Abstract: A digital video special effect system for merging or replacing a first video image with a second video image. A first special effect means receives digital video information relating to a first picture sequence and transitions can be implemented in order to change the format of the image. Second special effect means provides the same facility for a second video image whereby the first and second images can be combined. A common memory stores commands to cause the first and second special effect means to cooperate on a common time-line whereby the durations of the picture sequences are automatically adjusted in order to provide a smooth combination of video images.