Audio recorder example updated to display level using QAudioProbe.

Change-Id: I7d5aea306aeb3cd9109615f9ed4905c53125233a
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>

examples/audiorecorder/audiorecorder.cpp

@@ -43,6 +43,7 @@
 
 #include <qaudiorecorder.h>
 #include <qmediarecorder.h>
+#include <qaudioprobe.h>
 
 #include "audiorecorder.h"
 
@@ -61,6 +62,9 @@ AudioRecorder::AudioRecorder(QWidget *parent)
     ui->setupUi(this);
 
     audioRecorder = new QAudioRecorder(this);
+    probe = new QAudioProbe;
+    connect(probe, SIGNAL(audioBufferProbed(const QAudioBuffer&)), this, SLOT(processBuffer(QAudioBuffer)));
+    probe->setSource(audioRecorder);
 
     //audio devices
     ui->audioDeviceBox->addItem(tr("Default"), QVariant(QString()));
@@ -103,11 +107,12 @@ AudioRecorder::AudioRecorder(QWidget *parent)
             SLOT(updateState(QMediaRecorder::State)));
     connect(audioRecorder, SIGNAL(error(QMediaRecorder::Error)), this,
             SLOT(displayErrorMessage()));
-    }
+}
 
 AudioRecorder::~AudioRecorder()
 {
     delete audioRecorder;
+    delete probe;
 }
 
 void AudioRecorder::updateProgress(qint64 duration)
@@ -221,3 +226,89 @@ QUrl AudioRecorder::generateAudioFilePath()
     QUrl location(QDir::toNativeSeparators(outputDir.canonicalPath() + QString("/testclip_%1").arg(lastImage + 1, 4, 10, QLatin1Char('0'))));
     return location;
 }
+
+// This function returns the maximum possible sample value for a given audio format
+qreal AudioRecorder::GetPeakValue(const QAudioFormat& format)
+{
+    // Note: Only the most common sample formats are supported
+    if (!format.isValid())
+        return 0.0;
+
+    if (format.codec() != "audio/pcm")
+        return 0.0;
+
+    switch (format.sampleType()) {
+    case QAudioFormat::Unknown:
+        break;
+    case QAudioFormat::Float:
+        if (format.sampleSize() != 32) // other sample formats are not supported
+            return 0.0;
+        return 1.00003;
+    case QAudioFormat::SignedInt:
+        if (format.sampleSize() == 32)
+            return 2147483648.0;
+        else if (format.sampleSize() == 16)
+            return 32768.0;
+        else if (format.sampleSize() == 8)
+            return 128.0;
+        break;
+    case QAudioFormat::UnSignedInt:
+        // Unsigned formats are not supported in this example
+        break;
+    }
+
+    return 0.0;
+}
+
+qreal AudioRecorder::GetBufferLevel(const QAudioBuffer& buffer)
+{
+    if (!buffer.format().isValid() || buffer.format().byteOrder() != QAudioFormat::LittleEndian)
+        return 0.0;
+
+    if (buffer.format().codec() != "audio/pcm")
+        return 0.0;
+
+    qreal peak_value = GetPeakValue(buffer.format());
+    if (qFuzzyCompare(peak_value, 0.0))
+        return 0.0;
+
+    switch (buffer.format().sampleType()) {
+    case QAudioFormat::Unknown:
+    case QAudioFormat::UnSignedInt:
+        break;
+    case QAudioFormat::Float:
+        if (buffer.format().sampleSize() == 32)
+            return GetBufferLevel(buffer.constData<float>(), buffer.sampleCount()) / peak_value;
+        break;
+    case QAudioFormat::SignedInt:
+        if (buffer.format().sampleSize() == 32)
+            return GetBufferLevel(buffer.constData<long int>(), buffer.sampleCount()) / peak_value;
+        else if (buffer.format().sampleSize() == 16)
+            return GetBufferLevel(buffer.constData<short int>(), buffer.sampleCount()) / peak_value;
+        else if (buffer.format().sampleSize() == 8)
+            return GetBufferLevel(buffer.constData<signed char>(), buffer.sampleCount()) / peak_value;
+        break;
+    }
+
+    return 0.0;
+}
+
+template <class T>
+qreal AudioRecorder::GetBufferLevel(const T* buffer, int samples)
+{
+    qreal max_value = 0.0;
+
+    for (int i = 0; i < samples; i++) {
+        qreal value = qAbs((qreal)buffer[i]);
+        if (value > max_value)
+            max_value = value;
+    }
+
+    return max_value;
+}
+
+void AudioRecorder::processBuffer(const QAudioBuffer& buffer)
+{
+    qreal level = GetBufferLevel(buffer);
+    ui->audioLevel->setLevel(level);
+}

examples/audiorecorder/audiorecorder.h

@@ -54,6 +54,8 @@ namespace Ui {
 }
 
 class QAudioRecorder;
+class QAudioProbe;
+class QAudioBuffer;
 QT_END_NAMESPACE
 
 QT_USE_NAMESPACE
@@ -65,6 +67,9 @@ public:
     AudioRecorder(QWidget *parent = 0);
     ~AudioRecorder();
 
+public slots:
+    void processBuffer(const QAudioBuffer&);
+
 private slots:
     void setOutputLocation();
     void togglePause();
@@ -76,10 +81,16 @@ private slots:
     QUrl generateAudioFilePath();
 
 private:
+    static qreal GetPeakValue(const QAudioFormat& format);
+    static qreal GetBufferLevel(const QAudioBuffer& buffer);
+
+    template <class T>
+    static qreal GetBufferLevel(const T* buffer, int samples);
+
     Ui::AudioRecorder *ui;
 
     QAudioRecorder* audioRecorder;
-    QAudioEncoderSettings  audioSettings;
+    QAudioProbe* probe;
     bool outputLocationSet;
 
 };

examples/audiorecorder/audiorecorder.pro

@@ -4,11 +4,13 @@ TARGET = audiorecorder
 QT += multimedia
 
 HEADERS = \
-    audiorecorder.h
+    audiorecorder.h \
+    qaudiolevel.h
   
 SOURCES = \
     main.cpp \
-    audiorecorder.cpp
+    audiorecorder.cpp \
+    qaudiolevel.cpp
 
 maemo*: {
     FORMS += audiorecorder_small.ui

examples/audiorecorder/audiorecorder.ui

@@ -155,6 +155,17 @@
       </property>
      </widget>
     </item>
+    <item row="3" column="0">
+     <widget class="QLabel" name="levelLabel">
+      <property name="text">
+       <string>Audio Level:</string>
+      </property>
+     </widget>
+    </item>
+    <item row="3" column="1" colspan="-1">
+     <widget class="QAudioLevel" name="audioLevel">
+     </widget>
+    </item>
    </layout>
   </widget>
   <widget class="QStatusBar" name="statusbar"/>

examples/audiorecorder/qaudiolevel.cpp

@@ -0,0 +1,68 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** 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 "qaudiolevel.h"
+#include <QPainter>
+
+QAudioLevel::QAudioLevel(QWidget *parent)
+  : QWidget(parent)
+  , m_level(0.0)
+{
+}
+
+void QAudioLevel::setLevel(qreal level)
+{
+    if (m_level != level) {
+        m_level = level;
+        update();
+    }
+}
+
+void QAudioLevel::paintEvent(QPaintEvent *event)
+{
+    Q_UNUSED(event);
+
+    QPainter painter(this);
+    // draw level
+    qreal widthLevel = m_level * width();
+    painter.fillRect(0, 0, widthLevel, height(), Qt::red);
+    // clear the rest of the control
+    painter.fillRect(widthLevel, 0, width(), height(), Qt::black);
+}

examples/audiorecorder/qaudiolevel.h

@@ -0,0 +1,64 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** 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."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QAUDIOLEVEL_H
+#define QAUDIOLEVEL_H
+
+#include <QWidget>
+
+QT_USE_NAMESPACE
+
+class QAudioLevel : public QWidget
+{
+    Q_OBJECT
+public:
+    explicit QAudioLevel(QWidget *parent = 0);
+
+    // Using [0; 1.0] range
+    void setLevel(qreal level);
+
+protected:
+    void paintEvent(QPaintEvent *event);
+
+private:
+    qreal m_level;
+};
+
+#endif // QAUDIOLEVEL_H