This website advocates using SMIL as an open standard for digital signage.
SMIL as an Open Standard for Digital Signage
SMIL (pronounced "smile") stands for "Synchronized Multimedia Integration Language" and defines scheduling ("synchronized"), video, audio, images, text ("multimedia"), multi-zone screen layout ("integration") in an XML-based text file format ("language"). It is an open specification (royalty-free to use) created by the World-Wide Web Consortium, the same organization responsible for defining the HTML language, an open standard for the Internet. Products that utilize SMIL are available from leading companies such as Adobe, Apple, Microsoft, and Real Networks.
Why SMIL for Digital Signage
Digital signage deals with scheduling multimedia files for playback on digital displays connected on an IP network. The industry has roots tracing back for a few decades, but has recently expanded rapidly due to the proliferation of low-cost flat panel displays that are easy to install and maintain in public space. As the market expands out of the "emerging" status, mainstream customers demand compatibility and interoperability among products from different vendors. SMIL appears to be an ideal technology to answer the needs of the industry.