How My NVR Cuts Recording Storage by 75% — Without AI, and Without Dropped Frames

Description and use

MiBeeNvr cuts storage usage by 75 % using compressed‑domain P‑frame size to trigger adaptive recording, preserving all frames at activity onset.

Problem

Continuous recording on security cameras writes full‑rate video even when nothing happens, wasting storage.

Outcome

Adaptive recording based on compressed‑domain P‑frame size reduces storage by 75 % while preserving all frames at activity onset.

Workflow

• 1. Monitor P‑frame sizes in the compressed stream.
• 2. Maintain a rolling baseline of typical P‑frame size using median absolute deviation.
• 3. If a P‑frame exceeds the baseline by the spike_factor (default 5×), trigger activity.
• 4. Flush the 32 MB ring buffer containing the last GOP to disk to avoid missing initial frames.
• 5. Switch to full frame rate recording immediately, with zero dropped frames.
• 6. If the scene stays quiet for calm_threshold (default 60 s), downgrade to sparse mode: one keyframe every timelapse_interval (default 30 s) and pause audio.
• 7. Continue monitoring; any of five signals (video spike, audio trigger, pixgate, ONVIF event, external semantic trigger) can restore full frame rate.

Evidence

MiBeeNvr’s adaptive recording: drops to time‑lap‑grade sparse writes (one keyframe every 30s) when the scene is quiet; snaps back to full frame rate the instant activity is detected, with zero dropped frames at the switch; measures –75% disk on a static 2K/H.265 scene (~2700 → ~688 MB/h)

Source

The NVR never decodes the picture. It watches each P‑frame's size against a rolling baseline — the typical P‑frame size of that stream recently, maintained with MAD (median absolute deviation, a statistic that resists jitter). A P‑frame suddenly several times the baseline (default 5×) means "activity": switch back to full frame rate immediately.

Source

While in sparse mode, a 32 MB ring buffer in memory always holds the most recent complete GOP. The moment an activity spike appears: 1) the buffered GOP is flushed to disk; 2) then the recorder switches back to full frame rate, and everything after lands on disk as usual.

Source