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...
New Dirac encoder and MP3 fixed-point encoder
Video scaling in fullscreen
RTSP Trickplay support
Zipped file playback
Easier encoding GUI in Qt interface
Better integration in Gtk environments
MTP devices on linux
New skin for the skins2 interface