utils.cpp Example File

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  #include <QAudioFormat>
  #include "utils.h"

  qint64 audioDuration(const QAudioFormat &format, qint64 bytes)
  {
      return (bytes * 1000000) /
          (format.sampleRate() * format.channelCount() * (format.sampleSize() / 8));
  }

  qint64 audioLength(const QAudioFormat &format, qint64 microSeconds)
  {
     qint64 result = (format.sampleRate() * format.channelCount() * (format.sampleSize() / 8))
         * microSeconds / 1000000;
     result -= result % (format.channelCount() * format.sampleSize());
     return result;
  }

  qreal nyquistFrequency(const QAudioFormat &format)
  {
      return format.sampleRate() / 2;
  }

  QString formatToString(const QAudioFormat &format)
  {
      QString result;

      if (QAudioFormat() != format) {
          if (format.codec() == "audio/pcm") {
              Q_ASSERT(format.sampleType() == QAudioFormat::SignedInt);

              const QString formatEndian = (format.byteOrder() == QAudioFormat::LittleEndian)
                  ?   QString("LE") : QString("BE");

              QString formatType;
              switch (format.sampleType()) {
              case QAudioFormat::SignedInt:
                  formatType = "signed";
                  break;
              case QAudioFormat::UnSignedInt:
                  formatType = "unsigned";
                  break;
              case QAudioFormat::Float:
                  formatType = "float";
                  break;
              case QAudioFormat::Unknown:
                  formatType = "unknown";
                  break;
              }

              QString formatChannels = QString("%1 channels").arg(format.channelCount());
              switch (format.channelCount()) {
              case 1:
                  formatChannels = "mono";
                  break;
              case 2:
                  formatChannels = "stereo";
                  break;
              }

              result = QString("%1 Hz %2 bit %3 %4 %5")
                  .arg(format.sampleRate())
                  .arg(format.sampleSize())
                  .arg(formatType)
                  .arg(formatEndian)
                  .arg(formatChannels);
          } else {
              result = format.codec();
          }
      }

      return result;
  }

  bool isPCM(const QAudioFormat &format)
  {
      return (format.codec() == "audio/pcm");
  }

  bool isPCMS16LE(const QAudioFormat &format)
  {
      return isPCM(format) &&
             format.sampleType() == QAudioFormat::SignedInt &&
             format.sampleSize() == 16 &&
             format.byteOrder() == QAudioFormat::LittleEndian;
  }

  const qint16  PCMS16MaxValue     =  32767;
  const quint16 PCMS16MaxAmplitude =  32768; // because minimum is -32768

  qreal pcmToReal(qint16 pcm)
  {
      return qreal(pcm) / PCMS16MaxAmplitude;
  }

  qint16 realToPcm(qreal real)
  {
      return real * PCMS16MaxValue;
  }