ActiveMovie and DirectShow
DirectShow was known internally as Quartz during its development. The first release was ActiveMovie 1.0, released in July 1996. This provided an ActiveX control for media playback that supported playback of MPEG 1,AVI and QuickTime videos as well as audio files. There is an SDK that provides tools and information for developing filters and applications.
However, for the second release a year later, Microsoft renamed it to DirectShow to provide a more consistent naming scheme along with a re-organisation of the DirectX, ActiveAnimation and ActiveMovie development groups. Release 5 of DirectShow provided support for DVD playback as well as a limited set of video and audio capture/recording and editing features. Release 6 of DirectShow was released in September 1998 and includes an MPEG-2 splitter (but not decoder) and a number of bugfixes and (relatively minor) enhancements. The latest version is DirectX 9.0.
DirectX 8 contained features only available on XP. In particular, the Video Mixing Render -- a substantial improvement on previous video renderers -- was only available on Windows XP. This has now been rectified in DirectX 9, which includes a version of the VMR for non-XP platforms.
The most recent version of DirectShow for Windows NT is DirectX Media v6 (DirectShow and DirectX did not merge until release 8).