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Learn The Perks of Ableton Live's Warp Function

January 5, 2010
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In the mid-1900s, flange effects were first made possible chiefly as a side effect of tape players' design and operation. With two tapes simultaneously playing the same track, a person could achieve a sweeping phase effect by pressing on the flange of one tape, slowing the track down and forcing the two tracks in and out of phase. Since flange effects were first discovered, many devices have been manufactured strictly for the purpose of reproducing them. What modern experimental musicians should bear in mind, however, is that flange — despite being a commonplace insert effect for music production — was first made possible by equipment that was designed for an almost entirely unrelated purpose.

So why should this plain observation be borne in mind by experimentally minded electronic musicians? Because today, there are a tremendous amount of software and hardware tools to work with. When one thinks of the relatively simple mechanics of tape players and the relative complexity of many modern sequencers and synthesizers, it isn't difficult to imagine that some of the new musical innovations can produce sounds that they were not initially designed to produce. There are many programs available that are capable of far greater novelty than they're given credit for.

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One such program that I find particularly fruitful is Ableton Live. Live has a well-rounded array of effects, including the usuals such as delay, reverb and chorus. Particularly attractive to those who like their music to sound strange is Live's versatile grain delay. Although these are all essential production tools, something equally as interesting and infinitely more novel lies in Live's sharply engineered Warp function.

The Warp function uses granular resynthesis to make pitch-shifting a sample possible without altering its tempo. Normally, to pitch-shift a sample up, the tempo must increase proportionally with the pitch shifting. To avoid this problem, Live uses granular resynthesis to cut up the sample into very small slices, or grains. Grains increase in pitch and become separated from one another, but the sample stays the same length because the grains stay put relative to their original position in that sample. Because the grains are very small and blended together, their effects are unnoticeable, enabling for clean time-stretching and transposition. So how does flange figure in all of this? Well, it doesn't. But in the same way that flange was made possible by the invention of tape players, so have the effects to be described been made possible by Live's use of granular resynthesis. Both are the fortunate accidental side effects of technological progress. Now, have a look at what these distinct effects are, how they're produced and what each one sounds like.

With Live, generally, the effects produced by granular resynthesis occur when the sample is substantially transposed up or substantially slowed down. Usually, a combination of both will produce the most dramatic effects. So if you want to apply these effects to midrange song elements, then you usually have to start with samples containing mostly bass frequencies. If you want to apply them to bass song elements, then usually the only option is to substantially decrease the loop tempo or start with loops recorded at a much higher tempo than your song tempo. If this sounds like an inconvenience, recognize that these are side effects of a set of processes designed for a different purpose. For this reason, some planning ahead is usually necessary when selecting samples to be processed with these various techniques. Different samples respond better to different processing techniques. The variety of effects produced by these techniques is possible because of Live's various Warp modes.

Live uses four different Warp modes: Beat, Tone, Texture and Repitch. (Because Repitch does not use any novel processing, it is not part of this discussion.) The Warp modes are designed for different kinds of samples. As stated in Live's owner's manual, “The Warp modes differ by the selection of grains, as well as by the details of overlapping and crossfading between grains.” It is these differences that correspond to the different effects you're concerned with here. Although the following list doesn't cover every possible type of effect, these are a few that seem to be the easiest to achieve.

TRANSIENT DISTORTION

For the Beat mode of the Warp function, the manual recommends trying “large transient values in conjunction with pitch transposition” for “interesting rhythmic artifacts.” Transient distortion can be achieved in two different ways: pitch-shifting the sample up or slowing down the sample's tempo. Beat mode uses a type of resynthesis geared toward rhythmic samples. In Beat mode, the granulation process is optimized to preserve transients (attacks, note onsets). The user can specify where the transients of the sample are located (at half notes, quarter notes, 16th notes and so forth). Transient distortion occurs when the transients control is set to 16ths or 32nds.

What results in either case is a distinctive buzz or vibration added to the sample as the grains become separated from one another. Layered in with the buzz is the loop's original content. There is normally a threshold at which the original content of the loop begins to disappear, giving way to frequencies created by granular separation, but it never fully does. To produce transient distortion, follow these steps:

STEP 1 > Select your sample and set the sequencer tempo. So that these steps can be repeated exactly, use the “Combo 34” percussion sample from Live's sound bank. This image shows how the first few beats of the sample appear in Live's Clip window unprocessed. The original tempo of the sample is 120 bpm. The effects described here are more easily attained at tempos that are slower than the original, so the sequencer will be set at 70 bpm. Because this sample's default setting has the Warp function set to Beat, you should already start to hear traces of transient distortion without further processing.

STEP 2 > In the sample section of the Clip window located at the bottom of Live's sequencer, transpose the sample up roughly 12 semitones. Make sure the Warp function is set to Beat mode and the transients are set to either 16ths or 32nds. The decrease in tempo plus the transposition should produce the desired effect.

STEP 3 > In Live's File menu, you'll find the option to Render-to-Disk. Here is the rendered waveform of the “Combo 34” sample processed using steps 1 and 2. Note the repetitions extending across each 16th-note section. Transient distortion looks like this picture.

STEP 4 > This is a destructive edit of the same sample processed in the same way. The only difference is that instead of the sequencer tempo set to 70 bpm, it has been set to 20. At 20 bpm, transient distortion produces a buzzing effect that changes abruptly at fixed intervals. This can turn the plainest club beat into a provocative ambient song element. The only disadvantage of this process is that it can leave you guessing at the final product. Fortunately, it does not take a long time to do.

SLICE PINCHING WITH TRANSIENT DISTORTION

Another interesting way to take advantage of the sound properties within Live is to pinch time slices within a sample. The program's warp marker determines where a certain note of a sample will be played. For example, if a certain drum hit occurs at an odd spot in a loop and you want it to coincide with a certain 16th note, simply move the corresponding warp marker to the attack of that drum hit. This makes it tremendously easy to requantize beats and melodies to correspond with a song. The side effect of this is that if you pinch a certain loop section (by moving two warp markers very close together, one at the attack of the note and the other not much farther along in the sample), then you can produce the described transient distortion for just one section of the loop, putting an electronic-sounding accent in the middle of what might be an acoustic loop. The resulting hybrid sounds quite a bit like something you would hear coming from Aphex Twin or Squarepusher. Here is the process:

STEP 1 > Select your sample and set the Warp mode. Starting again with a loop from Live's sample bank — this time “drms140a” — set the warp to Beat mode with transients at 16ths, as in the first example.

STEP 2 > Isolate your time slice. Before you pinch the time slice that you want to place an accent on, you have to enclose it between warp markers by double-clicking on them. Otherwise, when you move one warp marker, the other warp markers also move. In this case, you want to pinch the slice between warp markers 1.1.3 and 1.1.4. Because 1.1.4 will need to be moved and 1.1.3 will not, you should double-click on 1.2 to keep the rest of the sample in place.

STEP 3 > Move the warp markers. Moving the 1.1.4 marker back in the sample forces Live to compensate for more time using less original material. Effectively, this is a slowing of the tempo for that one time slice, and the accompanying glitch-style effects are the result.

SCRUB

In both the Tone and the Texture modes of the Warp function, you can adjust the grain size. In Tone mode, a unique scrub effect is made possible with loops that have sharp attacks and lots of tonal content such as bells, xylophone or tabla. As with the other granular effects produced by Live's Warp function, scrub usually occurs when the sample is slowed down or its pitch is increased (although it can be achieved solely by adjusting grain size, depending on the sample). After transposing the sample to the desired pitch and stretching it to the right speed, you can search through the grain size using the bisection algorithm or trial and error to locate the scrub effect. The effect is characterized by its vague resemblance to the sound of scrubbing wet crystal or glazed ceramic dishware with a drying cloth. Although any sample can be processed this way, only samples with sharp attacks produce this particular sound.

If the sample is transposed up high enough in Tone mode and the grains are set to a low value, their overlap causes a strange gulping sound that bears little resemblance to the scrub effect. Although this is not the effect that this exercise works to achieve, its presence does suggest that the types of effects discussed here are only a few among what could be many different effects made possible by Live's granular resynthesis processes. Here are the steps to follow for the scrub effect:

STEP 1 > Assume that all of the variables are kept as they were for the transient-distortion example. The sequencer is at 70, the pitch is transposed up 12 semitones, and the sample used is “Combo 34.” All that you need to do is switch the Warp mode to Tones, and the scrub effect appears. You can adjust the grain size depending on your preference, but, usually, a moderate value is needed to produce the effect.

STEP 2 > This image displays the “Combo 34” sample rendered with the scrub effect applied. The waveform is marked by a repeated attack that tapers more gradually than transient distortion. Any “scrubbed” sample should bear some resemblance to this one.

GRANULAR TRILLS

A granular trill is basically the same as a scrub in terms of mechanics. Usually, it can be achieved in Tone mode or in Texture mode with a sample that has been slowed down substantially. Pitch transposition does not seem to bear heavily on whether you will achieve a trill effect. As with the scrub effect, you can usually search for trills through trial-and-error adjustments to the grain size. Trills occur with large grain sizes; for this reason, Texture mode, with its larger grain-size settings, is preferable. This effect works for all kinds of samples. With solo wind-instrument samples, it can sound remarkably like a natural trill produced by a musician; with strings and percussion, it sounds a little more unnatural. With guitar samples, it occasionally sounds like someone may be bouncing a drumstick in a sloppy closed roll on the strings. Regardless of the sample, using Texture or Tone mode to effect a trill always produces a novel and interesting result. Trill sounds natural with saxophone samples, as it resembles something that saxophonists can perform on their own, but that's not the case with guitar. Here is the process:

STEP 1 > You will again use the “Combo 34” sample. Generally speaking, for this effect, it isn't necessary to transpose the pitch. The Warp mode is set to Texture, and the grain size has been set to a large value — 179.40 — to get something that sounds like a trill. With guitar samples, it occasionally sounds like someone may be bouncing a drumstick in a sloppy closed roll on the strings.

STEP 2 > Here is a destructive edit of “Combo 34” with a granular trill effect applied. The attacks of each note are broken up into large pieces and occur erratically. It best suits melodic samples, but for the sake of illustrating its appearance in contrast to the first two effects, the same sample is the example.

MULTIPLE-NOTE TRANSIENT TRILLS

At this point, you're getting to one of the more bizarre and complex manipulations that is possible with Live's Warp function. This particular effect is related to the design of the Beat mode of the Warp function. When you specify a low transient value, say half- or quarter-note values, Live assumes that what happens at the beginning of any given half note ought to be repeated through the rest of the half note (thereby preserving the transients that occur at the beginning of the note). At very low sequencer or loop tempos, this property of the program makes it possible to achieve multiple-note trills like a violinist, a flautist or a bagpipe player might perform. Alternatively, if the sample is not a melodic one, this same process will introduce strange repetitions in any sample, possibly forming the basis of a percussive element.

Increasing pitch increases the amount of note data in the grain of the sample and the speed at which it plays. The result is, at every different pitch, you get a trill at a different speed with a greater or lesser number of notes. This usually defies a standard 4/4 time signature (or whatever time signature you're using). The good news is, if the rhythm isn't quite what you desire, a destructive edit and some requantizing with Live's Warp markers put you a few minutes away from correcting the problem.

Before taking your results and requantizing them, it is an interesting experiment to layer a trilled sample with the same trilled sample transposed up a third or a fifth playing on another track. This way, corresponding parallel harmonies occur with polyrhythmic syncopations over the same span of time — the higher trill playing more notes than the lower one. These harmonies can sometimes collide with one another in curious ways that don't sound like typical musical performance. In this way, it is possible to use the Beat mode of the Warp function as a kind of structural parameter linking pitch to speed of performance and combining the results. Here are the steps to produce a multinote transient trill:

STEP 1 > Starting with the “AC Guit_C_107” sample from Live's sound bank, set your sequencer tempo to 20 bpm.

STEP 2 > Adjust the transients to half or quarter notes. In this case, half sounds better. If needed, the pitch can be transposed depending on preference, but it isn't essential for this demonstration. After these steps are completed, the sample should be full of odd-timed repetitions. It may not sound terrific, but you are not finished yet.

STEP 3 > In Live's Sequencer window, copy the sample and paste the copy parallel to the original. You can do this two, three or four times, depending on how many voices you want in your parallel harmony. (Continued on p. 54.)

STEP 4 > On the second copy of the sample, transpose the pitch up five semitones. Normally, this would create a parallel third harmony, but because you are splitting the sample into grains, it also creates a bizarre polyrhythmic phenomenon. In this case, it sounds better to switch the transients to quarter notes.

How is this effect so different than doing the same thing with looped samples in a conventional sequencer? First, you are creating odd-sounding polyrhythmic trills by manipulating grains, but equally as important, for every half- or quarter-note section (which at 20 or 30 bpm will sound like bars of a song), the content of the loop changes, introducing a new section of note data. Usually, the changes reflect the note progression of the original sample, but because of the rhythm changes and the extra repetition, the results yield something much more complex than what is possible with a conventional sequencer (which is the desired effect, of course). As with all of the effects discussed here, this process can be further refined by stacking it with other ones or by augmenting it with the more conventional effects provided by Live.

This last process doesn't produce quite as specific and identifiable a sound as do the other techniques. The first three techniques are primarily concerned with altering the original timbral quality of what is played in the sample by adjusting granular parameters. The final technique, however, does not alter timbral quality at all: Because the grain size is so large and the tempo of the sample is so low, you're hearing larger sections of the original sample being looped at odd intervals without any other changes except for pitch. If some sections sound out of place, you can simply replace them with ones that sound better. It is a bit of a hit-and-miss process, but when it works, it works wonders.

A MOVING TARGET

This exercise showcases a few distinctive sound-design processes that are possible with Live's Warp function. As you have seen with tape players and flange effects, sometimes misusing a tool or technology can be as useful as what it was intended for. The effects described in this article are ways in which Ableton Live can be consistently misused to produce a similar-sounding result in most cases. Whether or not these effects will become standard sounds in other software or hardware applications is anyone's guess, although it is unlikely that you will find a scrub pedal for your guitar anytime soon — but anything is possible. At the very least, these are powerful tools for anyone interested in a glitchy-sounding production style. What can be concluded is that because of Live's Warp function, completely new types of sounds are now possible.

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