You can put a display into power-saving, screen-saving stand-by mode by scheduling it to play a special A-SMIL media item adapi:blankScreen as the source of a <ref> item.
For example, to play a playlist that have the display put in stand-by for 2 minutes after play a 5-minute image, you can use the following SMIL script.
<smil> <head/> <body> <seq repeatCount="indefinite"> <img id="mm1" src="media/CEC_before.jpg" fit="fill" dur="300s"/> <ref dur="120s" src="adapi:blankScreen"/> </seq> </body> </smil>
Note. For full sample code, please refer to the SMIL folder that exported by SignApps Express.
SignApps Express download link: 
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