Master Class: Pitch Shifting in Pro Tools 8

Jun 1, 2009 12:00 PM, By Brian Smithers

           
 

EXPLORING ELASTIC AUDIO'S NEW DIMENSION

FIG. 1: The Elastic Audio plug-in button shows the name of the current plug-in, and the green light indicates that it is processing in real time. Command+Control-click (Control+Start-click on Windows) on the button to toggle between real-time and rendered processing.

Digidesign introduced Elastic Audio in Pro Tools 7.4, offering powerful and flexible time correction within its industry-leading DAW. In Pro Tools 8, Elastic Audio sprouts a new ability to change the pitch of an audio region. Transposing a loop or tuning a vocal is just a few clicks away.

Don't put away your Melodyne just yet, however. Elastic Audio has no intelligent algorithm for determining pitch — there's no auto to this tuning. You can change a region's pitch by as much as two octaves in either direction in increments of a cent, but it's up to you to decide how much tuning is required. Furthermore, pitch changes are applied only to entire audio regions, so to change the pitch of a syllable you must first separate that syllable from the rest of the word.

Still, even as we wait and hope for the wizard to grant Elastic Audio a brain for tuning, we can get a lot of creative and corrective mileage out of its existing capabilities. In this “Master Class,” I'll share some techniques I use to make quick work of pitch manipulation in Pro Tools 8.

Bonus Material

EM EM May 2009 Review on Pro Tools 8

EM Pro Tools 7.4 Review, Including "Elastic Fantastic"

Remix Elastic Audio Feature

Remix Pro Tools 8 Tips

Mix Pro Tools 7 Review, Elastic Pitch

Mix Video Demo of Pro Tools 8

Digidesign Explains How to Quantize Audio using Elastic Time

Jeff Dykhouse Explains Elastic Audio on YouTube

Elasticity

As with time correction, Elastic Audio pitch correction requires first that the track in question be declared an Elastic Audio track. Of the four available Elastic Audio plug-ins, only Polyphonic and Rhythmic allow pitch manipulation independent of time manipulation. Varispeed, of course, ties the two together, but it's counterintuitive that Monophonic doesn't work. If you have X-Form installed, it can be used for pitch manipulation, but not in real time. Given a fast processor, that may not be a problem as the rendering of a short phrase takes only a few seconds. If the delay is a problem, you can always work in real time with the Polyphonic or Rhythmic plug-in and then change the track to X-Form when you have it tuned. Polyphonic and Rhythmic can both operate in either real-time or rendered mode, and you can toggle that behavior by Command+Control-clicking (Control+Start-clicking on Windows) on the Elastic Audio plug-in button (see Fig. 1).

Whether Polyphonic or Rhythmic is best for a particular source is something only your ears can judge; no description I could offer would be a worthy substitute. X-Form, however, is better than either under almost any circumstance. You can set a default real-time Elastic Audio plug-in in Pro Tools' Preferences under Processing (see Fig. 2). Unfortunately, no third-party algorithms can be assigned for use by Elastic Audio. Given that the TCE Trim tool can use third-party plug-ins, I hope that Elastic Audio will eventually follow suit.

FIG. 2: Elastic Audio preferences let you choose which of the real-time plug-ins will be the default for new Elastic Audio–enabled tracks. This preference is linked to the plug-in chosen for preview in a browser.

When using Elastic Audio for time correction, it's standard to make the track tick-based, but this may not be the best course for pitch correction. If you make the track tick-based, then Elastic Audio will automatically adjust to tempo changes, but you may not want your precisely edited and tuned lead vocal to do that. If not, make the track sample-based to preserve its timing regardless of tempo tweaks. For pitch-shifting loops, tick-based is still probably best.

Two caveats related to Elastic Audio pitch manipulation might affect your workflow when comping tracks. First, in Pro Tools HD you cannot use Elastic Audio on tracks with explicitly assigned voices. Elastic Audio tracks must use dynamic voice allocation. (This does not affect LE or M-Powered as they always use dynamic voice allocation.) Second, although region groups can include pitch-shifted regions and you can crossfade pitch-shifted regions, you cannot group crossfaded regions on an Elastic Audio-enabled track. Instead of grouping edited regions on a comp track, create a duplicate playlist and consolidate them. You can go back to the unconsolidated playlist to make changes if necessary; it's only one step more complex than grouping and ungrouping the regions.

Care in Carving

Because tuning is a region property, the first step is to separate the parts that need tuning. To change individual notes of a bass loop or any other part with clearly defined attacks, try using Tab to Transient to move the cursor from note to note. To toggle Tab to Transient on and off, press Command+Option+Tab (Control+Alt+Tab). Turn Commands Keyboard Focus on by pressing Command+Option+1 (Control+Alt+1). To separate an individual note in preparation for tuning, you can then press Tab until you locate the beginning of the note, Shift+Tab to select to the next note, and B to separate the note into a new region. Work your way through the part until you have separated all the notes you intend to retune. Note that in Pro Tools 8, Tab to Transient is much more sensitive (some say too sensitive) than in the previous version, so you may find it locating to events you don't consider transients.

Unlike AudioSuite processing, which names processed regions to reflect the process used, Elastic Audio does not reveal itself in region names. Once you've satisfactorily pitch-shifted a loop, you should immediately rename it to reflect its new pitch. If it's already selected, press Command+Shift+Option+R (Control+Shift+Alt+R); if not, double-click it with the Grabber (not the Separation Grabber) to open the Region Name dialog. If you've retuned individual notes, you'll first want to consolidate the loop by pressing Shift+Option+3 (Shift+Alt+3).