1. MF answer is nice, but not quite correct.
If we capture fast moving ball at 30fps, it'll NOT must be a blur.
Camera's (camcorder) frame shooting time (exposition) is dependent on record mode ("normal", "sport", "golf"). This time of course is not large than 1/fps (1/60 sec), but may be quite small for bright scenes (up to 1/2000 sec). The fast moving ball may be quite sharp, and framerate interpolation (with motion compensation) will be sharp too.
2. GenMotion may be used, for example, to change framerate with factor=1.5, from 16.6 fps (old 8 mm film) to 25 fps.
Script:
Avisource("kino.avi")
loadplugin("avisynth_c.dll")
converttoYV12()
loadCplugin("genmotion.dll")
i=ConvertToYV12()
f1_3=GenMotion(i,filename="c:\deshaker.log",delta=1./3)
b1_3=GenMotion(i,filename="c:\deshaker.log",delta=-1./3)
interleave(f1_3,i,b1_3)
selectevery(6,0,1,2)
Crop(48,32,720-48-32,576-32-32).AddBorders(48,32,32,32)
converttoYUY2()