Free codecs

FFmpeg is a free and open-source software project consisting of a suite of libraries and programs for handling video, audio, and other multimedia files and streams. At its core is the command-line ffmpeg tool itself, designed for processing video and audio files. It is widely used for format transcoding, basic editing (trimming and concatenation), video scaling, video post-production effects, and standards compliance (SMPTE, ITU).

ffdshow is an open-source unmaintained codec library that is mainly used for decoding of video in the MPEG-4 ASP (e.g. encoded with DivX or Xvid) and H.264/MPEG-4 AVC video formats, but it supports numerous other video and audio formats as well. It is free software released under GNU General Public License 2.0, runs on Windows, and is implemented as a Video for Windows (VFW) codec and a DirectShow filter.

libavcodec is a free and open-source library of codecs for encoding and decoding video and audio data.

libdvdcss (or libdvdcss2 in some repositories) is a free and open-source software library for accessing DVDs encrypted with Content Scramble System (CSS). libdvdcss is part of the VideoLAN project and is used by VLC media player and other media player software, such as Ogle, xine-based players, and MPlayer.

video codec