EffectStage.h

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/**********************************************************************
 
  Audacity: A Digital Audio Editor
 
  @file EffectStage.h
  @brief decorator of a Sink with a non-time-warping effect
 
  Dominic Mazzoni
  Vaughan Johnson
 
  Paul Licameli split from Effect.h
 
**********************************************************************/
 
#ifndef __AUDACITY_EFFECT_STAGE__
#define __AUDACITY_EFFECT_STAGE__
 
#include "AudioGraphSource.h" // to inherit
#include "EffectInterface.h"
#include "SampleCount.h"
#include <functional>
 
class WideSampleSequence;
 
class MIXER_API EffectStage final : public AudioGraph::Source {
   // To force usage of Create() instead
   struct CreateToken {};
public:
   using Factory = std::function<std::shared_ptr<EffectInstance>()>;
 
 
   EffectStage(
      CreateToken, int channel, int nInputChannels, Source& upstream,
      Buffers& inBuffers, const Factory& factory, EffectSettings& settings,
      double sampleRate, std::optional<sampleCount> genLength);
 
   static std::unique_ptr<EffectStage> Create(
      int channel, int nInputChannels, Source& upstream, Buffers& inBuffers,
      const Factory& factory, EffectSettings& settings, double sampleRate,
      std::optional<sampleCount> genLength);
 
   EffectStage(const EffectStage&) = delete;
   EffectStage &operator =(const EffectStage &) = delete;
   ~EffectStage() override;
 
   bool AcceptsBuffers(const Buffers &buffers) const override;
   bool AcceptsBlockSize(size_t size) const override;
 
   std::optional<size_t> Acquire(Buffers &data, size_t bound) override;
   sampleCount Remaining() const override;
   bool Release() override;
 
private:
   sampleCount DelayRemaining() const
      { return std::max<sampleCount>(0, mDelayRemaining); }
 
 
   bool Process(EffectInstance &instance, size_t channel,
      const Buffers &data, size_t curBlockSize, size_t outBufferOffset) const;
 
   [[nodiscard]] std::optional<size_t> FetchProcessAndAdvance(
      Buffers &data, size_t bound, bool doZeros, size_t outBufferOffset = 0);
 
   Source &mUpstream;
   Buffers &mInBuffers;
   const std::vector<std::shared_ptr<EffectInstance>> mInstances;
   EffectSettings &mSettings;
   const double mSampleRate;
   const bool mIsProcessor;
 
   sampleCount mDelayRemaining;
   size_t mLastProduced{};
   size_t mLastZeroes{};
   bool mLatencyDone{ false };
   bool mCleared{ false };
};
 
/*
 @param channel selects one channel if non-negative; else all channels
 @param[out] map terminated with ChannelNameEOL
 @return 1 if `channel >= 0`, else the number of channels
 
 @pre `channel < nInputChannels`
 */
MIXER_API
unsigned MakeChannelMap(
   int nInputChannels, int channel,
   // TODO: more-than-two-channels
   ChannelName map[3]);
 
#endif