this problem is a ffmpeg command parameter wrong!
It should be modified like bellow :
video_writer = ffmpeg_writer.FFMPEG_VideoWriter(path_out, video_clip.size, video_clip.fps, codec="libx264",
preset="slow", bitrate="2000k",
audiofile=None, threads=None,
ffmpeg_params=None)
this problem is a ffmpeg command parameter wrong!
It should be modified like bellow : video_writer = ffmpeg_writer.FFMPEG_VideoWriter(path_out, video_clip.size, video_clip.fps, codec="libx264", preset="slow", bitrate="2000k", audiofile=None, threads=None, ffmpeg_params=None)