Ubiquitous open-source command-line tool for video/audio transcoding and processing. Used as the transcoding engine throughout the talk. Supports per-input custom arguments, presets (ultrafast…ultraslow), H.264 profiles, pixel format selection, and can transcode either a local file or a remote URL (downloading on the fly). Also provides ffprobe for inspecting media metadata (can approximate duration from bitrate/size when duration is missing, which may be off by several seconds). Has a documented history of security vulnerabilities that can compromise the host server.