Getting an interesting picture of a festival is a tall order in my opinion, especially when the ratio of attendees to performers is high. If I think back at all the photos I've really liked that had a lot of people in them, almost all of them have been with the camera in a superior, usually higher, position. A picture of a crowd at eye level, or of a performer on a stage above the camera position just doesn’t do it for most people. If your intended subject matter is really the festival, and not individual people that just happen to be there, I would think less about film and more about finding of a way to get a superior position from which to capture your intended subjects. Scouting the venue in advance might help.
Denis K