AetherCut^™ video stabilizer

Sub-pixel handheld smoothing via optical flow + RANSAC + Kalman filtering. 100% on-device.

AetherCut's stabilizer is a three-stage pipeline that runs entirely on your device. Stage 1 computes optical flow between frames to estimate camera motion. Stage 2 fits a smooth global motion model using RANSAC, throwing out outliers from foreground subjects. Stage 3 applies a Kalman filter to the camera path so the corrected footage smooths jitter but preserves intentional pans.

All three stages run in JavaScript and WebAssembly in your browser. No frame is uploaded. You can verify this in DevTools.

The three-stage stabilization pipeline

The optical flow stage uses a Lucas-Kanade tracker on a grid of feature points per frame. We sample roughly 200 points per frame; that's enough density to estimate global motion accurately without saturating CPU on mobile devices.

RANSAC robustly fits a 2D affine motion model to those tracked points, automatically rejecting points that belong to moving foreground subjects (cars, people, anything that's not the background). This is what stops the stabilizer from accidentally locking onto a moving subject and making the background swim.

Finally, a Kalman filter smooths the per-frame motion estimates into a clean camera path. The corrected frame is then warped into that smoothed coordinate space. Slight edge cropping is inevitable to hide the boundary — adjustable via a single slider.

When the stabilizer struggles

Rolling-shutter artifacts (the 'jello' wobble on iPhone footage during fast pans) are technically a separate problem from camera shake. AetherCut's stabilizer reduces the appearance of rolling shutter but does not run a full rolling-shutter correction pass. For that, Premiere's Warp Stabilizer with the Rolling Shutter Repair option is still the right tool.

Severe shake (a runner with the phone in hand) needs aggressive smoothing, which means heavy edge cropping. The slider lets you pick the trade-off between smoothness and how much of your frame survives. For shake that severe, the answer is often 'no software will save this — reshoot' — but the slider gives you the best result possible from what you have.

Stabilization on long clips

The stabilizer streams frame-by-frame and only holds the working frame plus a small Kalman state in memory. There's no requirement to load the whole clip — a 30-minute 1080p video stabilizes without exhausting browser memory.

Stabilization is a one-time pre-render on the clip; the result is cached for the rest of the session so subsequent timeline edits don't re-run the optical flow pass.

Frequently asked questions

Does the stabilizer upload my footage?

No. All three pipeline stages — optical flow, RANSAC, Kalman — run in your browser. DevTools Network tab confirms zero outbound frame traffic.

How long does stabilization take?

Roughly real-time on a 2024 MacBook Air for 1080p. A 60-second clip takes about 60 seconds. Older hardware is proportionally slower.

Will I lose part of my frame?

Some edge cropping is unavoidable — that's how stabilization mathematically works. AetherCut's crop slider lets you pick the trade-off between smoothness and visible frame area.

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