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.
Try DiffALL free — no sign-up neededWhat 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 keeps processing fast on the free tier — full results in under 30 seconds for a 1-minute clip.
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 samples frames at 5-second intervals, calculates SSIM and PSNR per frame, and shows a chart and worst-frame screenshot. No install required.
What video formats does DiffALL support?
MP4, MKV, WebM, AVI, MOV, FLV, M4V, TS, and MTS. Files up to 200 MB and 1 minute long on the free tier.
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 →