Achieving the right audio loudness is essential to create professional-sounding videos. Whether you are working on YouTube videos, podcasts, or broadcast material, maintaining consistent loudness levels can significantly enhance the listening experience. FFmpeg offers excellent capabilities to normalize audio with precision and ease.
How FFmpeg Excels at Normalizing Loudness
FFmpeg is an industry-standard tool that excels at advanced audio processing tasks, including loudness normalization. But how does it work?
When we talk about loudness normalization, we mean adjusting the audio to ensure consistent levels across the entire track. This process balances soft and loud sections to prevent abrupt volume spikes or dips. FFmpeg achieves this using its built-in loudnorm filter, which adheres to professional loudness standards like EBU R128.
What makes FFmpeg stand out is its flexibility. It allows you to fine-tune parameters such as integrated loudness, true peak, and loudness range. This precision ensures your content sounds polished and meets the requirements of platforms like YouTube, Spotify, or broadcast channels.
While FFmpeg is excellent for normalization, it notes that the tool mainly focuses on applying audio adjustments. If your source audio has severe issues, you will need additional tools to clean the audio before normalizing it with FFmpeg.
What Parameters Should You Aim for in Loudness Normalization?
Before diving into FFmpeg commands, it's crucial to understand the key loudness parameters and the common normalization targets. Here is a breakdown of Key Loudness Parameters:
Integrated Loudness (I)
Integrated Loudness refers to the overall perceived loudness of an entire audio or video track over time. Integrated Loudness considers the whole track's dynamics, offering a more accurate representation of how the human ear perceives sound over time. It is crucial to create consistent audio experiences across different content.
Integrated Loudness is measured in LUFS (Loudness Units Full Scale). 0 LUFS represents the maximum loudness without clipping, and negative values indicate quieter audio. Common targets include -23 LUFS for broadcast standards (EBU R128) and -14 LUFS for online platforms like YouTube and streaming services. These standards ensure a consistent and pleasant listening experience.
True Peak (TP)
True Peak refers to the highest point of an audio signal, specifically when it reaches its loudest before causing clipping. This parameter ensures that audio does not exceed the maximum limit, avoiding distortion and maintaining clarity.
For example, if an audio track's True Peak exceeds 0 dBTP, it could lead to clipping, which results in a harsh, distorted sound. The goal is to keep True Peak levels within a safe range, typically around -1 to -2 dBTP, to ensure the audio sounds clean and clear without unwanted distortion.
Loudness Range (LRA)
Loudness Range is a metric that measures the variation between the quietest and loudest parts of an audio track. It indicates how dynamic or "alive" the audio feels by evaluating the differences in loudness throughout the track. A high LRA means the track has a broad range of loud and quiet sections, while a low LRA indicates a more uniform sound. Managing LRA is crucial for maintaining an engaging listening experience without overwhelming or underwhelming the listener.
In FFmpeg, controlling LRA helps you maintain an audio track's emotional impact. For example, a movie soundtrack might need a higher LRA to emphasize dramatic moments, while a podcast might benefit from a lower LRA for consistent, clear speech. Using FFmpeg, you can adjust LRA to meet the desired dynamic range for your content, ensuring the audio feels just right for your audience.
Common Target of I, TP, and LRA
| Media Type | Integrated Loudness (I) | True Peak (TP) | Loudness Range (LRA) |
| Broadcast TV | -23 LUFS | -1 dBTP | 7 to 14 LU |
| Streaming Platforms (Youtube, Vimeo, etc) |
-14 LUFS | -1 to -2 dBTP | 7 to 10 LU |
| Podcasts | -16 LUFS | -1 dBTP | 3 to 6 LU |
| Film (Theatrical) | -24 LUFS | -2 dBTP | 20 to 25 LU |
| Film (Home Video) | -27 LUFS | -2 dBTP | 20 to 25 LU |
Steps for Loudness Normalization Using FFmpeg
In this session, we will walk you through the FFmpeg command to normalize the audio loudness. Normalizing the loudness ensures the volume is adjusted consistently, improving the overall audio quality and ensuring it does not feel too soft or loud across different segments.
Define Target Loudness
The first step in the normalization process is to determine the loudness target. The common target for loudness normalization is -23 LUFS, a standard recommended by organizations such as the EBU (European Broadcasting Union).
However, you can choose another target, such as -14 LUFS for online content or -16 LUFS for certain broadcast standards.
Use the FFmpeg Loudnorm Filter
The main filter for loudness normalization in FFmpeg is loudnorm. This filter adjusts the overall loudness of the audio while ensuring it adheres to the target loudness value. The code for this filter looks like this:
- I=-23: Sets the target integrated loudness to -23 LUFS (this is the standard for broadcast).
- TP=-1.5: Sets the target True Peak to -1.5 dB. This setting ensures that the audio peaks do not exceed this value to prevent clipping.
- LRA=7: Defines the Loudness Range (LRA), which controls the variation in loudness. A value of 7 is typical for maintaining a balanced dynamic range to prevent extreme volume shifts.
Want to Hear the Result?
Seeing is believing - and hearing is even better! To showcase FFmpeg normalization capabilities, we've processed a video. Check it out!
With FFmpeg loudness normalization, you can transform your audio and ensure a seamless listening experience for your audience, no matter the platform.