Developer switches As a developer, you may want to change Chrome autoplay policy behavior locally to test your website depending on user engagement.
You can decide to disable entirely the autoplay policy by setting the Chrome flag "Autoplay Policy" to "No user gesture is required" at chrome://flags/#autoplay-policy. This allows you to test your website as if user were strongly engaged with your site and playback autoplay would be always allowed.
You can also decide to make sure playback autoplay is never allowed by disabling use of MEI, applying autoplay policy to Web Audio, and whether sites with the highest overall MEI get playback autoplay by default for new users. This can be done with three internal switches with chrome.exe --disable-features=PreloadMediaEngagementData,AutoplayIgnoreWebAudio, MediaEngagementBypassAutoplayPolicies.
Iframe delegation A feature policy allows developers to selectively enable and disable use of various browser features and APIs. Once an origin has received autoplay permission, it can delegate that permission to cross-origin iframes with a new feature policy for autoplay. Note that autoplay is allowed by default on same-origin iframes.
<!-- Autoplay is allowed. --> <iframe src="https://cross-origin.com/myvideo.html" allow="autoplay">
<!-- Autoplay and Fullscreen are allowed. --> <iframe src="https://cross-origin.com/myvideo.html" allow="autoplay; fullscreen">
When the feature policy for autoplay is disabled, calls to play() without a user gesture will reject the promise with a NotAllowedError DOMException. And the autoplay attribute will also be ignored.
Warning: Older articles incorrectly recommend using the attribute gesture=media which is not supported. Example scenarios Example 1: Every time a user visits VideoSubscriptionSite.com on their laptop they watch a TV show or a movie. As their media engagement score is high, autoplay is allowed.
Example 2: GlobalNewsSite.com has both text and video content. Most users go to the site for text content and watch videos only occasionally. Users' media engagement score is low, so autoplay wouldn't be allowed if a user navigates directly from a social media page or search.
Example 3: LocalNewsSite.com has both text and video content. Most people enter the site through the homepage and then click on the news articles. Autoplay on the news article pages would be allowed because of user interaction with the domain. However, care should be taken to make sure users aren't surprised by autoplaying content.
Example 4: MyMovieReviewBlog.com embeds an iframe with a movie trailer to go along with their review. The user interacted with the domain to get to the specific blog, so autoplay is allowed. However, the blog needs to explicitly delegate that privilege to the iframe in order for the content to autoplay.