Digital signage system control is provided by delivering media content from a digital signage system to display devices. A terminal's display of a custom channel producer may be controlled to display media asset options. The selection by the custom channel producer of media assets is detectable based on selection of displayed media asset options of media assets. The selected media assets are stored in a media store external to the system. The media store stores media assets that are deliverable to a viewing device responsive to a viewer's selection of the viewing device. The display parameters of further media asset stored in a media store external to the system may be validated and selected by the custom channel producer to produce a custom channel that includes the selected media assets with further media assets that are dependent on the display parameters. The custom channel is deliverable to the display devices.