Adjust FFmpeg Crossfeed Level and Cutoff Frequency

This article provides a quick guide on how to configure the crossfeed audio filter in FFmpeg to improve headphone listening. You will learn the specific parameters used to adjust the crossfeed strength (level) and the cutoff frequency, complete with practical command-line examples to help you achieve the perfect stereo blend.

Understanding the Crossfeed Parameters

The FFmpeg crossfeed filter reduces ear fatigue when listening to extreme stereo mixes on headphones by mixing a portion of the left and right channels. This process is controlled by two primary parameters:

strength (or s): This controls the amount of crossfeed applied. It defines the level of signal mixed between the left and right channels. The value ranges from 0.0 (completely disabled) to 1.0 (maximum crossfeed/almost mono). The default value is 0.2.
cutoff (or c): This sets the cutoff frequency in Hertz (Hz). Frequencies below this limit are passed to the opposite channel to simulate how low-frequency sound waves bend around the human head. The range is from 0 to 20000 Hz. The default value is 700 Hz.

How to Apply the Filter

To adjust these settings, use the -af (audio filter) flag in your FFmpeg command followed by the crossfeed filter and your desired arguments.

Syntax

crossfeed=strength=VALUE:cutoff=VALUE

You can also use the shorthand aliases s and c:

crossfeed=s=VALUE:c=VALUE

Practical Examples

Example 1: Moderate crossfeed with standard cutoff If you want a moderate blending effect with a slightly higher cutoff frequency (800 Hz) to simulate wider speaker placement, use the following command:

ffmpeg -i input.mp3 -af "crossfeed=strength=0.4:cutoff=800" output.mp3

Example 2: Subtle crossfeed for natural stereo imaging For a subtle effect that barely alters the original mix but reduces fatigue during long listening sessions, lower the strength to 0.15 and set the cutoff to 650 Hz:

ffmpeg -i input.wav -af "crossfeed=s=0.15:c=650" output.wav

Example 3: Strong crossfeed for early stereo recordings For older music track releases (such as early Beatles albums where instruments are hard-panned to one side), a much higher strength is required:

ffmpeg -i input.flac -af "crossfeed=s=0.6:c=700" output.flac