firstly you concentrate on getting the best music,camera shots in my opinion should be of secondary importance.
what should not happen,is that musicians become bored with what they are playing because they have to play it ad nauseam,to satisfy a photographers desire for good camera shots.
The best way to do it is to catch musicians playing in a non contrived situation, an artificial session is in danger of coming over as contrived,that is why nicolas carolans archives programmes are so much better,they show and reflect musicans playing in a natural[rather than artificial situation].
cameramen should keep it simple,[photographs of the crowds as well as the musicians are interesting as is the architectural environment, yes and even motor vehicles],years later, they show us much.,and reflect historical and social change
the producer should concentrate on the music first,try and capture genuine live music at a fleadh or wherever.