Change the video speed using MoviePy

Imagine watching a video in the fast-forward mode, where time seems to slip through your fingers, or a video that unfolds smoothly, allowing you to enjoy every moment. This control over the speed of videos is more than just a cinematic trick. It is the power of technology combined with creative expression. In this Answer, we will explore how you can change the speed of a video using MoviePy, a versatile Python library for video editing.

What is MoviePy?

MoviePy is a helping tool for video enthusiasts and creators. It's a Python library that enables you to manipulate videos in various ways, from cutting and merging to adding effects and altering playback speed. Whether you want to create captivating time-lapses, humorous sped-up sequences, or dramatic slow-motion shots, MoviePy will be able to achieve it.

Applications of MoviePy

Before we dive into the code, let's take a quick look at some applications of MoviePy:

Content creation: MoviePy allows content creators to craft engaging videos for social media platforms. Speeding up or slowing down clips can add flair to tutorials, vlogs, or travel documentaries.
Educational videos: Educators can leverage MoviePy to emphasize specific points by manipulating the video speed. Concepts that require attention to detail can be explained in slow motion, while repetitive parts can be accelerated.
Artistic expression: Filmmakers and artists can play with time manipulation to evoke emotions. Think of an action-packed scene slowed down to savor every intense moment.

Program overview

Here's a glimpse of what our program does before we dissect it further:

Load the video clip using MoviePy.
Set the desired speed factor.
Adjust the frames per second (fps) of the video.
Apply the speed manipulation effect.
Display the final clip with the altered speed.

Libraries used

The libraries we use in this program are:

MoviePy
OpenCV

For moviepy:

import cv2
from moviepy.editor import VideoFileClip
import moviepy.video.fx.all as vfx

video_path_1 = "clip.mp4"
video_clip_1 = VideoFileClip(video_path_1)

speed_factor = 10


final_clip = video_clip_1.fx(vfx.speedx, speed_factor)
check= False
while True:
    for frame in final_clip.iter_frames(fps=final_clip.fps):
        frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
        cv2.imshow("Final Clip", frame)
        if cv2.waitKey(1) & 0xFF == ord('q'):
            check=True
            break
        
    if check!=True:
        # Reset the video reader to loop indefinitely
        final_clip=final_clip.set_start(0)
    else:
        break
cv2.destroyAllWindows()

Code explanation

Line 1: The cv2 module is imported from OpenCV, a computer vision library.
Line 2: From the moviepy.editor module, the VideoFileClip class is imported, allowing the loading and manipulation of video clips.
- moviepy.video.fx.all is imported as vfx to access various video effects.
Line 5: A string variable video_path_1 is assigned the file path of the video.
Line 6: The VideoFileClip class is used to load the video from video_path_1 into the video_clip_1 variable.
Line 8: A numerical value, speed_factor, is assigned a value of 10. This factor will determine the speed adjustment of the video clip.
Line 11: A new video clip, final_clip, is created by applying the speedx effect from the vfx module to video_clip_1 using the fx method.
- The speedx effect adjusts the speed of the video by the factor specified earlier.
Line 12–25: The final video frames are iterated and converted to OpenCV format (BGR). The frames are displayed in real-time using cv2.imshow, and the loop is interrupted when the 'q' key is pressed.
Line 26: The OpenCV windows are closed after the loop exits.

Let's take a small quiz to understand better the program we discussed in this Answer.