Despite all the hype over digital technologies, anyone who works in forensics and video surveillance knows very well that analog video is still alive. It’s dying, of course, but sometimes you will still have to digitize old VHS for two reasons:

• The source is a surveillance VCR that is still working (it hasn’t been replaced yet)
• The source is from an old case (I’ve been found myself working on cases spawning from the eighties to yesterday)

Of course, it does not happen often (at least to me) to work in VHS;  but it happens.  I’m usually happy since it sometimes leaves more room for processing than super compressed digital videos so widely used today.

However, in this post I will speak of a more specific thing related to analog: tampering.

In the last year I’ve been working on three forensic cases where there was the strong suspicion of working on video material that was not original. The interesting thing was that all of this cases the suspicion was confirmed to be true. The cases were very different: in one case I had some avi and audio files, in one case a MiniDV cassette (digital), and in another case a VHS tape. Continue reading →