Calibration, dynamics test, and demonstration of a 1920 player piano. Mechanism revealed: "bellows", pneumatic motor, tracker bar, paper tracking system. Roulette Rag and Hot Dog. Note: Music rolls or piano rolls were almost never played or recorded by a pianist. Even when the artist was part of the process, arrangers, some skilled, some not, edited the rolls heavily and limited by factory rules and equipment. The person pedaling the player piano and operating the control levers (sustain, tempo, piano, and forte) has the final say in the piano roll performance.