前言
阅读此教程需要一定的C++和JUCE基础。
我的Bilibili频道：香芋派Taro
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最近学生的合成器设计课要结课了，为了帮他更好地梳理一遍（也为了帮我自己更好地梳理一遍…），所以还是开了这个坑…从零到一来聊聊怎么去搭建一个合成器。当然在这之前我还是希望你有一定的C++基础，最好知道什么指针什么是虚函数balabala的，否则可能阅读起来还是比较痛苦的。
创建项目
创建一个叫做synthTutorial的Plugin项目：
如下创建SynthVoice.h/.cpp：
如下创建SynthSound.h：
确保勾选了这些选项：
记得添加dsp module：
完成SynthSound和SynthVoice的基本框架
SynthSound
参考官方doc：https://docs.juce.com/master/classSynthesiserSound.html
代码如下：
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#pragma once
#include <JuceHeader.h>
class SynthSound : public juce::SynthesiserSound
{
public:
bool appliesToNote (int midiNoteNumber) override { return true; }
bool appliesToChannel (int midiChannel) override { return true; }
};
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注意由于是虚函数，记得使用override增加可读性。
SynthVoice
参考官方doc：https://docs.juce.com/master/classSynthesiserVoice.html
代码如下：
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#pragma once
#include <JuceHeader.h>
#include "SynthSound.h"
class SynthVoice : public juce::SynthesiserVoice
{
public:
bool canPlaySound (juce::SynthesiserSound* sound) override;
void startNote (int midiNoteNumber, float velocity, juce::SynthesiserSound* sound, int currentPitchWheelPosition) override;
void stopNote (float velocity, bool allowTailOff) override;
void controllerMoved (int controllerNumber, int newControllerValue) override;
void pitchWheelMoved (int newPitchWheelValue) override;
void renderNextBlock (juce::AudioBuffer< float > &outputBuffer, int startSample, int numSamples) override;
private:
};
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#include "SynthVoice.h"
bool SynthVoice::canPlaySound (juce::SynthesiserSound* sound)
{
return dynamic_cast<juce::SynthesiserSound*>(sound) != nullptr;
}
void SynthVoice::startNote (int midiNoteNumber, float velocity, juce::SynthesiserSound* sound, int currentPitchWheelPosition)
{
}
void SynthVoice::stopNote (float velocity, bool allowTailOff)
{
}
void SynthVoice::controllerMoved (int controllerNumber, int newControllerValue)
{
}
void SynthVoice::pitchWheelMoved (int newPitchWheelValue)
{
}
void SynthVoice::renderNextBlock (juce::AudioBuffer< float > &outputBuffer, int startSample, int numSamples)
{
}
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搭建Synth基本框架
首先来到PluginProcessor.h中的private处，初始化synth对象：
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private:
juce::Synthesiser synth;
JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (SynthTutorialAudioProcessor)
};
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addSound/addVoice
一切从简，我们暂时只搭建一个只有一个SynthSound一个SynthVoice且单声道的synth，来到PluginProcessor.cpp的构造函数中，添加如下：
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| SynthTutorialAudioProcessor::SynthTutorialAudioProcessor()
#ifndef JucePlugin_PreferredChannelConfigurations
: AudioProcessor (BusesProperties()
#if ! JucePlugin_IsMidiEffect
#if ! JucePlugin_IsSynth
.withInput ("Input", juce::AudioChannelSet::stereo(), true)
#endif
.withOutput ("Output", juce::AudioChannelSet::stereo(), true)
#endif
)
#endif
{
synth.addSound(new SynthSound());
synth.addVoice(new SynthVoice());
}
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oh，记得要在PluginProcessor.h中先引入，否则会报错：
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#pragma once
#include <JuceHeader.h>
#include "SynthSound.h"
#include "SynthVoice.h"
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来到PluginProcessor.cpp中的prepareToPlay设定samplerate：
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...
void SynthTutorialAudioProcessor::prepareToPlay (double sampleRate, int samplesPerBlock)
{
synth.setCurrentPlaybackSampleRate(sampleRate);
}
...
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来到PluginProcessor.cpp中的processBlock设定处理框架和renderNextBlock：
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...
void SynthTutorialAudioProcessor::processBlock (juce::AudioBuffer<float>& buffer, juce::MidiBuffer& midiMessages)
{
juce::ScopedNoDenormals noDenormals;
auto totalNumInputChannels = getTotalNumInputChannels();
auto totalNumOutputChannels = getTotalNumOutputChannels();
for (auto i = totalNumInputChannels; i < totalNumOutputChannels; ++i)
buffer.clear (i, 0, buffer.getNumSamples());
for (int i = 0; i < synth.getNumVoices(); ++i)
{
if (auto voice = dynamic_cast<juce::SynthesiserVoice*>(synth.getVoice(i)));
{
}
}
synth.renderNextBlock(buffer, midiMessages, 0, buffer.getNumSamples());
}
...
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