • Web metrics such as Player Startup Time, Page Load Time, etc
  • Can infer CDN identification from response headers
  • Custom Dimensions
  • Average Bitrate metrics and renditionchange events
  • Request metrics
  • Customizable Error Tracking
  • Custom Beacon Domain

1Install mux-embed

Include the Mux JavaScript SDK on every page of your web app that includes video. You can use the Mux-hosted version of the script or install via npm. mux-embed follows semantic versioning and the API will not change between major releases.

npm install --save mux-embed

2Initialize Mux Data

Get your ENV_KEY from the Mux environments dashboard.

Env Key is different than your API token

ENV_KEY is a client-side key used for Mux Data monitoring. These are not to be confused with API tokens which are created in the admin settings dashboard and meant to access the Mux API from a trusted server.

import dashjs from "dashjs";
import mux from "mux-embed";
const dashjsPlayer = dashjs.MediaPlayer().create();
const videoEl = document.querySelector('#my-player');
dashjsPlayer.initialize(videoEl, '', true);
mux.monitor(videoEl, {
debug: false,
dashjs: dashjsPlayer,
data: {
env_key: 'ENV_KEY', // required
// Metadata fields
player_name: 'Main Player', // any arbitrary string you want to use to identify this player
player_init_time: window.muxPlayerInitTime // ex: 1451606400000
// ...

Call mux.monitor and pass in a valid CSS selector or the video element itself. Followed by the SDK options and metadata. If you use a CSS selector that matches multiple elements, the first matching element in the document will be used.

In the SDK options, be sure to pass in the dashjs player instance.

Alternatively, if your player does not immediately have access to the dash.js player instance, you can start monitoring dash.js at any time in the future. In order to do this, you can call either of the following:

mux.addDashJS("#my-player", options)
// or

Log in to the Mux dashboard and find the environment that corresponds to your env_key and look for video views. It takes about a minute or two from tracking a view for it to show up on the Metrics tab.

If you aren't seeing data, check to see if you have an ad blocker, tracking blocker or some kind of network firewall that prevents your player from sending requests to Mux Data servers.

3Make your data actionable

The only required field in the options that you pass into mux-embed is env_key. But without some metadata the metrics in your dashboard will lack the necessary information to take meaningful actions. Metadata allows you to search and filter on important fields in order to diagnose issues and optimize the playback experience for your end users.

Pass in metadata under the data key when calling mux.monitor.

mux.monitor('#my-player', {
debug: false,
dashjs: dashjsPlayer,
data: {
env_key: 'ENV_KEY', // required
// Site Metadata
viewer_user_id: '', // ex: '12345'
experiment_name: '', // ex: 'player_test_A'
sub_property_id: '', // ex: 'cus-1'
// Player Metadata
player_name: '', // ex: 'My Main Player'
player_version: '', // ex: '1.0.0'
player_init_time: '', // ex: 1451606400000
// Video Metadata
video_id: '', // ex: 'abcd123'
video_title: '', // ex: 'My Great Video'
video_series: '', // ex: 'Weekly Great Videos'
video_duration: '', // in milliseconds, ex: 120000
video_stream_type: '', // 'live' or 'on-demand'
video_cdn: '' // ex: 'Fastly', 'Akamai'

For more information, view Make your data actionable.

4Changing the video

There are two cases where the underlying tracking of the video view need to be reset:

  1. New source: When you load a new source URL into an existing player.
  2. New program: When the program within a singular stream changes (such as a program change within a continuous live stream).

Note: You do not need to change the video info when changing to a different source of the same video content (e.g. different resolution or video format).

New source

If your application plays multiple videos back-to-back in the same video player, you need to signal when a new video starts to the Mux SDK. Examples of when this is needed are:

  • The player advances to the next video in a playlist
  • The user selects a different video to play

See metadata in Make your data actionable for the full list of video details you can provide. You can include any metadata when changing the video but you should only need to update the values that start with video_.

It's best to change the video info immediately after telling the player which new source to play.

mux.emit('#my-player', 'videochange', {
video_id: 'abc345',
video_title: 'My Other Great Video',
video_series: 'Weekly Great Videos',
// ...

New Program

In some cases, you may have the program change within a stream, and you may want to track each program as a view on its own. An example of this is a live stream that streams multiple programs back to back, with no interruptions.

In this case, you emit a programchange event, including the updated metadata for the new program within the continuous stream. This will remove all previous video data and reset all metrics for the video view, creating a new video view. See Metadata for the list of video details you can provide. You can include any metadata when changing the video but you should only need to update the values that start with video.

Note: The programchange event is intended to be used only while the player is currently not paused. If you emit this event while the player is paused, the resulting view will not track video startup time correctly, and may also have incorrect watch time. Do not emit this event while the player is paused.

mux.emit('#my-player', 'programchange', {
video_id: 'abc345',
video_title: 'My Other Great Video',
video_series: 'Weekly Great Videos',
// ...

5Advanced options

Disable cookies

By default, mux-embed uses a cookie to track playback across subsequent page views. This cookie includes information about the tracking of the viewer, such as an anonymized viewer ID that Mux generates for each user. None of this information is personally-identifiable, but you can disable the use of this cookie if desired. For instance, if your site or application is targeted towards children under 13, you should disable the use of cookies.

This is done by setting disableCookies: true in the options.

mux.monitor('#my-player', {
debug: false,
disableCookies: true,
dashjs: dashjsPlayer,
data: {
env_key: 'ENV_KEY',
// ... rest of metadata

Over-ride 'do not track' behavior

By default, mux-embed does not respect Do Not Track when set within browsers. This can be enabled in the options passed to Mux, via a setting named respectDoNotTrack. The default for this is false. If you would like to change this behavior, pass respectDoNotTrack: true.

mux.monitor('#my-player', {
debug: false,
dashjs: dashjsPlayer,
respectDoNotTrack: true, // Disable tracking of browsers where Do Not Track is enabled
data: {
env_key: 'EXAMPLE_ENV_KEY',
// ... rest of metadata

Customize error tracking behavior

Errors are fatal

Errors tracked by mux are considered fatal meaning that they are the result of playback failures. If errors are non-fatal they should not be captured.

By default, mux-embed will track errors emitted from the video element as fatal errors. If a fatal error happens outside of the context of the player, you can emit a custom error to the mux monitor.

mux.emit('#my-player', 'error', {
player_error_code: 100,
player_error_message: 'Description of error',
player_error_context: 'Additional context for the error'

When triggering an error event, it is important to provide values for player_error_code and player_error_message. The player_error_message should provide a generalized description of the error as it happened. The player_error_code must be an integer, and should provide a category of the error. If the errors match up with the HTML Media Element Error, you can use the same codes as the corresponding HTML errors. However, for custom errors, you should choose a number greater than or equal to 100.

In general you should not send a distinct code for each possible error message, but rather group similar errors under the same code. For instance, if your library has two different conditions for network errors, both should have the same player_error_code but different messages.

The error message and code are combined together and aggregated with all errors that occur in your environment in order to find the most common errors that occur. To make error aggregation as useful as possible, these values should be general enough to provide useful information but not specific to each individual error (such as stack trace).

You can use player_error_context to provide instance-specific information derived from the error such as stack trace or segment-ids where an error occurred. This value is not aggregated with other errors and can be used to provide detailed information. Note: Please do not include any personally identifiable information from the viewer in this data.

Error translator

If your player emits error events that are not fatal to playback or the errors are unclear and/or do not have helpful information in the default error message and codes you might find it helpful to use an error translator or disable automatic error tracking all together.

function errorTranslator (error) {
return {
player_error_code: translateCode(error.player_error_code),
player_error_message: translateMessage(error.player_error_message),
player_error_context: translateContext(error.player_error_context)
mux.monitor('#my-player', {
debug: false,
errorTranslator: errorTranslator,
dashjs: dashjsPlayer,
data: {
env_key: 'ENV_KEY', // required
// ... additional metadata

If you return false from your errorTranslator function then the error will not be tracked. Do this for non-fatal errors that you want to ignore. If your errorTranslator function itself raises an error, then it will be silenced and the player's original error will be used.

Disable automatic error tracking

In the case that you want full control over what errors are counted as fatal or not, you may want to consider turning off Mux's automatic error tracking completely. This can be done by passing automaticErrorTracking: false in the configuration object.

mux.monitor('#my-player', {
debug: false,
automaticErrorTracking: false,
dashjs: dashjsPlayer,
data: {
env_key: 'EXAMPLE_ENV_KEY', // required
// ... additional metadata

Use TypeScript with mux-embed Beta

mux-embed now provides TypeScript type definitions with the published package! If you want to opt in, you can check out how here.

Release Notes

Current release


  • Bug fix to not de-dupe error event metadata
  • Extend errorTranslator to work with player_error_severity and player_error_business_exception

Previous releases


  • Target ES5 for bundles and validate bundles are ES5

  • fix an issue where seeking time before first play attempt counted towards video startup time


  • Add opt-in TypeScript Types to Mux Embed and use + refactor for other dependent data SDKs. Update published dists to include CJS and ESM.
  • Mux Embed now provides (opt in) TypeScript types in its published package, as well as publishes CJS and ESM versions of the package.
  • This allows us to provide a lower risk and iterative roll out of official TypeScript types for mux-embed. The export types updates were required to ensure actual matches between the dist package and corresponding TypeScript types.
  • This should have no direct impact on users, though different build tools will now potentially select one of the new export types (e.g. the ESM "flavor" of mux-embed). TypeScript types should not be applied unless they are explicitly referenced in app (discussed in docs updates).


  • fix an issue causing certain network metrics to not be available for dashjs v4.x

  • fix an issue where certain IDs used may cause a DOM exception to be raised


  • fix(mux-embed): avoid using element id for muxId. attach muxId to element.


  • fix an issue where beaconDomain deprecation line was incorrectly logged


  • Deprecate beaconDomain in favor of beaconCollectionDomain. The beaconDomain setting will continue to function, but integrations should change to beaconCollectionDomain instead.


  • Fix an issue where playback time was incorrectly counted during seeking and other startup activities
  • Add events for the collection of ad clicks
  • fix an issue where seek latency could be unexpectedly large
  • fix an issue where seek latency does not include time at end of a view
  • Add events for the collection of ad skips


  • muxData cookie expiration should be one year


  • Do not deduplicate ad IDs in ad events


  • Include ad watch time in playback time


  • Fix an issue where beacons over a certain size could get hung and not be sent


  • Collect Request Id from the response headers, when available, for HLS.js (requestcompleted and requestfailed) and Dash.js (requestcompleted). The following headers are collected: x-request-Id, cf-ray (Cloudflare), x-amz-cf-id (CloudFront), x-akamai-request-id (Akamai)

  • Fix an issue where tracking rebuffering can get into an infinite loop

  • Update Headers type


  • Send errors, requestfailed, and requestcancelled events on Dash.js. Because of this change, you may see the number of playback failures increase as we now automatically track additional fatal errors.


  • Include Ad metadata in ad events


  • Support for new dimension, view_has_ad


  • End views after 5 minutes of rebuffering


  • Add audio, subtitle, and encryption key request failures for HLS.js
  • Capture ad metadata for Video.js IMA
  • Capture detailed information from HLS.js for fatal errors in the Error Context


  • Extend errorTranslator to work with player_error_context


  • Add new renditionchange fields to Shaka SDK
  • Adds support for new and updated fields: renditionchange, error, DRM type, dropped frames, and new custom fields
  • Add frame drops to Shaka SDK
  • Add new renditionchange info to Web SDKs
  • Adds the new Media Collection Enhancement fields


  • update to use navigationStart for timing reference

  • fix issue where views after videochange might incorrectly accumulate rebuffering duration

  • Resolved issue sending beacons when view is ended

  • Record request_url and request_id with network events


  • Tracking FPS changes if specified in Manifest


  • Resolved issue sending beacons when paused


  • Fixed issue with monitoring network events for hls.js monitor


  • Fix an issue with sending unnecessary heartbeat events on the window visibilitychange event


  • Fixes an issue with accessing the global object


  • Collect the x-request-id header from segment responses to make it easier to correlate client requests to other logs

  • Upgraded internal webpack version

  • Flush events on window visibilitychange event


  • Use Fetch API for sending beacons


  • Generate a new unique view if the player monitor has not received any events for over an hour.


  • Detect fullscreen and player language


  • Replace query string dependency to reduce package size
  • Remove ImageBeacon fallback, removing support for IE9


  • Generate all view_id's internally


  • Use common function for generating short IDs


  • Fixed an issue around the disablePlayheadRebufferTracking option


  • Fix issue where getStartDate does not always return a date object


  • Support PDT and player_live_edge_program_time for Native Safari

  • Set a max payload size in mux-embed


  • Add option disablePlayheadRebufferTracking to allow players to disable automatic rebuffering metrics. Players can emit their own rebufferstart or rebufferend events and track rebuffering metrics.

  • Fix an issue with removing player_error_code and player_error_message when the error code is 1. Also stops emitting MEDIA_ERR_ABORTED as errors.

  • Now leaving Player Software Version for HTML5 Video Element unset rather than "No Versions" as it is no longer needed.


  • Add an option to specify beaconCollectionDomain for Data custom domains


  • Fix an issue with emitting heartbeat events while the player is not playing


  • Fix an issue with removing event listeners from window after the player monitor destroy event


  • Update hls.js monitor to record session data with fields prefixed as
  • Update the manifest parser to parse HLS session data tags


  • Add short codes to support internal video experiments
  • Collect request header prefixed with x-litix-*
  • Capture fatal hls.js errors
  • Make envKey an optional parameter


  • Add a player events enum on the mux object (e.g.
  • Use the browser visibilitychange listener instead of unload to handle destructuring the player monitor.


  • Fix: Specify video_source_is_live for HLS.js monitor


  • Group events into 10 second batches before sending a beacon


  • Exclude latency metrics from beacons if video_source_is_live is not true


  • Add a lightweight HLS manifest parser to capture latency metrics for player's that don't expose an API for accessing the manifest.
  • Allow players to emit player_program_time instead of calculating internally


  • Add support for calculating latency metrics when streaming using HLS


  • Remove default video_id when not specified by the developer.


  • Add minified keys for latency metrics


  • Add minified keys for new program time metrics


  • Fix bug causing missing bitrate metrics using HLS.js >v1.0.0


  • (video element monitor) Fix an issue where some non-fatal errors thrown by the video were tracked as playback failures


  • Fix an issue where views triggered by programchange may not report metrics correctly
  • Fix an issue where calling el.mux.destroy() multiple times in a row raised an exception


  • Fix an issue where player_remote_played wasn't functioning correctly


  • Add support for custom dimensions


  • Support HLS.js v1.0.0


  • Enable sending optional ad quartile events through.
  • Move device detection server-side, improving data accuracy and reducing client SDK size.
  • Fix an issue where jank may be experienced in some web applications when the SDK is loaded.


  • Setting to disable rebuffer tracking disableRebufferTracking that defaults to false.


  • Adds viewer_connection_type detection.


  • Adds support for renditionchange.


  • Add checks for window being undefined and expose a way for SDKs to pass in platform information. This work is necessary for compatibility with react-native-video.


  • Setting to disable Mux Data collection when Do Not Track is present now defaults to off
  • Do not submit the source URL when a video is served using the data: protocol


  • Use Performance Timing API, when available, for view event timestamps


  • Fix an issue with server side rendering


  • Support for Dash.js v3


  • Submit Player Instance Id as a unique identifier


  • Fixed a bug when using mux.monitor with Hls.js or Dash.js the source hostname was not being properly collected.

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