Incorporating graphics and interactive triggers in a video stream

Abstract

Triggers for interactive television display are incorporated into a video stream in coordination with graphics associated with the triggers. Graphic sources such as channels ( 16, 18 ) of a character generator ( 21 ) supply graphics associated with the triggers to graphic signal inputs ( 26, 28 ) of a switch. When a channel supplies a graphic, a message denoting the associated trigger and associating the trigger with the channel is forwarded to a gateway computer ( 60 ). The gateway computer monitors connections between graphic signal inputs ( 26, 28 ) and the video output ( 32 ) of the switch, and forwards triggers associated with a particular channel to an inserter ( 40 ) only if such channel is connected to output ( 32 ).

1 . A method of providing a trigger to be associated with a graphic in a video stream comprising: 
 (a) providing graphic data specifying a graphic to be displayed, said graphic data including template data specifying a graphic region of the video screen to be occupied by the displayed graphic, said template data being in a form intelligible to a video graphic generator; and    (b) automatically deriving from said template data an interactive trigger specifying a hot spot responsive to a cursor click in a hot spot region having a predetermined spatial relationship to the graphic region.    
   
   
       2 . A method as claimed in  claim 1  further comprising the steps of operating a graphic generator to generate the graphic specified by the graphic data and incorporating the graphic in an output video stream, said step of automatically deriving said trigger being performed in response to said step of operating the graphic generator.  
   
   
       3 . A method as claimed in  claim 2  wherein said step of operating a graphic generator includes the step of operating the graphic generator to retrieve a specification unit incorporating said template data for one or more graphics, graphic content data defining the content of each said one or more graphics, and trigger data specifying one or more triggers associated with one or more of said one or more graphics specified by the template data and content data in such specification unit.  
   
   
       4 . A method as claimed in  claim 3  wherein said step of operating a graphic generator includes the step of automatically sending from said graphic generator a message including said template data, said step of automatically deriving said trigger including receiving said message at a gateway circuit separate from the graphic generator and deriving said trigger in said gateway circuit.  
   
   
       5 . A method as claimed in  claim 1  wherein said interactive trigger specifies a hot spot substantially coextensive with the graphic region.  
   
   
       6 . A method as claimed in  claim 1  wherein said interactive trigger specifies a hot spot outside of said graphic region but adjacent thereto.