Machines · Study 071
Piano Roll
A player piano roll scrolls past the tracker bar and each punched hole presses a key. The tune is composed on the fly, bass and melody.
What you're looking at
Holes move down the paper toward a dark bar. While a hole is over the bar, the key in that column is held down, so a long slot is a long note. The music is generated as it goes: a bass note on the beat taken from a four chord loop, and a melody that wanders up and down the upper keys in small steps.
The idea behind it
In a real player piano the bar is a row of small openings connected to a vacuum. A hole in the paper lets air in, which trips a pneumatic valve that throws the hammer. Rolls were the main way recorded piano music reached homes in the 1910s and 1920s, before radio and electrical recording took over.
Try this
Watch a hole reach the bar and its key light up. Restart for a different tune.
