Qt 5.6 | Qt Multimedia | Spectrum Example | utils.cpp Example File

Qt 5.6.2 Reference Documentation

# utils.cpp Example File

multimedia/spectrum/app/utils.cpp

      /****************************************************************************
      **
      ** Copyright (C) 2015 The Qt Company Ltd.
      ** Contact: http://www.qt.io/licensing/
      **
      ** 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 The Qt Company Ltd 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 <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;
      }