Written 1999/08/05
The wonderful thing about digital audio is that there are virtually no limits to the ways it can be produced and processed, all it takes is a concept and a skilled programmer. One such concept is using graphics to represent various properties of sound, allowing one to literally paint a compostion on a computer. One such programmer is Rasmus Ekman, the author of Coagula Light for Windows 95.
While the concept has been done before in a commercial program for the MacIntosh platform, Ekman claims to have improved upon its faults with his own PC freeware version. Having never used a Mac, I am in no position to confirm or disprove this claim. What I will tell you, however, is what Coagula is like to work with.
The premise is that various colors and shapes drawn on a bitmap represent aspects of sound. As in a standard spectral display of audio, the horizontal axis is time, while the vertical axis is frequency. The brightness of color determines amplitude, with black being silence and white being maximum output. Unlike your usual spectrum, however, stereo position is represented by three colors: red for left, green for right, and yellow for center.
When you open the program you are given an all-black bitmap to work upon. To make your mark on this canvas you switch to the Brush Tools dialog, displaying color fields for the panning, amplitude, and spectrum (not yet implemented), brush shape and style options with buttons for 16 brush presets, color fade and color mix sections. The color fade section dictates what colors will be present in the brush, and whether the gradient fade goes horizontally or vertically, or is randomly mixed as "noise". A left mouse click on the Brush Tools color spectra changes the first color value, a right click changes the second. As you might have known, you simply point and click the left button on the bitmap to paint, while using the right button to make a selection that can be copied, pasted, or affected by filters. Cursor coordinates are shown in the lower-right corner as seconds and hertz. Not only can you paint your own bitmaps, but you can also import bitmaps to render waveforms from.
Upon first painting with or loading an image into Coagula, one is eager to hear the results. To do so press F5, which creates a .WAV file in
the Windows TEMP directory, unless you specify another destination. Then you can open the file with whatever playback program you prefer.
The Render Options dialog lets you set the duration, amplitude, and frequency range of the image/sound. It also lets you set the size of a
new bitmap. Sample rate is controlled in the Sound I/O Options submenu found under the Options menu.
The sound of the .WAVs vary widely depending on the bitmap used to render them. Single-pixel width lines will yield sinewaves, slightly larger bursts of color have an additive sound, while complex images can be very noisy or very beautiful. Images full of square, geometrical shapes will sound highly computerized and synthetic, while flowing, organic curves can sometimes have a birdsong quality. Fractals are especially intriguing bitmaps to use. A red Symbol of Baphomet on a black background is also pretty pleasant to listen to, and it wards off the superstitious to boot!
A retail version of Coagula has yet to be released, which promises use of the blue spectrum, automatic playback of rendered .WAVs, and the creation of bitmaps from imported sounds. The freeware version however, Coagula Light, is still a very engrossing and creative program which is great fun to use. It is highly recommended. Download Coagula and its filter bitmaps at:
