Wednesday, 03 September 2025

Create a slideshow video for multiple images

Manually making a slideshow video is difficult. You need handle every single frame, which is a tedious and error-prone process. You are forced to write complex, low-level code to manage image decoding, video encoding, and color space conversions. Synchronizing audio and video correctly becomes a significant technical challenge, often leading to sync issues. Implementing simple effects like fades or transitions requires advanced mathematical operations on each pixel for every frame. Ultimately, you need deep expertise in video codecs and file formats just to create a basic video, turning a simple creative task into a complex software engineering project.

The Python library, MoviePy, makes creating slideshow videos easy because it handles all the complex, technical work for you. It abstracts away the low-level complexity of video encoding, frame management, and format handling. The library automates tedious processes like duplicating frames for duration and synchronizing audio. Furthermore, it simplifies advanced features by turning them into simple, one-line methods for effects, transitions, and editing, allowing you to focus on the creative result rather than the technical execution.

Here’s a detailed breakdown of how to make a slideshow video for multiple images:

1. Define the list of image files

Create a Python List to store the file paths for all images intended for the slideshow. If background music is desired, load it from a file using the AudioFileClip() function. You can use the with_effects() function to adjust the audio volume.

from moviepy import ImageClip, AudioFileClip, concatenate_videoclips, vfx, afx
from sys import exit
import os

# List of image files
image_paths = ["data/image1.jpeg", "data/image2.jpeg", "data/image3.jpeg", "data/image4.png"]
# Get the background music
background_music = AudioFileClip("data/background.mp3")
# Adjust the volume if needed
# 40% volume
background_music = background_music.with_effects([afx.MultiplyVolume(0.4)])  

2. Check if images files are valid

Use Python's os.path module to check if the image files exist. If none are found, the script will exit.

# Filter out non-existent images
valid_images = [img for img in image_paths if os.path.exists(img)]

if not valid_images:
    exit("No valid images found!")

3. Create clips for each image

To load the images, use MoviePy's ImageClip() function for each file, which will create an ImageClip object. For each clip, you can set its display duration with the duration parameter and apply fade-in or fade-out effects using the with_effects() function.

# Create clips for each image
clips = []
for img_path in valid_images:
    clip = ImageClip(img_path, duration=3)     # 3 seconds per image
    clip = clip.with_effects([vfx.FadeIn(1)])  # Fade in first 1 second
    clip = clip.with_effects([vfx.FadeOut(1)]) # Fade out last 1 second
    clips.append(clip)

4. Concatenate all clips

You can use the function concatenate_videoclips() to create a video clip by concatenating all the image clips. You can use the parameter method to choose different concatenating methods:

• method="chain": this method concatenates video clips together sequentially, without any resizing or correction for clips of different dimensions. The resulting clip's mask is the combination of the individual clip masks, with any unmasked clips treated as fully opaque.
• method="compose": this method is used for concatenating video clips with different resolutions. It automatically determines a final resolution that is large enough to contain all the clips without resizing them.The output video's resolution will have the maximum width and maximum height of all the combined clips. Any clips with smaller dimensions will be automatically centered within the larger frame.

The background music can be attached and synchronized to match the final video's length.

# Concatenate all clips
final_clip = concatenate_videoclips(clips, method='compose')
# Cut the background music to the same length as the video
final_clip.audio = background_music.subclipped(0, final_clip.duration)

5. Write the final clip to a video file

You can use the function write_videofile() to write the final clip to a video file. You can use the codec and audio_codec parameters to define the image and audio encodings. mpeg4 produces higher quality videos by default. The fps parameter defines the number of frames per second in the resulting video file. The audio codec aac stands for Advanced Audio Coding. It is a lossy audio compression format designed to be the successor of MP3. It offers better sound quality at the same bitrate, making it the standard for many modern applications.

# Write the video
final_clip.write_videofile(
    "data/slideshow_video.mp4",
    codec='mpeg4',
    fps=24,
    audio_codec='aac'
    )

print("Slideshow video created successfully!")