Photoshop for Sound: Izotope’s New RX7 Audio Restoration Software
Back in the fall of 2007, when Roger L. Simon asked me to produce PJM's late lamented weekly series on Sirius-XM’s POTUS channel, I stumbled into a serious bit of good luck that made my life much easier: Boston-based Izotope, Inc. had just released the first iteration of their RX Audio Restoration and Post-production Processing Software. Right from the start, the RX line did a brilliant job of reducing hum, clicks, plosives (those popped-P sounds when someone is too close to the mic), and other noise from a recording. Being tasked with getting audio from a wide variety of sources, including podcasts, video recordings and telephone interviews and cleaning it up for radio presentation, RX was my secret weapon. I found it also worked terrifically on music recording, reducing or eliminating such distracting elements as finger squeaks when changing chords on a guitar, amplifier hum, and digital clicks.
Unlike most earlier noise reduction programs, RX made it possible to zoom into a individual distracting click or pop and drill down into tight granular-level details, much like Photoshop makes it possible to manipulate individual pixels in a Photo. This means it’s often possible to remove those tiny imperfections, without removing the actual musical or vocal content.
Later versions of RX became increasingly aimed at the world of video post production, with such features as Dialogue Isolate and Ambience Match. (Regarding the latter, Izotope’s help files note that it “lets you match the noise floor of one recording to another recording. For example, you can recreate the ambience of a live set on your ADR tracks.”) Beginning with RX5, Izotope split its RX program into standard and advanced versions, with the latter aimed towards film and video post-production houses who do extensive dialogue editing. (There is now a stripped-down RX Elements version as well. This chart lists the differences between the three programs.)
In Through the Music Rebalance Door
Izotope recently released the latest iteration of RX, RX7. While all of the previous modules are still there, in a return to Izotope's origins as a music-oriented company, one of RX7’s most intriguing new features is called Music Rebalance. Professional audio mixers routinely create audio "stems" to group related elements of a multitrack recording mix. This way, a 24 to 48 track or more (sometimes waaay more) recording can quickly be boiled down to its core elements and reassembled, in case something needs to be remixed to create, say, a karaoke version of the song that will have all of the instruments mimed on TV, with only a live lead vocal. Or a different mix for a soundtrack or 12-inch version of a recording. Or if the record label decides it wants the lead vocal louder -- or even if a band’s singer quits the group at the 13th hour.