In recent years, web browsers have been defining stricter policies regarding video auto-play.
Historically, auto-play was allowed on Desktop browsers and not allowed on mobile ones (mostly to avoid unwanted data consumption on a mobile network connection) but this is not as simple as that anymore.
Stricter auto-play policies allow for improved user experience, reduce incentives to install ad blockers, and reduce data consumption on expensive and/or constrained networks.
The player doesn't have complete control on auto-play, the browser decides if the video or audio file shall be auto-played or not. Please note, in most environments, after a video/audio is played, the next one can automatically start without any need of further user interaction.
Chrome
Chrome updated their Auto-play Policies in April 2018. Usually, If the video/audio is muted, then auto-play will be allowed.
The media is also allowed to auto-play with sound, depending on the users' Media Engagement Index(MEI), previous interaction with the domain or the user has added the website to their home screen on their mobile.
The MEI is a measurement of the individual's media consumption per origin. Therefore, your MEI score will be highest on sites where you regularly play media. You can check your media engagement index score here: chrome://media-engagement/.
More about Chrome's Policies here.
Safari
Starting from Safari 11, users are able to switch between different Auto-play configurations. The user has control over which sites are allowed to auto-play by default, by configuring the "Websites" preference window. Preferences> Websites> Auto-Play.
Safari blocks nearly all auto-playing media with sound by default. Except for the larger sites like YouTube & Facebook. In order to allow auto-playing on other sites, it's possible to simply change the auto-play configuration, head to that site and click 'Settings for This Website', in the Safari tab from the menu bar.
In the pop-up window, you can toggle between different auto-play parameters [Allow all Auto-Play], [Stop Media with Sound] or [Never Auto-play].
More about Safari's Policies here.
Firefox
Firefox prevents all video/audio with sound from auto-play by default. If you want to change these settings, Firefox offers a number of easy methods to quickly reconfigure the auto-play parameters.
- Disable it, in the advanced settings of the web browser. Preferences > Privacy & Security.
- Toggle the site permissions, by clicking the info button, in the address bar.
- Navigate to the advanced settings using about:config in the search bar, change the option to media.autoplay.enabled to [true] or [false].
More about Firefox's policies here.