D:/work/code_by/Wave/WaveFile.cpp

查看本檔案說明文件.

#include <string.h>
#include "WaveFile.h"

TWaveFile::TWaveFile()
{
  wave = NULL;
  userData = NULL;
  Clear();
  sampleRate = 11025;
  bitRate = 8;
  bytesPerSample = bitRate / 8;
}

TWaveFile::~TWaveFile()
{
  Clear();
}

void TWaveFile::Skip(FILE *fin, int size)
{
  char skip[256];

  while (size >= 256)
  {
    fread(skip, 1, 256, fin);
    size -= 256;
  }
  fread(skip, 1, size, fin);
}

int TWaveFile::FindChunk(FILE *fin, char *name)
{
  char chunk[5];
  int size;

  while (true)
  {
    chunk[4] = '\0';
    fread(chunk, 1, 4, fin);
    fread(&size, 4, 1, fin);
    if (strcmp(chunk, name) == 0)
      return size;
    Skip(fin, size);
    if (feof(fin))
      return 0;
  }
}

bool TWaveFile::ReadChunk(FILE *fin, void *data, int size, int &restSize)
{
  int s;

  s = fread(data, 1, size, fin);
  restSize -= s;
  return s == size && restSize >= 0;
}

bool TWaveFile::Load(char *name)
{
  FILE *fin;
  char data[5], *cwave;
  int totalSize, chunkSize, format, channel;

  Clear();

  fin = fopen(name, "rb");
  if (fin == NULL)
    return false;

  data[4] = '\0';
  fread(data, 1, 4, fin);
  if (strcmp(data, "RIFF"))
    goto ERROR;
  if (fread(&totalSize, 4, 1, fin) < 1)
    goto ERROR;
  if (!ReadChunk(fin, data, 4, totalSize))
    goto ERROR;
  if (strcmp(data, "WAVE"))
    goto ERROR;

  chunkSize = FindChunk(fin, "fmt ");
  if (!ReadChunk(fin, data, 4, chunkSize))
    goto ERROR;
  format = data[0];
  if (format != 1 && format != 7)
    goto ERROR;
  channel = data[2];
  if (channel != 1)
    goto ERROR;
  if (!ReadChunk(fin, &sampleRate, 4, chunkSize))
    goto ERROR;
  if (!ReadChunk(fin, data, 4, chunkSize))
    goto ERROR;
  if (!ReadChunk(fin, data, 4, chunkSize))
    goto ERROR;
  bitRate = (data[0] / channel) * 8;
  bytesPerSample = bitRate / 8;
  Skip(fin, chunkSize);

  chunkSize = FindChunk(fin, "data");
  cwave = new char[waveSize = chunkSize];
  if (!ReadChunk(fin, cwave, waveSize, chunkSize))
  {
    delete[] cwave;
    waveSize = 0;
    goto ERROR;
  }

  wave = new int[waveSize /= bytesPerSample];
  WaveCopy(wave, cwave, waveSize);
  delete[] cwave;

  chunkSize = FindChunk(fin, "user");  //自己加的
  if (chunkSize > 0)
  {
    userData = new char[chunkSize + 1];
    userData[chunkSize] = 0;
    ReadChunk(fin, userData, chunkSize, chunkSize);
  }

  fclose(fin);

  if (format == 7)
    MuLawToPcm();

  return true;

ERROR:
  fclose(fin);
  return false;
}

bool TWaveFile::Save(char *name)
{
  FILE *fout;
  int i, userChunkSize;
  char *cwave;

  fout = fopen(name, "wb");
  if (fout == NULL)
    return false;

  userChunkSize = userData? strlen(userData) + 8 : 0;

  fprintf(fout, "RIFF");
  i = 38 + userChunkSize + waveSize * bytesPerSample;
  fwrite(&i, 4, 1, fout);
  fprintf(fout, "WAVEfmt ");
  i = 0x12;
  fwrite(&i, 4, 1, fout);
  i = 0x10001;
  fwrite(&i, 4, 1, fout);
  fwrite(&sampleRate, 4, 1, fout);
  i = sampleRate * bytesPerSample;
  fwrite(&i, 4, 1, fout);
  i = bytesPerSample | (bitRate << 16);
  fwrite(&i, 4, 1, fout);
  i = 0;
  fwrite(&i, 2, 1, fout);
  fprintf(fout, "data");
  i = waveSize * bytesPerSample;
  fwrite(&i, 4, 1, fout);

  cwave = new char[i];
  WaveCopy(cwave, wave, waveSize);
  fwrite(cwave, 1, i, fout);
  delete[] cwave;

  if (userData)
  {
    userChunkSize -= 8;
    fprintf(fout, "user");
    fwrite(&userChunkSize, 4, 1, fout);
    fwrite(userData, 1, userChunkSize, fout);
  }

  fclose(fout);

  return true;
}

int TWaveFile::GetSampleRate(void)
{
  return sampleRate;
}

int TWaveFile::GetBitRate(void)
{
  return bitRate;
}

void TWaveFile::SetFormat(int newSampleRate, int newBitRate)
{
  int i;

  if (newBitRate != bitRate)
  {
    if (newBitRate == 8)
      for (i = 0; i < waveSize; i++)
        wave[i] = wave[i] >> 8;
    else
      for (i = 0; i < waveSize; i++)
        wave[i] = wave[i] << 8;
  }
  Resample(newSampleRate);

  sampleRate = newSampleRate;
  bitRate = newBitRate;
  bytesPerSample = bitRate / 8;
}

int TWaveFile::GetDuration(void)
{
  //return (float)waveSize / sampleRate;
  return waveSize / sampleRate;
}

void TWaveFile::SetWave(int *w, int size)
{
  Clear();
  wave = new int[waveSize = size];
  memcpy(wave, w, waveSize * sizeof(int));
}

void TWaveFile::Clear(void)
{
  delete[] wave;
  wave = NULL;
  waveSize = 0;
  delete[] userData;
  userData = NULL;
}

void TWaveFile::Resample(int newSampleRate)
{
  int i, j, r, n;
  int *newWave;

  if (newSampleRate == sampleRate || waveSize == 0)
    return;

  //本來是 waveSize = (waveSize - 1) * newSampleRate / sampleRate，
  //但是 (waveSize - 1) * newSampleRate 可能會overflow，所以寫成這樣
  r = (waveSize - 1) % sampleRate;
  waveSize = (waveSize - 1 - r) / sampleRate * newSampleRate + r * newSampleRate / sampleRate;
  newWave = new int[waveSize];
  for (i = 0; i < waveSize; i++)
  {
    //本來是 j = i * sampleRate / newSampleRate
    r = i % newSampleRate;
    j = (i - r) / newSampleRate * sampleRate + r * sampleRate / newSampleRate;
    n = (10.0f * i * sampleRate) / newSampleRate - 10 * j;
    newWave[i] = (wave[j] * (10 - n) + wave[j + 1] * n) / 10;
  }
  delete[] wave;
  wave = newWave;
}

void TWaveFile::MuLawToPcm(void)
{
  int i;
  static int exp_lut[8] = {0, 132, 396, 924, 1980, 4092, 8316, 16764};
  unsigned char mulaw;
  int sign, exponent;

  for (i = 0; i < waveSize; i++)
  {
    mulaw = wave[i] + 128;
    mulaw = ~mulaw;
    sign = mulaw & 0x80;
    exponent = (mulaw >> 4) & 0x07;
    wave[i] = ((exp_lut[exponent]) + ((mulaw & 0x0F) << (exponent + 3))) >> 8;
    if (sign != 0)
      wave[i] = -wave[i];
  }
}

void TWaveFile::WaveCopy(char *dst, int *src, int size)
{
  int i;
  unsigned char *ucp;
  short *sp;

  if (bytesPerSample == 1)
  {
    ucp = (unsigned char *)dst;
    for (i = size - 1; i >= 0; i--)
      ucp[i] = src[i] + 128;
  }
  else
  {
    sp = (short *)dst;
    for (i = size - 1; i >= 0; i--)
      sp[i] = src[i];
  }
}

void TWaveFile::WaveCopy(int *dst, char *src, int size)
{
  int i;
  unsigned char *ucp;
  short *sp;

  if (bytesPerSample == 1)
  {
    ucp = (unsigned char *)src;
    for (i = size - 1; i >= 0; i--)
      dst[i] = ucp[i] - 128;
  }
  else
  {
    sp = (short *)src;
    for (i = size - 1; i >= 0; i--)
      dst[i] = sp[i];
  }
}

/* added by angie */
void TWaveFile::WaveCopy(int *dst, char *src, int size, int offset)
{
  int i;
  unsigned char *ucp;
  short *sp;

  if (bytesPerSample == 1)
  {
    ucp = (unsigned char *)src;
    for (i = size - 1; i >= 0; i--)
      dst[i+offset] = ucp[i] - 128;
  }
  else
  {
    sp = (short *)src;
    for (i = size - 1; i >= 0; i--)
      dst[i+offset] = sp[i];
  }
}

int TWaveFile::WaveCopy(char *dst, int off, int len)  //dst以byte為單位；off、len以sample為單位
{
        int i;

        if (wave == NULL)
                return 0;

  if (off+len > waveSize)
    len = waveSize - off;

        if (bytesPerSample == 1)
                for (i = 0; i < len; i++)
                        dst[i] = wave[i+off] + 128;
        else
                for (i = 0; i < len; i++)
    {
                        dst[i*2] = wave[i+off] & 0xFF;
      dst[i*2 + 1] = (wave[i+off] >> 8) & 0xFF;
    }
        
        return len;
}

void TWaveFile::Trim(int from, int to)
{
  int *newwave;

  if (from < 0)
    from = 0;
  if (to >= waveSize)
    to = waveSize - 1;
  newwave = new int[waveSize = to - from + 1];
  memcpy(newwave, wave + from, waveSize * sizeof(int));
  delete[] wave;
  wave = newwave;
}

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