Trumpeters from the Central Band of the Royal Air Force (RAF) will accolade Prince William and Catherine Middleton once they have signed the register making them husband and wife.
A practice session was held at RAF Northolt in Middlesex.
Wing Commander Duncan Stubbs, who will be directing the band of seven trumpeters and one drummer, composed a new fanfare for the day.
The piece, which will not be heard until the wedding, is called Valiant and Brave and will last for about 30 seconds.
The title is the same as the motto used by RAF 22 Squadron of which Prince William is serving as a search and rescue pilot in North Wales.