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| WaveWarp 2.0 Example DrawingBoard
LiveGuitarThreeVoiceDownsampledVocoderSynth_3
Description
Live Guitar Three Voice Downsampled Vocoder Synth
Demonstrates the use of WaveWarp's live input functionality, modular sample-by-sample architecture, spectral analysis and
synthesis capabilities, and the powerful multirate functionality. Plug an electric guitar (or any other audio source!) into the
"input" of your soundcard and hit "Play". You will experience an interesting synthesiser effect which generates tones in
accordance with the notes played on the guitar (or any other chosen instrument!)
This is an elaboration of the simple vocoder illustrated in "LiveGuitarSingleVoiceVocoderSynth.dwb". Instead of a single
oscillator, three are used to generate a more interesting output signal (see also
"LiveGuitarSixVoiceDownsampleVocoderSynth.dwb" for a six voice variant, and
"LiveGuitarThreeAnalysisVoiceDownsampledVocoderSynth.dwb" for a three-analysis channel variant). Furthermore, the
original audio signal has been downsampled by a factor of 20 before the spectral Tracking Peak Detection. This leads to a
significant improvement in computational efficiency. Since the guitar (the instrument used when designing this algorithm)
typically generates tones below 1 kHz, there is no degradation when downsampling by a factor of 20 (which corresponds to
a new Nyquist rate of about 1 kHz assuming an input sample rate of 44.1 kHz). Furthermore, since the control signals do
not need to vary very quickly, they are further downsampled by a factor of 10 for further improved efficiency. Ultimately, the
control signals are upsampled (by a factor of 200) before driving the audio oscillators which generate the output at the
desired sample rate of 44.1 kHz.
Note that the frequencies of the second and third voices are simply generated as multiples of the first (via the Large Control
Gain blocks). The multiplication factors can be arbitrarily adjusted. For more bizarre effects, try some nonlinear manipulations
rather than simple gains, as demonstrated in "LiveGuitarThreeVoiceDownsampledNonlinearVocode Synth.dwb". Also note
that the bank of oscillators which perform the resynthesis can each have different and arbitrary waveforms, leading to a
high degree of flexibility when creating the synthesiser.
The synthesiser has been constructed from the basic elements of a single analysis-channel "vocoder" driving a bank of
three synthesis oscillators. The key components are the Spectral Peak Detector and the Controllable Combo Oscillator. The
Tracking Peak Detector measures (approximately) the amplitude and frequency of the dominant spectral component in the
live audio input. In this example, only the frequency measurement (the first output of the Tracking Peak Detector) is used
(the second output -- the rms amplitude measurement -- is unconnected). The frequency measurement (in Hz) is used to
drive the bank of Controllable Combo Oscillators which are combined in the mixer to produce a sequence of synthesised
tones derived from the time-varying spectrum of the input audio.
Try experimenting with all settings of all components in order to appreciate the wide range of synthesiser effects achievable
from this combination.
Components used:
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