The exif comment of the resulting gif file is 'Lavc54.59.100'. So it's most likely ffmpeg/libav or a tool that utilizes their libraries, such as mplayer. It's f

The exif comment of the resulting gif file is 'Lavc54.59.100'. So it's most likely ffmpeg/libav or a tool that utilizes their libraries, such as mplayer. It's fairly simple to produce a GIF from a video file using the ffmpeg cli.