APU – Loudness Compressor 3.7.2 for WiN

Free Download APU Loudness Compressor for Windows. APU Loudness Compressor is a compressor/expander designed to support modern loudness metering types (LUFS, True Peak). This means that the compression curve is based on LUFS measurements rather than RMS or Peak. 

Since LUFS is a more accurate measure of loudness, the result is very transparent compression, making it particularly suitable for mastering and post-production. The compressor can also operate in a more traditional mode using RMS and Peak, so you can get both.

By default, the compressor operates using the “source range” and “target range” instead of the threshold and ratio controls. If desired, you can also enable the traditional threshold and ratio controls. The drop-down menu located in the upper right corner of the “Compressor Dynamics” section allows you to switch between these operating modes and others such as expander, limiter, etc.

With the “learn” mode enabled, the compressor automatically adjusts the source or target range to the source material. This is a great way to get started with the compressor, and can be used as a starting point for further fine-tuning.

Check if it fits your workflow. If you have any questions or suggestions, feel free to contact us via the “Contact Developer” button on this site.

Loudness Adjustment Options

One of the key features of this compressor is its support for various types of loudness adjustment. The compressor’s detection scheme can be configured to use either LUFS or traditional units of measurement (RMS, peak). You can also split or link channels, which is especially useful for multi-channel audio formats such as Dolby Atmos®.

The compressor detection circuit can be configured to use any of the following volume types:

Instant

Instant mode is a LUFS measurement over a short period of time (400 ms), which is useful for handling the dynamics of sound at any given moment. This mode is responsive yet transparent, making it a good default mode for the compressor. K-weighting and channel weighting are applied to the compressor detection scheme, which improves perceptual accuracy.

Instantaneous LUFS

Short-term is a LUFS measurement with a longer dwell time (3 seconds), which is useful for processing large-scale audio dynamics. Due to the longer dwell time, this mode is less sensitive than Instantaneous, but it can be useful for adjusting the overall picture of audio dynamics. K-weighting and channel weighting are applied in the same way as with Instantaneous metering.

Short-term LUFS

RMS loudness measurement types use a sliding time interval of 300 ms. RMS is a traditional loudness measurement that is a good first-order approximation to perceived loudness. This mode does not use K-weighting or channel weighting in the compressor detection circuit, giving it a more traditional character.

RMS

True Peak Loudness measurement types are similar to traditional peak loudness measurements, but are more accurate because they take into account peaks between samples. These measurements use a time interval equal to the specified block size (default 1 ms). This mode has a high response speed, making it suitable for very fast attack and release times.

True Peak

Peak Loudness Types – This is a standard peaking scheme that operates for a time interval equal to the specified block size (default 1ms). This is another measurement in the traditional compressor style. Technically, this mode is even slightly more sensitive than True Peak, but it is less accurate because it does not take into account the peaks between samples.