Acceleration of Music Rolls Whilst Playing

Twice recently I have played the YouTube examples of player piano rolls;
the latest was "The Ice Skaters" Fox Trot mentioned in MMD 31/01/17:

  https://www.youtube.com/watch?v=dGXZdY0-h18 

In each case the music appeared to be playing considerably faster at
the end of the roll than at the beginning.  Was this a characteristic
of music rolls that had to be controlled by the pianolist?  I thought
that I had read that the mechanism automatically compensated for the
changing dimensions of the spools as the tune progressed.

Jon Polden

 [ In all player pianos the take-up spool motor is regulated to maintain
 [ constant take-up spool revolutions per minute.  Thus the paper speed
 [ increases during the performance as the take-up diameter increases.
 [
 [ Classical performances recorded live at a recording piano generally
 [ were processed to compensate for the acceleration caused by the paper
 [ building up on the take-up spool.  Virtually all other piano rolls
 [ had no such compensation and so it was left to the Pianolist to
 [ diminish the take-up spool speed during the performance.
 [
 [ MMD articles on this topic are indexed at
 [ http://www.mmdigest.com/archives/KWIC/A/acceleration.html 
 [ In particular, see the article by Wayne Stahnke concerning Ampico at
 [ http://www.mmdigest.com/archives/Digests/199811/1998.11.01.18.html 
 [ -- Robbie