> ## Documentation Index
> Fetch the complete documentation index at: https://docs.medera.info/llms.txt
> Use this file to discover all available pages before exploring further.

# Quality Requirements

> Conditions for reliable facial signal

| Factor             | Requirement                              |                                                                                                                                                                                                                 |
| :----------------- | :--------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Resolution         | ≥ 480p                                   |                                                                                                                                                                                                                 |
| Frame rate         | ≥ 15 fps (engine default `fps=30`)       |                                                                                                                                                                                                                 |
| Face angle         | Within ±30° of camera                    |                                                                                                                                                                                                                 |
| Lighting           | Avoid harsh backlight                    |                                                                                                                                                                                                                 |
| ROI                | Forehead (default), cheeks, or full face |                                                                                                                                                                                                                 |
| rPPG SNR           | > 3.0 required                           |                                                                                                                                                                                                                 |
| Min duration (HR)  | 30 s                                     |                                                                                                                                                                                                                 |
| Min duration (HRV) | 60 s                                     |                                                                                                                                                                                                                 |
| Min duration (BP)  | 60 s                                     | If the requirements aren't met, the engine returns the metric with `confidence: 0.0`. The downstream analyzer falls back to a Medera reasoning transcript-inferred analysis with `requires_human_review: true`. |