SynthLab SDK
SynthLab::VAFilterCore Class Reference

Implements all of the virtual analog (VA) filters in the Synth Book using sub-filtering objects. More...

#include <vafiltercore.h>

Inheritance diagram for SynthLab::VAFilterCore:
SynthLab::ModuleCore

Public Member Functions

 VAFilterCore ()
 Constructs Construction: Cores follow the same construction pattern. More...
 
virtual ~VAFilterCore ()
 
virtual bool reset (CoreProcData &processInfo) override
 Resets object to initialized state. More...
 
virtual bool update (CoreProcData &processInfo) override
 Updates the object for the next block of audio processing. More...
 
virtual bool render (CoreProcData &processInfo) override
 Renders the output of the module. More...
 
virtual bool doNoteOn (CoreProcData &processInfo) override
 Note-on handler for the ModuleCore. More...
 
virtual bool doNoteOff (CoreProcData &processInfo) override
 Note-off handler for the ModuleCore. More...
 
- Public Member Functions inherited from SynthLab::ModuleCore
 ModuleCore ()
 Constructs a ModuleCore. More...
 
virtual int32_t getState ()
 
virtual bool shutdown ()
 
virtual void setSustainOverride (bool sustain)
 
virtual void setStandAloneMode (bool b)
 
bool startGlideModulation (GlideInfo &glideInfo)
 
uint32_t getModuleType ()
 
const char * getModuleName ()
 
void * getModuleHandle ()
 
void setModuleHandle (void *handle)
 
uint32_t getModuleIndex ()
 
void setModuleIndex (uint32_t index)
 
int32_t getPreferredModuleIndex ()
 
void setPreferredModuleIndex (uint32_t index)
 
ModuleCoreDatagetModuleData ()
 provides access to the core data: More...
 

Protected Attributes

VA1Filter va1 [STEREO]
 1st order VA
 
VASVFilter svf [STEREO]
 SVF.
 
VAKorg35Filter korg35 [STEREO]
 Korg35.
 
VAMoogFilter moog [STEREO]
 moog
 
VADiodeFilter diode [STEREO]
 diode
 
FilterModel selectedModel = FilterModel::kFirstOrder
 
uint32_t outputIndex = 0
 selected output
 
double outputAmp = 1.0
 filter output amplitude, tweked from GUI in dB
 
bool forceDualMonoFilters = false
 DM option for slow machines.
 
Limiter limiter [STEREO]
 limiters to squelch oscillations
 
double midiPitch = 440.0
 key tracking
 
- Protected Attributes inherited from SynthLab::ModuleCore
uint32_t moduleType = UNDEFINED_MODULE
 type of module, LFO_MODULE, EG_MODULE, etc...
 
const char * moduleName = nullptr
 module name must be set in derived constructor
 
void * moduleHandle = nullptr
 used for dynamically loading cores from DLLs
 
uint32_t moduleIndex = 0
 index of this core
 
int32_t preferredIndex = -1
 preferred index of this DYNAMIC core
 
ModuleCoreData coreData
 core strings (16) and mod knob labels (4)
 
bool standAloneMode = false
 flag for stand-alone mode of operation outside of SynthLab
 
std::unique_ptr< GlideModulatorglideModulator
 built-in glide modulator for oscillators
 

Detailed Description

Implements all of the virtual analog (VA) filters in the Synth Book using sub-filtering objects.

  • breaks filters into families (1st order, SVF, Korg, Moog, Diode) and generates ALL outputs for that family at once

Demonstrates use of following VAFilter objects:

Base Class: ModuleCore

  • Overrides the five (5) common functions plus a special getParameters() method to return a shared pointer to the parameters structure.
  • NOTE: These functions have identical names as the SynthModules that own them, however the arguments are different. ModuleCores use the CoreProcData structure for passing arguments into the cores because they are thunk-barrier compliant.
  • This means that the owning SynthModule must prepare this structure and populate it prior to function calls. The large majority of this preparation is done in the SynthModule constructor and is one-time in nature.

GUI Parameters: FilterParameters

  • GUI parameters are delivered into the core via the thunk-barrier compliant CoreProcData argument that is passed into each function identically
  • processInfo.moduleParameters contains a void* version of the GUI parameter structure pointer
  • the Core function casts the GUI parameter pointer prior to usage

Access to Modulators is done via the thunk-barrier compliant CoreProcData argument

  • processInfo.modulationInputs
  • processInfo.modulationOutputs

Access to audio buffers (I/O/FM) is done via the thunk-barrier compliant CoreProcData argument

  • processInfo.inputBuffers
  • processInfo.outputBuffers
  • processInfo.fmBuffers

Construction: Cores follow the same construction pattern

  • set the Module type and name parameters
  • expose the 16 module strings
  • expose the 4 mod knob label strings
  • intialize any internal variables

Standalone Mode:

  • These objects are designed to be internal members of the outer SynthModule that owns them. They may be used in standalone mode without modification, and you will use the CoreProcData structure to pass information into the functions.

Module Strings, zero-indexed for your GUI Control:

  • No_Filter, LPF1, HPF1, APF1, SVF_LP, SVF_HP, SVF_BP, SVF_BS, Korg35_LP, Korg35_HP, Moog_LP1, Moog_LP2, Moog_LP3, Moog_LP4, Diode_LP4

ModKnob Strings, for fixed GUI controls by index constant

  • MOD_KNOB_A = "Key Track"
  • MOD_KNOB_B = "Drive"
  • MOD_KNOB_C = "EG Int"
  • MOD_KNOB_D = "BP Int"

Render:

  • renders into the output buffer using pointers in the CoreProcData argument to the render function
  • processes one block of audio input into one block of audio output per render cycle
  • processes in mono that is copied to the right channel as dual-mono stereo
Author
Will Pirkle http://www.willpirkle.com
Remarks
This object is included and described in further detail in Designing Software Synthesizer Plugins in C++ 2nd Ed. by Will Pirkle
Version
Revision : 1.0
Date
Date : 2021 / 04 / 26

Constructor & Destructor Documentation

◆ VAFilterCore()

SynthLab::VAFilterCore::VAFilterCore ( )

Constructs Construction: Cores follow the same construction pattern.

simple default constructor

  • set the Module type and name parameters
  • expose the 16 module strings
  • expose the 4 mod knob label strings
  • intialize any internal variables

Core Specific:

  • note the way this core stores families of filters
  • each filter family produces all filter outputs at once
Returns
the newly constructed object

◆ ~VAFilterCore()

virtual SynthLab::VAFilterCore::~VAFilterCore ( )
inlinevirtual

Destructor is empty: all resources are smart pointers

Member Function Documentation

◆ doNoteOff()

bool SynthLab::VAFilterCore::doNoteOff ( CoreProcData processInfo)
overridevirtual

Note-off handler for the ModuleCore.

  • parameters are accessed via the processInfo.moduleParameters pointer
  • MIDI note information is accessed via processInfo.noteEvent

Core Specific:

  • nothing to do
Parameters
processInfois the thunk-barrier compliant data structure for passing all needed parameters
Returns
true if successful, false otherwise

Implements SynthLab::ModuleCore.

◆ doNoteOn()

bool SynthLab::VAFilterCore::doNoteOn ( CoreProcData processInfo)
overridevirtual

Note-on handler for the ModuleCore.

  • parameters are accessed via the processInfo.moduleParameters pointer
  • MIDI note information is accessed via processInfo.noteEvent

Core Specific:

  • saves MIDI pitch for key tracking
Parameters
processInfois the thunk-barrier compliant data structure for passing all needed parameters
Returns
true if successful, false otherwise

Implements SynthLab::ModuleCore.

◆ render()

bool SynthLab::VAFilterCore::render ( CoreProcData processInfo)
overridevirtual

Renders the output of the module.

  • processes input to output buffer using pointers in the CoreProcData argument Core Specific:
  • process left and right channels through independent filters
  • apply peak limiter
  • renders one block of audio per render cycle
  • renders in mono that is copied to the right channel as dual-mono stereo
Parameters
processInfothe thunk-barrier compliant data structure for passing all needed parameters
Returns
true if successful, false otherwise

Implements SynthLab::ModuleCore.

◆ reset()

bool SynthLab::VAFilterCore::reset ( CoreProcData processInfo)
overridevirtual

Resets object to initialized state.

ModuleCore Overrides

  • parameters are accessed via the processInfo.moduleParameters pointer
  • reset all filters
  • reset limiters
Parameters
processInfothe thunk-barrier compliant data structure for passing all needed parameters
Returns
true if successful, false otherwise

Implements SynthLab::ModuleCore.

◆ update()

bool SynthLab::VAFilterCore::update ( CoreProcData processInfo)
overridevirtual

Updates the object for the next block of audio processing.

  • parameters are accessed via the processInfo.moduleParameters pointer
  • modulator inputs are accessied via processInfo.modulationInputs
  • mod knob values are accessed via parameters->modKnobValue[] Core Specific:
  • calculates the fc modulation value from GUI controls, input modulators kBipolarMod, and kEGMod
  • monitors key-tracking to adjust fc again if needed
  • calcualtes new filter coeffients once, then copies into reolicated filters (left/right)
  • calculates final gain and drive values
Parameters
processInfothe thunk-barrier compliant data structure for passing all needed parameters
Returns
true if successful, false otherwise

Implements SynthLab::ModuleCore.


The documentation for this class was generated from the following files: