import numpy as np
[docs]def fadein(clip, duration, initial_color=None):
"""Makes the clip progressively appear from some color (black by default),
over ``duration`` seconds at the beginning of the clip. Can be used for
masks too, where the initial color must be a number between 0 and 1.
For cross-fading (progressive appearance or disappearance of a clip
over another clip, see ``transfx.crossfadein``
"""
if initial_color is None:
initial_color = 0 if clip.is_mask else [0, 0, 0]
initial_color = np.array(initial_color)
def filter(get_frame, t):
if t >= duration:
return get_frame(t)
else:
fading = 1.0 * t / duration
return fading * get_frame(t) + (1 - fading) * initial_color
return clip.transform(filter)