Generate a poster that tells viewers what the clip contains.
Choose meaning, not just a timestamp
The first frame may be black, a fade, or a title card with no context. Sample candidate frames after probing duration, then reject frames that are blank, blurred, or misleading. For product demos, an editor-selected still is often better than any automatic sample.
Generate for the actual slot
Create a poster at the player’s display ratio and an appropriate pixel density. Keep the original frame or source time in metadata so the image can be regenerated. A poster is part of the video asset’s delivery state, not an unrelated decorative upload.
Check loading behavior
A poster can be the page’s largest image, so give it the same sizing and priority attention as a hero image. Test the transition from poster to playback and confirm controls remain clear over light and dark frames.
A concrete acceptance test
Generate poster candidates for a clip with a black opening frame and a fade. Check the chosen image at mobile size and verify that playback replaces it cleanly. Run this test with a realistic asset and record the observed state, output URL, and failure reason.
Implementation check
- Reject blank or misleading candidate frames.
- Generate at the player slot ratio.
- Check poster loading priority on the actual page.
Related guides
Primary reference: Official documentation.