WaveWarp Users' Guide: last updated 28 February 2002

8.2-- Controllable Playback Engine

8.2.1-- Basic functionality of the Controllable Playback Engine

WaveWarp allows complete control over the manner in which the audio files(s) are played back. To enable the controllable playback functionality for any desired WAV file, select the WAV file from the Controllable Input Audio Files category of the Component Library (rather than from the conventional Input Audio Files category) and drag it onto the DrawingBoard. The icon will look like a conventional WAV file icon, except it will have a Control Signal input, as well as the conventional audio output. An example of a DrawingBoard featuring controllable playback is shown in Figure 85.

Figure 85 Screenshot illustrating the versatility of WaveWarp's controllable file playback feature. By selecting the audio file (in this case "bass.wav") from the Controllable Input Audio File category of the Component Library, the resulting component has a Control Signal input as well as the usual audio output. In this example, a constant negative value (created by the red blocks) is fed into the Control Signal input of "bass.wav". This has the effect of playing the file in reverse at a user-determined rate (adjustable via the Constant Control Generator: a value of -1 corresponds to pure file reversal).

The Control Signal input can be used to manipulate playback of the file in a totally flexible manner. It works as follows: the numerical value of the Control Signal input is truncated to the nearest integer, and this integer value is used as the step-size (in samples) for advancing the file location pointer during playback. For example, if the Control Signal has a constant value of 1, then the file playback will be entirely normal, since the playback pointer simply advances by one sample at a time through the audio file. If the Control Signal has a constant value of 2, then the file playback will be accelerated, since the playback pointer will advance by two samples at a time through the audio file, etc. Likewise, if the Control Signal has a negative value, as illustrated in Figure 85, the file playback will be reversed at the corresponding rate. If the Control Signal is time-varying, then the file will be played at a time-varying rate, with the instantaneous rate determined by the instantaneous integer value of the Control Signal. The Playback Controllers category of the Component Library contains various components (with internal buffers) which facilitate playback at any fractional (non-integer) rate, allowing full playback flexibility.

Important note: all WAV files will appear in both the standard Input Audio Files category and

the Controllable Input Audio Files category of the Component Library, so any file can be played

normally or with flexible playback control.

8.2.2-- Granular synthesis

Furthermore, there are various components which facilitate "granular" playback of an audio file by grouping successive samples into "grains", and manipulating the playback of the grains. This is best explained by example. Refer to the "Help" for the components in the Controllable Input Audio Files and the Playback Controllers categories of the Component Library as well as the relevant Example DrawingBoards for further information on this powerful feature.