Description of the PA file formats

Why three types of files?
A piano roll contains perforations that control the piano's notes, pedals, and in a reproducing piano like the Ampico, the pneumatic expression system. A computer file of a piano roll (called an eroll) therefore has to store all this information. There are three formats that do this: MIDI (for any MIDI instrument) and, for pneumatic pianos, Bar/Ann and e-MIDI.

The Bar/Ann format was developed especially for piano rolls and has two files: Bar file (musical information); Ann file (information such as title, composer etc). Bar/Ann files are played with a program called WindPlay, which was developed for the PowerRoll.

An e-MIDI file is a MIDI file that records each perforation in a piano roll as a MIDI note code. If you play an e-MIDI file on an electric MIDI piano, you'll hear the expression data sounding as extra notes. An e-MIDI file can be played with any MIDI sequencer, but only into a pneumatic piano fitted with a system like the Gerety/Chase MIDI valve system.

Standard MIDI 0 files (SMF)
An SMF file suits most MIDI instruments. Here the expression (called the MIDI velocity) is a number (0 to 127) that tells a MIDI instrument how loudly to play a note. MIDI instruments include mechanical pianos like the Disklavier, any electronic piano or MIDI sound generator (even a computer). The PA MIDI files are all type 0, and play on any MIDI instrument. The expression was converted from Ampico coding to MIDI velocity values with an "emulator", in this case with WindPlay.

How do they sound?
We believe these files give an excellent performance, because:
1. The rolls (mostly quality originals) were 'read' with air rather than light, eliminating potential sources of error. (See Q&A page)

2. All recordings were monitored during the recording process, allowing adjustments to be made as the recording progressed to ensure best results on a mechanical piano, not just a computer.

3. The Ampico expression system is predictable, allowing excellent emulations of the dynamics.