Runway and Veo lock every clip to 24fps. Kling lets you pick 60. Nobody tells you what happens when you edit them into the same scene.
I cut a Lost Garden scene together last month from three shots: two from Runway, one from Kling. On my laptop screen it looked fine. On a projector, the Kling shot stuttered like a bad GIF while the Runway shots played smooth. Same sequence, same footage, same export. The problem wasn’t the footage. It was that one clip was running at 60 frames per second and the other two were running at 24, and my timeline had quietly picked one of those numbers as correct and started dropping or duplicating frames on the other.
That’s the answer to the question a lot of AI filmmakers eventually type into Google: a frame rate mismatch happens when clips generated at different frame rates get placed on a single editing timeline, and it’s the single most common reason a technically good AI video looks choppy in the edit. Here’s what causes it, which tools you need to watch, and the fix that actually holds.
What Is a Frame Rate Mismatch, and Why Does AI Video Cause It?
A frame rate mismatch is what happens when footage shot or generated at one frame rate gets played, edited, or exported at a different one. The editing software has to reconcile the gap somehow, and it does that by dropping frames, duplicating frames, or blending them, which is exactly the judder, stutter, or slow-motion-that-shouldn’t-be-slow-motion look you get when a clip doesn’t match.
Traditional film sets rarely hit this problem, because one camera shoots the whole project at one frame rate someone chose on day one. AI filmmaking breaks that assumption. Every generation is its own tiny production, and different AI video models default to different frame rates by design, not by accident.
Which AI Video Models Actually Lock You to 24fps?
Two of the tools most AI filmmakers reach for are more rigid here than people assume:
- Runway’s Gen-4 outputs video at a fixed 24 frames per second, in 5 or 10 second durations, at 720p across several fixed aspect ratios. That number isn’t a default you can nudge, it’s the spec, confirmed directly in Runway’s own Gen-4 documentation.
- Google’s Veo 3.1 does the same thing: 720p or 1080p output at a fixed 24fps, no option to change it inside the tool. Google’s own guidance goes further and warns that forcing that footage to 60fps in post, or upscaling it aggressively, can introduce visible artifacts rather than smoother motion.
In other words, two of the most widely used AI video generators in 2026 hard-lock you to the same cinematic 24fps that film has used for a century. That part isn’t the problem.
Why Does Kling Let You Pick 60fps When Runway and Veo Don’t?
Kling breaks the pattern. Kling’s newer models let you choose the frame rate per generation, including a 4K-at-60fps option marketed specifically for smooth, high-motion shots, alongside a 24fps cinematic setting for anything meant to look like film. That flexibility is genuinely useful if you’re generating one isolated clip for a platform that wants 60fps. It becomes a trap the moment that clip gets cut next to a Runway or Veo shot that’s locked at 24.
A prompt describes what a shot should look like. It says nothing about what frame rate it was born at. Two clips can match perfectly in lighting, color, and composition and still fight each other the instant they land on the same timeline.
This is the actual mechanism behind the why does my AI video look choppy problem: it’s rarely the generation quality. It’s an unexamined number sitting in each clip’s metadata that nobody checked before cutting.
Runway’s homepage. Gen-4 fixes every video output at 24fps.
Google DeepMind’s Veo page. Veo 3.1 also outputs a fixed 24fps.
How Do You Spot a Frame Rate Mismatch Before It Wrecks a Cut?
Check before you cut, not after you’ve already exported and wondered why one shot looks wrong:
- Look at the clip’s properties in your NLE (Premiere, Resolve, Final Cut) before dropping it on the timeline. Every one of them will show you the source frame rate in a media info panel or clip inspector.
- Compare that number to your sequence/timeline frame rate. If your project is set to 24fps and you drop in a 60fps Kling clip without converting it, the software will either play it back at the wrong speed or start dropping frames to force it to fit, and it usually won’t warn you loudly enough to notice on a small preview window.
- Watch fast pans and handheld-style camera moves first. Judder from a frame rate mismatch shows up worst on motion, not on static shots, which is exactly why it can hide in a quiet dialogue scene and ambush you on an action beat.
What’s the Fix: Conform Your Timeline, Don’t Guess
The fix isn’t picking a favorite frame rate and hoping. It’s conforming deliberately:
- Decide your project’s frame rate before you generate anything, the same way a real production locks it in prep. 24fps is the safe cinematic default and matches what Runway and Veo already give you natively.
- If a shot has to come from a tool set to a different frame rate, convert it on ingest, not on export. Most professional editors (Premiere’s Interpret Footage, Resolve’s clip attributes) let you conform a clip’s frame rate cleanly before it ever touches the timeline, instead of letting the software guess during playback.
- Avoid forcing a 24fps clip up to 60fps or vice versa unless you have to. As Google’s own Veo guidance notes, heavy retiming introduces artifacts. If a platform genuinely requires 60fps delivery, generate for that frame rate from the start rather than stretching 24fps footage to fit after the fact.
- Treat the frame rate like any other shot decision and log it, the same way you’d log a lens choice or a lighting setup. On ScreenWeaver, that line sits next to the rest of the shot plan, so nobody has to reverse-engineer which model made which clip three weeks later while trying to figure out why one shot won’t sit still.
What Frame Rate Should You Deliver to a Festival?
Festival specs are more forgiving on frame rate than most filmmakers expect, but only if you deliver a conformed, consistent file rather than a folder of mismatched clips stitched together and hoped for. DCP masters generally accept 24, 25, or 30fps. Individual festivals still publish their own numbers: Berlinale’s media requirements ask for standard HD delivery in mp4 with H.264 encoding, while Cannes accepts a wider range including H.264 at a minimum bitrate around 2Mbps and uncompressed formats, alongside general bitrate guidance in the range of 8 to 15Mbps for 1080p and 15 to 25Mbps for 4K delivery. None of that forgives an internal frame rate mismatch.
A judder that shows up on your laptop shows up worse on a festival’s projector, in front of the audience you spent months trying to reach.
The Lost Garden Fix
I re-cut that Lost Garden scene the boring way: opened the Kling clip’s properties, saw 60fps sitting there next to two 24fps Runway shots, and conformed it down before touching the timeline again. The stutter disappeared completely. Nothing about the footage itself changed. The only thing that changed was that I finally checked a number I’d never once looked at while three separate tools quietly disagreed about how fast a second of film should move.
Why does my AI-generated video look choppy after editing?
Most often because a clip’s and the software is dropping or duplicating frames to reconcile the difference rather than playing the footage as generated
What frame rate should I generate AI video at?
24fps is the safest default: it’s the fixed native output of both Runway Gen-4 and Veo 3.1, it’s cinema-standard, and DCP festival masters accept it directly.
Can I convert a 24fps AI clip to 60fps without hurting quality?
You can, but expect visible artifacts on fast motion. Google’s own Veo guidance specifically warns against heavy retiming; generate at your target frame rate from the start when possible instead of stretching footage after the fact.
If you’re building a scene from more than one AI video tool, check every clip’s frame rate before you cut, not after. It takes thirty seconds and it’s the difference between a scene that holds together and one that quietly falls apart the first time it plays somewhere other than your laptop.
