I'm not going to try to get terribly definitive here because my
knowledge on the subject is incomplete (difficult for a Genius to admit)
but my understanding is that the mechanical principals of player pianos
actually derive from automated European (English?) textile looms
developed during (perhaps precipitating) the Industrial Revolution, in
which a perforated medium, perhaps similar to band organ "book" music
was used to automatically weave repetitive patterns in cloth. It is
entirely possible that the Frenchman Forneaux conceived his ideas for
controlling a piano by mechanical (pneumatic) means from this
technology, culminating in his 1863 patents for the mechanism.  But if
not the "first", player pianos certainly rank very high (or low,
depending on your viewpoint) in the family tree of "computers".
Contributions from those with more (documentable) information are
welcome.  -John Grant