vfx.scroll giving TypeError: slice indices must be integers or None or have an __index__ method

[tburrows13]

I run:

new_clip = vfx.scroll(clip, w=1000, x_speed=5)
new_clip = new_clip.set_duration(float(clip.w - 1000) / 5)
new_clip.write_videofile("pano.mp4", fps=24)

as recommended by Zulko in #240, but it gives the following error:

  File "/Users/tomburrows/Dropbox/Python Programming/QF_Editor/panorama_scroll.py", line 8, in <module>
    new_clip.write_videofile("pano.mp4")
  File "<decorator-gen-51>", line 2, in write_videofile
  File "/anaconda/lib/python3.5/site-packages/moviepy/decorators.py", line 54, in requires_duration
    return f(clip, *a, **k)
  File "<decorator-gen-50>", line 2, in write_videofile
  File "/anaconda/lib/python3.5/site-packages/moviepy/decorators.py", line 137, in use_clip_fps_by_default
    return f(clip, *new_a, **new_kw)
  File "<decorator-gen-49>", line 2, in write_videofile
  File "/anaconda/lib/python3.5/site-packages/moviepy/decorators.py", line 22, in convert_masks_to_RGB
    return f(clip, *a, **k)
  File "/anaconda/lib/python3.5/site-packages/moviepy/video/VideoClip.py", line 345, in write_videofile
    progress_bar=progress_bar)
  File "/anaconda/lib/python3.5/site-packages/moviepy/video/io/ffmpeg_writer.py", line 209, in ffmpeg_write_video
    fps=fps, dtype="uint8"):
  File "/anaconda/lib/python3.5/site-packages/tqdm/_tqdm.py", line 833, in __iter__
    for obj in iterable:
  File "/anaconda/lib/python3.5/site-packages/moviepy/Clip.py", line 475, in generator
    frame = self.get_frame(t)
  File "<decorator-gen-14>", line 2, in get_frame
  File "/anaconda/lib/python3.5/site-packages/moviepy/decorators.py", line 89, in wrapper
    return f(*new_a, **new_kw)
  File "/anaconda/lib/python3.5/site-packages/moviepy/Clip.py", line 95, in get_frame
    return self.make_frame(t)
  File "/anaconda/lib/python3.5/site-packages/moviepy/Clip.py", line 136, in <lambda>
    newclip = self.set_make_frame(lambda t: fun(self.get_frame, t))
  File "/anaconda/lib/python3.5/site-packages/moviepy/video/fx/scroll.py", line 17, in f
    return gf(t)[y:y+h, x:x+w]
TypeError: slice indices must be integers or None or have an __index__ method

Doing some research, this is because x is 0 when you first call it, but then when it writes the video to a file, it iterates for each frame, and the second time, x is 1.0. This is a float, not an int so it fails.
A solution that worked for me is to change lines 14 and 15 of scroll.py to change the float into a int.
Can anyone repro this, and shall we make the suggested changes?

[ghost]

I believe this is the code causing the issues:

 x = max(0, min(xmax, x_start+ np.round(x_speed*t)))
 y = max(0, min(ymax, y_start+ np.round(y_speed*t)))

could we change np.round to just round? I assume np.round is returning a float instead of an int. Is that correct?

[tburrows13]

@Earney, yes that is the code I figured is the error. I just stuck and int(max..)))) round the whole thing, but yours sounds better (I've never used numpy).

[tburrows13]

Changing np.round to round does not fix it.
The code that is called each frame is here:

def f(gf,t):
    x = max(0, min(xmax, x_start+ np.round(x_speed*t)))
    y = max(0, min(ymax, y_start+ np.round(y_speed*t)))
    print(t, y, h, x, w)  # Added by me for tests
    return gf(t)[y:y+h, x:x+w]

The above prints 0 0 1080 0 2000 when the scroll effect is applied. Then it prints 0.0 0 1080 0 2000 after write_videofile is called for the first frame. Then for the second frame, it prints 0.0666666666667 0 1080 10.0 2000 which causes it to error, because 10.0 is a float, not an integer.

[tburrows13]

This is the picture that fails.

[ghost]

awesome.. I'll give this a try..

[ghost]

this works for me without modifications.