c# - 在 C# 中将双精度数组写入波形文件
问题描述
我正在尝试使用 c# 从头开始编写波形文件。我设法毫无问题地编写了 16 位样本。但是当谈到 24 位时,显然所有的赌注都没有了。我尝试了各种将 int 转换为 3 字节数组的方法,我将继续将其写入数据块 LLLRRR(作为 24 位立体声 PCM wav)。
对于 16 位部分,我使用它来生成样本:
//numberOfBytes = 2 - for 16bit. slice = something like 2*Math.Pi*frequency/samplerate
private static byte[,] BuildByteWave(double slice, int numberOfBytes=2)
{
double dataPt = 0;
byte[,] output = new byte[Convert.ToInt32(Samples),numberOfBytes];
for (int i = 0; i < Samples; i++)
{
dataPt = Math.Sin(i * slice) * Settings.Amplitude;
int data = Convert.ToInt32(dataPt * Settings.Volume * 32767);
for (int j = 0; j < numberOfBytes; j++)
{
output[i, j] = ExtractByte(data, j);
}
}
return output;
}
这将返回一个数组,我稍后使用它来写入数据块,如下所示
writer.WriteByte(samples[1][0]); //write to the left channel
writer.WriteByte(samples[1][1]); //write to the left channel
writer.WriteByte(samples[2][0]); //now to the second channel
writer.WriteByte(samples[2][1]); //and yet again.
其中 1 和 2 代表某个正弦波。但是,如果我在 numberOfBytes = 3 的情况下尝试上述方法,它就会失败。波是一堆废话。(标题格式正确)。
我知道我需要将 int32 转换为 int24 并且我需要“填充”样本,但我在任何地方都找不到具体的 24 位教程。你能指出我正确的方向吗?
为清晰起见进行了编辑。
解决方案
没有int24
- 你需要自己做。 for/switch
也是一种反模式。
int[] samples = /* samples scaled to +/- 8388607 (0x7f`ffff) */;
byte[] data = new byte[samples.Length * 3];
for (int i = 0, j = 0; i < samples.Length; i++, j += 3)
{
// WAV is little endian
data[j + 0] = (byte)((i >> 0) & 0xff);
data[j + 1] = (byte)((i >> 8) & 0xff);
data[j + 2] = (byte)((i >> 16) & 0xff);
}
// data now has the 24-bit samples.
例如,这是一个程序 ( Github ),它生成一个15 秒的 44.1kHz 24 位立体声 wav 文件,左声道为 440 Hz,右声道为 1 kHz:
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
namespace WavGeneratorDemo
{
class Program
{
const int INT24_MAX = 0x7f_ffff;
static void Main(string[] args)
{
const int sampleRate = 44100;
const int lengthInSeconds = 15 /* sec */;
const int channels = 2;
const double channelSamplesPerSecond = sampleRate * channels;
var samples = new double[lengthInSeconds * sampleRate * channels];
// Left is 440 Hz sine wave
FillWithSineWave(samples, channels, channelSamplesPerSecond, 0 /* Left */, 440 /* Hz */);
// Right is 1 kHz sine wave
FillWithSineWave(samples, channels, channelSamplesPerSecond, 1 /* Right */, 1000 /* Hz */);
WriteWavFile(samples, sampleRate, channels, "out.wav");
}
private static void WriteWavFile(double[] samples, uint sampleRate, ushort channels, string fileName)
{
using (var wavFile = File.OpenWrite(fileName))
{
const int chunkHeaderSize = 8,
waveHeaderSize = 4,
fmtChunkSize = 16;
uint samplesByteLength = (uint)samples.Length * 3u;
// RIFF header
wavFile.WriteAscii("RIFF");
wavFile.WriteLittleEndianUInt32(
waveHeaderSize
+ chunkHeaderSize + fmtChunkSize
+ chunkHeaderSize + samplesByteLength);
wavFile.WriteAscii("WAVE");
// fmt header
wavFile.WriteAscii("fmt ");
wavFile.WriteLittleEndianUInt32(fmtChunkSize);
wavFile.WriteLittleEndianUInt16(1); // AudioFormat = PCM
wavFile.WriteLittleEndianUInt16(channels);
wavFile.WriteLittleEndianUInt32(sampleRate);
wavFile.WriteLittleEndianUInt32(sampleRate * channels);
wavFile.WriteLittleEndianUInt16((ushort)(3 * channels)); // Block Align (stride)
wavFile.WriteLittleEndianUInt16(24); // Bits per sample
// samples data
wavFile.WriteAscii("data");
wavFile.WriteLittleEndianUInt32(samplesByteLength);
for (int i = 0; i < samples.Length; i++)
{
var scaledValue = DoubleToInt24(samples[i]);
wavFile.WriteLittleEndianInt24(scaledValue);
}
}
}
private static void FillWithSineWave(double[] samples, int channels, double channelSamplesPerSecond, int channelNo, double freq)
{
for (int i = channelNo; i < samples.Length; i += channels)
{
var t = (i - channelNo) / channelSamplesPerSecond;
samples[i] = Math.Sin(t * (freq * Math.PI * 2));
}
}
private static int DoubleToInt24(double value)
{
if (value < -1 || value > 1)
{
throw new ArgumentOutOfRangeException(nameof(value));
}
return (int)(value * INT24_MAX);
}
}
static class StreamExtensions
{
public static void WriteAscii(this Stream s, string str) => s.Write(Encoding.ASCII.GetBytes(str));
public static void WriteLittleEndianUInt32(this Stream s, UInt32 i)
{
var b = new byte[4];
b[0] = (byte)((i >> 0) & 0xff);
b[1] = (byte)((i >> 8) & 0xff);
b[2] = (byte)((i >> 16) & 0xff);
b[3] = (byte)((i >> 24) & 0xff);
s.Write(b);
}
public static void WriteLittleEndianInt24(this Stream s, Int32 i)
{
var b = new byte[3];
b[0] = (byte)((i >> 0) & 0xff);
b[1] = (byte)((i >> 8) & 0xff);
b[2] = (byte)((i >> 16) & 0xff);
s.Write(b);
}
public static void WriteLittleEndianUInt16(this Stream s, UInt16 i)
{
var b = new byte[2];
b[0] = (byte)((i >> 0) & 0xff);
b[1] = (byte)((i >> 8) & 0xff);
s.Write(b);
}
}
}
生成:
推荐阅读
- c++ - C ++ windows ui自动化:无法列出所有子窗口
- themes - 奇怪和混合的 Gnome 窗口主题
- python - Python if 函数具有多个条件,包括无
- anaconda - 从本地 pkgs 目录创建自定义 conda 通道
- html - 第二页上的背景图像将不相等
- python - 具有 ManyToMany 的 django 抽象基类
- django - 带有 html 链接的 Django 错误 TypeError at / 'set' object is not reversible
- python - 如何在同一行中打印浮点数和字符串
- r - 提高采样填充数据集的效率
- python - 将动态dicts传递给python线程出来的结果是一样的