Until about two years ago, it wasn't that often that I’d encounter Variable Frame Rate (VFR) video evidence, unless of course the case included video recorded by mobile phones. Times, they are a changing my friend.
DVR/NVR manufacturers are leveraging the advantages of VFR more often these days. And why shouldn't they be, especially when we’re seeing even the high-end professional video recording equipment start to use VFR more frequently. Throw in the want/need to get to Ultra HD before the next guy, and suddenly you've got a decent argument for VFR.
Here’s the thing, if you’re dealing with VFR material that is evidence, you need to be (1) aware that you have VFR material, and (2) have the proper tools and workflow for processing that material. I know, seems like a no-brainer, but how does your NLE handle VFR material, if at all? Do you have control over how it’s interpolated or converted? What’s going on in the background to “make your life easier”?
Be aware, be very aware.