SOLVED: Why Movie Theaters Still Use 24 FPS (& Why Your TV / Computer Screen Is So Confusing) – Up & Running Inc

The frame rate of films has long been a source of bewilderment in the realm of digital cinema. Having worked at Canada’s largest drive-in theatres as a child, I’ve had my share of experience splicing film reels for our exceptionally bright projector, and I can affirm that traditional film operates at 24 frames per second (FPS).

Despite advancements in technology, with current 4K digital projectors capable of 120 Hz refresh rates (i.e. 120 updates per second), major cinema chains such as Cineplex and Loews continue to screen nearly all feature films at the same slow speed of 24 FPS.

Understanding HD TV & Streaming at 24 FPS

It’s important to realise that major television providers like Rogers and Comcast, as well as streaming behemoths such as Netflix and Disney+, deliver both films and scripted television series at a mere 24 FPS (or technically 23.976 FPS). This is based on the frame rate of the original source video.

This remains true even for premium 4K packages. While the higher subscription tiers provide better resolution (e.g., 4K) and enhanced colour (HDR/Dolby Vision), they do not offer a higher frame rate for films, which means that 3:2 judder continues to affect viewing on 60Hz displays.

Enjoying 60 FPS for Sports

Conversely, it is certainly possible to find higher frame rates, as 24 FPS is typically reserved for dramatic narratives, rather than fast-paced action like Hockey, Football, and Soccer. Live sports, along with some reality-based television, are sometimes broadcast at 60 FPS (or the broadcast standard 59.94 FPS) to ensure clarity in motion. You can likely find 60 FPS content through specific sports channels offered by your cable provider (such as ESPN or Fox Sports), in addition to dedicated streaming platforms like YouTube TV, Hulu Live TV, and DAZN.

Moreover, niche High Frame Rate (HFR) films like segments of James Cameron’s Avatar sequels have been released at 48 FPS on select apps and devices, although this remains infrequent.

Understanding the Confusion: FPS vs Hz

Confusion often arises due to the distinction between a film’s frame rate and a display’s refresh rate, along with how each device manages the conversion.

1. Content Standard: 24 FPS – The Cinematic Experience

The industry steadfastly adheres to 24 FPS for two primary reasons:

1. Aesthetics and Tradition: The 24 FPS speed introduces a specific level of motion blur, which audiences have associated with “cinema” for a century. In contrast, higher frame rates like 60 FPS or 120 FPS create an unnaturally smooth effect, often labelled as the “video game” or “soap opera” look, which many viewers rejected during major HFR projects like The Hobbit and Gemini Man.
2. Efficiency: This standard was initially adopted as the minimum frame rate to synchronise sound effectively while conserving costly film stock. Despite the advent of digital storage, this traditional “look” remains the hallmark of film quality.

2. The Home Cinema Challenge: 3:2 Pulldown

A familiar issue on most home displays, especially older 60 Hz TVs in North America, is the jerky, uneven motion known as “judder.” This is caused by a conversion process called 3:2 Pulldown (officially termed “telecine”):

• A 60 Hz display cannot evenly process 24 frames per second.
• To accommodate 24 frames within the 60 Hz refresh cycle, the TV alternates frame display in a “3:2” pattern:
  • Frame 1 is displayed for 3 refresh cycles.
  • Frame 2 is shown for 2 refresh cycles.
  • Frame 3 is displayed for 3 refresh cycles.
  • Frame 4 is shown for 2 refresh cycles.
  • And so on.
• This alternating cycle results in uneven image duration, causing noticeable stutters or judder, particularly during camera pans.

3. The Cinema Solution: Even Flashing (The 1:5 Pulldown)

In cinemas, whether utilising a 1980s film projector or a contemporary digital projector, the goal is always “even flashing” to eradicate judder and flicker.

• Film Projectors: These often used a double or triple bladed shutter to flash each unique frame two or three times, resulting in output at 48 Hz or 72 Hz.
• Modern Digital Projectors (such as those at Cineplex/AMC): These are considerably more powerful, frequently operating at 120 Hz. To display a 24 FPS film, they employ an “even pulldown” method known as 1:5 pulldown, meaning each frame is flashed five times before moving on to the next one.

This technique ensures each frame remains on screen for precisely the same duration, 1/120th of a second, providing a smooth, consistent motion flow reminiscent of traditional film but without unsightly flicker.

The misunderstanding surrounding elevated frame rates in theatres stems from this display technology. The projector refreshes (i.e. flashes) 120 times per second, while the source film only delivers 24 distinct images per second.

Frame Rate Comparisons and Pulldown Techniques

Below is a table outlining various content frame rates and the respective methods displays use to manage conversions:

Conclusion

The film industry continues to favour 24 FPS because a century of cinema has conditioned audiences to appreciate its specific motion blur as the definitive “cinematic look.” While higher frame rates (HFR) like 60 FPS and 120 FPS provide clearer motion, they are often eschewed in dramatic films because they appear excessively smooth and can seem unrealistic (like a video game).

The industry maintains 24 FPS content even though it creates the problematic choppy nature from 3:2 judder on over 90% of TVs and computer monitors running at 60 Hz. Theatres, however, circumvent this judder by using 120 Hz projectors to flash each 24 FPS frame five times evenly.

Ultimately, those most affected by judder from lower refresh and frame rates are typically enthusiasts watching live sports and playing video games.