Fix/synth crackle cpu#8
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Intermittent crackle in Synth mode came from per-block CPU spikes, not sustained load (the watchdog only sheds after ~150ms, so transient peaks slipped through). Two changes attack the peak: - voice.h: recompute the filter SetFreq (Svf sinf+powf / Moog polynomial) at control rate (every kCoefInterval=8 samples, ~6 kHz) instead of every sample. A moving filter envelope changes fc every sample, which used to force a per-sample SetFreq on every voice; a chord put all 6 voices on that path at once and spiked a block past the deadline. Unchanged-coef skip is kept (static patches stay free); a filter-type switch still forces an immediate recompute. Inaudible for sweeps. - params.h: audio block size 48 -> 64 (~1.3 ms @ 48 kHz) for more headroom against transient spikes and to amortize per-block control work. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Describes the heaviest engine configuration (Synth + 6 voices/4 unison/ analog/Moog + reverb + master filter, MIDI-flooded) and how to read the SysEx CPU meter and watchdog when changing DSP or voice counts. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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What this changes
Fix: intermittent crackle in Synth mode under load. The crackle was a per-block CPU
spike, not sustained load (so the watchdog, which only sheds after ~150 ms, never caught
it): a moving filter envelope changed the cutoff every sample, forcing a per-sample
SetFreq(Svfsinf+powf/ Moog polynomial) on every voice — and a chord put all 6voices on that path at once, tipping a block past its deadline. The voice filter now
recomputes its coefficients at control rate (every 8 samples, ~6 kHz — inaudible for
sweeps) while keeping the existing "skip when unchanged" fast path for static patches.
The audio block size also goes 48 → 64 (~1.3 ms @ 48 kHz) for more headroom against
transient spikes.
Checklist
src/config/params.hdocs/MIDI_PROTOCOL.mdand theparams::midimap