These changes are more invasive than my previous conversions.
a) Some private/protected method signatures now take a size parameter.
b) Deleted vtkMPEG2Writer entirely, because 1) it uses sprintf and I can’t find the size of the buffer, I think it’s been removed. 2) The class hasn’t been built in years.
c) some new defines introduced to avoid copy-pasting magic numbers.

The only remaining sprintf, I think, are in third party or C code.