Qt 5.9 | Qt Multimedia | Spectrum Example | utils.cpp Example File

Qt 5.9.4 Reference Documentation

# utils.cpp Example File

multimedia/spectrum/app/utils.cpp

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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;
      }