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Oscillator

Oscillator. Sawtooth/ramp wave Band-limited to avoid aliasing: “Naïve” sawtooth aliases badly, especially at high frequencies Audio example: [from wikipedia.org/wiki/Aliasing]. Wavetable Oscillator. Pre-generate band-limited waveforms, then upsample on the fly.

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Oscillator

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  1. Oscillator • Sawtooth/ramp wave • Band-limited to avoid aliasing:“Naïve” sawtooth aliases badly, especially at high frequencies • Audio example: [from wikipedia.org/wiki/Aliasing]

  2. Wavetable Oscillator • Pre-generate band-limited waveforms, then upsample on the fly A1 A2 A3 … A9 Wavetables F2 F2 F2 Oscillator output block

  3. Envelopes • ADSR: Attack, Decay, Sustain, Release Attack time Release time level Decay time Sustain level time

  4. Expression Control • Intensity • Articulation + Envelope * Oscillator * output

  5. Double Buffering (Batching) • More efficient to synthesize in blocks • Introduces 64 samples of latency (2 ms) • Block error averages to another 32 samples. Playback Buffer Synthesis Buffer (to be filled) Synthesis Buffer (full) Playback Buffer

  6. Note Sequences • Big array of bytes – each byte is a note. • 0 means “no change”, 1 means “stop note” • 12 – 127 are C0 through G9 by halfsteps • Merry Had a Little Lamb:

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