Plug-ins, Loudness

Loudness Align Entire Libraries of Sound Files in One Easy Go with CLC

CLC - Continuous Loudness Control is a plug-in and stand-alone app for Mac and PC. In this article I will focus on the powerful batch-processor.

Thomas ValterAugust 23, 2019

Playback for Experimenting

With the big focus on Loudness the audio world has been experiencing through the last 5 years, the world has come a big step closer to avoiding annoying loudness jumps between songs.

As I'm sure you know, the idea is that if all songs in a library have the same Loudness LUFS, those songs will be played back at approximately the same loudness, and jumps are minimal: the user does not need to continuously reach out for the volume control to turn the volume up or down between each song.

The Continuous Loudness Control offers a very strong batch processor, that enables you to loudness process an entire library of songs in one go. But not only that: the processor is also able to adjust the Loudness Range of the songs, so not only will the songs play back at approximately the same loudness, they are also kept within a certain loudness range, significantly improving the listening experience across the entire library.

All that is possible due to a state-of-the-art loudness-focused algorithm that is able to adjust Loudness LUFS and Loudness Range (LRA) in one go while preserving the quality of the original audio source.

Before you set your final parameters, you will want to start experimenting with the various settings.

To do so, you can enter Playback mode, which basically lets you load an audio file and nudge the parameters while playing back, before you start batch processing.

The UI shows the most important loudness measures for both input (the original file) and output (what's being played back).

Also, two diagrams show the input/output ratio of Loudness LUFS (I) and Loudness Range (LRA).

Playback Mode for Testing Different Settings Before Starting the Batch Job

The Main Loudness Parameters

Main Loudness Parameters

If you compare the CLC with a traditional multi band compressor/limiter, you will be surprised how few parameters it has, and how easy it is to operate.

The main parameter, Target Loudness LUFS (or "Integrated Loudness, I") sets the loudness target. For example, television broadcasters would go for -23 or -24 depending on region, and if you are processing for web-based distribution, you would set it higher, to -15 or -16 LUFS.

The Maximum LRA is the second parameter. Only songs with an LRA larger than the setting will be processed. Traditionally, you would use a setting that fits the content, so for instance classical music would have a larger LRA than pop or country. However, if you are processing a large library of songs, you would rather have the end listener application in mind. If your library is going to be played back in an environment with heavy background noise, you would select a smaller LRA (6 or 8 LU), and if it will be played back in a hi-fi friendly quiet living room with a powerful speaker system you wouldn't be limiting the LRA too much (12-15 LU).

Max Momentary and Max Short Term are primarily there to limit very short passages, for instance in commercials. If you are working with a music library, you don't need to set these two values.

True-peak Limit is the safety-belt that ensures that you get no overloads in case the LUFS is increased. It prevents distortion thru transmission lines and in case you choose to data-compress your audio at a later point. For standard TV broadcast, most standards recommend a setting of -1 dBTP. For low bit-rate data-compression you might need to go significantly lower than -1 dBTP.

When you have found the optimal settings, you naturally want to save them to a CLC Preset.

Creating the Batch Job

Batch Mode Configuration

Once you have saved your Loudness parameters as a CLC Preset, you can turn to the Batch Mode.

First of all, you select which CLC Preset should be used in the batch job. Here I've selected the one I created before.

The channel mode tells the batch processor which audio channel format to expect. For Music you'd, select Stereo, but CLC is also able to accept other channel formats, up to 22.2 (!).

You will also need to pick a source folder. This is the folder that will be watched by the batch processor, and any files that are added to this folder will be processed. Be aware that this can also be a network drive, so if you are working in a large facility it is possible to configure a "CLC server".

Also set the Output Folder and the Report folder. After each process, CLC will make a report that you can use to see exactly what has been done to the file. In this case, I have chosen to create a specific folder for these reports, but you can also chose to let CLC put the reports in your Output folder.

Input/Output formats

CLC will accept almost any audio file format, including wav, aiff, ac3 and mp3. It even accepts MXF files for those working in the video world.

On the output side, CLC is able to write to a number of formats, including wav, aiff and MXF. It is also able to export to data-compressed formats such as mp3, but only if external software is installed.

Once you've set your parameters, save the batch configuration to a batch Preset.

Time to Run!

In Batch mode, make sure you set the Mode to Process, rather than just Analyze.

CLC will be watching your input folder for new files with regular intervals, and those intervals are set in the Global part of the Batch Menu.

So whenever you add audio files - or folders with audio files - CLC will automatically add them to the batch job, process them and put the processed file in your output folder.

Batch job is running

The Processing Technology

The CLC is indeed a great tool for those of you who need to process entire libraries with regards to Loudness LUFS and Loudness Range. 

The patented, amazing look-ahead low latency algorithm used in the CLC allows dynamic loudness processing with a so far unseen result with regards to audio quality and transparency.


Technically Spoken

What is required to run CLC - Continuous Loudness Control?

The CLC is a plug-in and stand-alone application for PC and Mac.

It is available in two versions:

  • Full version with support for up to 22.2. 
  • Price-friendly stereo version

The supported audio channel format is the only difference between the two.

They are both available in our international Web Store right here:




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CLC Features

  • Live Audio, DAW Audio, and Audio File modes in multi-channel applications
  • Batch processing
  • Extended audio format support (e. g. MXF)
  • Loudness acc. to all global standards
  • Adjustable Target Loudness and Loudness Range (LRA)
  • Adjustable TP Limiter
  • Mmax and Smax limiting
  • Expert mode to process very special audio material
  • Optimized presets for e. g. streaming audio
  • Graphical routing overview with channel presence and activity indicator
  • Loudness reporting (Java Runtime Environment required)
  • Dynamic Low Latency Algorithm
  • Adaptive Morphing Technology
  • Stand-alone and DAW-PlugIn
  • Common plug-in formats for Windows® and Mac® OS X
  • iLok copy protection