VLC media player is a highly portable multimedia player for various audio and video formats (MPEG-1, MPEG-2, MPEG-4, DivX, mp3, ogg, ...) as well as DVDs, VCDs, and various streaming protocols. It can also be used as a server to stream in unicast or multicast in IPv4 or IPv6 on a high-bandwidth network. It doesn't need any external codec or program to work.
Free, Open Source and cross-platform
Independant of systems codecs to support most video types
Instant pausing and Frame-by-Frame support
Finer speed controls
New HD codecs (AES3, Dolby Digital Plus, TrueHD, Blu-
Ray Linear PCM, Real Video 3.0 and 4.0, ...)
New formats (Raw Dirac, M2TS, ...) and major improvements in many formats...