Configure FFmpeg Crystalizer Filter Expansion Factor

This article explains how to configure the expansion factor in the FFmpeg crystalizer audio filter. You will learn how to locate the correct parameter, understand its range of values, and apply practical command-line examples to adjust the dynamic range of your audio files.

In the FFmpeg crystalizer filter, the expansion factor is controlled by the intensity (or i) parameter. This filter expands the dynamic range of audio, making quiet passages quieter and loud passages louder, which can breathe life back into heavily compressed audio tracks.

The Intensity Parameter Syntax

The basic syntax for applying the filter is:

crystalizer=intensity=value

Or using the shortform:

crystalizer=i=value

Parameter Values and Behavior

• Default Value: 2.0
• Allowed Range: -10.0 to 10.0
• Value of 0.0: Has no effect on the audio.
• Positive Values (0.1 to 10.0): Expands the dynamic range. Higher numbers increase the intensity of the expansion, making the audio sound sharper and more “crystalized.”
• Negative Values (-10.0 to -0.1): Reverses the process, narrowing the dynamic range.

Practical Command Examples

To apply an expansion factor of 3.0 to an audio file, use the following command:

ffmpeg -i input.wav -af "crystalizer=i=3.0" output.wav

Managing Clipping

Because expanding the dynamic range increases the volume of the loudest peaks, it can cause digital clipping (distortion). The crystalizer filter has a built-in clipping prevention parameter (clip or c) enabled by default.

To explicitly enable clipping protection alongside a custom intensity factor of 4.5, use:

ffmpeg -i input.mp3 -af "crystalizer=i=4.5:c=1" output.mp3

Setting c=0 disables clipping prevention, which is only recommended if you plan to manually lower the volume upstream using a volume filter to prevent distortion.