在 C# 中创建正弦波或方波
Posted
技术标签:
【中文标题】在 C# 中创建正弦波或方波【英文标题】:Creating sine or square wave in C# 【发布时间】:2010-09-17 06:17:27 【问题描述】:如何生成给定频率的音频正弦波或方波?
我希望这样做是为了校准设备,那么这些波有多精确?
【问题讨论】:
最好使用真正的信号发生器(已知校准) 【参考方案1】:使用 Math.NET 数值
https://numerics.mathdotnet.com/Generate.html
正弦曲线
生成给定长度的正弦波数组。这相当于 将缩放的三角正弦函数应用于周期性锯齿 幅度为 2π。
s(x)=A⋅sin(2πνx+θ)
Generate.Sinusoidal(length,samplingRate,frequency,amplitude,mean,phase,delay)
例如
Generate.Sinusoidal(15, 1000.0, 100.0, 10.0);
返回数组 0, 5.9, 9.5, 9.5, 5.9, 0, -5.9, ...
还有
Generate.Square(...
这会
创建一个周期性方波...
无法谈论精确度。
【讨论】:
【参考方案2】:您可以使用NAudio 并创建一个派生的WaveStream 输出正弦波或方波,您可以将其输出到声卡或写入WAV 文件。如果您使用 32 位浮点样本,您可以直接从 sin 函数中写入值,而无需缩放,因为它已经在 -1 和 1 之间。
至于准确度,您是指完全正确的频率,还是完全正确的波形?没有真正的方波这样的东西,即使是正弦波也可能在其他频率上有一些非常安静的伪影。如果重要的是频率的准确性,那么您将依赖声卡中时钟的稳定性和准确性。话虽如此,我想对于大多数用途来说,准确性已经足够了。
下面是一些示例代码,它以 8 kHz 采样率和 16 位样本(即非浮点)生成 1 kHz 样本:
int sampleRate = 8000;
short[] buffer = new short[8000];
double amplitude = 0.25 * short.MaxValue;
double frequency = 1000;
for (int n = 0; n < buffer.Length; n++)
buffer[n] = (short)(amplitude * Math.Sin((2 * Math.PI * n * frequency) / sampleRate));
【讨论】:
这里没有真正的方波,甚至没有正弦波:非常正确,我实际上是指频率,谢谢【参考方案3】:从Creating sine and save to wave file in C#试试
private void TestSine()
IntPtr format;
byte[] data;
GetSineWave(1000, 100, 44100, -1, out format, out data);
WaveWriter ww = new WaveWriter(File.Create(@"d:\work\sine.wav"),
AudioCompressionManager.FormatBytes(format));
ww.WriteData(data);
ww.Close();
private void GetSineWave(double freq, int durationMs, int sampleRate, short decibel, out IntPtr format, out byte[] data)
short max = dB2Short(decibel);//short.MaxValue
double fs = sampleRate; // sample freq
int len = sampleRate * durationMs / 1000;
short[] data16Bit = new short[len];
for (int i = 0; i < len; i++)
double t = (double)i / fs; // current time
data16Bit[i] = (short)(Math.Sin(2 * Math.PI * t * freq) * max);
IntPtr format1 = AudioCompressionManager.GetPcmFormat(1, 16, (int)fs);
byte[] data1 = new byte[data16Bit.Length * 2];
Buffer.BlockCopy(data16Bit, 0, data1, 0, data1.Length);
format = format1;
data = data1;
private static short dB2Short(double dB)
double times = Math.Pow(10, dB / 10);
return (short)(short.MaxValue * times);
【讨论】:
【参考方案4】:这可以让您给出频率、持续时间和幅度,它是 100% 的 .NET CLR 代码。没有外部DLL。它通过创建 WAV 格式的 MemoryStream
来工作,这就像只在内存中创建文件,而不将其存储到磁盘。然后它会播放 MemoryStream
和 System.Media.SoundPlayer
。
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Windows.Forms;
public static void PlayBeep(UInt16 frequency, int msDuration, UInt16 volume = 16383)
var mStrm = new MemoryStream();
BinaryWriter writer = new BinaryWriter(mStrm);
const double TAU = 2 * Math.PI;
int formatChunkSize = 16;
int headerSize = 8;
short formatType = 1;
short tracks = 1;
int samplesPerSecond = 44100;
short bitsPerSample = 16;
short frameSize = (short)(tracks * ((bitsPerSample + 7) / 8));
int bytesPerSecond = samplesPerSecond * frameSize;
int waveSize = 4;
int samples = (int)((decimal)samplesPerSecond * msDuration / 1000);
int dataChunkSize = samples * frameSize;
int fileSize = waveSize + headerSize + formatChunkSize + headerSize + dataChunkSize;
// var encoding = new System.Text.UTF8Encoding();
writer.Write(0x46464952); // = encoding.GetBytes("RIFF")
writer.Write(fileSize);
writer.Write(0x45564157); // = encoding.GetBytes("WAVE")
writer.Write(0x20746D66); // = encoding.GetBytes("fmt ")
writer.Write(formatChunkSize);
writer.Write(formatType);
writer.Write(tracks);
writer.Write(samplesPerSecond);
writer.Write(bytesPerSecond);
writer.Write(frameSize);
writer.Write(bitsPerSample);
writer.Write(0x61746164); // = encoding.GetBytes("data")
writer.Write(dataChunkSize);
double theta = frequency * TAU / (double)samplesPerSecond;
// 'volume' is UInt16 with range 0 thru Uint16.MaxValue ( = 65 535)
// we need 'amp' to have the range of 0 thru Int16.MaxValue ( = 32 767)
double amp = volume >> 2; // so we simply set amp = volume / 2
for (int step = 0; step < samples; step++)
short s = (short)(amp * Math.Sin(theta * (double)step));
writer.Write(s);
mStrm.Seek(0, SeekOrigin.Begin);
new System.Media.SoundPlayer(mStrm).Play();
writer.Close();
mStrm.Close();
// public static void PlayBeep(UInt16 frequency, int msDuration, UInt16 volume = 16383)
【讨论】:
以上是关于在 C# 中创建正弦波或方波的主要内容,如果未能解决你的问题,请参考以下文章