Cocoa Touch中的音调生成

本文介绍了Cocoa Touch中的音调生成的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我需要生成一种可以操纵频率和波形的音调。总体目标是创建一个基本的钢琴。有谁知道我怎么做到这一点？

I need to generate a tone that I can manipulate frequency and wave. The overall goal is to create a basic piano. Does anyone know how I can achieve this?

我的开发平台是iPhone 2.x

My development platform is the iPhone 2.x

推荐答案

你总是可以从 sin 波开始。： - ）

You could always start with sin waves. :-)

#include <cmath>

typedef double Sample;
typedef double Time;

class MonoNote {
protected:
    Time start, duration;
    virtual void internalRender(double now, Sample *mono) = 0;
public:
    MonoNote(Time s, Time d) : start(s), duration(d) {}
    virtual ~MonoNote() {}
    void render(double now, Sample *mono) {
        if (start <= now && now < start + duration) {
            internalRender(now, mono);
        }
    }
};

class MonoSinNote : public MonoNote {
    Time freq;
    Sample amplitude;
protected:
    void internalRender(double now, Sample *mono) {
        const double v = sin(2*M_PI*(now - start) * freq);
        *mono += amplitude*v;
    }
public:
    MonoSinNote(Time s, Time d, Time f, Sample a) : MonoNote(s, d), freq(f), amplitude(a) {}
    ~MonoSinNote() {}
};

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