C++使用MIDI库实现演奏晴天

目录

• 前言
• 开始工作
• 1. 引入MIDI库和相关控制类
• 2. 初始化和结束
• 自制简易乐谱
• 合成演奏

前言

那些在MIDI库里徘徊的十六分音符

终究没能拼成告白的主歌

我把周杰伦的《晴天》写成C++的类

在每个midiEvent里埋藏故事的小黄花

调试器的断点比初恋更漫长

而青春不过是一串未导出的cmake工程文件

在堆栈溢出的夜晚

终将明白

有些旋律永远停在#pragma once的注释里

有些人永远停在未定义的引用里

或许你我的心跳终归运行在不同的时钟频率

却愿始终记得如何编译出一场永不落幕的晴天

--题记

就像在题记里说的一样，这是一个从未导出成功的工程文件。

所以如果你也想听听，可以在PowerShell里运行以下指令：

git clone https://github.com/TwilightLemon/SunnyDays
cd SunnyDays
mkdir build
cd build
cmake .. -G "MinGW Makefiles"
mingw32-make
./SunnyDays.exe

没环境？巧了，她也如是说。

幸运的话能得到以下效果：

下面来简单讲讲如何使用C++和MIDI库作曲吧。

开始工作

1. 引入MIDI库和相关控制类

在CMakeLists.txt中：

target_link_libraries(SunnyDays winmm)

在MIDIHelper.h中：

#include <Windows.h>
#pragma comment(lib,"winmm.lib")

定义Scale(音阶), Instrument(乐器, 仅包括部分)等枚举。我把Drum单独提IIAFSC了出来。

enum Scale
{
    X1 = 36, X2 = 38, X3 = 40, X4 = 41, X5 = 43, X6 = 45, X7 = 47,
    L1 = 48, L2 = 50, L3 = 52, L4 = 53, L5 = 55, L6 = 57, L7 = 59,
    M1 = 60, M2 = 62, M3 = 64, M4 = 65, M5 = 67, M6 = 69, M7 = 71,
    H1 = 72, H2 = 74, H3 = 76, H4 = 77, H5 = 79, H6 = 81, H7 = 83,
    LOW_SPEED = 500, MIDDLE_SPEED = 400, HIGH_SPEED = 300,
    _ = 0XFF
};
enum Drum{
    BassDrum = 36, SnareDrum = 38, ClosedHiHat = 42, OpenHiHat = 46
};
enum Instrument{
    AcousticGrandPiano = 0, BrightacousticPiano = 1,
    ElectricGrandPiano = 2, HonkyTonkPiano = 3,
    ElectricPiano1 = 4, ElectricPiano2 = 5
};

一些基础方法，包括初始化/关闭设备、设置参数、播放单个音符和播放和弦等。

void initDevice();
void closeDevice();
void setInstrument(int channel, int instrument);
void setVolume(int channel, int volume);

void PlayNote(HMIDIOUT handle, UINT channel, UINT note, UINT velocity);

void playChord(HMIDIOUT handle, UINT channel, UINT note1, UINT note2, UINT note3, UINT note4, UINT velocity);

void playChord(HMIDIOUT handle, UINT channel, UINT note1, UINT note2, UINT note3, UINT velocity);

在MIDIHelper.cpp中：

void initDevice(){
    midiOutOpen(&hMidiOut, 0, 0, 0, CALLBACK_NULL);
}

void closeDevice(){
    midiOutClose(hMidiOut);
}

void setInstrument(int channel,int instrument){
    if (channel > 15 || instrument > 127) return;
    dwORD message = 0xC0 | channel | (instrument << 8);
    midiOutShortMsg(hMidiOut, message);
}

void setVolume(int channel,int volume){
    if (channel > 15 || volume > 127) return;
    DWORD message = 0xB0 | channel | (7 << 8) | (volume << 16);
    midiOutShortMsg(hMidiOut, message);
}

//播放单个音符，note是音符，velocity是力度
void PlayNote(HMIDIOUT handle, UINT channel, UINT note, UINT velocity) {
    if (channel > 15 || note > 127 || velocity > 127) return;
    DWORD message = 0x90 | channel | (note << 8) | (velocity << 16);
    midiOutShortMsg(handle, message);
}

//四指和弦
void playChord(HMIDIOUT handle, UINT channel, UINT note1, UINT note2, UINT note3, UINT note4, UINT velocity){
    if (channel > 15 || note1 > 127 || note2 > 127 || note3 > 127 || note4 > 127 || velocity > 127) return;
    DWORD message1 = 0x90 | channel | (note1 << 8) | (velocity << 16);
    DWORD message2 = 0x90 | channel | (note2 <&lhttp://www.devze.comt; 8) | (velocity << 16);
    DWORD message3 = 编程客栈0x90 | channel | (note3 << 8) | (velocity << 16);
    DWORD message4 = 0x90 | channel | (note4 << 8) | (velocity << 16);
    midiOutShortMsg(handle, message1);
    midiOutShortMsg(handle, message2);
    midiOutShortMsg(handle, message3);
    midiOutShortMsg(handle, message4);
}

//三指和弦
void playChord(HMIDIOUT handle, UINT channel, UINT note1, UINT note2, UINT note3, UINT velocity) {
    if (channel > 15 || note1 > 127 || note2 > 127 || note3 > 127 || velocity > 127) return;
    DWORD message1 = 0x90 | channel | (note1 << 8) | (velocity << 16);
    DWORD message2 = 0x90 | channel | (note2 << 8) | (velocity << 16);
    DWORD message3 = 0x90 | channel | (note3 << 8) | (velocity << 16);
    midiOutShortMsg(handle, message1);
    midiOutShortMsg(handle, message2);
    midiOutShortMsg(handle, message3);
}

2. 初始化和结束

先在头文件中定义一个全局MIDI句柄:

extern HMIDIOUT hMidiOut;

在入口处初始化MIDI设备并在结束时关闭：

HMIDIOUT hMidiOut;
int main() {
    initDevice();
    //...
    closeDevice();
    return 0;
}

初始化MIDI设备之后，为每一个乐器分配一个通道channel（0~15，通常9分配给打击类乐器,例如鼓组），控制音量volume，然后就可以开始演奏了。

自制简易乐谱

以Voice.cpp为例,定义一个数组为频谱，控制停顿和音符，遍历数组播放：

 namespace SunnyDays{
      int channelVoice=1;
      void playVoice(int note, int velocity){
          PlayNote(hMidiOut, channelVoice, note, velocity);
      }
      void voice(){
         Sleep(13100);//等待前奏
          int sleep = 390;
          int data[] =
                 {
                     //故事的小黄花
                     -90,
                     300,M5,M5,M1,M1,_,M2,M3,_,
                     //从出生那年就飘着
                     -90,
                     M5,M5,M1,M1,0,M2,M3,300,M2,M1,_,
                    //童年的荡秋千
                     -90,
                     300,M5,M5,M1,M1,_,M2,M3,_,
                     //随记忆一直晃到现在
                     -90,  
                     M3,_,500,M2,M3,M4,M3,M2,M4,M3,700,M2,700,_,
                     //...
                 }
         for (auto i : data) {
            if(i==-30){logTime("Enter chorus");continue;}//调试用
             if(i==-90){NextLyric(); continue;}
             if (i == 0) { sleep = 180; continue; }
             //...
             if (i == _) {
                 Sleep(390);
                 continue;
             }
 
             playVoice(i, 80);
             Sleep(sleep);
         }
     }
 }

打个鼓：

 namespace SunnyDays{
      int channelBassDrum=9;
  
      void playDrum(int note, int velocity, int duration){
          PlayNote(hMidiOut, channelBassDrum, note, velocity);
          if(duration>0) {
              Sleep(duration);
              PlayNote(hMidiOut, channelBassDrum, note, 0);
         }
     }
 
     void bassDrum(){
         Sleep(11260);
         cout<<"Drum Bass Start!"<<endl;
         playDrum(SnareDrum,100,180);
         playDrum(SnareDrum,100,210);
         playDrum(BassDrum, 100, 210);
         playDrum(SnareDrum,100,190);
         playDrum(BassDrum, 100, 210);
         playDrum(SnareDrum,100,200);
         playDrum(SnareDrum,100,200);
         playDrum(OpenHiHat,100,-1);
         Sleep(200);
         //...
     }
 }

简易副歌和弦，是从B站一位up主那里学的（已经忘记是哪位了qwq）：

 namespace SunnyDays {
      int channelChord=2;
      void chordLevel(int level,int sleep,int repeat=2,int vel=70){
          repeat--;
          int down=8;
        if(level==1){
            //一级和弦 加右指
              playChord(hMidiOut, channelChord, M1, M3, M5, L1, vel);
              while(repeat--) {
               Sleep(sleep);
                playChord(hMidiOut, channelChord, M1, M3, M5, vel - down);
            }
         }else if(level==3){
             //三级和弦 加右指
             playChord(hMidiIIAFSCOut, channelChord, M3, M5, M7, L3, vel);
            while(repeat--) {
                Sleep(sleep);
                playChord(hMidiOut, channelChord, M3, M5, M7, vel - down);
             }
         }
         //...
     }
     void chord(){
         Sleep(63724);
         int sleep=740;
        int data[]={
                //刮风这天 我试过握着你手
                 1,4,
                 6,4,
                //但偏偏 雨渐渐
                 4,2,
                5,2,
                 //大到我看你不见
                 1,4,
                 //还有多久 我才能
                 3,4,
                 //↑ 在你身边
                 6,4,
                 //↓ 等到放晴的那天
                 4,4,
                 //↑ 也许我会比IIAFSC较好一点
                 5,4,
                 //..
         }
         int count=sizeof(data)/sizeof(int);
        for(int i=0;i<count;i+=2){
             cout<<"chord "<<data[i]<<"  x"<<data[i+1]<<endl;
             chordLevel(data[i],sleep,data[i+1]);
             Sleep(sleep);
         }
         //...
     }
 }

合成演奏

我用了一个笨蛋方法，用多线程单独控制每一个通道，然后在主线程中调用：

int main(){
      //...
      initDevice();
     //设置音量
      setVolume(channelChord,80);
      setVolume(channelMainLine,80);
      setVolume(channelVoice,120);
      setVolume(channelBassDrum,80);
  
    //设置乐器（特定音色）
     setInstrument(channelChord,ElectricPiano1);
     setInstrument(channelMainLine,ElectricPiano1);
 
 
     system("pause");//按下回车，就开始啦
     beginLogger();
 
 
     thread t0(voice);
     thread t1(mainLine);
     thread t2(bassDrum);
     thread t3(chord);
     t0.join();
     t1.join();
     t2.join();
     t3.join();
 
     closeDevice();
     //...
 }

（最后叠个甲，俺不懂音乐制作，更不会什么C++）

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