Good to have this filter for vapoursynth, tested on amp and acv curve file and both work fine.
Though your description of the filter is wrong, this is a curve reader, it doesn't create or edit curve like what it was descripted.
And I'm reporting a bug, if I declared a wrong type in the argument for the input curve file, the editor will crash. The 2 crashs I found are
Code:
cur_path = r'test.amp'
clip = core.grad.Curve(clip, cur_path, ftype=2, pmode=1)
cur_path = r'test.acv'
clip = core.grad.Curve(clip, cur_path, ftype=6, pmode=1)