我目前正在尝试使用此算法对波形文件进行音高变换
https://sites.google.com/site/mikescoderama/pitch-shifting
这里我的代码使用了上面的实现，但没有运气。输出的wave文件似乎已损坏或无效。
代码非常简单，除了音高变换算法:)
我错过了什么吗？
static void Main(string[] args)
{
// Read the wave file data bytes
byte[] waveheader = null;
byte[] wavedata = null;
using (BinaryReader reader = new BinaryReader(File.OpenRead("sound.wav")))
{
// Read first 44 bytes (header);
waveheader= reader.ReadBytes(44);
// Read data
wavedata = reader.ReadBytes((int)reader.BaseStream.Length - 44);
}
short nChannels = BitConverter.ToInt16(waveheader, 22);
int sampleRate = BitConverter.ToInt32(waveheader, 24);
short bitRate = BitConverter.ToInt16(waveheader, 34);
// Normalized data store. Store values in the format -1.0 to 1.0
float[] in_data = new float[wavedata.Length / 2];
// Normalize wave data into -1.0 to 1.0 values
using(BinaryReader reader = new BinaryReader(new MemoryStream(wavedata)))
{
for (int i = 0; i < in_data.Length; i++)
{
if(bitRate == 16)
in_data[i] = reader.ReadInt16() / 32768f;
if (bitRate == 8)
in_data[i] = (reader.ReadByte() - 128) / 128f;
}
}
//PitchShifter.PitchShift(1f, in_data.Length, (long)1024, (long)32, sampleRate, in_data);
// Backup wave data
byte[] copydata = new byte[wavedata.Length];
Array.Copy(wavedata, copydata, wavedata.Length);
// Revert data to byte format
Array.Clear(wavedata, 0, wavedata.Length);
using (BinaryWriter writer = new BinaryWriter(new MemoryStream(wavedata)))
{
for (int i = 0; i < in_data.Length; i++)
{
if(bitRate == 16)
writer.Write((short)(in_data[i] * 32768f));
if (bitRate == 8)
writer.Write((byte)((in_data[i] * 128f) + 128));
}
}
// Compare new wavedata with copydata
if (wavedata.SequenceEqual(copydata))
{
Console.WriteLine("Data has no changes");
}
else
{
Console.WriteLine("Data has changed!");
}
// Save modified wavedata
string targetFilePath = "sound_low.wav";
if (File.Exists(targetFilePath))
File.Delete(targetFilePath);
using (BinaryWriter writer = new BinaryWriter(File.OpenWrite(targetFilePath)))
{
writer.Write(waveheader);
writer.Write(wavedata);
}
Console.ReadLine();
}
答案 0 :(得分：4)
这里的算法运行良好
https://sites.google.com/site/mikescoderama/pitch-shifting
我的错误在于我如何阅读波形标题和波形数据。我在这里发布了完整的代码
警告：此代码仅适用于PCM 16位（立体声/单声道）波。可以很容易地适应PCM 8位。
static void Main(string[] args)
{
// Read header, data and channels as separated data
// Normalized data stores. Store values in the format -1.0 to 1.0
byte[] waveheader = null;
byte[] wavedata = null;
int sampleRate = 0;
float[] in_data_l = null;
float[] in_data_r = null;
GetWaveData("sound.wav", out waveheader, out wavedata, out sampleRate, out in_data_l, out in_data_r);
//
// Apply Pitch Shifting
//
if(in_data_l != null)
PitchShifter.PitchShift(2f, in_data_l.Length, (long)1024, (long)10, sampleRate, in_data_l);
if(in_data_r != null)
PitchShifter.PitchShift(2f, in_data_r.Length, (long)1024, (long)10, sampleRate, in_data_r);
//
// Time to save the processed data
//
// Backup wave data
byte[] copydata = new byte[wavedata.Length];
Array.Copy(wavedata, copydata, wavedata.Length);
GetWaveData(in_data_l, in_data_r, ref wavedata);
//
// Check if data actually changed
//
bool noChanges = true;
for (int i = 0; i < wavedata.Length; i++)
{
if (wavedata[i] != copydata[i])
{
noChanges = false;
Console.WriteLine("Data has changed!");
break;
}
}
if(noChanges)
Console.WriteLine("Data has no changes");
// Save modified wavedata
string targetFilePath = "sound_low.wav";
if (File.Exists(targetFilePath))
File.Delete(targetFilePath);
using (BinaryWriter writer = new BinaryWriter(File.OpenWrite(targetFilePath)))
{
writer.Write(waveheader);
writer.Write(wavedata);
}
Console.ReadLine();
}
// Returns left and right float arrays. 'right' will be null if sound is mono.
public static void GetWaveData(string filename, out byte[] header, out byte[] data, out int sampleRate, out float[] left, out float[] right)
{
byte[] wav = File.ReadAllBytes(filename);
// Determine if mono or stereo
int channels = wav[22]; // Forget byte 23 as 99.999% of WAVs are 1 or 2 channels
// Get sample rate
sampleRate = BitConverter.ToInt32(wav, 24);
int pos = 12;
// Keep iterating until we find the data chunk (i.e. 64 61 74 61 ...... (i.e. 100 97 116 97 in decimal))
while(!(wav[pos]==100 && wav[pos+1]==97 && wav[pos+2]==116 && wav[pos+3]==97)) {
pos += 4;
int chunkSize = wav[pos] + wav[pos + 1] * 256 + wav[pos + 2] * 65536 + wav[pos + 3] * 16777216;
pos += 4 + chunkSize;
}
pos += 4;
int subchunk2Size = BitConverter.ToInt32(wav, pos);
pos += 4;
// Pos is now positioned to start of actual sound data.
int samples = subchunk2Size / 2; // 2 bytes per sample (16 bit sound mono)
if (channels == 2)
samples /= 2; // 4 bytes per sample (16 bit stereo)
// Allocate memory (right will be null if only mono sound)
left = new float[samples];
if (channels == 2)
right = new float[samples];
else
right = null;
header = new byte[pos];
Array.Copy(wav, header, pos);
data = new byte[subchunk2Size];
Array.Copy(wav, pos, data, 0, subchunk2Size);
// Write to float array/s:
int i=0;
while (pos < subchunk2Size)
{
left[i] = BytesToNormalized_16(wav[pos], wav[pos + 1]);
pos += 2;
if (channels == 2)
{
right[i] = BytesToNormalized_16(wav[pos], wav[pos + 1]);
pos += 2;
}
i++;
}
}
// Return byte data from left and right float data. Ignore right when sound is mono
public static void GetWaveData(float[] left, float[] right, ref byte[] data)
{
// Calculate k
// This value will be used to convert float to Int16
// We are not using Int16.Max to avoid peaks due to overflow conversions
float k = (float)Int16.MaxValue / left.Select(x => Math.Abs(x)).Max();
// Revert data to byte format
Array.Clear(data, 0, data.Length);
int dataLenght = left.Length;
int byteId = -1;
using (BinaryWriter writer = new BinaryWriter(new MemoryStream(data)))
{
for (int i = 0; i < dataLenght; i++)
{
byte byte1 = 0;
byte byte2 = 0;
byteId++;
NormalizedToBytes_16(left[i], k, out byte1, out byte2);
writer.Write(byte1);
writer.Write(byte2);
if (right != null)
{
byteId++;
NormalizedToBytes_16(right[i], k, out byte1, out byte2);
writer.Write(byte1);
writer.Write(byte2);
}
}
}
}
// Convert two bytes to one double in the range -1 to 1
static float BytesToNormalized_16(byte firstByte, byte secondByte)
{
// convert two bytes to one short (little endian)
short s = (short)((secondByte << 8) | firstByte);
// convert to range from -1 to (just below) 1
return s / 32678f;
}
// Convert a float value into two bytes (use k as conversion value and not Int16.MaxValue to avoid peaks)
static void NormalizedToBytes_16(float value, float k, out byte firstByte, out byte secondByte)
{
short s = (short)(value * k);
firstByte = (byte)(s & 0x00FF);
secondByte = (byte)(s >> 8);
}
答案 1 :(得分：0)
很抱歉重振了这个，但是我尝试了这个变速器课程，虽然它有效，但我在音调时发出噼啪声（0.5f）。你找到了解决方法吗？