CODEC - COder-DECoder. In the videoconferencing world, a video codec converts analog video signals from a video camera to digital signals for transmission over digital circuits, and then converts the digital signals back to analog signals for display. In the audio world, an audio codec converts analog audio signals to digital signals for transmission over digital circuits, and then converts the digital signals back to analog signals for reproduction.
From : www.region-s.de/technik/glossary.htm