Qt Reference Documentation

# wavfile.cpp Example File

demos/spectrum/app/wavfile.cpp

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     #include <QtCore/qendian.h>
     #include <QVector>
     #include <QDebug>
     #include "utils.h"
     #include "wavfile.h"

     struct chunk
     {
         char        id[4];
         quint32     size;
     };

     struct RIFFHeader
     {
         chunk       descriptor;     // "RIFF"
         char        type[4];        // "WAVE"
     };

     struct WAVEHeader
     {
         chunk       descriptor;
         quint16     audioFormat;
         quint16     numChannels;
         quint32     sampleRate;
         quint32     byteRate;
         quint16     blockAlign;
         quint16     bitsPerSample;
     };

     struct DATAHeader
     {
         chunk       descriptor;
     };

     struct CombinedHeader
     {
         RIFFHeader  riff;
         WAVEHeader  wave;
     };

     WavFile::WavFile(QObject *parent)
         : QFile(parent)
         , m_headerLength(0)
     {

     }

     bool WavFile::open(const QString &fileName)
     {
         close();
         setFileName(fileName);
         return QFile::open(QIODevice::ReadOnly) && readHeader();
     }

     const QAudioFormat &WavFile::fileFormat() const
     {
         return m_fileFormat;
     }

     qint64 WavFile::headerLength() const
     {
     return m_headerLength;
     }

     bool WavFile::readHeader()
     {
         seek(0);
         CombinedHeader header;
         bool result = read(reinterpret_cast<char *>(&header), sizeof(CombinedHeader)) == sizeof(CombinedHeader);
         if (result) {
             if ((memcmp(&header.riff.descriptor.id, "RIFF", 4) == 0
                 || memcmp(&header.riff.descriptor.id, "RIFX", 4) == 0)
                 && memcmp(&header.riff.type, "WAVE", 4) == 0
                 && memcmp(&header.wave.descriptor.id, "fmt ", 4) == 0
                 && (header.wave.audioFormat == 1 || header.wave.audioFormat == 0)) {

                 // Read off remaining header information
                 DATAHeader dataHeader;

                 if (qFromLittleEndian<quint32>(header.wave.descriptor.size) > sizeof(WAVEHeader)) {
                     // Extended data available
                     quint16 extraFormatBytes;
                     if (peek((char*)&extraFormatBytes, sizeof(quint16)) != sizeof(quint16))
                         return false;
                     const qint64 throwAwayBytes = sizeof(quint16) + qFromLittleEndian<quint16>(extraFormatBytes);
                     if (read(throwAwayBytes).size() != throwAwayBytes)
                         return false;
                 }

                 if (read((char*)&dataHeader, sizeof(DATAHeader)) != sizeof(DATAHeader))
                     return false;

                 // Establish format
                 if (memcmp(&header.riff.descriptor.id, "RIFF", 4) == 0)
                     m_fileFormat.setByteOrder(QAudioFormat::LittleEndian);
                 else
                     m_fileFormat.setByteOrder(QAudioFormat::BigEndian);

                 int bps = qFromLittleEndian<quint16>(header.wave.bitsPerSample);
                 m_fileFormat.setChannels(qFromLittleEndian<quint16>(header.wave.numChannels));
                 m_fileFormat.setCodec("audio/pcm");
                 m_fileFormat.setFrequency(qFromLittleEndian<quint32>(header.wave.sampleRate));
                 m_fileFormat.setSampleSize(qFromLittleEndian<quint16>(header.wave.bitsPerSample));
                 m_fileFormat.setSampleType(bps == 8 ? QAudioFormat::UnSignedInt : QAudioFormat::SignedInt);
             } else {
                 result = false;
             }
         }
         m_headerLength = pos();
         return result;
     }