# RTSP Heartbeat Logging Design

**Date:** 2026-04-08

**Goal:** Add periodic heartbeat logs to the RTSP pipeline so operators can confirm the stream is still being processed during long 30-minute windows.

## Scope

- Keep the existing RTSP counting behavior unchanged.
- Print one heartbeat line every 60 seconds while the RTSP loop is running.
- Include the current demographic counts in the heartbeat output.
- Do not change JSON payload structure or window timing.

## Heartbeat Format

Each heartbeat line should report:

- runtime seconds
- current window index
- current window frame count
- total people in the active window
- age counts
- gender counts
- unknown attributes
- last processed timestamp

This output is intended for `tail -f` style monitoring and should remain single-line and compact.

## Approach

Reuse the existing live stats helper to avoid recomputing counting rules in a second place. The RTSP loop already knows when each sampled frame is processed, so it can track the last successful processing timestamp and emit a heartbeat when 60 seconds have elapsed since the last log.