Altered CCTV Footage

[phk23 0]

Hi everyone,

 

Is there any way to detect if CCTV surveillance footage of an empty room has been tampered with? I am writing a scene for my spec screenplay where a federal agent figures out the CCTV footage of a secure room has been altered. In my story, a security guard is in on the heist and alters the footage so it looks like no one has entered the room. Other than digital watermarking, are there other ways to prove/detect footage tampering?

 

Any advice would be greatly appreciated.

 

Thanks,

Peter

[SectorSecurity 0]

I would start by looking at date and time stamps and go over the logs to see who has accessed the DVR.

[phk23 0]

Okay, thanks. Assuming they could edit/alter the date and time stamp at the bottom of the footage, I'm guessing the best way is to checked who accessed the footage. What if they obtained the administrator's password and accessed it? Does that mean one can go into the system and check what time the logged footage was accessed?

[SectorSecurity 0]

Yes, once you have admin access it is very easy to change the date and time settings on the DVR.

[jeromephone 6]

I saw a similar problem on some tv show or something where they figured the footage had been tampered with because they copied over some video to fill in the time gap but someone was smart enough to see the same housefly at the same time and same place for two nights in a row.

[phk23 0]

I thought of a potential solution, but it needs validation. Is the following possible/plausible?

 

Is there a way that CCTV footage of a still room has been duplicated just by looking at it? CCTV cameras record light information onto a pixel grid, but even if we’re looking at a still room, the light variations in pixels change, right? Would that light variation create a unique pattern from frame-to-frame? Ex: Minute 3:56 of Footage A and minute 3:56 of Footage B will look like the same image to the naked eye, but zoomed in, you can see the exact same light variation of pixels. An exact match would only be possible if the footage were duplicated. Is that feasible?

 

Thanks. I appreciate the feedback!

[Kawboy12R 0]

Does the room have windows? Clouds vary light levels significantly. Duplicated footage could easily have light from a sunny or partly cloudy day when the other day was cloudy. If audio recording is involved, train whistles/school buzzers/church bells from a different day or time could be clues. Barely visible date changes on a flip-over desk calendar that're clear when zoomed in? Days crossed off on a wall calendar? Blown light bulb changed from warm white to cool white so the white balance is off?

[phk23 0]

Does the room have windows? Clouds vary light levels significantly. Duplicated footage could easily have light from a sunny or partly cloudy day when the other day was cloudy. If audio recording is involved, train whistles/school buzzers/church bells from a different day or time could be clues. Barely visible date changes on a flip-over desk calendar that're clear when zoomed in? Days crossed off on a wall calendar? Blown light bulb changed from warm white to cool white so the white balance is off?

 

 

Thanks a bunch. Great notes!!!