The “old player” setting enables the native iOS media player (called AVPlayer) which is made by Apple themselves and is therefore super optimized. It’s used by Netflix, Disney+, Paramount, HBO, etc…
It’s much more performant & power efficient, works perfectly with HomePods/AirPods and supports Dolby Atmos & Vision, and opens the door for newer features like “enhance dialogue” on Homepods.
Dev Tip: The only way to properly support Atmos on Apple devices is to feed eac3 to AVPlayer (via m3u8 with correct manifest or mp4 with correct dec3 atom). Check links for details.
Dolby Vision also works with AVPlayer as long as FourCC is set to hvc1.
Biggest problem is, as with anything Apple, it doesn’t support mkv containers. But it DOES support most common streams contained in those mkv files anyway (h264/265, vp9, av1, aac/ac3/eac3).
Currently, when you force AVPlayer, the Plex SERVER demuxes the file and sends the raw streams from inside the mkv and feeds them to AVPlayer - and that works 10x better on my Apple TV with Homepods.
MY SUGGESTION:
Local, on-device on-the-fly demuxing and feeding the streams via an m3u8 to AVPlayer. This also opens the door to modding the FourCC and dec3 ATOM and providing proper support for files not encoded to Apple’s standards.
Fallback to mpv ONLY when unsupported codecs are encountered.
RATIONALE:
1- This frees up server resources in certain use cases (like large shared servers).
2- AVPlayer integrates best with the rest of the Apple ecosystem. Future proof.
3- Proper Dolby Vision & Atmos support - done the right way.
4- More power efficient. No 3rd party player will ever be as efficient as Apple’s native player which will help on mobile devices.
5- Will avoid certain problems for certain people (mpv causes annying microstutters in my case)
6- It’s the native platform player!
So why not use it if we can.