libavcodec is a free and open-source library of codecs for encoding and decoding video and audio data. Because of a project fork, libraries with this name are provided by FFmpeg and Libav, but they are incompatible.libavcodec is an integral part of many open-source multimedia applications and frameworks. The popular MPlayer, xine and VLC media players use it as their main, built-in decoding engine that enables playback of many audio and video formats on all supported platforms.