Understanding Limiters: The Intelligent Release Control (IRC) Algorithm

The Intelligent Release Control (IRC) in Ozone's maximizer manages diverse material transparently, unlike FabFilter Pro 2, making it suitable for varied sound qualities.

### Understanding the IRC (Intelligent Release Control) Limiter in Ozone
* 🛠 There are various limiters on the market, each with unique technologies and DSP, and they sound different due to their **release times**.
* 🧠 The Intelligent Release Control (IRC) in the maximizer uses **psychoacoustic modeling** to manipulate the **release values** of the limiter.
* 📜 The IRC algorithm generates multiple **attack and release times**, creates a **masking threshold specific to the input signal**, and selects the most **aggressively limited signal** whose distortion score is below the masking threshold.
* 🔄 It continuously recalculates and assesses the **optimal setting for the incoming signal** to avoid distortion.
* 🎚 The IRC maximizer is best used on material with a lot of variation between sections, such as **drastic changes in low frequencies, RMS values, and from transient to sustained sections**.
* 🔊 In an example comparing the IRC maximizer and FabFilter Pro-L 2, the IRC maximizer manages diverse material **transparently without distortion**, while the Pro-L 2 **distorts when it can't adjust its release time dynamically**.
* 🎵 FabFilter Pro-L 2's unique clipping feature makes it suitable for crafting **high-energy pop or EDM tracks** with **consistent energy and repetition** in choruses and verses.

there are so many limiters on the market, and they all have their own unique technologies and DSP. But which is best, and why do they sound different? And ultimately, when and why should you use one limiter over another? Understanding how tools help us push those boundaries, and when I came across the pattern for the IRC (Intelligent Release Control) used in the maximizer, it's like nothing I've seen before. And it's gonna help us answer why this limiter in Ozone is so revered. So let's think of your typical limiter. You're setting it up. You set the release time too fast, and it's going to introduce audible distortions. You set it too slow, and it's gonna start to pump against the music. The release is what makes the difference. And there's a history of dynamics processes with auto-release. The ARC in Waves limiters vary the release times through calculating the difference between constantly traced peak and RMS values of a signal. Then you go back further. Order release modes on hardware gear operate through a series

of time constant circuits connected together, and each of them will have different discharge values. Where the top capacities arranged have a very fast release time, and the subsequent capacitors slower and slower. And what that does, it allows the release time to vary based on a signal strength that's exciting in of itself. And I can make some videos on that later. But what makes the intelligent Release Control in the maximizer different? Well, it relies on psychoacoustic modeling to dictate how the release values of the limiter are manipulated. And that might sound pretty techy, but let me break it down for you. And then I'll share with you an example of how I choose and when I choose to use the IRC limiter over another. Before we get stuck into it, don't forget to smash that like button, subscribe, and let's get to the juicy bits. Here I've got the patent, which I've linked down below, and it's figure two we're going to look at. To start with, let's start with amplitude envelopes. So after it takes an input signal, it will

generate six to eight individual attack and release times, and construct them in parallel with one another. Some with a fast attack, fast release, fast attack, slow release, and various combinations of all in between. Then, that process signal is normalized and subtracted from the original input signal. What that does is it provides a Delta signal with the resulting artifacts for each of those envelopes. Now, while that's happening, it's also creating a masking threshold. And that masking threshold is created from the input signal, and it's based on an FFT ear model in Picaval's paper Perceptual Evaluation for Audio Quality. What that returns is a masking threshold specific for that input signal, and that is used to calculate a relative distortion score by comparing each of the amplitude envelopes Delta signals to the masking threshold. And then, what IRC algorithm does is it selects the most aggressively limited signal whose distortion score is below the masking threshold. That's a lot to take in, but on top of that, it's also doing it continuously to the incoming signal, so it's not set and

forget it's constantly recalculating and assessing what setting is best for that audio to avoid distortion. Now that's how the IRC algorithm works, and it's a lot to process. But in the field, how do I use the IRC maximize, and when do I opt to use FabFilter Pro 2? I'll tend to use IRC maximizer on material which contains a lot of variation from one section to the next between these various sound qualities. If lots of low frequencies or subs are being introduced and taken away, if RMS values are changing very drastically in the same sections, and also transit and punchy sections to sustain and open sections, that's where I find the IRC maximizer does a great job. And it manages sparse and diverse material like no other limiter does. In this example, I overtrack which embodies all of these sound qualities, and what I want you to listen for is how the maximizer manages it in such a transparent way in opposition of FabFilter Pro 2. What I've had to do

is to match these up. I've had to manipulate the attack time to be relatively fast, but still open enough that it is as equally aggressive as the IRC one, so giving me the same amount of loudness. I've actually had to drive the compression on the FabFilter parallel to a little bit more, an extra half a dB, in order to match its overall loudness. What I want you to do is I'm going to loop these sections, can be two bars of lots of sub, and then two bars of lots of open tone, and you're going to hear how the Pro-L 2 ends up distorting those subs when they come in because it can't manage to manipulate its release time dynamically with the material. [Music] I wish. [Music] Now you can definitely hear as soon as that sub bass comes in, the FabFilter Pro-Q 2 just starts breaking up. You can hear these little crackles, and that's because I can't adjust its release time for the material appropriately, whereas the IRC maximizer does it.

beautifully. That said, there are still instances where I'm going to use FabFilter Pro 2 over the maximizer. You see, FabFilter Pro 2 has a unique clipping feature for some of its modes when setting the attack time, and I go into full detail on this in this video here, because it's a great tool for crafting slapping pop or EDM tracks, which are consistently high energy and have a lot of repetition in the choruses and verses. With that said, I hope you've enjoyed the video, and if you've enjoyed this, I know you'll enjoy the FabFilter Pro-L 2 as well.

Ozone Maximizer IRC mode, the Reason Why It Sounds BETTER Than Other Mastering Limiters?🙂

Hello. I'm Nicholas Di Lorenzo. I'm a mixing and mastering engineer and owner of Panorama Mastering Studio in Melbourne, Australia. I’m an Italian-Australian. born and raised in Melbourne.

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The Impact of Different Limiters and the Unique Technology of IRC

Limiters have unique technologies and DSP, with the Intelligent Release Control (IRC) in Ozone's maximizer standing out for its use of psychoacoustic modeling.

The release time of a limiter is crucial, as setting it too fast can cause distortions, while setting it too slow can result in pumping against the music.

The IRC limiter stands out for its use of psychoacoustic modeling to manipulate release values, offering a different approach from other limiters.

Understanding the IRC Algorithm and Its Practical Application

The IRC algorithm generates individual attack and release times in parallel, normalizes the process signal, and subtracts it from the original input to provide a Delta signal.

It then creates a masking threshold based on an FFT ear model to calculate a relative distortion score for each envelope Delta signal.

The IRC maximizer is best used for audio with a lot of variation in sound qualities, especially in sections with drastic RMS changes and diverse material, offering transparent management compared to FabFilter Pro 2.

Adjusting Attack and Release Times for Dynamic Music

The speaker manipulated the attack time to match the aggressiveness and loudness of the IRC plugin.

They had to increase the compression on the FabFilter parallel to achieve the same overall loudness, but it still ended up distorting the subs.

The FabFilter Pro-Q 2's inability to dynamically adjust its release time led to noticeable crackles when the sub bass came in, unlike the IRC maximizer.

Using FabFilter Pro 2 for Crafting High-Energy Tracks

FabFilter Pro 2 is preferred over the maximizer for its unique clipping feature and attack time control.

It is a great tool for crafting high-energy pop or EDM tracks with a lot of repetition in choruses and verses.

The video provides in-depth coverage of how FabFilter Pro 2 can be used for this purpose, and suggests that the viewers will also enjoy using FabFilter Pro-L 2.