FFmpeg

The FFmpeg project publishes three command line programs and the libraries beneath them. ffprobe reads a file and reports its container, streams, codecs, frame rate, duration and timestamps, down to the type and timing of every frame, in text or JSON. ffmpeg decodes, encodes, converts between formats, cuts by time, joins files, remuxes streams into a new container without re-encoding, extracts frames as images and applies filters such as cropping, scaling and deinterlacing. ffplay is a small player. The libraries, libavcodec, libavformat, libavfilter and the rest, are what many players and forensic products build on. FFmpeg is licensed under the GNU Lesser General Public License version 2.1 or later, with the GNU General Public License applying when optional GPL parts are compiled in. The project's About page lists Linux, macOS, Windows, the BSDs and Solaris.

In a laboratory the first command run on any new file is ffprobe, to record what the file is before anything plays it. Remuxing with stream copy keeps the original encoded data and only changes the container, which is the right way to make a stubborn file playable. Exporting frames to a lossless format such as PNG keeps pixel values intact. Any re-encode changes pixels and must be labelled a working copy, never presented as the original. Timestamps deserve care: CCTV exports often have a variable frame rate with gaps, and a conversion to a constant rate can drop or duplicate frames unless the examiner chooses the settings deliberately. Every command line used is written into the notes, together with the FFmpeg version, because builds differ. FFmpeg decodes many formats but not the proprietary wrappers some DVR makers use, which need the vendor's player or a product such as Amped FIVE.