Qt Reference Documentation

# wavfile.cpp Example File

demos/spectrum/app/wavfile.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
     ** All rights reserved.
     ** Contact: Nokia Corporation (qt-info@nokia.com)
     **
     ** This file is part of the examples of the Qt Toolkit.
     **
     ** $QT_BEGIN_LICENSE:BSD$
     ** You may use this file under the terms of the BSD license as follows:
     **
     ** "Redistribution and use in source and binary forms, with or without
     ** modification, are permitted provided that the following conditions are
     ** met:
     **   * Redistributions of source code must retain the above copyright
     **     notice, this list of conditions and the following disclaimer.
     **   * Redistributions in binary form must reproduce the above copyright
     **     notice, this list of conditions and the following disclaimer in
     **     the documentation and/or other materials provided with the
     **     distribution.
     **   * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
     **     the names of its contributors may be used to endorse or promote
     **     products derived from this software without specific prior written
     **     permission.
     **
     ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
     ** $QT_END_LICENSE$
     **
     ****************************************************************************/

     #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;
     }