Sometimes you just want to massage that audio, knead it like dough, and stretch it out just a little bit.  We all know that the TCE trim tool can let you shorten or lengthen a region’s duration without changing pitch, but it renders a new file each time you use it.  If you change your mind on the change, you have to un-do it and re-do it differently (if you kept stretching the file over and over without undoing, you’d destroy the sonic fidelity very quickly).  If it’s a long region, you’ll be left waiting a while before that finishes.  And if you need to change duration a few different times within a region, you have no choice but to split it up first.

Elastic Audio, a handy feature of Pro Tools that is typically targeted at musicians, actually addresses many issues quite well for post.  Is sync a little off for that ADR?  Use Elastic Audio.  Do you need to stretch out a few chopped up words in that reality show Franken-Bite to make it sound at least a little more natural?  Use Elastic Audio.  Did they manage to record the set audio for that shot without reference, so it’s drifting?  Use Elastic Audio!  Is someone cut off mid-sentence, and you just want to make that last word a little longer so it feels a bit more natural?  Use Elastic Audio already!

Elastic Audio works as a plugin that can be assigned to an audio track on the Edit Window only in a designated spot separate from the normal inserts.  You pick from a series of 4 real-time engines (and one render-only engine).  It looks like this:

And once one of those is inserted (in this case, Polyphonic):

Pro Tools quickly analyzes the audio files on the track (during which time all regions are temporarily greyed out), and then Elastic Audio is enabled.

So what does that mean?  It means that now all the audio on that track can be stretched or compressed (as well as be pitch-shifted) all in real time without having to render anything.  Let’s look at an example.

First, a region of ADR as originally recorded:

Then, the region stretched using elastic audio (this was done using the TCE trim tool, but no new media was rendered):

Notice the tiny icon in the top right of the region that looks like a triangle with a line sticking out of it; this “warp indicator” tells us that the region has been modified by elastic audio in some way.  In this case we’ve simply taken the TCE trim tool and stretched the audio out.  This is known as “telescoping warp” since it extends the region like a telescope.

Telescoping warp of a region with the TCE trim tool is the simplest way to work with elastic audio.  But what if you need to change the duration of just one part of a region?  Or what if you just need to change the timing of syllables and words within a region of dialog so that the ADR matches better?  For that, you’ll need to get into the new “warp” track view.  On the Edit window click on the track view selector where it says “Waveform” by default, and change it to warp.  Like so:

Those grey vertical lines are called “event markers.”  You see, since elastic audio is targeted as music users primarily, one of the things it does automatically is attempt to identify all the transients in your audio (such as drum hits or guitar plucks).  The idea is that elastic audio can be used to snap all of those hits to the beat, “quantizing” your performance.  Of course in post that’s not the objective.  Nevertheless, it’s helpful to see where Pro Tools has found transients, because they’re probably right at the start of each syllable of dialog.

So we’re in warp view, and we want to just re-time a few syllables of our ADR so it matches sync better.  What do we do?  We’re going to add a few warp markers and use them to stretch the words we want to work on.

First identify the word or words you want to work on, and then using the grabber tool, double-click on the event marker that immediately precedes them.  This will add a warp marker at the very start of the region as well as one where you double-clicked.  It looks like this:

The warp markers are the tiny blue triangles at the bottom of the event marker lines (which have now turned solid black).  The one at the beginning of the region functions as an “anchor” that locks the start of the region to that point on the timeline.  All other warp markers allow you to stretch the audio relative to any adjacent warp markers.  Right now since we only have that anchor marker and one other, any stretching we do will simply be “telescopic” warping just like before.  Things don’t really get interesting until we add a few more warp makers.

To add more warp makers, use the grabber tool and either single-click on any event marker to the left of the first warp marker you added, or double-click on any event marker to the right of that first warp maker you added.  If you want to add one at a position that doesn’t have an event marker at all, just control-click with the grabber tool at the desired location.  Pretty soon things can look like this:

Now you can just click and drag these warp makers around with the grabber tool to stretch and compress your audio like a rubber band!  The above region can now look like this:

Let’s take a look at a slightly simplified situation to see more clearly what’s going on.  Here’s a region with just three warp makers (the anchor and two others to the right of it):

This is an example of a situation where you want to adjust timing within a region, but you want the overall region length and position to remain the same.  Here the first and third markers are acting as anchors that are keeping our region in place.  We’ll use that middle marker for our elastic stretching.  Like so:

Here we’ve moved that middle warp marker over to the right.  This slows down those first few syllables, speeds up the next few, and leaves the remainder of the region untouched.  We could also stretch it the other direction:

Here of course the first few syllables are greatly sped up, the next few are slowed down, and the remainder is unchanged.  The best part is that all of these adjustments are done in real time to a single region with no rendering!

The main point here is that in order to stretch just part of a region without changing its overall position or duration, you need “anchor” markers on either side of the one you want to move.  Basically you need at least 3 markers to do this kind of elastic audio work.  The two outside markers lock things in place while the middle marker does the stretching.  The fastest way to create those 3 markers is to shift-click an event marker with the grabber tool; this immediately creates a warp marker where you clicked and also on the directly adjacent event markers.  You go from this:

To this:

in a single mouse click!  This is mainly helpful when you just want to stretch a small area.

So those are the basics of working with elastic audio.  In the next post I’ll take a closer look at using this powerful tool to solve real-world problems in post production sound!