Whats the difference between schedule, preroll and execute splicing commands?
The schedule command is used to tell a downstream splicer a schedule of upcoming splices. The schedule command must be followed by a separate execute command for each splice event. The preroll command is optional. It gives a relative time warning of a splice. Prerolls are sent a few seconds prior to the arrival of the splice point and may be sent repeatedly as a countdown to the splice execute command. The execute command is the only command that actually causes a splice to occur.
