At last, Safari 17.1 brings the new Managed Media Source API to iPhone

Last updated on October 27, 2023 - Back to blog home page

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WebKit Features in Safari 17.1

Hi guys, so you have probably read the news by now: Safari 17.1 now brings the new Managed Media Source API to iPhone.

The streaming media industry has been waiting this for years, so this is definitely a step in the right direction. But let me try to break down the news for you to put it back in context:

• First I would recommend watching this Apple video - https://developer.apple.com/videos/play/wwdc2023/10122/ - starting at 8:00. This will tell you most of what you need to know about the announcement.
• The second things that catch my attention: Apple has banned MSE in iOS for years because they feel it was too taxing for the battery. According to Apple, native HLS provides better performance and energy efficiency when using iOS Safari (rather than MSE HLS) - they have not been banning MSE on iPhone for years to bug video developers - but because they did not want customers watching video on iPhone to complain about poor battery life.
• Apple adds support for Managed Media Source (MSS), an evolution of Media Source Extensions (MSE), so existing players will need to migrate from MSE to MSS for this feature to work on iOS.
• A "managed" MediaSource is one where more control over the MediaSource and its associated objects has been given over to the User Agent. For video developers it means that more of the adaptive bitrate streaming logic and device capabilities detection will be transferred to the browser (e.g. User Agent) from the video app.
• Apple presents this evolution as "Managed Media Source API draws less power than Media Source Extensions (MSE) and explore how you can use it to more efficiently manage streaming video over 5G". It is not only an energy/device issue there is also a network optimisation to MSS. This however happens under the hood of the browser, video app developers will not have access to it - this is the whole point of MSS - the browser could have access to more information about the device/network/energy and make better decision than the video app.
• Apple still recommends using native HLS over MSS HLS in Safari if you only intend to support Apple devices! This is in the video at 17:53.
• After checking in Safari for iOS 17.1 we can confirm that the feature is enabled by default. In your iPhone go to Settings > Safari > Advanced > Feature flags > Managed Media Source API should be turned on.

Will you support MSS in iPhone Safari with Radiant Media Player?

Yes, we will. As soon as we are done with the testing and have a better understanding about how actual devices react to MSS we will add support for it. Though as Apple recommends, native HLS will still be the preferred option on Apple devices. MSS can however enable MPEG-DASH streaming on iOS and some users may have a need to support MSS in iPhone (DVR UI, Quality selection menu) so we are already working on adding support for MSS. Check our release history for updates on player features.