Moviepy: Duration floating point round-off causes "IndexError: list index out of range" in write_videofile

[pkarp0]

The sample code creates a color clip with a duration of 2.24, a size of [1080, 1080] and fps=50.0
The clip writes properly after CompositeVideoClip but if it is concatenated then the duration changes slightly and writing fails.

>>> vclip = ColorClip([1080, 1080], color=[255, 128, 64], duration=2.24)
>>> vclip.duration
2.24
>>> vclip.size
(1080, 1080)
>>> comp = CompositeVideoClip([vclip])
>>> comp = comp.set_fps(50.0)
>>> comp.fps
50.0
>>> comp.write_videofile('comp.mp4', preset='ultrafast')

The file writes successfully

>>> concat = concatenate([comp])
>>> concat.duration
2.2400000000000002
>>> concat.write_videofile('concat.mp4', preset='ultrafast')

The write_videofile() fails with IndexError

  Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<decorator-gen-51>", line 2, in write_videofile
  File "/usr/local/lib/python3.6/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 "/usr/local/lib/python3.6/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 "/usr/local/lib/python3.6/site-packages/moviepy/decorators.py", line 22, in convert_masks_to_RGB
    return f(clip, *a, **k)
  File "/usr/local/lib/python3.6/site-packages/moviepy/video/VideoClip.py", line 349, in write_videofile
    progress_bar=progress_bar)
  File "/usr/local/lib/python3.6/site-packages/moviepy/video/io/ffmpeg_writer.py", line 209, in ffmpeg_write_video
    fps=fps, dtype="uint8"):
  File "/usr/local/lib/python3.6/site-packages/tqdm/_tqdm.py", line 833, in __iter__
    for obj in iterable:
  File "/usr/local/lib/python3.6/site-packages/moviepy/Clip.py", line 475, in generator
    frame = self.get_frame(t)
  File "<decorator-gen-14>", line 2, in get_frame
  File "/usr/local/lib/python3.6/site-packages/moviepy/decorators.py", line 89, in wrapper
    return f(*new_a, **new_kw)
  File "/usr/local/lib/python3.6/site-packages/moviepy/Clip.py", line 95, in get_frame
    return self.make_frame(t)
  File "/usr/local/lib/python3.6/site-packages/moviepy/video/compositing/concatenate.py", line 83, in make_frame
    return clips[i].get_frame(t - tt[i])
IndexError: list index out of range

[tburrows13]

Can confirm this problem, thanks for spotting!

[pkarp0]

@tburrows13 Who are you asking for confirmation?

[tburrows13]

I meant that I can confirm this problem, sorry!

[pkarp0]

@tburrows13 Great. Thanks for your help.

[AidasLiaudanskas]

Can confirm this is still happening. the output of concatenate_videoclips assumes there's one more frame than there are in the clips that were merged. Seems to happen because of the float precision when the time of certain clip cannot be represented exactly.

[AidasLiaudanskas]

Temporary workaround if anyone's still stuck:

    final_clip = concatenate_videoclips(list_of_clips)
    try:
        final_clip.write_videofile(save_path,  threads=6, logger=None)
        logger.info("Saved .mp4 without Exception at {}".format(save_path))
    except IndexError:
        # Short by one frame, so get rid on the last frame:
        final_clip = final_clip.subclip(t_end=(clip.duration - 1.0/final_clip.fps))
        final_clip.write_videofile(save_path, threads=6, logger=None)
        logger.info("Saved .mp4 after Exception at {}".format(save_path))
    except Exception as e:
        logger.warning("Exception {} was raised!!".format(e))  

[Ierezell]

Still get the same IndexError problem but the @AidasLiaudanskas patch works perfectly fine ! Thanks