DP Fast Slow Motion

Retime a clip without leaving ComfyUI. This node takes a frame batch and speeds it up or slows it down - either the whole thing, or just a chosen range so you get a speed-ramp effect (normal, then slo-mo on the good bit, then normal again). It's the quick way to add a bit of drama to an AI-generated clip.

It's part of the animation set in DesertPixelAi's Desert Pixel pack.

How it works

A clip is a batch of frames, and retiming means resampling that batch - dropping frames to speed up, repeating or spacing them to slow down. You feed frames into frames (IMAGE) and control it with:

• speed (−4 to 4) - the core knob. Positive speeds up, negative slows down; the magnitude sets how much. 0 is the default and effectively a no-op, so remember to move it off zero.
• process_all_frames (bool) - apply the speed change to the entire clip.
• start_frame / end_frame - when process_all_frames is off, these bound the section that gets retimed, leaving the rest at normal speed. That's how you get the "ramp into slow motion" look.

The output, IMAGE, is the retimed frame batch, ready for a video-combine node.

The inputs and outputs that matter

speed is the one you'll actually reach for. Then decide scope: process_all_frames on for a uniform speed change, or off with start_frame/end_frame set to retime just a segment.

One thing to keep in mind: this operates on frames only - there's no audio track in a ComfyUI image batch, so any sound you add later in an editor won't magically follow the retime. And because it changes how many frames come out, whatever frame rate you set on your final video-combine node determines the actual perceived speed. The two work together: this node changes the frame count, the combine node's fps turns that into wall-clock timing.

How to install it

ComfyUI Manager: search Desert Pixel, install, restart. Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/DesertPixelAi/ComfyUI-Desert-Pixel-Nodes

Restart ComfyUI. No downloads. Under the DP category.

Common issues & troubleshooting

Slow motion looks choppy, not smooth. This is the big one to understand: retiming by resampling frames isn't the same as interpolating new ones. When you slow a clip down, it stretches the existing frames rather than generating in-between frames, so heavy slowdown gets visibly stuttery. For buttery slow-mo you want a real frame-interpolation model - RIFE or FILM (via a node like ComfyUI-Frame-Interpolation) - to invent the intermediate frames. A common recipe is to interpolate first to raise the frame count, then slow down, so there's enough material to stretch.

Nothing changed. speed is probably still at its default of 0. Push it positive or negative.

The wrong part of the clip got retimed. If process_all_frames is off, only the start_frame–end_frame window changes. Double-check those bounds, or turn process_all_frames on to affect everything.

Speeding up made it look like it skips. Speed-up drops frames, so at high positive speed motion gets jumpy - that's inherent to dropping frames. Ease the speed back, or accept it as the fast-cut aesthetic.