Video Editing with MoviePy: A Comprehensive Python Guide

Introduction

MoviePy is a Python library designed for video editing and creation. It provides a simple and intuitive interface for:

• Video cutting and concatenation
• Adding text, images, and audio
• Applying video effects and transitions
• Creating animated GIFs
• Basic video composition and editing

Installation & Setup

1. Install MoviePy and its dependencies:

pip install moviepy

The moviepy.editor has been removed from moviepy since its 2.0 version
So for old moviepy run command:

pip install moviepy==1.0.3
pip install imagemagick

2. Import required modules:

from moviepy.editor import *
# imported all the fuctions of moviepy.editor
import moviepy.config as mpy_config
# added file path of Imagemagick to add text to the video while editing
mpy_config.IMAGEMAGICK_BINARY = r"C:\Program Files\ImageMagick-7.1.1-Q16-HDRI\magick.exe"

Key Features & Examples

Here is the basic folder structure for video editing

Explaination of functions used in below code:
VideoFileClip(input) - Loads the input video

.subclip(starting time , ending time) - trims the part of video

write_videofile(output) - exports output video

video.close() - closes the video

1. Basic Video Operations

def cliping(input_path, output_path):

    vid = VideoFileClip(input_path)
    
    clip = vid.subclip(0, 10)
    
    clip.write_videofile(output_path)
    
    vid.close()
    clip.close()
inputpath = "test.mp4"
outputpath = "test1.mp4"
cliping(inputpath, outputpath)

Moviepy - Building video test1.mp4.
MoviePy - Writing audio in test1TEMP_MPY_wvf_snd.mp3

MoviePy - Done.
Moviepy - Writing video test1.mp4

Moviepy - Done !
Moviepy - video ready test1.mp4

Before:

After:

2. Adding Text Overlays

Explaination of functions used in below code:

TextClip("word",fontsize,color) - Generates text video clip with word as "word" and respective font size and color

.set_pos("location") - sets location

.set_duration - sets the duration of the text video clip

def textadd(videopath, outputpath):

    vid = VideoFileClip(videopath) 
    
    txt = TextClip("Hello World!", fontsize=70, color='white')
    txt = txt.set_pos('center').set_duration(vid.duration)
    
    final = CompositeVideoClip([vid, txt])
    
    final.write_videofile(outputpath)
    
    vid.close()
    final.close()
inputpath = "test1.mp4"
outputpath = "out1.mp4"
textadd(inputpath, outputpath)

Moviepy - Building video out1.mp4.
MoviePy - Writing audio in out1TEMP_MPY_wvf_snd.mp3

MoviePy - Done.
Moviepy - Writing video out1.mp4

Moviepy - Done !
Moviepy - video ready out1.mp4

Before:

After:

3. Video Effects

Explaination of functions used in below code:

video.fx(vfx.function) - is used to apply effects on video

clip = VideoFileClip("test1.mp4")

bnw = clip.fx(vfx.blackwhite)

fast = bnw.fx(vfx.speedx, 2)

rotated = fast.fx(vfx.rotate, 90)

rotated.write_videofile("rotated.mp4")
clip.close()
bnw.close()

Moviepy - Building video rotated.mp4.
MoviePy - Writing audio in rotatedTEMP_MPY_wvf_snd.mp3

MoviePy - Done.
Moviepy - Writing video rotated.mp4

Moviepy - Done !
Moviepy - video ready rotated.mp4

After:

Practical Use Cases for this library

1. Content Creation

• YouTube video editing
• Social media content
• Educational materials
• Marketing videos

2. Automation

• Batch processing videos
• Automated video generation
• Adding watermarks to multiple videos

3. Data Visualization

• Creating animated graphs
• Scientific visualization
• Time-lapse videos

4. Video Analytics

• Frame extraction for analysis
• Motion detection
• Video summarization

Example code for editing batch of videos togethor

def editAll (inputpath, outputpath):
    for i in range(100):
        clip = VideoFileClip(inputpath + str(i) + ".mp4").subclip(0, 10)
        bnw = clip.fx(vfx.blackwhite)
        bnw.write_videofile(outputpath + str(i) + ".mp4")

Best Practices

1. Always close your clips to free up memory
2. Use context managers (with statement) when possible
3. Process videos in chunks for large files
4. Handle errors appropriately

Given a template for proper error handling:

def process(inputpath, outputpath):
    try:
        with VideoFileClip(inputpath) as video:
            
            processed = video.resize(0.5).subclip(0, 10)
            processed.write_videofile(outputpath)
    except IOError as e:
        print(f"Error loading video: {e}")
    except Exception as e:
        print(f"An error occurred: {e}")

FAQs

1. Previewing videos make them slower than they are?
   It means that your computer is not good enough to render the clip in real time. Don’t hesitate to play with the options of preview: for instance, lower the fps of the sound (11000 Hz is still fine) and the video. Also, downsizing your video with resize can help.

2. MoviePy generated a video that cannot be read by my favorite player?
   Known reason: one of the video’s dimensions were not even, for instance 720x405, and you used a MPEG4 codec like libx264 (default in MoviePy). In this case the video generated uses a format that is readable only on some readers like VLC.

3. I can’t seem to read any video with MoviePy
   Known reason: you have a deprecated version of FFmpeg, install a recent version from the website, not from your OS’s repositories! (see Installation).

Conclusion

MoviePy is a versatile library that makes video editing in Python accessible and efficient. Key benefits include:

• Simple and intuitive API
• Wide range of video editing features
• Good documentation

References & Further Reading

1. Official MoviePy Documentation
2. MoviePy GitHub Repository
3. FFmpeg Documentation
4. ImageMagick Documentation

Authors:
Kavyansh Shandilya - 24110163@iitgn.ac.in
Hem Tilva - 24110374@iitgn.ac.in
Amar Khatri - 24110033@iitgn.ac.in