Beats Detection & Optimized Photo Transitions Timing for Reels

Do you know you can use Python for automatic beats detection and to optimize the photo transitions timing in your IG and FB reels?

Creating engaging Instagram and Facebook reels can be difficult, especially when it comes to timing your photo transitions to match the beats of your chosen music. Fortunately, Python provides a great answer to this problem. In this blog article, we’ll look at how to utilize the librosa package for automatic beats detection in audio files and discover the optimal times to change photographs in your reels. This method not only saves time but also adds professionalism to your social media posts.

What Are Instagram and Facebook Reels?

Instagram and Facebook Reels are short, engaging videos that you can create and share with your followers on these social media platforms. Here’s a brief introduction:

  • Instagram Reels: Instagram introduced Reels as a way to compete with TikTok. Reels allow users to create 15 to 60-second multi-clip videos with audio, effects, and new creative tools. These short videos can be shared on your feed, in stories, or on the Reels Explore page, where they can reach a wider audience.
  • Facebook Reels: Following Instagram’s success, Facebook launched Reels to allow users to create and share short, engaging videos on their platform. Similar to Instagram Reels, these videos can be enhanced with music, effects, and various editing tools.

Why Are Reels Important?

For all the creators, Reels are an essential tool for several reasons:

  1. Engagement: Short form videos are extremely interesting. They instantly attract viewers’ attention and keep them entertained, making them ideal for today’s fast-paced social media landscape.
  2. Creativity: Reels provide you a platform to express your creativity. Whether you enjoy dance, humor, fashion, or simply sharing moments from your life, Reels provide a fun way to express yourself.
  3. Reach: Reels have the ability to reach a larger audience. Both Instagram and Facebook promote Reels in their algorithms, so your work is more likely to be spotted by people who do not follow you.
  4. Trend Participation: Reels are frequently influenced by trends. Participating in these trends allows you to acquire attention and contribute to the wider debate on social media.

Why Timing Matters

The timing of photo changes in reels is critical to keeping viewers engaged. Poorly placed transitions can be abrupt and disrupt the flow of your content, whereas well-timed shifts can increase the emotional impact of your reel, making it more memorable and pleasant for your target audience. Synchronizing your transitions with the rhythms of your music creates a harmonious and fascinating experience.

There are already some solutions available on the market that make it easier to create Facebook and Instagram reels. Most of them rely on Artificial Intelligence (AI), hence they are frequently not free of charge.

In this article, I’m proposing a solution that is simple and free, but it might have some limitations as the results might depend a lot on the processed audio file (type of music, quality, etc.).


Before diving into the code, make sure you have the following tools installed:

  • Python 3.6 or higher
  • librosa library for audio processing
  • matplotlib library for visualization

You can install the necessary libraries using pip:

pip install librosa matplotlib

Also, you need your an audio file to be processed. So, where to find free audio files or music?

I downloaded some free audio samples from and

The Code

Here’s a Python script that analyzes the beats in an audio file and prints the best instants to change photos.

import librosa
import matplotlib.pyplot as plt
import sys

def analyze_beats(audio_path):
    # Load the audio file
    y, sr = librosa.load(audio_path)

    # Analyze the tempo and beats
    tempo, beats = librosa.beat.beat_track(y=y, sr=sr)

    # Convert beat frames to time instants
    beat_times = librosa.frames_to_time(beats, sr=sr)

    # Print the beat times
    print("Best instants to change the photo (in seconds):")
    for time in beat_times:

    # Plot the waveform and beat times
    plt.figure(figsize=(14, 5))
    librosa.display.waveshow(y, sr=sr)
    plt.vlines(beat_times, -1, 1, color='r', alpha=0.75, linestyle='--', label='Beats')
    plt.xlabel('Time (s)')
    plt.title('Audio waveform with beat times')

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print("Usage: python <path_to_audio_file>")
        audio_path = sys.argv[1]
Code language: Python (python)

How It Works

  1. Loading the Audio File:
   y, sr = librosa.load(audio_path)

The librosa.load function loads the audio file specified by audio_path. It returns the audio time series y and the sampling rate sr.

  1. Analyzing Tempo and Beats:
   tempo, beats = librosa.beat.beat_track(y=y, sr=sr)

The librosa.beat.beat_track function analyzes the audio and identifies the beats. It returns the estimated tempo and the frame indices of the detected beats.

  1. Converting Beat Frames to Time Instants:
   beat_times = librosa.frames_to_time(beats, sr=sr)Code language: Python (python)

The librosa.frames_to_time function converts the frame indices of the beats to time instants in seconds.

  1. Printing Beat Times:
   for time in beat_times:
       print(time)Code language: Python (python)

This loop prints the time instants where the beats occur, which are the best moments to change photos in your reel.

  1. Visualizing the Beat Times:
   plt.figure(figsize=(14, 5))
   librosa.display.waveshow(y, sr=sr)
   plt.vlines(beat_times, -1, 1, color='r', alpha=0.75, linestyle='--', label='Beats')
   plt.xlabel('Time (s)')
   plt.title('Audio waveform with beat times')
   plt.legend() language: Python (python)

This code visualizes the waveform of the audio file and marks the beat times with vertical lines. This visualization helps you understand how the beats align with the audio signal.

Running the Script

To use the script, save it as and run it from the command line with the path to your audio file:

python <path_to_audio_file>Code language: HTML, XML (xml)

For example:

python your_song.mp3Code language: CSS (css)

The script will print the best times to change photos and display a plot of the waveform with beat times.

An example

When the script is executed, the estimated time instants will be shown as in the example below:

Best instants to change the photo (in seconds):
15.046530612244897Code language: Bash (bash)

The script also generates a figure containing the audio waveform with the beat times.

Beats Analyzer - Generated Audio Wave and Beats

Practical Application

Now that you have the beat times, you can use them to synchronize your photo transitions in video editing software. Here’s a step-by-step guide:

  1. Choose Your Music: Select an audio track that fits the mood and theme of your reel.
  2. Run the Script: Use the Python script to analyze the beats in your chosen music.
  3. Note the Beat Times: Write down or copy the beat times printed by the script.
  4. Edit Your Reel: Import your photos and music into a video editing software like Adobe Premiere Pro, Final Cut Pro, or even free tools like DaVinci Resolve. Align your photo transitions with the beat times for a seamless and engaging reel.


By using Python and the librosa library, you can automate the process of identifying the best time instants for photo transitions in your Instagram and Facebook reels. This not only saves time but also enhances the quality of your content, making your reels more engaging and professional. Give it a try and see how this technique transforms your social media presence!

Feel free to share your experiences or ask questions in the comments below.

Happy coding and happy creating!


Pietro L. Carotenuto
Pietro L. Carotenuto

C++ Software Engineer, Ph.D. in Information Engineering. I like reading and learning new things while working on new projects. Main author on looking for contributions and guest authors.

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