A small explainer on video "framerates" in the context of Wan
I see some people who are very new to video struggle with the concept of "framerates", so here's an explainer for beginners.

The video above is not the whole message, but it can help illustrate the idea. It's leftover clips from a different test.

A "video" is, essentially, a sequence of images (frames) played at a certain rate (frames per second).

If you're sharing a single clip on Reddit or Discord, framerates can be whatever. But outside of that, standards exist. Common delivery framerates (regional caveats aside) are 24fps (good for cinema and anime), 30fps (console gaming usually TV stuff), 60fps (good for clear smooth content like YouTube reviews).

Your video models will likely have a "default" framerate at which they are assumed (read further) to produce "real speed" motion (as in, a clock will tick 1 second in 1 second of video), but in actuality, it's complicated. That default framerate is 24 for LTXV and Hunyuan, but for Wan it's 16, and default output in workflows would also be 16fps, so it poses some problems (because you can't just plop that onto a 30fps timeline at 100% speed in something like Resolve and have smooth, judder-free motion straight away).

Good news is, you can treat your I2V model as a black box (in fact, you can still condition framerate for LTXV, but not Wan or Hunyuan). You give Wan an image and a prompt and ask for, say, 16 more frames; it gives you back 16 more images. Then you assume that if you play those frames at 16fps, you'll get "real speed" where 1 second of motion fits into 1 second of video, so you set your final SaveAnimatedWhatever or VHS Video Combine node to 16fps, and watch the result at 16fps (kinda - because there's also your monitor refresh rate, but let's not get into that here). As an aside: you can as well just direct the output to a Save Image node and save everything as a normal sequence of images, which is quite useful if you're working on something like animation.

But those 16fps producing "real speed" is only an assumption. You can ask for "a girl dancing", and Wan may give you "real speed" because it learned from regular footage of people dancing; or it may give you slow-motion because it learned from music videos; or it may give you sped-up footage because it learned from funny memes. It even gets worse because 16fps is not common anywhere in the training data: most all of it will be 24/25/30/50/60. So there's no guarantee that Wan was trained on "real" speed in the first place. And on top of that, that footage itself was not always "real speed" either. Case in point - I didn't prompt specifically for slow-motion in the panther video, quite the opposite, and yet it was slow-motion because that's a "cinematic" look.

So - you got your 16 more images (+1 for the first one, but let's ignore it for ease of mental math); what can you do now? You can feed them to your frame interpolators like RIFE or GIMM-VFI, and create one more intermediate image between each image. So now you have 32 images.

What do you do now? You feed those 32 images to your output (video combine/save animated) node, where you set your fps to 30 (if you want as close to assumed "real speed" as possible), or to 24 (if you are okay with a bit slower motion and a "dreamy" but "cinematic" look - this is occasionally done in videography too). Biggest downside, aside from speed of motion? Your viewers are exposed to the interpolated frames for longer, so interpolation artifacts are more visible (same issue as with DLSS framegen at lower refresh rates). As another aside: if you already have your 16fps/32fps footage, you don't have to reprocess it for editing, you can just re-interpret it in your video editor later (in Resolve that would be through Clip Attributes).

Obviously, it's not as simple if you're doing something that absolutely requires "real speed" motion - like a talking person. But this has its uses, including creative ones. You can even try to prompt Wan for slow motion, and then play the result at 24fps without interpolation, and you might luck out and get a more coherent "real speed" motion at 24fps. (There are also shutter speed considerations which affect motion blur in real-world footage, but let's also not get into that here either.)

When Wan gets replaced in the future with a better 24fps model, this all will be of less relevance. But for some types of content - and for some creative uses - it still will be, so understanding these basics is useful regardless.


"explain in simple term"