PulpEffect

Category: validation Type: Effect Path: examples/pulp-effect/

Summary

A biquad filter effect with frequency, resonance, filter type (lowpass/highpass/bandpass), dry/wet mix, and bypass parameters. Validates diverse parameter types and more complex DSP than PulpGain across the three plugin formats.

What It Demonstrates

• Multiple parameter types: continuous (frequency, resonance, mix), stepped enum (filter type), boolean (bypass)
• Wide-range frequency parameter (20 Hz to 20 kHz)
• Biquad filter DSP with coefficient computation for lowpass, highpass, and bandpass modes
• Dry/wet mix blending
• Per-channel filter state management (supports up to 8 channels)
• The release() lifecycle method for clearing DSP state
• Parameter diversity validation across VST3, AU, and CLAP adapters

Supported Formats

Format	Supported
VST3	Yes
AU v2	Yes
CLAP	Yes
Standalone	No

Supported Platforms

Platform	Supported
macOS	Yes
Windows	Build stubs present, not yet validated
Linux	Build stubs present, not yet validated

Key Files

File	Purpose
pulp_effect.hpp	Processor with biquad filter, coefficient computation, and mix parameter
vst3_entry.cpp	VST3 format entry point
au_v2_entry.cpp	Audio Unit v2 entry point
clap_entry.cpp	CLAP format entry point
test_pulp_effect.cpp	Unit tests for filter processing and state serialization
Info.plist.au	AU bundle metadata
CMakeLists.txt	Build configuration using pulp_add_plugin()

Parameters

ID	Name	Unit	Range	Default
1	Frequency	Hz	20 to 20000	1000
2	Resonance	(Q)	0.1 to 10	0.707
3	Type	(stepped)	0 to 2	0 (lowpass)
4	Mix	%	0 to 100	100
5	Bypass	(toggle)	0 to 1	0

Known Limitations

• Filter coefficients are recalculated per block rather than per sample. Fast frequency sweeps may produce audible artifacts.
• No standalone target is configured for this example.

Related Examples

• PulpGain -- simpler effect with fewer parameters
• PulpCompressor -- another effect example with sidechain and multi-bus support