Butter-smooth slow motion is one of the things that makes a sports broadcast feel high quality. Traditionally, that required expensive high-speed cameras. With modern image processing on Apple Silicon, there is another way: a normal 50-fps signal can be turned into much smoother slow motion. This article explains how it works and where the limits are.
Why ordinary slow motion often stutters
If you record video at 50 frames per second and slow it down to a quarter of the speed, only a limited number of real frames remain for the same time span. The software has to fill the gaps. The simplest method repeats existing frames, which makes the result look choppy. A slightly better method blends neighbouring frames, but that creates a muddy ghosting effect. Both are immediately visible in a good broadcast.
How frame interpolation solves the problem
Instead of repeating or blending frames, modern slow motion calculates completely new intermediate frames. To do that, a model analyses two consecutive frames and estimates how every object moved between them - this is motion estimation, also called optical flow. Based on that motion, it creates a new plausible image for the moment in between. Repeat this several times and 50 fps effectively becomes a multiple of the original frame rate, for example 200 fps, with newly calculated intermediate steps instead of duplicates.
The role of the Neural Engine
This calculation is demanding, especially when it needs to become available quickly in a live production. That is where the Neural Engine comes in: a specialised part of Apple Silicon chips built exactly for AI-style workloads. It handles motion estimation and image generation efficiently without blocking the main processor. That leaves enough performance to record multiple camera channels in parallel and keep replay control responsive. The result is smooth slow motion from standard footage without buying special cameras.
What this means in practice
The practical benefit is twofold. First, you save hardware cost because your existing cameras at standard frame rates are enough. Second, you gain flexibility: you decide during replay which scene should be slowed down and by how much, instead of configuring a camera for high frame rates in advance. Especially in sports with fast and unpredictable action, that is a real advantage.
Where the limits are
Calculated intermediate frames are a very good approximation, but they are not magic. Extremely fast motion, heavy occlusion where one object briefly disappears behind another, or very unstable footage can push the estimate to its limits. For the vast majority of sports and broadcast scenes, however, the method produces a result that comes surprisingly close to real high-speed recording at a fraction of the cost. Good source material matters: the cleaner and sharper the 50-fps signal, the better the interpolated slow motion.
Conclusion
Neural Engine assisted frame interpolation makes professional slow motion accessible to many more productions. 50 fps becomes a smooth replay without special cameras and without an enterprise budget. For live sports on the Mac, it is one of the biggest quality leaps of recent years.
GLENDALE LIVE Replay uses the Neural Engine for smooth slow motion directly inside the replay workflow. Watch the demo.