Recently I used the program FFmpeg to automatically extract metadata about the time and date some videos I’ve been using for my research were created. FFmpeg is a really useful tool for manipulating videos and images at the command-line. You can do things like change the format, quality or length of your video files with relative ease. The image processing library OpenCV even uses FFmpeg under the hood for opening videos you want to process. You can also use FFmpeg to extract metadata about your video files, and that is what I was using it for. However, I soon discovered that the metadata I retrieved with the program wasn’t completely accurate. Video file creation times were off by a couple of hours. Normally that doesn’t matter much, however if you’re breaking your data down hour-by-hour over a 2 week period, having these kinds of discrepancies really throws your analysis out. It was a great reminder to always thoroughly check the output of your analysis pipelines and to never assume that a tool will work perfectly all the time.