Originally Posted by Andrew Stirling
No. Just that there’s some kind of workaround for iTunes material which involves disabling QuickStart. This seems to result in a 23.976hz source being used though rather than an ability to play 24hz.
So, I'm jumping into the 24fps fray a little bit late, but some notes:
All Apple film-sourced content is encoded at 23.976fps (you can see this is you download one of your iTunes movies and play it back in QuickTime Player). The iTunes-downloadable version happens to be the same version you'll buffer if you turn off
QuickStart in Apple TV's settings…but you shouldn't do that. That setting remains for users who have sub-5Mbps network connections and need to force buffering to get consistent HD quality. If your connection is faster than 5Mbps and you want 4K, HDR, and Atmos, leave QuickStart on and never touch it again.
Once QuickStart is on, Apple uses HLS to stream the content. This stream is still encoded at 23.976fps
, and can adjust between multiple quality tiers as bandwidth allows. If you're seeing frame skips when QuickStart is on, it's more likely a streaming glitch than a 23.976 vs. 24p frame mismatch. Even with high bandwidth connections, momentary glitches show up as throughput fluctuates, and 4K/HDR movie can stress residential networking by demanding a stable 35Mbps. If turning QuickStart off "fixes the problem", it's likely because the Apple TV is buffering a fixed-bandwidth version, thus avoiding these momentary network hiccups. (If you're seeing this on locally-encoded source material like ripped Blu-rays etc., it's hard for me to diagnose without knowing which codecs, bitrates, and optimizations are at play.)
I realize that 24fps and 23.976 Hz are distinct, and that it's possible that some media out there (maybe even some Netflix stuff) is encoded at exactly
24fps. But Apple TV doesn't make a distinction between 23.976 and 24fps, because the overwhelming
majority of professionally encoded films are encoded at 23.976 (even on Blu-ray). So, Apple always syncs with your TV at 23.976Hz, even if the UI uses the colloquial "24" integer for simplicity.
All of that said, if you have a modern, highish-end TV
, chances are you don't need to switch the Apple TV to 24fps (23.976Hz) mode at all…you can just let Apple TV send its default 60p (59.94 if you want to get technical)…it'll map the 24fps into the 60p output (3:2), which the TV will notice and decode accordingly, ultimately rendering a literal 24fps. That would effectively reconcile any 23.976/24Hz variation (however rare) that you run into.