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iZotope RX 3 vs. Adobe Audition, Part 1: Declipping and Crackle-and-Pop Removal--UPDATED with iZotope Tutorial!

In this first installment of a two-part series, Jan Ozer compares the declipping and crackle and pop-removal features in iZotope's new RX 3 pro audio editor to the parallel features in Adobe Audition CC.

For many Creative Cloud users, Adobe Audition is the obvious choice for audio editor. Not only is the price right, you get roundtrip editing with other CC tools like Adobe Premiere Pro. So when I saw the press release on iZotope RX 3, I wondered, does this provide any functions I can’t get in Audition, or perform any functions better?

Since I’m primarily a shooter/editor, as opposed to an audio guy, I figured I would focus on those problems that occur most frequently in my productions. In the first of this two-part article, I’ll focus on declipping and crackle-and-pop removal; in the second I’ll compare functionality for noise and echo/reverb removal. This isn’t a full review of RX 3; just a comparison with Audition for these video-related functions.

How I Tested

For all these tasks, I came up with a sample file or two, and performed the function in RX 3, Adobe Audition CC, and Audition CS6. All before-and-after files are included below so you can hear the problem and how well each program resolved it.

As a preview, though I’ve sworn by Audition’s Auto Heal function since it appeared many years and many versions ago, I produced much better results faster with iZotope’s Spectral Repair, which performs the same function. Though I haven’t finished my testing, I’m leaning towards a similar conclusion for noise reduction, though in each instance, Audition CC seemed to outperform Audition CS6. If you experience either of these problems, iZotope is worth a look, and there is a ten-day free trial available.

For the record, there are two iZotope versions, RX 3 (regularly $349, on sale for $249), and RX 3 Advanced ($1,199/$749). You can see a comparison here; I used some of the Advanced configuration functions in my tests, and some functions, like the Dereverb module, are available only in the Advanced version.


Clipping is what occurs when you record the audio so hot that it flatlines against the edges of the waveform. I’ve never done this, of course (har, har), so I recorded a new audio file to use specifically for this test. You can see the file in Figure 1 (below), with flatlines atop each audio peak. Not only do these peaks sound distorted, but the resulting audio file lacks dynamic range, since the true high points were given a digital crew cut. The obvious measure of the repair tool is how much it minimizes this distortion and how much it restores the dynamic range.

Figure 1. The declipping function in iZotope RX 3. (Click on the image to see a larger version of the screenshot.)

Declipping was not a function that I was familiar with, so I relied on company-supplied tutorials to learn how to use the function in the respective programs. You can see the iZotope tutorial here, and the Adobe tutorial here. While I’m clearly not an expert, these aren’t rocket scientist-type functions and I spent a good bit of time experimenting to get the best results.

While all tested programs did a good job eliminating the distortion, I found iZotope easier to use and thought that it produced a slightly greater dynamic range. When using Audition CC and CS6, the Restore Heavily Clipped setting reduced gain by 12dB, and created a waveform that was deeper on the bottom than on top. Normalization pushed the bottom peaks to 0dB, but left the top peaks at about 4.5dB. I boosted these by 3dB to get the overall levels consistent with the iZotope file, though it’s still a bit louder.

Of all the tests that I performed, I’m least confident about the results produced for this one. Not only was the test file synthetic, but it was a problem that I’ve never attempted to resolve in the real world. If you have a file that needs declipping, I recommend downloading the iZotope file, watching the tutorial and giving it a shot.

The declip audio files follow.

Top to bottom: the original source file, the iZotope version, the Audition CS6 version, and the Audition CC version.

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