First-Last-Frame Interpolation (FLF2V)

Two keyframe images, a start frame and an end frame, are generated (or sourced) independently; a specialised first-last-frame-to-video model then fills in all intermediate frames, producing a coherent motion arc between the two endpoints. Chained passes can drive longer transformations by treating the last frame of one pass as the first frame of the next.

Properties

family: image-to-video
modality: image + image -> video
whyMultiModel: Conventional i2v only anchors the start; FLF2V anchors both endpoints, so the transformation arc is determinate. The two keyframes are typically generated by a separate t2i model (FLUX, SDXL), making this a t2i -> FLF2V two-stage chain where each model handles only what it excels at.
steps: [object Object], [object Object], [object Object]
controls: Positive/negative prompts to describe the in-between motion; video size and length; denoising schedule for early vs. late timesteps; chained FLF passes for longer sequences.
exampleStack: FLUX.1 dev (start frame) + FLUX.1 dev (end frame) -> Wan 2.2 FLF2V interpolation -> optional RIFE 60fps pass. Alternative: FLUX.1 dev keyframes -> LTX-2.5 FLF2V (ComfyUI native workflow).
useCases: [Transformation and morph effects][Matched cuts and transitions][Character pose changes]
pitfalls: Extreme pose or scene changes can cause incoherent mid-motion; chained passes must carefully manage extracted last-frame quality. FLF2V clips are short (up to ~5 s per pass).
source: Apatero: WAN 2.2 FLF First-Last Frame Video Guide - ComfyUI 2025

Provenance

Source: https://apatero.com/blog/wan-2-2-flf-first-last-frame-video-generation-comfyui-2025

First-Last-Frame Interpolation (FLF2V)

Properties

family

image-to-video

modality

image + image -> video

whyMultiModel

Conventional i2v only anchors the start; FLF2V anchors both endpoints, so the transformation arc is determinate. The two keyframes are typically generated by a separate t2i model (FLUX, SDXL), making this a t2i -> FLF2V two-stage chain where each model handles only what it excels at.

steps

[object Object], [object Object], [object Object]

controls

Positive/negative prompts to describe the in-between motion; video size and length; denoising schedule for early vs. late timesteps; chained FLF passes for longer sequences.

exampleStack

FLUX.1 dev (start frame) + FLUX.1 dev (end frame) -> Wan 2.2 FLF2V interpolation -> optional RIFE 60fps pass. Alternative: FLUX.1 dev keyframes -> LTX-2.5 FLF2V (ComfyUI native workflow).

useCases

[Transformation and morph effects][Matched cuts and transitions][Character pose changes]

pitfalls

Extreme pose or scene changes can cause incoherent mid-motion; chained passes must carefully manage extracted last-frame quality. FLF2V clips are short (up to ~5 s per pass).

source

Apatero: WAN 2.2 FLF First-Last Frame Video Guide - ComfyUI 2025