Question 2:
The MPEG-1 frame rate from AFNI is 24 frames per second, the slowest that
the mpeg_encode software allows. This value is hardwired into AFNI; the
mpeg_encode software (and apparently the MPEG-1 standard) only has a
fixed set of rates allowed. As far as I can tell, these rates are 24,25,30,50
and 60 frames/sec. I could modify AFNI to allow the other rates as options,
if you need.
If you create an animated GIF, the default delay between frames is 20/100
of a second. You can alter that by altering (before you start AFNI, or in
the .afnirc file) the environment variable AFNI_AGIF_DELAY -- the units
are 0.01 seconds. PowerPoint will play these files, usually.
bob cox