24p Video Playback

No, the device output framerate is fixed, and content is automatically converted during playback to match the selected device output framerate. Apps do not have the ability to affect the device output framerate.

If you have a scenario where you believe that this would be required, please file a bug at bugreporter.apple.com with details as to why this would be required for your application.

Perhaps you don't understand the issue at hand. Film or movies are shot at 24 frames per second. Historically, TV’s VSYNC ran at 60 Hz in order to match the AC frequency at the outlet (in North America), and the first content was shown at 60 interlaced fields per second. So VCRs and the first DVD players needed to fit 24 fps into 30 fps (and then interlaced to make it 60 fields per second). This requires adding some frames more than others to fit 24 nicely into 30 (a process called Telecine or 2:3 pulldown). This leads to judder, which is most prominent in scenes that pan from side to side. Eventually DVD players came out that offered 24p output (or 24 progressive fps), the native rate of the movie. This of course still requires a TV that can properly display the 24 fps without needing to apply its own Telecine. TVs that have a 120 Hz panel work (as 120 is exactly five times 24), as do 240 Hz panels. Problem is, the Apple TV, Fire TV, Chromecast, and others always output at 60 Hz. They don’t support 24 fps output, so we’re stuck watching movies with crummy Telecine applied. Again, this is a feature that has been available for 10 years on DVD players. No excuse not to have it with the modern boxes, as I’m sure the video chipsets they’re using already allow for that video frequency. Are there no movie buffs working at Apple? Because no self respecting movie purist would use an Apple TV if it can't support a movie's native frame rate. It blows my mind that a $200 box does not support this. It's akin to a music player adding spurious samples into music for it to fit into a sampling rate other than the digital music file's original sampling rate.

I get the impression Tidbit didnt understand the question (no offense TB), or isnt familar with Intel's integrated graphics/24p debacle has had on movie purists.

Hey guys - No, I fully understand your question. Have spent over a decade in broadcast and media 🙂

At this time, the device performs framerate conversion on media during playback, and thus the output framerate is fixed. But if you would like to see other options, please file a bug as suggested above.

In the interim, if you find any errors or issues in our framerate conversion, we would also like to hear about those.

Hi TidBits,

Is your answer about iTunes movie playback? Or is it about in-app video playback in apps that have a surrounding UI, such as via the youtube app?

http://www.apple.com/tv/specs/ only mentions 60fps.

Certainly the studios are uploading 24p ProRes files? Are you saying that they are pulldown'ed on the device as they are streamed? That seems kind of crazy.

I understand your call out to file a bug, but I won't file a bug on hardware that I won't buy because it doesn't do the basics 🙂

I'll restate the question for clarity -- If I buy a film in the iTunes store and play it on the new apple tv, will it play back at 24p?

-neil

Am I missing something here? 24p translates to NTSC standard of 23.976 fps. 25 fps in PAL/SECAM...

This isn't the same as the accelorated framerates used in some current big budget films which cram

40fps or more in "The Hobbit" trilogy is one such example.

Clearly, TidBits answer was directly in response to apps " Apps do not have the ability to affect the device output framerate."

That's very disappointing. European TV is 50Hz, which produces nasty judder viewed on a 60Hz display. To me this means that in Europe this device will be an "Apple TV" without the "TV".

Users can select their preferred output framerate in Settings, so you could set your device to output to your TV at 50Hz if this is your preference.

The device does not adapt it's output framerate to the content being played back, so a 24 FPS film will be framerate converted as required to match the output framerate selection of the device as chosen in Settings.

Ah, OK. Thanks. That's much better than I feared.

Is it possible to select 24Hz output to the TV too?

Do you also know what happens when you run a game at 60 FPS on a 50 Hz TV? I was unable to find information about this in the documentation. Also there seems to be no way to access the vsync rate from public APIs.

24 FPS is not an available output mode.

Your CADisplayLink callbacks provide you with the info you need to know in order to be ready for the next screen refresh via the duration property, from which you can derive the current refresh rate.

The problem is that we do not use CADisplayLink, but run everything in a background thread. Ideally there would be a way to get the vsync rate from a UIScreen so we can then adjust our frame times accordingly.

Regardless of where your drawing logic resides, you could still use that property to determine current frame rate.

Well the duration property is only set when the display link is actually used/firing. We could indeed start a display link, sample the duration and derive from there, but it is hardly an elegant solution. A simple property somewhere would be a lot more convenient.

bugreporter.apple.com is your friend 🙂

Just make sure you provide some use case detail that helps make it clear why the CADisplayLink property won't serve your needs.