Google Chrome 66 - Enters The Autoplay Interference Engine

Radiant Media Player Blog

Last updated on April 13, 2018 - Back to blog home page

Google Chrome 66 new HTML5 video autoplay policies

With Google Chrome 66 public release at our doors, we thought it would be good to remind our readers how this update will change the HTML5 video autoplay game in the web industry. If you have been following us you already know that autoplay with sound is getting the axe progressively and we have been advising our customers to move to a unified muted autoplay approach to avoid quirks with those new autoplay policies being rolled-out by major browser/WebView vendors. Muted autoplay in Radiant Media Player can be achieved by using autoplay and muted settings set to true.

So, what is the fuzz with Chrome 66 update? This is explained in full on Google site here.

TL;DR with Chrome 66 all those new autoplay policies become available to the public, to sum up:

  • Muted autoplay is always allowed.
  • Autoplay with sound is allowed if:
    • User has interacted with the domain (click, tap, etc.).
    • On desktop, the user's Media Engagement Index threshold has been crossed, meaning the user has previously play video with sound.
    • On mobile, the user has added the site to his or her home screen.
  • Top frames can delegate autoplay permission to their iframes to allow autoplay with sound.

Note about un-muting: this new policy in Chrome 66 also affects un-muting of video content or video ads. Specifically a mouseenter or mouseover event is not enough anymore to un-mute content if the user has not interacted with document prior to un-muting (this would cause the player to pause and throw a warning in the browser console). A full click or touchend event is now required.

What is an autoplay interference engine?

An autoplay interference engine is a software layer added to a browser (or OS) to impose specific autoplay policies to an audience accessing media content. Most of the time it is here to block autoplay, this means the HTML5 video player is forced in a paused state when it attempts to autoplay, if the autoplay interference engine considers that allowing autoplay could negatively impact user experience when accessing a web page. As of April 2018, all major web browser vendors (Google, Apple, Mozilla) have implemented an autoplay interference engine in their browser. Additionally, browser plugins or ad-blockers can also interfere with HTML5 video autoplay.

The state of HTML5 video autoplay as of April 2018

With all those new autoplay policies coming in play, it is a bit difficult to understand where we at, so we will try to make a quick summary.

Mobile browsers (iOS, Android): historically autoplay has always been blocked by Apple and Google. With Safari for iOS 10 and Chrome 53 for Android, Apple and Google allowed muted autoplay for HTML5 video. Autoplay with sound is still not possible on mobile devices and we do not expect this to change in the short-term future. Other mobile browsers (like Firefox, Opera) may have different autoplay behaviours but will generally follow Apple and Google guidelines.

Mobile WebViews (iOS, Android): autoplay with sound is allowed in WebView generated by native code or through hybrid frameworks like Ionic, Flutter, Apache Cordova, assuming the WebView is properly configured to allow autoplay with sound. Otherwise it generally follows mobile browsers behaviour.

Desktop browsers:

  • macOS Safari 11+: HTML5 video autoplay capabilities are now managed in Safari preferences. By default only muted autoplay is allowed, but a user can tweak Safari preferences to allow autoplay with sound on specific sites or completely disable autoplay (even muted).
  • Chrome 66+: the new autoplay policies are outlined above. Essentially muted autoplay is always allowed, autoplay with sound will either require a user interaction with the domain or your site to be allowlisted in Chrome Media Engagement Index. Chrome 65 and below allow autoplay with sound.
  • Firefox: Firefox has its own autoplay interference engine, which can be enabled through about:config (entered in the address bar) and searching for media.autoplay.enabled setting, however, this remains a power user option which is currently disabled by default for the public.

Outstream video ads: in order to comply with the Initial Better Ads Standards from the Coalition for Better Ads, autoplay of outstream video ads should always be muted either on mobile or desktop devices.

iframe autoplay: as explained in our previous blog post, since Chrome 65, allowing iframes to autoplay video content requires explicit permission from the parent window.

How an autoplay interference engine can impact viewers and ad-based revenue?

Most of the time it is not a good thing when an autoplay interference engine abruptly paused an autoplayed HTML5 video player. It can create poor user experience but also negatively impact video-ads-based revenue, as the ad-loading process is likely to start before autoplay is blocked (and thus the returned ad is likely to be discarded). Badly coded browser plugins/extensions that are supposed to prevent autoplay can also mess with HTML5 video advanced use-cases and prevent playback all together. This is why an autoplay interference engine strategy is paramount if you intend to use HTML5 video autoplay, even muted on your web pages.

How can Radiant Media Player help you with a valid autoplay interference engine strategy?

With our 4.7.4 release, we have tested Radiant Media Player against the most common autoplay interference engines of the market: macOS Safari 11+, Chrome 66+, Firefox, iOS 10+ Safari and Chrome 53+ for Android. Through the implementation of Promise-based autoplay we are able to catch scenario where autoplay is blocked and provide a fallback play button to allow viewers to start playback when they feel like it. We also have various autoplay-related settings and API to allow our customers to fine tune a positive autoplay strategy.

In short: if you need autoplay for your project with Radiant Media Player, you need not worry about this new autoplay complexity, we take care of this for you.


Those new autoplay policies in the industry should beg the following questions for your project:

  • Do I need autoplay for my content and what is going to be the impact on my audience?
  • If I need autoplay, am I following best practices for my use-case (e.g. outstream video ads)?
  • If I need autoplay, is muted autoplay not a better option for my project?
  • If I need autoplay, do I have a player that can deal with the autoplay interference engines complexity for me while I focus on my core business?
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