How to Use the FFmpeg Mandelbrot Filter

This article provides a quick guide on how to use the mandelbrot video source filter in FFmpeg to generate fractal animations. You will learn the basic command syntax, key parameters for customization, and practical examples to render your own Mandelbrot video sequences.

What is the FFmpeg Mandelbrot Filter?

The mandelbrot filter is a library filter (lavfi) source in FFmpeg that generates an animated video of the Mandelbrot set. Instead of processing an existing input video file, it procedurally generates frames on the fly, making it an excellent tool for testing render speeds, generating visuals, or creating motion graphics.

Basic Command Syntax

To generate a default Mandelbrot video, you must tell FFmpeg to use the lavfi virtual input format. Here is the simplest command to create a 10-second video:

ffmpeg -f lavfi -i mandelbrot -t 10 output.mp4

In this command: - -f lavfi specifies the library filter input container. - -i mandelbrot calls the Mandelbrot source generator. - -t 10 sets the duration of the output video to 10 seconds.

Customizing Parameters

You can customize the resolution, frame rate, zoom level, and rendering depth of the fractal by passing parameters to the filter. The options are appended to the filter name using an equals sign = and separated by colons :.

Here are the key parameters:

• size (or s): Sets the output resolution. Default is 640x480.
• rate (or r): Sets the frame rate. Default is 25.
• maxiter: Sets the maximum number of iterations. Higher values increase render detail but require more CPU power. Default is 7189.
• start_scale: The initial zoom scale. Default is 3.0.
• end_scale: The final zoom scale. Decreasing this value zooms into the fractal. Default is 0.3.

Practical Examples

1. Generating a High-Definition Video

To generate a 1080p video at 30 frames per second, use the following command:

ffmpeg -f lavfi -i mandelbrot=size=1920x1080:rate=30 -t 15 hd_mandelbrot.mp4

2. Creating a Deep Zoom Animation

To create a dramatic zoom effect, adjust the start_scale and end_scale values. Lower scale numbers represent a deeper zoom:

ffmpeg -f lavfi -i mandelbrot=s=1280x720:start_scale=3.0:end_scale=0.0005 -t 20 zoom.mp4

3. Increasing Fractal Detail

If you zoom in deeply, the fractal might lose detail. You can increase the maxiter parameter to keep the edges sharp, though this will increase rendering time:

ffmpeg -f lavfi -i mandelbrot=s=1280x720:maxiter=20000:start_scale=1.5:end_scale=0.001 -t 12 detailed_zoom.mp4