Video Quality Comparison Tool — Frame-by-Frame Analysis
Upload two video files and DiffALL analyses every sampled frame. See per-second SSIM scores, pinpoint the exact moment quality drops, and generate a live heatmap overlay.
Free, no sign-up — your files never leave the comparison.
Drop file here or click to browse
MP4 · MKV · WebM · AVI · MOV · FLV · M4V · TS · MTS
Drop file here or click to browse
MP4 · MKV · WebM · AVI · MOV · FLV · M4V · TS · MTS
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What DiffALL measures
Per-Second SSIM Chart
Interactive timeline chart showing structural similarity at every sampled second — spot degradation trends at a glance.
Worst-Frame Detection
DiffALL automatically identifies the single most-different moment and renders a heatmap screenshot with glowing bounding boxes.
Live Heatmap Preview
Generate a full heatmap video showing frame-by-frame differences side by side with the original footage.
PSNR Scoring
Frame-averaged Peak Signal-to-Noise Ratio for standard-compliant quality benchmarking.
Media Info
Codec, bitrate, fps, resolution, and duration extracted for both files via ffprobe.
Fast Sampling
One frame sampled per 5 seconds, plus full SSIM on any second that looks off — so processing time grows with the clip, not with its resolution.
Supported formats
Use cases
Transcoding QA
Verify that re-encoding a video to a different codec or bitrate doesn't introduce visible artifacts.
Broadcast QA
Compare the master file to the broadcast output to catch transmission errors and encoding issues.
A/B Encoding Tests
Objectively compare two codec settings — H.264 vs H.265, different CRF values — with a single score.
Streaming Quality
Detect quality drops in adaptive bitrate streams by comparing segment files to the source.
Frequently asked questions
How do I compare two video files for quality differences?
Upload your reference and distorted video files to DiffALL. It scans every second of both videos for differences, calculates SSIM and PSNR, and pinpoints the worst moment to the exact second with a chart and annotated screenshot. No install required.
What video formats does DiffALL support?
MP4, MKV, WebM, AVI, MOV, FLV, M4V, TS, and MTS. Clips up to 3 minutes, 40 MB on the free plan and 150 MB with Pro. Pro compares the full clip end to end.
What is a good SSIM score for video?
Above 95% is excellent — differences are imperceptible to most viewers. 85–95% is acceptable for highly compressed delivery formats. Below 85% indicates visible quality loss.
Can DiffALL compare videos with different resolutions?
Yes. Both videos are scaled to a common dimension before comparison. Codec and bitrate differences do not affect the comparison.
What is the worst-frame detection?
DiffALL tracks the single frame with the lowest SSIM score across the entire clip, renders a colour heatmap on it, and highlights the regions with the greatest differences using glowing bounding boxes.
Ready to compare videos?
Free, no install, no sign-up required for your first comparison.
Start comparing now ↑