为什么此代码会在波形序列中引入嘶嘶声/噪声

问：

我正在尝试从不同的文件中提取 PCM 波形序列（不是音频文件但包含音频数据和其他数据的文件都在一个文件中），虽然此代码确实提取了预期的音频，但它似乎在序列中引入了非常可听的嘶嘶声/噪音。

我试图找到类似的主题，但我遇到的唯一问题是“混叠”或“抖动”？我已经用一堆不同的文件和格式尝试了这段代码，它似乎在所有内容中都添加了相同的嘶嘶声，所以嘶嘶声绝对不包含在我试图从中提取数据的原始文件中。

我知道原始文件包含 MONO 16 位 48Khz PCM 数据。

int main()
{
const int               lenght  = 180; //file length, just a "long enough" number to make sure there's enough space for the whole sequence from the original file

const unsigned short    bits    = 16;
const unsigned int      bitrate = 48000;
const unsigned short    channels= 1;

std::ifstream file("samplesfile.img", std::ios::binary); //the original file that contains all sorts of data, plus a simple wave sequence

// Offset 1byte to align with the wave sequence bytes
unsigned int offsetAmount = 1;

if (offsetAmount > 0)
{
    unsigned char tmp[bits];
    file.read(reinterpret_cast<char*>(tmp), sizeof(unsigned char) * offsetAmount);
}


// Read everything from file after the offset and interpret it as a wave sequence
unsigned char* samples = new unsigned char[bitrate * lenght];
file.read(reinterpret_cast<char*>(samples), sizeof(unsigned char) * bitrate * lenght);
file.close();


// creating a .wav file, calculating chunk data

unsigned short  PCM         = 1;
unsigned int    chunk1size  = 16;
unsigned int    chunk2size  = lenght * bitrate;
unsigned int    chunkSize   = chunk2size + 40;
unsigned int    byteRate    = (bitrate * channels * bits) / 8;
unsigned short  blockAlign  = (bits * channels) / 8;    



std::ofstream file2("res.wav", std::ios::binary);

if (file2.good())
{
    file2.flush();
    file2.write("RIFF", sizeof(char) * 4);
    file2.write(reinterpret_cast<const char*>(&chunkSize), sizeof(unsigned int));
    file2.write("WAVE", sizeof(char) * 4);

    file2.write("fmt ", sizeof(char) * 4);
    file2.write(reinterpret_cast<const char*>(&chunk1size), sizeof(unsigned int));
    file2.write(reinterpret_cast<const char*>(&PCM),        sizeof(unsigned short));
    file2.write(reinterpret_cast<const char*>(&channels),   sizeof(unsigned short));
    file2.write(reinterpret_cast<const char*>(&bitrate),    sizeof(unsigned int));
    file2.write(reinterpret_cast<const char*>(&byteRate),   sizeof(unsigned int));
    file2.write(reinterpret_cast<const char*>(&blockAlign), sizeof(unsigned short));
    file2.write(reinterpret_cast<const char*>(&bits),       sizeof(unsigned short));

    file2.write("data", sizeof(char) * 4);
    file2.write(reinterpret_cast<const char*>(&chunk2size), sizeof(unsigned int)); // 40 bytes up to here
    file2.write(reinterpret_cast<const char*>(samples),     chunk2size);
}

file2.close();

delete[] samples;

return 0;
}

结果：