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Getting Started with RTGS3

What is granular synthesis, and what can I do with it?
Why I made this program
Quickstart instructions

What is granular synthesis, and what can I do with it?

Granular synthesis is, in a nutshell, the process of creating new sounds using tiny fragments of existing sounds. These fragments of sound are normally referred to as 'grains', hence the term 'granular' synthesis. The idea that sound itself consists of particles goes back to 1947, when the physicist Denis Gabor presented his article "Acoustic Quanta and the Theory of Hearing" in the journal Nature. Some early proponents of granular techniques in music are the composer Iannis Xenakis (for example, listen to the great orchestral work Pithoprakta from 1955), Curtis Roads (probably the first guy to perform granular synthesis techniques with computers) and Barry Truax (listen to his seminal work Riverrun from 1986). I could go on forever about the science and theory behind granular synthesis, but I don't think this is the appropriate place to do so, since only a basic understanding of the technique is necessary for using RTGS. Anyone really interested in granular synthesis theory might want to check out Curtis Roads' "Computer music tutorial" (MIT press, Mass 1994).

Granular synthesis can be used to generate brand new sounds or to manipulate and distort existing sounds. It is very useful in generating dense sonic textures, which can evolve quickly or over long periods, to create alien soundscapes. It is also useful for creating short sound effects or sonic motives, which could be used in musical or theatrical situations. One of the most interesting applications of granular synthesis is the manipulation of existing sound through temporal distortion (time stretching, compression, reversal, and fragmentation). Taking a short sample of a sonically rich sound and stretching it to a hundred times its original length can yield some remarkably interesting results! I have been able to generate some wild, interesting and fresh sounds using granular synthesis. What I like most about it is that it is possible to generate sounds which have a certain "natural" quality to them, unlike sounds generated using FM or other oscillator-based synthesis techniques. I hope that in your exploration of granular synthesis you will also find sounds that stimulate your senses and creativity!

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Why I made this program

The early versions of RTGS were made around the time when consumer-level computers were just becoming fast enough to do granular synthesis in real-time. Nowadays of course any computer capable of running OSX is in practice fast enough to do granular synthesis in real-time, and more recent computers can even handle rather thick grain densities. But in spite of the advances in hardware performance, most granular synthesis programs and plugins still offer only a fraction of the possibilities of this great synthesis technique. They are often limited to generating a limited array of textures, either because they do not offer enough parameter control to the user or because their complicated interfaces hinder spontaneous creativity. The RTGS user interface was designed to allow instant and intuitive access to the main granular parameters, while still giving the user the power to exploit a wide range of modifications to and control over those parameters.

I believe that granular synthesis can become a musical and compositional tool for more people than just hard-core computer programmers or audio design specialists. RTGS was created with the intention of introducing granular synthesis to a wider audience, including musicians, composers, sound effects creators, and performance artists.

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Quickstart instructions

1. Get some sound into RTGS3

Most of the time, an RTGS3 session will begin by loading two soundfiles into memory. To do this, first click the "View Buffers..." button:
View Buffers...

This will open the Buffers window, and here you can load in an audio file by clicking the "Read File..." button corresponding to each of the buffers. The first ten seconds of the file are read into memory (only the first channel of stereo files will be read – to process stereo files split them into two mono files and read each one into its own buffer). If you want to process a single, mono audio file you will need to load it into both buffers, but if you want to mix two different files you can load different files into each buffer (this can produce some interesting effects, check out the tutorials for more info).

2. Get granulating!

Close the Buffers window and start the RTGS3's audio engine by clicking the Power button so that it lights up red:
Power Button

Click the switch labelled Grains On/Off so that a checkmark appears:
Grains Toggle

Next, try dragging the Buffer Position slider to the right with the mouse:
Buffer Slider

You should hear some sound now, and by moving the mouse around you can scrub through your soundfile. You can also automate the process by clicking on the Auto Scrubbing "Play" button underneath the Buffer Position slider:
Buffer Autoscrub Controls

Play around with the other sliders to get an idea of what they do – try moving the Grain Length slider a bit to the left and then play around with the Transposition Random slider, or try moving the Grain Delay and Grain Length sliders to the right. A time stretch effect can be done by setting the Grain Delay to about 10, the Grain Length to about 100, centering the Transposition slider and setting its randomness to zero, and then moving the Auto Scrub Speed slider to the right (click the Auto Scrubbing "Play" button if you haven't already done so).

3. Saving the output to disk

Once you've come up with some groovy sounds, you'll probably want to save them to disk as an audio file. Click the Gear Icon in the Output section of the main window:
Output Gear Icon

This will open the Audio Output Setup window. Clicking the "Create Audio File..." button will bring up the standard Save As... dialog box, in which you can create a new audio file to write into. Once the file has been created you may click the "START RECORDING" button to start writing sound into the file:
Record Output Buttons

Recording takes place in real-time, so any changes you make to the sound while recording is active will be heard in the resulting audio file. Note that you can set the maximum record time in the Capture Output window, this is to prevent you from accidentally filling your entire hard disk with audio.

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