StreetSign is a digital signage system, originally written for the TeenStreet 2013 (Germany) youth congress. It works with a single server, and multiple client computers connect over the network. It is lightweight enough that a Raspberry PI can run as the server for smaller installations.
xine is a free multimedia player. It plays back CDs, DVDs, and VCDs. It also decodes multimedia files like AVI, MOV, WMV, and MP3 from local disk drives, and displays multimedia streamed over the Internet. It interprets many of the most common multimedia formats available--and some of the most uncommon formats, too. All those features come in a reusable library (xine-lib) which can easily be embedded in your applications.
XMovie is a multimedia player for high quality Quicktime, MPEG, and DVD movies that supports 6 channel audio. The Quicktime decoder reads OpenDivx, assorted YUV formats, JPEG photo, MJPA, RGB, DV, IMA4, ULAW, Vorbis, and PCM codecs. The MPEG decoder reads MPEG-1 video, MPEG-2 video, MPEG-1 system streams, MPEG-2 system streams, VOB files, IFO files, MP2 and MP3 audio, and AC3 audio.