How do I read PSNR and SSIM?

PSNR is in dB, and higher means closer to the original: above 40 dB is usually invisible, 30–40 dB shows slight loss and below 30 dB the loss is obvious. SSIM runs from 0 to 1, where values above 0.98 typically look identical. Identical videos give an infinite PSNR and an SSIM of 1.

Can I compare videos with different resolutions or lengths?

Yes. The preview draws B at A’s size, and metrics scale B to A’s resolution before comparing each frame; with different lengths only the overlapping part is compared. Scaling itself adds a little difference, so keep resolutions equal when judging encoder quality.

The two videos don’t start at the same moment. What should I do?

Enter an offset in seconds under Offset of B vs A: positive if B has extra lead-in, negative if it starts later, and use ±1f to nudge one frame at a time. Flicker or difference view makes alignment easy — when it’s right the image stops jumping. The offset applies to metrics and export too.

Why is the difference view almost black?

Black means the two frames are nearly identical, which is what good encoding looks like. Raise Amplify difference to 8× or 16× to reveal blocking, ringing around edges and lost shadow detail; for color grades the difference concentrates where colors changed most.

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👀Video Compare - Synced Playback, Slider Wipe, PSNR and SSIM

How much quality did compression, transcoding, denoising or a color grade really cost? Load the before and after videos and see for yourself. Both play in sync with A as the master, in four views: side by side, slider wipe (drag the divider back and forth), difference (frames subtracted pixel by pixel and amplified 2–16× so blocking and color shifts jump out) and flicker (A and B alternate at your chosen interval, which makes subtle changes easy to spot). Scroll to zoom and drag to pan with both sides locked together, down to individual pixels; step frame by frame, and use an offset to line up clips whose starts don’t match. For objective numbers, FFmpeg’s psnr and ssim filters compute PSNR and SSIM for every frame, with averages, minimums and the worst frame, plus a per-frame graph you can click to jump to that moment. Finally, export both videos stacked side by side or top and bottom as an MP4 with labels drawn by the browser, so any language renders correctly. Everything stays on your device.

Free · No sign-up · Runs in your browserLast updated: 2026-10-26

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How to use Video Compare

1Add two videos: the first is A (original), the second is B (processed)
2Play them in sync side by side, with the slider, difference or flicker view; set an offset or zoom in as needed
3Compute PSNR / SSIM for objective metrics, or export a side-by-side or stacked comparison video

FAQ

How do I read PSNR and SSIM?: PSNR is in dB, and higher means closer to the original: above 40 dB is usually invisible, 30–40 dB shows slight loss and below 30 dB the loss is obvious. SSIM runs from 0 to 1, where values above 0.98 typically look identical. Identical videos give an infinite PSNR and an SSIM of 1.
Can I compare videos with different resolutions or lengths?: Yes. The preview draws B at A’s size, and metrics scale B to A’s resolution before comparing each frame; with different lengths only the overlapping part is compared. Scaling itself adds a little difference, so keep resolutions equal when judging encoder quality.
The two videos don’t start at the same moment. What should I do?: Enter an offset in seconds under Offset of B vs A: positive if B has extra lead-in, negative if it starts later, and use ±1f to nudge one frame at a time. Flicker or difference view makes alignment easy — when it’s right the image stops jumping. The offset applies to metrics and export too.
Why is the difference view almost black?: Black means the two frames are nearly identical, which is what good encoding looks like. Raise Amplify difference to 8× or 16× to reveal blocking, ringing around edges and lost shadow detail; for color grades the difference concentrates where colors changed most.