Going with the Grain

Oct 1, 2008 12:00 PM, By Dennis Miller

           
 

TEN GRANULAR-SYNTHESIS PROGRAMS TO SLICE AND DICE YOUR SOUNDS

You can choose what type of synthetic waveform you want for grains in several of the programs. Cloud Generator, for instance, includes only a sine wave (by far the most common), while Organik lets you choose from sine, saw, ramp, square, or pulse waves and, even more useful, create your own using a different 31-harmonic, user-defined additive-synthesis waveform for each of its four Generators. Stochos also supports additive synthesis as well as pulse-width, ring, and frequency modulation, and crusherX-Live offers sin, cos, triangle, rectangle, and random waveshapes, and a window for drawing and saving your own.

Zeroing In

Picking the region or range from which grains will be extracted from a sample is an important feature, and most of these programs offer flexible options in this area. Atomic Cloud, for example, has a Scan Rate slider that lets you determine how quickly the program will move through a sample and generate new grains. CrusherX has sliders for setting the region from which each of its four separate samplers will pick grains, and REplay PLAYer provides several modes (Walk, Jump, Regions, and so on) with adjustable parameters for the same purpose. GrainMill offers a Wander parameter to determine how random the process of picking grains will be: a value of 0 specifies that grains should be chosen in strict order, while a value of 100 specifies that grains should be chosen randomly from anywhere in the file.

RTGS-X provides a Buffer Position slider that can be automated to scan through a file at any speed, forward or backward, or to pick from random points, and Stochos can play back all or only a set range of a file in a variety of directions. Kenaxis has numerous flexible options for determining the portion of a sample that will be used, including a two-dimensional graph on which you can draw the playback trajectory (see Fig. 2). You can easily build a path that moves forward through the file quickly, then slows down, then reverses direction. (Graphs can be saved for reuse.)

Grain density, or the time between successive grains, is the parameter that most affects how quickly a massive grain cloud will build up. RTGS-X will produce grains from every 10 to every 5,000 ms, and REplay PLAYer lets you control density manually by using a two-dimensional grid or by applying a preset (Granular_lo and Granular_high, among others; see Web Clip 2). GrainMill's Density feature lets you set the number of new grains relative to the base grain size you've chosen (a value greater than 1 produces overlapping grains and a value less than 1 produces separation), and crusherX has a Birth parameter for setting grain density (from 10 to 1,000 ms) and can display a window that updates the actual number of grains produced in real time.

Windowing is the process of applying a smoothing envelope onto individual grains to avoid the clicks that such short-duration sonic events would typically produce — most common is a Gaussian (bell-shaped) curve, and linear fade-ins and -outs are also useful. All of the programs support this feature, and some offer several window types (or, in the case of REplay PLAYer, a Smoothing parameter) to choose from. CrusherX and RTGS-X even let you draw your own envelope shapes.

That's So Random

Because randomness and nonrepetition are such common qualities of grain clouds, you'll find random functions (called “variation,” “jitter,” “range,” “random,” or “drunken walk”) to be part of many of the offerings. At the very least, most of the programs provide a base setting for their individual parameters, then let you add some amount of jitter or randomness that offsets above or below the base value.

The distribution or probability curves that several of the programs provide are even more powerful than simply adding a touch of random jitter. In addition to Gaussian, you'll find Weibull, Cauchy, Poisson, and drunken walk curves in Stochos and elsewhere, each of which defines different probabilities of events occurring. (Distribution curves typically establish a mean and some variance or standard deviation from that mean. See en.wikipedia.org/wiki/Probability_distribution for more information.) Cloud Generator has various options for randomizing grain frequency and offers controls to transpose grains using both hertz and cents increments.

All of the programs except Atomic Cloud and Organik allow you to automate changes in parameters via MIDI controller messages, internal envelopes, or other means. Several let you use distribution curves to determine parameter values (in addition to using them for added randomness). More typical are internal functions that sweep through a sample file to locate grains or the ability to apply a ramp function to the amount of pitch transposition (in Stochos, for instance). Granulator has a MIDI Controls window where you can map any MIDI controller number to any of the program's parameters, and both crusherX and Kenaxis have dedicated MIDI setup screens where you can assign MIDI data to various parameters and also scale or otherwise process the data before it reaches its target. REplay PLAYer has a hardwired mapping of controllers to program function.