A piano roll is a music storage medium used to operate a player piano, piano player or reproducing piano. A piano roll is a continuous roll of paper with perforations (holes) punched into it. The perforations represent note control data. The roll moves over a reading system known as a 'tracker bar' and the playing cycle for each musical note is triggered when a perforation crosses the bar and is read.
The majority of piano rolls play on three distinct musical scales. The 65-note (with a playing range of A-1 to C#7) format was introduced in 1896 in the USA specifically for piano music. In 1900 a USA format playing all 88-notes of the standard piano scale was introduced. In 1902 a German 72-note scale (F-1, G-1 to E7) was introduced. All of these scales were subject to being operated by piano rolls of varying dimensions. The 1909 Buffalo Convention of US manufacturers standardized the US industry to the 88-note scale and fixed the physical dimensions for that scale.
Piano rolls were in continuous mass production from around 1896 to 2008, and are still available today, with QRS Music claiming to have 45,000 titles available with "new titles being added on a regular basis". Largely replacing piano rolls, which are no longer mass-produced today, MIDI files represent a modern way in which musical performance data can be stored. MIDI files accomplish digitally and electronically what piano rolls do mechanically. Software for editing a performance stored as MIDI data often has a feature to show the music in a piano roll representation.
Metronomic, hand played, and reproducing rolls 
Metronomic or arranged rolls are rolls produced by positioning the music slots without real-time input. The music, when played back, is typically purely metronomical. Metronomically arranged music rolls are deliberately left metronomic so as to enable a player-pianist to create their own musical performance via the hand controls that are a feature of all player pianos.
Hand played rolls are created by capturing in real-time the hand-played performance of one or more pianists upon a piano connected to a recording machine. The production roll reproduced the real-time performance of the original recording whilst played back at a constant speed. It is industry convention for recordings of music intended to be used for dancing to be regularized into strict tempo despite the original performance having the slight tempo fluctuations of all human performances.
Reproducing rolls are the same as hand-played rolls but have additional control codes to operate the dynamic modifying systems specific to whichever brand of reproducing piano it is designed to be played back on. The roll plays back at a fixed constant speed to preserve the inter-relationship of these control codes and the time it takes for the pianos dynamic mechanisms to operate between sequential control codes.
Compositions for pianola and reproducing piano 
The player piano gives the opportunity to create music that is impossible for humans to play, or, more correctly, music that was not conceived in terms of performance by hand. Over one hundred composers wrote music specially for the player piano during the course of the 20th century. Many mainstream composers experimented with its possibilities Igor Stravinsky, Alfredo Casella and Paul Hindemith and others, Conlon Nancarrow, made it their primary millieu.
The Duo-Art, Ampico and Welte-Mignon brands were known as "reproducing" piano rolls, as they could accurately reproduce the touch and dynamics of the artist as well as the notes struck, when played back on capable pianos.
Reproducing pianos 
Rolls for the reproducing piano were generally made from the recorded performances of famous musicians. Typically, a pianist would sit at a specially designed recording piano, and the pitch and duration of any notes played would be either marked or perforated on a blank roll, together with the duration of the sustaining and soft pedal.
Reproducing pianos can also re-create the dynamics of a pianist's performance by means of specially encoded control perforations placed towards the edges of a music roll, but this coding was never recorded automatically. Different companies had different ways of notating dynamics, some technically advanced (though not necessarily more effective), some secret, and some dependent entirely on a recording producer's handwritten notes, but in all cases these dynamic hieroglyphics had to be skillfully converted into the specialized perforated codes needed by the different types of instrument.
Recorded rolls play at a specific, marked speed, where for example, 70 signifies 7 feet of paper travel in one minute, at the start of the roll. On all pneumatic player pianos, the paper is pulled on to a take-up spool, and as more paper winds on, so the effective diameter of the spool increases, and with it the paper speed. Player piano engineers were well aware of this, as can be seen from many patents of the time, but since reproducing piano recordings were generally made with a similar take-up spool drive, the tempo of the recorded performance is faithfully reproduced, despite the gradually increasing paper speed.
The playing of many pianists and composers is preserved on reproducing piano roll. Gustav Mahler, Edvard Grieg, Claude Debussy, Scott Joplin, Sergei Rachmaninoff, Sergei Prokofiev, Alexander Nikolayevich Scriabin, Jelly Roll Morton and George Gershwin are amongst the composers who have had their performances recorded in this way.
Duo-Art featured artists such as Ignace Jan Paderewski, George Gershwin, Maurice Ravel, Percy Grainger, Leopold Godowsky and Ferruccio Busoni. The Ampico brand's featured artists included Sergei Rachmaninoff, Leo Ornstein, Mischa Levitzki, Winifred MacBride, and Marguerite Volavy. For Welte-Mignon, which was the first reproducing system, there played artists like Gustav Mahler, Claude Debussy, Alexander Scriabin, Eugen d'Albert, Josef Lhevinne, Raoul Pugno, and Carl Reinecke (who was the earliest-born pianist to record in any media format).
There were hundreds of companies worldwide producing rolls during the peak period of their popularity (1900–1927). Some other non-reproducing rolls makers of live performances are listed below together with their most memorable recording artistes.
- QRS Company — James P Johnson, Fats Waller, Zez Confrey, J. Lawrence Cook, Pete Wendling and Victor Arden
- Mastertouch Piano Roll Co Australia
- US Music Roll Company; Lee Sims, Robert Billings
- Imperial — Charley Straight, Roy Bargy
- Vocalstyle — Jelly Roll Morton, Walter Davison, Clarence Jones, Luckey Roberts, Cow Cow Davenport
- Capitol/Columbia; Jimmy Blythe, Clarence Johnson
See also 
- Book music
- Music roll is the generic term for similar rolls used to operate fairground organs (or band organs), calliopes, hand-cranked organs, orchestrions and other types of automatically played pipe organ or mechanical organ.
- Elaine Obenchain: The complete catalog of Ampico Reproducing Piano rolls. New York: American Piano Co., ca.. 1977. ISBN 0-9601172-1-0; (out of print).
- Charles Davis Smith: Duo-Art piano music: a complete classified catalog of music recorded for the Duo-Art reproducing piano compiled and annotated by Charles Davis Smith. Monrovia, California, ca. 1987; (out of print).
- Charles David Smith and Richard James Howe: The Welte-Mignon, its music and musicians; complete catalogue of Welte-Mignon reproducing piano recordings 1905–1932, historical overview of companies and individuals, biographical essays on the recording artists and composers. Vestal, NY: Vestal Press, 1994. ISBN 1-879511-17-7; (out of print).
- Gerhard Dangel und Hans-W. Schmitz: Welte-Mignon-Reproduktionen / Welte-Mignon Reproductions. Gesamtkatalog der Aufnahmen für das Welte-Mignon Reproduktions-Piano 1905-1932 / Complete Library Of Recordings For The Welte-Mignon Reproducing Piano 1905-1932. Stuttgart 2006. ISBN 3-00-017110-X
- Barbara Bryner: The piano roll: a valuable recording medium of the twentieth century. Dept. of Music, University of Utah, 2002. OCLC 50482085
- "The day the music died". Buffalo News. Retrieved 12 September 2010.
- "Music". QRS Music. Retrieved 12 September 2010.
- US-Patent 287.599, Emil Welte, New York, 30. October 1883
|Wikimedia Commons has media related to: Piano rolls|
- The Reproducing Piano Roll Foundation
- The Player Piano Group : the main UK society
- The Pianola Forum - online discussion group
- QRS Piano Rolls
- Julian Dyer Piano Rolls - new Duo-Art 100% accurate music rolls
- Pianola.co.nz - Listen to MIDI files created by scanning player piano rolls
- Information about Welte-Mignon
- Warren Trachtman's Piano Roll Scanning Information Page
- L. D. Henderson tells a modern roll-arranger's story.
- Maesto - Recuts of music- and piano-rolls
- Complete listing of all Welte-Mignon-Rolls