[Python] Python: editing a video file using opencv (and optionally moviepy, ipython)?

I need to read in a video using opencv, do some processing to it and export it. The code i have written is below. Right now the process is converting video to grayscale.

import cv2

# Define the codec and create VideoWriter object
fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('output.avi',fourcc, 25.0, (960,540))

cap = cv2.VideoCapture('input.mp4')

while(cap.isOpened()):
ret, frame = cap.read()
if ret == True:
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
out.write(gray)
else:
break

cap.release()
out.release()


The input file 'input.mp4' has these details. I am new to this so i don't know which attributes are necessarily needed, so i will post most of them. Right now the video is only writing 5.55 kb, and doesn't play the file if you click on it, says "Windows Media Player encountered a problem while playing this file".

File Item type: MP4 Video Size: 2.51 MB Video Length: 00:00:08 Frame width: 960 Frame height: 540 Data rate: 2634kbps Total bitrate: 2637kbps Frame rate: 25 frames/second Audio Bit rate: 2kbps Channels: 2(stereo) Audio sample rate: 48 kHz

Here is the more specific code of what i'm supposed to be doing, but i'm not sure if this is hacked up/pseudocode so i need to understand what i'm doing before i move to this step. If you understand on how to make this work, please clarify on this code as well. I just need to find a way to open, edit and save a working video file, it seems simple but a week has already passed...

# Import everything needed to edit/save/watch video clips
from moviepy.editor import VideoFileClip
from IPython.display import HTML

white_output = 'white.mp4'
clip1 = VideoFileClip("solidWhiteRight.mp4")
white_clip = clip1.fl_image(process_image)
%time white_clip.write_videofile(white_output, audio=False)

HTML("""
<video width="960" height="540" controls>
<source src="{0}">
</video>
""".format(white_output))

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