In WWDC2016[1] Apple announced In-Playlist Timed Metadata as an alternative to ID3 Timed Metadata. As far as I understood, the main idea is to use the m3u8 tag EXT-X-DATERANGE to describe the timed metadata in plain text on the playlist file, outside the video stream.

I think it would be great to have this feature implemented in the hls.js library, because that way it will no longer be necessary to use the Apple-only mediafilesegmenter tool to inject timed ID3 into video streams.

[1] https://developer.apple.com/videos/play/wwdc2016/504/