CCTV Overwrite Recovery: GOP Structure and Time-Slice Export
Surveillance storage is a ring buffer. What survives is whatever has not been overwritten yet — and that shrinks with every minute of recording.
How footage is stored
Most NVRs write proprietary containers with periodic index blocks. When the index is lost, H.264/H.265 NAL units can still be scanned and grouped into GOPs, then muxed into playable files.
Stop recording first
Any further recording overwrites the oldest data — often exactly what is needed. Power the NVR down, remove the disk, image it, then work on the image.
FAQ
Can overwritten footage come back?
No, once overwritten it is gone; adjacent GOPs may still be reusable.
Do I need the NVR to play the files?
No — exported clips play in standard players if muxed correctly.