When enabled, the Elastic Time plug-in analyzes two dimensions of your audio in order to calculate the recorded performance’s tempo. It looks at the audio region’s duration in bars and beats, and it looks for transients that represent a regular periodic rhythm in the recording. In theory, if the rhythmic content of your recording is clear, with distinct transients, Elastic Time can figure out a performance’s tempo regardless of whether the audio region is trimmed to a perfect loop or not. This is really neat when it works, but it doesn’t perform miracles (nor should you expect it to, that’s not producing your own music).

Instead of relying blindly on Elastic Time to perform your beat matching (as in, crossing your fingers and hoping for the best), there are several simple steps that you can take ahead of time to prepare the audio and ensure perfect results every time. Performing this pre-processing, even though it’s a tedious task, helps to preserve the audio quality and the groove of the original performance after your tempo change.

The easiest way to demonstrate my pre-processing approach is to take you step by step through the process. This is the best way to understand not only the steps in the process but the logic behind my approach. (Try it a different way and you’ll find out just how quickly you can end up with a train wreck.) The DRM (Digital Rights Management) free stems being offered for your remixing pleasure by Radiohead, of their song “Nude”, on iTunes is perfect for this example. The stems are $0.99 each and you only really need two of the five available, the “Drum Stem” and the “Voice Stem”. But, it’s nice to have all of the stems in your session, even if you don’t use the “Bass Stem” and “Guitar Stem” they’re handy for finding the key of the original, and the “String FX Etc. Stem” contains several sounds that are perfect for a remix.
iTunes Nude

Remixing Radiohead

1. Create a new Pro Tools session and import all of the “Nude” stems. When prompted, select the import Destination as New Track with a Location of Session Start.
step 1

2. Arrange the tracks in the Edit window with the Drum Stem on top and the Voice Stem just below.
step 2

3. Mute all of the tracks except the Drum Stem. Use Tab to Transient to locate the very first downbeat in front of the vocals (approximately 1946229 samples in from the session’s start) and separate the regions.
step 3

4. Select the Edit Group, double click on the latter Drum Stem region and separate all of the regions.
step 4

5. Select the Shuffle Edit Mode and delete the first set of regions so that the downbeat of the second set of regions scoots to the beginning of the session.
step 5

6. Disable the Edit Group and using Tab to Transient find the downbeat every two bars in the Drum Stem and separate the regions. (The only region that I left as 4 bars is the drum break, having 2 bars before the break itself.) In some instances, you can make the separations every 4 bars, but with “Nude” there’s a lot of human tempo variation and every 2 bars will produce the most precise overall beat match.
step 6

7. Select the Edit Group and double click on each 2 bar Drum Stem section and separate the sections.
step 7

8. Select each 2 bar section and apply Identify Beat to generate a tempo map for each section. This will beat match and lock each 2 bar section to your session’s tempo grid. (You could use Beat Detective to generate a tempo map, but my method preserves the original performance’s groove every two bars, while simultaneously guaranteeing that the original’s downbeat is locked exactly to the grid every two bars. This way, your beat match never drifts.) At this stage, it’s also helpful to create a Click track in order to audition your tempo lock.
step 8

9. Change the Timebase selector for all of the tracks to Ticks. This will lock the regions to their relative bar and beat positions so that they stay in beat when you make your tempo change. Then, enable the Elastic Time plug-in for each track. Set the Drum Stem to Rhythmic, the Voice Stem to Monophonic, the String FX Etc. Stem to Polyphonic, the Bass Stem to Monophonic, and the Guitar Stem to Polyphonic. Give Pro Tools time to analyze the audio. (For now, leave the Elastic Time plug-in set to Real-Time Processing.)
step 9

10. In the Transport bar, disable the Conductor and enter a new tempo in the Current Tempo field, or experiment with the Manual Tempo Slider. Since the original tempo is about 42 BPM, it’s nice to bring the tempo up to about 62 BPM. At this tempo you can then record drums in double-time (124 BPM) and be at a dance tempo! (Once you decide on your remix target tempo, if your computer is running short on processing power, your can set the Elastic Time plug-in to Rendered Processing.)
step 10

Here’s what the final results sound like, using all of the stems at 62 BPM, some effect processing, and backed by Digidesign’s Strike virtual drum instrument playing in double-time at 124 BPM:
Nude – The Strike Remix (by Erik Hawk)

With the introduction of Elastic Time, in Pro Tools 7.4, it’s clear that Digidesign is taking a proactive stance against competing programs boasting easy to use, time compression/expansion based, automatic beat matching algorithms. Though it’s tough to proselytize that Elastic Time is as easy to apply as similar functions in competing software applications, I can say, without a doubt, that it kicks butt in terms of its audio quality and the level of direct control you have over how the algorithm is processing your audio. It’s deep and offers a variety of ways to fine tune the processing, from multiple Elastic Audio “plug-ins” (Polyphonic, Rhythmic, Monophonic, and Varispeed), to individual control panels for each plug-in type, and the ability to freely edit Warp markers directly in the Edit window. Talk about control! Due to the simple fact that you have such a high degree of control over the Elastic Time processing, it requires a bit of homework to master, but once you do, you can achieve absolutely stunning results.

It’s important to note that Digidesign calls Elastic Audio a “plug-in”. However, it’s not applied in the way you’d normally think of a plug-in, as an insert on a mixer channel or an offline AudioSuite processor. Instead, it’s applied directly to a track in the Edit window, with its plug-in menu located just below the track’s Timebase selector.

ET Selector

Beat Matching Made Simple
Elastic Time is at its most intuitive when browsing for loops in the Workspace. Simply turn on the Audio Files Conform to Session Tempo button (it looks like the ticks metronome) in the Workspace, select one of the four plug-in types (they’re pretty self-explanatory), and when you click on a loop’s play button (the little speaker) the loop will be automatically analyzed and played back at your session’s tempo. You can even do this while your session is playing, allowing you to hear immediately whether the loop you’ve selected is a bang or a bust. Talk about optimizing your workflow! When you find the loop that you want, simply drag it into the Edit window and it will be deposited on a newly created ticks based audio track, and conformed to your session’s tempo. It doesn’t get much easier than this.

Workspace ET

For those of you who are used to working with REX loops, it should be noted that with the introduction of Elastic Time, the Processing Preference setting, Import REX Files as Region Groups is off by default. So, if you’ve recently updated to Pro Tools 7.4 and you’re wondering why when you drag in a REX file it no longer comes in as a region group, mystery solved. To return to your old way of working with REX loops, make sure that the Processing Preference for Import REX Files as Region Groups is checked, as well as the REX and Acid Files Only selection for Drag and Drop from Desktop Conforms to Session Tempo. From the Workspace, you can also audition REX loops at your session tempo when the Audio Files Conform to Session Tempo button is on. And, if when you drag a REX loop from the Workspace into the Edit window, you want the REX loop to automatically conform to your session’s tempo, again, the Audio Files Conform to Session Tempo button must be enabled.

REX Import Preferences

Of course, just because you don’t understand compression doesn’t mean that you’re mentally challenged. As a rule, the compressor, and how it controls a signal’s dynamics, is one of the more challenging processors to grasp. Learning how to effectively apply compression in your mix can take a significant amount of study time, patience, and good old fashioned experience.

Now, I could explain what each parameter of a compressor does and how it affects the signal. I could even give you some compression presets to get you started. But, this approach would be old hat and does nothing to help you actively hear compression and how each of its components work. You see, without the ability to hear in your mind how compression colors a signal, and to then know which parameters on a compressor to reach for in order to achieve your sound, you’re just fumbling blindly.

The skill necessary to properly operate a compressor is comparable to the ability you developed as a toddler to recognize and apply colors. You learned to visualize what color you wanted to apply to the flower in your coloring book, and you learned which color to reach for in your box of crayons to achieve your objective. The trick with compression, as with any type of processing or synthesis used in music production and sound design, is to know, instinctively, which parameters to reach for in order to create the sound you’re hearing in your head. It’s a deceptively simple process because it’s so easy to quantify, but as we all know from experience, it’s tough to put into practice.

With all this in mind, I’ve cooked up an interactive compression lesson to help you better hear compression, and learn to associate compression colors with specific compressor parameters. It’s a Reason song file full of MClass Compressors, with each Compressor adjusted slightly differently, but applied to the same snare drum signal. Each compressor’s label reflects its parameter change (such as “More Attack” or “Less Attack”), so that you can easily identify the Compressor’s parameter that you’re hearing, in relation to a base compression setting (the “Basic Compression” device). And, since a sound is rarely heard on its own, but, instead, always with accompaniment, I’ve included the rest of the drum mix as a stereo stem on Channel 12 of the mixer.

Here’s How You Work It
Press Play to start the drum pattern, then, to hear each compression setting, solo each snare drum signal on the mixer (Channels 1 to 10), one channel at a time. Leave the drum mix on Channel 12 in solo mode so that you can hear how the different compression settings make the snare “sit” in the drum mix.

Many of the changes to the snare drum’s sound are subtle and a challenge to hear, especially if you’re new to this sort of critical listening. Accurate monitors are also key in being able to hear the differences in the drum’s sound. So, if you’re not hearing the differences right out of the gate, not to worry, below is a description of what you’re listening for in each compression setting.

Channel 1: “No Compression”
This is the snare drum dry, with no compression processing.
Channel 2: “Basic Compression”
This is a decent snare drum compression setting. It is the starting point from which a single parameter is changed in the following Compressors. For example, on the “More Attack” Compressor, all the parameters are identical to the “Basic Compression” settings except the Attack parameter.
Channel 3: “Less Threshold”
Increasing the Threshold means that less of the incoming signal will be compressed. Another way of putting it is that the threshold at which the signal will begin being compressed is higher.
Channel 4: “More Threshold”
Decreasing the Threshold means that more of the incoming signal will be compressed. Another way of putting it is that the threshold at which the signal will begin being compressed is lower.
Channel 5: “Less Ratio”
There’s no easy way to explain the compression ratio. It’s math, there’s no getting around it. Ratio sets the amount of input signal necessary to cause a 1 dB increase in output signal. For example, with a ratio of 4:1, an 8 dB increase in input will produce a 2 dB increase in the output. So, less Ratio means that an increase in input signal will sound louder at the output, less compressed compared to the original “Basic Compression” setting.
Channel 6: “More Ratio”
With more compression ratio applied, more input signal will be required to produce a 1 dB increase in output signal. Consequently, the output signal will sound more compressed when compared to the original “Basic Compression” setting. At high compression ratios, limiting occurs, where, at the most extreme settings, the output level stops increasing no matter how loud the input level becomes (referred to as “brickwall” limiting). In situations where the output level is very low in volume, you can use the Compressor’s Output Gain control to turn it up.
Channel 7: “Less Attack”
The Attack parameter sets how quickly the compression will begin. So, turning the Attack up means that less of the signal’s initial transient (the very beginning of its waveform) will be compressed. This is good if you want to retain the crack and pop of the waveform’s start.
Channel 8: “More Attack”
Turning the Attack down means that more of the signal’s initial transient will be compressed. This is good if you want to diminish the crack and pop of a waveform’s start.
Channel 9: “Less Release”
The Release parameter determines how long it will take for the compression effect to fade out. So, less Release equals a shorter release time and the signal’s waveform will be compressed for a very limited duration. This is good if you want to retain the natural decay of a waveform.
Channel 10: “More Release”
Turning the Release up means that the time it takes for the compression effect to fade out will be longer. This is good if you want to compress the natural decay of a waveform, like increasing the volume as the signal fades out.

After you’ve listened carefully to each compression setting, try describing the changes in the sound that you hear. This will connect what you’re hearing to a concrete idea in your mind. And, ultimately, help you to associate a compression color with a specific compression parameter. Once you master hearing what each compression parameter can do on its own, then you will begin to hear how all of the compression settings work together to create a variety of compression effects and sonic colorations.

Here’s the Reason song file. Remember to press Play before you begin soloing each snare drum signal, and only audition one snare signal at a time.

Compression Lesson (Reason 3 Song File)