How to Use FFmpeg asubboost to Boost Bass

This article provides a straightforward guide on how to use the FFmpeg asubboost (Audio Sub-Bass Boost) filter to enhance low-frequency audio. You will learn the key parameters of this filter—such as cutoff frequency, boost gain, and wet/dry mix—and see practical command-line examples to help you achieve a deeper, richer bass in your audio and video files.

Understanding the asubboost Filter

The asubboost filter in FFmpeg is specifically designed to generate and boost sub-bass frequencies. It works by filtering out the low frequencies, processing them, and mixing them back into the original audio stream.

Key Parameters

You can customize the bass boost by adjusting the following parameters:

  • dry: The level of the original (unprocessed) sound. The default is 1.0.
  • wet: The level of the boosted sub-bass sound. The default is 1.0.
  • boost: The boost factor of the sub-bass frequencies. The value ranges from 0 to 12 dB, with a default of 2.0.
  • decay: Controls the decay of the sub-bass envelope. The value ranges from 0 to 1 (default is 0).
  • feedback: Controls the feedback loop of the sub-bass generator. The value ranges from 0 to 1 (default is 0.9).
  • cutoff: The cutoff frequency in Hz, below which the filter will boost the audio. The range is 50 to 200 Hz (default is 80 Hz).
  • slope: The filter slope. The range is 0.1 to 1.0 (default is 0.5).

Practical Examples

To apply these filters, use the -af (audio filter) flag in your FFmpeg command.

1. Basic Bass Boost (Default Settings)

To apply a standard sub-bass boost using the filter's default values (80 Hz cutoff, 2 dB boost), use the following command:

ffmpeg -i input.mp3 -af asubboost output.mp3

2. Increasing the Bass Intensity

If you want a more noticeable bass punch, you can increase the boost parameter. This command increases the boost to 5 dB:

ffmpeg -i input.mp3 -af "asubboost=boost=5" output.mp3

3. Lowering the Cutoff Frequency

If you only want to target very deep sub-bass (like sub-bass in electronic music or movies), lower the cutoff frequency to 60 Hz:

ffmpeg -i input.mp3 -af "asubboost=cutoff=60:boost=4" output.mp3

4. Adjusting the Dry/Wet Mix

To prevent the audio from distorting or sounding too muddy, you can lower the wet (boosted) signal or keep the dry (original) signal prominent. This command applies a heavy 6 dB boost but reduces the wet mix to 0.7 to keep the audio balanced:

ffmpeg -i input.mp3 -af "asubboost=boost=6:wet=0.7:dry=1.0" output.mp3

5. Applying Bass Boost to Video Files

To boost the bass of a video file while copying the video stream without re-encoding (which saves time and preserves video quality), use:

ffmpeg -i input.mp4 -c:v copy -af "asubboost=boost=3:cutoff=70" output.mp4