APU Software

APU Loudness Optimizer

Loudness Optimizer (LUFS, True Peak, RMS, Peak)

The APU Loudness Optimizer is an automatic compressor/expander designed to support modern loudness types (LUFS, True Peak). Underneath the hood, the optimizer uses the same compression engine as the APU Loudness Compressor, but derives its gain envelope from the full audio waveform instead of real-time measurements. This allows the gain envelope to be meticulously optimized across the entire waveform, resulting in a more transparent and consistent gain envelope.

This tool is especially well suited for mastering and post-production workflows, where the goal is to optimize the loudness of an entire waveform. Once the gain envelope has been optimized, you can playback the result in real-time while adjusting the character of the sound with the same collection of parameters from the compressor plug-in.

If you have any questions or feedback, you can reach me (Aaron) using the “Contact the Developer” beacon on this website.

Loudness flavors

One of the key features of this optimizer is its support for a variety of loudness types. The optimizer’s detection circuitry can be configured to use either LUFS or traditional measurement units (RMS, Peak). You can also choose to split or link channels, which is particularly useful for multi-channel audio formats such as Dolby Atmos®.

The optimizer’s detection circuitry can be configured to use any of the following loudness types:

Momentary

Momentary is a short duration LUFS measurement (400ms), which is useful for processing the audio’s moment-by-moment dynamics. This mode is responsive but also transparent, making it an appropriate default for the optimizer. K-weighting and channel weighting are applied to the optimizer’s detection circuitry, improving perceptual accuracy.

Momentary LUFS

Short-Term

Short-Term is a longer duration LUFS measurement (3 seconds), which is useful for processing the audio’s large scale dynamics. Given the longer duration, this mode is less responsive than momentary, but it can be useful for adjusting the bigger picture of the audio’s dynamics. K-weighting and channel weighting are applied as with momentary.

Short-Term LUFS

RMS

RMS loudness types use a rolling time interval of 300ms. RMS is a traditional loudness measurement, which is a good first-order approximation of perceived loudness. This mode doesn’t apply K-weighting or channel weighting to the optimizer’s detection circuitry, giving it a more traditional character.

RMS

True Peak

True Peak loudness types are similar to traditional peak measurements, but they are more accurate as they take into consideration inter-sample peaks. These measurements use a time interval equal to the configured block size (1ms by default). This mode is extremely responsive, making it suitable for very fast attack and release times.

True Peak

Peak

Peak loudness types are a standard peak circuit, operating on a time interval equal to the configured block size (1ms by default). This is another traditional compressor style measurement. Technically, this mode is even slightly more responsive than True Peak, but it is less accurate as it doesn’t take into consideration inter-sample peaks.

True Peak

License key purchase (w/free lifetime updates)

You can purchase a license key for the optimizer using one of the payment buttons below. The license key will be emailed to you after payment confirmation. The license key can be entered in the About tab on the plug-in.

Don’t hesitate to reach out if you have any questions or feedback!



Download and install (free trial)

Choose your operating system to download the latest installer below.

MacOS Windows User Manual

The user manual above is also available on the live docs site.

System requirements: macOS 10.14 (x86, x64, ARM), Windows 10 (x86, x64), OpenGL 3.2.
Supported plug-in types: VST, AU, AAX (Pro Tools 11+).
Free trial: 10 days, no limitations.