How to Set Loudness Range in FFmpeg Loudnorm

This guide explains how to configure the loudness range target (LRA) using the loudnorm filter in FFmpeg. You will learn the specific parameter used for adjusting the loudness range, the syntax required for command-line implementation, and how this setting interacts with other EBU R128 normalization parameters to optimize your audio output.

The Loudness Range Parameter

In the FFmpeg loudnorm filter, the loudness range target is controlled using the loudness_range parameter (or its shorthand alias lra).

• Default value: 7.0 LU (Loudness Units)
• Allowed range: 1.0 to 20.0 LU

The loudness range represents the generic variation of volume over the duration of the audio. A lower LRA value results in a more compressed, consistent volume level (ideal for podcasts or noisy environments), while a higher LRA value preserves more of the original dynamic range (ideal for movies or classical music).

Basic Command Syntax

To configure the loudness range target, pass the lra option to the -af (audio filter) flag.

ffmpeg -i input.mp3 -af loudnorm=lra=15 output.mp3

In this example, the loudness range target is set to 15 LU, which allows for a wider dynamic range.

Setting LRA alongside Other Targets

For optimal EBU R128 compliance, you should configure the loudness range target alongside the integrated loudness target (I) and the true peak target (TP).

Here is how to set a target of -16 LUFS integrated loudness, a 10 LU loudness range, and a -1.5 dBTP true peak:

ffmpeg -i input.wav -af loudnorm=I=-16:LRA=10:TP=-1.5 output.wav

Parameter Breakdown:

• I: Integrated loudness target (range: -70.0 to -5.0 LUFS; default is -24.0).
• LRA: Loudness range target (range: 1.0 to 20.0 LU; default is 7.0).
• TP: Maximum true peak target (range: -9.0 to 0.0 dBTP; default is -2.0).

Recommended Targets for Common Use Cases

Depending on your distribution platform, you should adjust the lra and I settings accordingly:

• Podcasts and Dialogue-Heavy Content:
  • Target: loudnorm=I=-16:LRA=5:TP=-1.5
  • Reasoning: A lower LRA (5 LU) keeps voices consistently audible over ambient background noise.
• Home Video and Broadcast (EBU R128):
  • Target: loudnorm=I=-23:LRA=7:TP=-2.0
  • Reasoning: Matches the European broadcast standard with a balanced dynamic range.
• Cinematic Soundtracks and High-Fidelity Music:
  • Target: loudnorm=I=-24:LRA=15:TP=-2.0
  • Reasoning: A higher LRA (15 LU) preserves the artistic difference between quiet whispers and loud explosions.