Choose the source and crop for the container the video must fill, not one universal pixel dimension.
Use 16:9 as a common landscape starting point, consider a dedicated 9:16 mobile source for portrait compositions, and test real content at each breakpoint.
Common source strategies
| Use | Starting ratio | What to verify |
|---|---|---|
| Inline video | 16:9 | Player width, captions, controls, and minimum readable size. |
| Wide background | 16:9 or wider crop | Object-fit cropping, focal point, text contrast, and load cost. |
| Portrait mobile background | 9:16 when composition requires it | Separate source switching, focal point, file size, and reduced-motion fallback. |
Export checklist
- Keep essential subjects away from crop-sensitive edges.
- Use a poster image and meaningful fallback content.
- Compress to the lowest size that still meets the visual requirement.
- Test actual phones and slower connections, not only a desktop responsive preview.
- Do not place essential instructions only inside a silent decorative video.