Deep in the source code of Fire OS 6 on the all-new 3rd generation Amazon Fire TV is an unreleased new setting called “Cinema Mode.” Based on the setting’s description, it appears to enable synchronization between the frame rate of the video being played with the refresh rate of the television. This is a feature that home theater enthusiasts have been wanting for a long time.
All Fire TV and Fire TV Sticks have always displayed their interfaces and content at 60Hz. This means that the image on your TV updates 60 times per second. The more often the image updates, the smoother things like the user interface and games will look. The problem comes when you play a movie or a TV show, which was likely shot at 23.976 frames per second, at that same 60Hz refresh rate. Since the number of video frames available do not match the number of times the TV screen is being changed, you end up with an issue called 3:2 pulldown. Since 23.976 does not divide evenly into 60, the video player must alternate between duplicating 3 frames half the time and duplicating 2 frames the other half of the time. This results in unwanted artifacts appearing on the screen, which are especially noticeable during fast motion scenes.
The solution to the issue is to simply switch the TV to 24Hz when playing video and switch back to 60Hz when displaying other content like the user interface. Fire TV owners used to do this manually by access hidden resolution options, but this often broke or became unavailable with software updates. More recently, media player apps like MrMC, Kodi, and SPMC have been taking advantage of undocumented developer options in Fire OS 5 to switch the Fire TV’s refresh rate automatically when video is played. However, this too has proven unreliable since Fire OS 6 appears to break the functionality.
It seems as if Amazon is listening to enthusiasts who have been asking for official support for refresh rate syncing because Fire OS 6 on the new Fire TV has an unreleased “Cinema Mode” option that appears to officially enable support for switching refresh rates. The setting is described by Amazon in the source code as: “When Cinema Mode is on, supported apps will use native frame rate during video playback. Video Resolution must be set to Auto to enable Cinema Mode.”
For the time being, the Cinema Mode option is not available on any device. Fire OS has a portion of the source code where it specifies which Fire TV and Fire TV Stick models are able to access the various features of the operating system, like UHD resolutions. That code normally returns “true” if certain Fire TV models are used and returns “false” otherwise. The code that relates to Cinema Mode doesn’t currently check for any Fire TV models and simply returns “false” no matter what.
Since this new feature is completely hidden from the user, there is no guarantee that it will ever be released. I have found plenty of hints at new features in the past that we’ve yet to see released, so there’s no telling if a future Fire TV software update will enable Cinema Mode or not. At the very least, it’s great to see that it’s at least being considered and worked on.