How I converted Pianola Rolls to MIDI Files

I wanted to convert the pianola rolls to MIDI files for two reasons:

Firstly the pianola rolls were old (probably up to 80 years old). The paper had turned yellow and it was becoming brittle. It was clear that the rolls would not last for very much longer.

Secondly the pianola itself was old and some of its internal mechanisms needed repair. Therefore often there would not be enough power for the pianola to play all the required notes simultaneously.

Over many years I had tried a number of methods to convert the pianola rolls, including transcribing to sheet music, building a circuit board to mimic the pianola electronically, and videoing a pianola roll as it played to measure note positions

However, I was not successful.

Eventually I decided to photograph the rolls using a digital camera (a Sony Digital Mavica) creating a series of photographs along the pianola roll.

These photographs could then be placed side by side to create a long and thin bitmap image (typically 480 pixels wide by 12,000 to 20,000 pixels high) of each pianola roll

I also wrote a computer program to display these photographs and allow me to locate the start and end positions of each note on the computer screen.

The computer program then calculated when each note should start and finish playing, and created the MIDI file for each pianola roll. The program also allowed me to allocate an instrument to each pianola roll, and to control the speed and volume of playback.

It was quite a slow process. A typical roll would require 40 or 50 photographs, depending on its length, which took at least an hour to take. Identifying the start and end of all the notes on the computer screen took 3 or 4 hours per roll.

However, I am very pleased with the end results.

When a friend heard one of the completed MIDI files playing, they initially thought that they were listening to a tape-recording of the pianola playing. This proved to me that the process had accurately recorded the pianola roll music, and that I had finally succeeded in converting the pianola rolls to a more durable format.