Slow the review down to observable moments
Use a local clip to inspect the setup, contact point and follow-through of a movement. Pause near the action, choose a time-step size and compare nearby pictures. Capture the moments you want to discuss, then download them for notes or a side-by-side layout in an editor. Choose recordings where the subject is visible and the camera position is useful; an obstructed view cannot become a reliable comparison just by sampling more stills.
Timestamp steps are not certified frame indexing
The 1/24, 1/30 and 1/60-second controls request small time changes. A variable-frame-rate recording or a browser decoder may not deliver an exact adjacent source frame for every request. Match the step to the approximate recording rate, inspect what changes and keep the timestamps as navigation references. This tool is not a biomechanics measurement system: it does not calculate joint angles, speed, force or injury risk from a two-dimensional picture.
Make comparisons that respect the recording
Changing camera angle, zoom and perspective can make the same movement look different. When comparing sessions, use similar camera placement and choose comparable phases rather than simply matching elapsed seconds. Motion blur and rolling-shutter distortion can also affect apparent positions. Export a few clear PNG images, annotate observations separately and retain the video context. Avoid treating one captured instant as proof of a technical or medical conclusion.
Start with a short test
- Choose a compatible local video and wait for a playable preview.
- Capture one useful moment, or select a short range and interval.
- Compare the actual subject, then download an image or gallery ZIP.
The workspace accepts sources up to 2 GB and 8.3 million decoded pixels per frame. A gallery holds up to 120 images or 96 MB. Seeking depends on the browser and source timing. Keep the source, use media you have permission to process, and check a small output before starting a larger batch.
Questions for this workflow
Can this measure an athlete’s speed or joint angles?
No. It supports visual review and still capture, without calibrated movement measurements.
Does 1/30-second stepping always mean one frame?
No. Frame rate, timing and browser seeking can differ. Use a dedicated analyzer when exact source-frame identity is essential.
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