Perfect Cross-fade with Izotope RX
Up until recently, my field recording processing workflow consisted of using two applications. First, Izotope RX for auditioning, marking regions for cuts or other purposes, and fine-tuning the recording's gain and loudness. I would then follow up with reopening files in REAPER to make the actual cuts, cross-fading, and exporting for encoding and sharing. Honestly, I find REAPER to be a more intuitive tool for cutting tracks into segments, re-arranging, and cross-fading. It is a proper, full-featured, and powerful DAW, after all! But when there is only a single cut or two to take care of, I still prefer avoiding the hassle of exporting from Izotope RX to an intermediate file, reopening in REAPER, exporting again, etc.
Coming from a DAW experience, implementing cross-fades in RX might not be that obvious. Yet, it is possible, and here is a step-by-step guide about achieving exactly that.
Note: I include a sample track for download here, in case you want to follow along.
The Anatomy of a Cut
Let's say we want to get rid of a one-second segment somewhere in the middle of an audio file. In order to keep the post-cut transition audibly smooth, the following steps have to take place:
The end of the preceding audio segment faded out
The start of the following audio segment faded in
The fade out and fade in regions overlapped (mixed in)
The cut region and one of the fades deleted
Step 1. Placing Marker Regions
At this stage, I prefer time ruler and time readouts to display Time (h:m:s) format. It is more natural to work with field recordings referencing wall clock time. You can switch between various time format display options in View -> Time Format menu.
Let's set the three marked regions as shown below. To do so, drag the mouse cursor in the main window and select a portion of the audio. Hit M to make it into a marked region. Repeat the steps for Cut, Fade-Out, and Fade-In regions.
Note that all three regions must be adjacent with no gaps between them. Also, Fade-Out, and Fade-In regions must be of the same length.
Now bring Markers and Regions window (Option+M), give the regions names, and switch time ruler and time readouts to Samples via View -> Time Format -> Samples. Having sample for markers’ Start, Stop, and Length values is necessary because we have to nudge the regions' lengths. By default, RX's regions are inclusive, meaning that the previous region's End value is the same as Start value of the next. Leaving them like that will delete two extra sample points at Step 3 below, resulting in a non-perfect stitch with an audible click. (I will leave it up to you to experiment with this yourself if you wish.) It does not matter whether to increment Start values by one or decrement End / Length values by one as long as it is consistent between all three marked regions.
Step 2. Applying Fades
Before proceeding with this step, go to Preferences -> Misc and turn Selection Feathering to 0 ms. Selection Feathering affects how much outside of the selected region gets feathered in and copied to the clipboard. It also controls selection-based operations like Fades.
Keeping the Markers and Regions window open, click on a small yellow pin (Playhead symbol) next to the Fade-Out region to recall the Fade-Out region's selection. Next, open Fade module window and make sure to choose Fade out and Equal Pwr. Click Render button to modify the selection of Fade-Out region.
Back in Markers and Regions window, click on a yellow pin next to the Fade-In region; in the Fade module window switch to Fade in (keep it at Equal Pwr) and Render again.
While Fade-In region is still selected, copy it to the clipboard (Command+C).
Select Fade-Out region one more time and from the menu choose Edit -> Paste Special -> Mix (or Shift+V). This mixes the Fade-In region waveform from the clipboard with the selected Fade-Out region waveform.
Step 3. Deleting Unwanted Material
Now all that's left to do is to delete the Cut and Fade-In regions. Make selections by clicking on those yellow pins next to the regions in question and execute deletions via Edit -> Delete menu.
Did I miss anything? Is there a better way out there that I am not aware of?
I am interested to hear your thoughts! Please leave your comment below.
