Edit Review: iZotope RX
Feb 1, 2008 12:00 PM, Reviewer: Gary Eskow
Audio editing application offers creative audio-restoration features.
Declipper
No matter how careful you try to be, the time will come when your signal has been recorded too hot. Clipping — particularly the digital variety — is obnoxious. Fortunately, the Declipper in RX is quite good. Reversing the effect is a fairly simple procedure, and this function is the same whether you're using the advanced or the basic version of RX. You can choose a multiband processor, but most of the time, single-band mode will work fine. You'll be able to scale back the offending portions of your audio with just a little experimentation with setting the threshold level.
Declicker
Although they can be used to fix a myriad of problems, Declickers are most often the go-to tool when vinyl recordings are transferred to digital media and the operator wants to remove the damage that phonograph needles introduced to the original. The RX Declicker will eventually get the job done, but it cannot process — or even preview — more than 4 seconds at a time in either the basic or advanced Manual mode. If you need to preview your work in even a slightly longer context, you must use the Automatic mode, which offers you control over the sensitivity of the operation and the width of the audio that you're attempting to declick. For detailed work, you need to zoom in to a particular click, zap it, and then listen to it in context. If you're unsatisfied with the results, you can undo your operation. I did not find the Declicker to be the most intuitive or effective component in RX.
Hum Removal
Air conditioners — can't live without ‘em, but they can wreak havoc on your audio tracks. In order to get the most out of the Hum Removal tool in RX, you need to be comfortable working with filters. Hum Removal is essentially a powerful multiband equalizer that lets you isolate the frequencies where line noise is most often a problem (50Hz and 60Hz), or operate in Free mode. In Free mode, you can roam freely across the audio spectrum searching for the exact spot where a problem occurs and attenuate it appropriately. If you're timid about working with filters, don't worry — the presets in Hum Removal should solve most of your problems.
Spectral Repair
As I mentioned in my Audition review, spectral analysis is one of the hottest areas in audio-restoration work, and the hype is justified. There's something magical about visually identifying an unwanted sound — a car horn blasting away during an interview, for example — and zapping it instantly without compromising any of the material that surrounds it.
RX's Spectral Repair has something special going for it. If your audio includes a temporary dropout — lasting less than a second or two, ideally — Spectral Repair can help enormously. Instead of simply borrowing material from either side of the gap and smudging it into the empty space, Spectral Repair analyzes the data on both sides and does its best to create audio as it would have appeared had there been no disruption of signal.
For example, iZotope sent me a sine wave that sweeps from low to high. This file has a gap of approximately 1.5 seconds in it. By creating a region around the gap, zooming in all the way in order to butt the edges of the region right up to both ends of the remaining sweep, and instructing Spectral Repair to do its thing, I was able to fill in the sweep perfectly. Impressive.
On the other hand, no application I've seen so far, including RX, beats the Pan View feature that Audition 3's Spectral Frequency display offers — particularly when cost is factored in.
Conclusion
Is RX the right tool for your studio? A better question might be, does RX — or any other piece of software — have anything going for it that other applications don't? In my opinion, the Denoiser alone makes RX (the basic version, at least) a worthy contender for almost any audio studio that does repair work. Even if you're looking for a Swiss Army knife and can only afford to purchase one application of this kind, the RX demo is worth downloading and checking out.
Bottomline
Company: iZotope www.izotope.com
Product: RX
Assets: Outstanding Denoiser and spectral synthesis function, basic version provides high performance value.
Caveats: Advanced version expensive, confusing nomenclature, Declicker requires finesse.
Demographic: Audio post professionals looking for an effective noise-reduction tool and videographers who work on their own audio tracks and need an all-in-one toolset.
PRICE: $349 (BASIC); $1,199 (ADVANCED)
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