Video your agent can measure

Cuts, easing, colour and beats from any video, to the frame.

npx -y framelens init

Star on GitHub

Free, local and MIT. Works in Claude Code, Codex, Cursor and any MCP client.

Frame of the Big Buck Bunny trailer at 26.5 seconds — The Big Buck Bunny trailer, read by Frame Lens: red cuts, pale fades and dissolves, green moves.

Frame Lens read our curve back within 0.18 px

What we animated in HyperFrames

cubic-bezier(0.22, 1, 0.36, 1)

640 px in 18 frames at 30 fps

Measured curve: cubic-bezier(0.231, 0.951, 0.384, 0.996)
Start: 10.600 s, 0 frames off
Largest gap on any frame: 0.18 px
Grade: exact

The demo above was rendered, then measured by Frame Lens. A spring of stiffness 170 read back as 170.01.

A podcast gets one sheet, a promo gets every frame

“Use this as a reference for my product promo.”

boundaries every cut, ten samples a second
frames one sheet of the whole piece
frames every frame around each move
style shots, palette, moves and curves
export a starter project, then compare

“Turn this tutorial into a step-by-step guide.”

transcript every word with its time
boundaries each screen change
frames one frame per screen, with the words said there

“Summarize this three-hour podcast.”

transcript the words carry the content
frames one overview sheet, nothing more

“Where does he set up DNS?”

transcript find the phrase
frames around the moment it is said

“What is the sound design here?”

audio loudness, hits, tempo, beat grid, spectrogram
boundaries cuts, to check which land on the beat

The style goal’s first pass: a frame a second, red where a cut falls.

Video is measured; Lottie, Rive and websites are read exactly

Source	How	What Frame Lens read
The trailer above, a video file	From pixels	20 shots, 11 cuts, 10 fades and dissolves
A live website, makkov-harness	From the browser	328 animations, mostly 500 ms on cubic-bezier(0.16, 1, 0.3, 1)
A Lottie file, our export read back	From keyframes	Its keyframes and curves, back exactly
Rive files and Figma prototypes	From the file	Keyframes and transitions
YouTube and most video sites	From pixels	Through a pinned yt-dlp

The measured move in five renderers

Frame Lens writes the curve it measured into each tool. Render yours, then compare names what drifted.

Dots: where the square was on each frame. Line: the fitted curve.

/* motion.css */
#shot-15 h1 { animation: fl-enter 0.542s
  cubic-bezier(0.2312, 0.9511, 0.3843, 0.9964)
  10.6s both; }

// src/timing.ts
{ id: "shot-15", from: 317,
  enterAt: 1, enterFrames: 16,
  bezier: [0.2312, 0.9511, 0.3843, 0.9964] }

<!-- compositions/shot-15.html -->
tl.fromTo("#shot-15-title",
  { opacity: 0, y: 60 },
  { opacity: 1, y: 0, duration: 0.542,
    ease: flBezier(0.2312, 0.9511, 0.3843, 0.9964) },
  0.033); // tracked t1

// framelens-reference.jsx
"keyStart": 10.6, "keyEnd": 11.142,
"bezier": [0.2312, 0.9511, 0.3843, 0.9964],
"positionEase": { "outSpeed": 455.3972,
  "outInfluence": 23.12,
  "inSpeed": 0.6473, "inInfluence": 61.57 }

// reference.json, frame 318 to 334
"p": { "a": 1, "k": [
  { "t": 318, "s": [960, 600, 0],
    "o": { "x": [0.2312], "y": [0.9511] },
    "i": { "x": [0.3843], "y": [0.9964] } },
  { "t": 334, "s": [960, 540, 0] } ] }

Tested at 24, 30 and 60 fps against known answers

33/33
cuts found on the exact frame: 36/36
easing families named right: 1.00
frame, the mean error on where a move starts

Synthetic clips with known cuts and curves. Read the benchmark.

Point it at a video tonight

Star on GitHub

Node 20 and ffmpeg on your computer. framelens doctor --prepare checks the rest.

This project

npx -y framelens init

Adds .mcp.json and the agent skill here.
Claude Code, everywhere

claude mcp add framelens -s user -- npx -y framelens

On Windows, cmd /c before npx.

Any MCP client

"framelens": {
  "command": "npx",
  "args": ["-y", "framelens"] }