wavpcmfile.cpp

#include "wavpcmfile.h"

#include <QDataStream>

WavPcmFile::WavPcmFile(const QString & name, const QAudioFormat & format_, QObject *parent_)
  : QFile(name, parent_), format(format_)
{
}

bool WavPcmFile::hasSupportedFormat()
{
  return (format.sampleSize() == 8
          && format.sampleType() == QAudioFormat::UnSignedInt)
      || (format.sampleSize() > 8
          && format.sampleType() == QAudioFormat::SignedInt
          && format.byteOrder() == QAudioFormat::LittleEndian);
}

bool WavPcmFile::open()
{
  if (!hasSupportedFormat()) {
    setErrorString("Wav PCM supports only 8-bit unsigned samples "
                   "or 16-bit (or more) signed samples (in little endian)");
    return false;
  } else {
    if (!QFile::open(ReadWrite | Truncate))
      return false;
    writeHeader();
    return true;
  }
}

void WavPcmFile::writeHeader()
{
  QDataStream out(this);
  out.setByteOrder(QDataStream::LittleEndian);

  // RIFF chunk
  out.writeRawData("RIFF", 4);
  out << quint32(0); // Placeholder for the RIFF chunk size (filled by close())
  out.writeRawData("WAVE", 4);

  // Format description chunk
  out.writeRawData("fmt ", 4);
  out << quint32(16); // "fmt " chunk size (always 16 for PCM)
  out << quint16(1);  // data format (1 => PCM)
  out << quint16(format.channelCount());
  out << quint32(format.sampleRate());
  out << quint32(format.sampleRate() * format.channelCount()
                 * format.sampleSize() / 8 ); // bytes per second
  out << quint16(format.channelCount() * format.sampleSize() / 8); // Block align
  out << quint16(format.sampleSize()); // Significant Bits Per Sample

  // Data chunk
  out.writeRawData("data", 4);
  out << quint32(0);  // Placeholder for the data chunk size (filled by close())

  Q_ASSERT(pos() == 44); // Must be 44 for WAV PCM
}

void WavPcmFile::close()
{
  // Fill the header size placeholders
  quint32 fileSize = size();

  QDataStream out(this);
  // RIFF chunk size
  seek(4);
  out << quint32(fileSize - 8);

  // data chunk size
  seek(40);
  out << quint32(fileSize - 44);

  QFile::close();
}