I've just put this JS FX together in response to:
http://forum.cockos.com/showthread.php?t=26833
It selects MIDI notes within a velocity range and rescales the velocity into a new range.
Here's the link to the JS FX:
https://stash.reaper.fm/v/1901/DS_MIDI_Vel_Ranger
In Reaper:
- add the FX to a MIDI track,
- select the MIDI channel you want to affect,
- select the range for the input velocities,
- select the range for the output velocities,
- right-click the MIDI item and select "Apply FX to item as new take".
- this writes the MIDI output the FX to a new lane (take) on the same track
[Edit]
Thanks to those whose JS snippets I've used.
Let me know if there's any problems.