Using QMicrophone

Article Metadata

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Tested with

Devices(s): Nokia N8, Nokia C7-00, N950

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Compatibility

Platform(s): Symbian^3 and later, Qt 4.7 and later, Meego

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Platform Security

Capabilities: UserEnvironment

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Article

Keywords: Microphone, lmmfdevsound,multimedia

Created: galazzo (04 Apr 2012)

Last edited: galazzo (05 Apr 2012)

Introduction

This article explains how to QMicrophone, a class to easy manage microphone on your device. Will be explained how to record a file and manage volume. The idea behind the volume management is the ability to trigger events with sounds. Take, for example, to change a page, snapping his fingers, or trigger an event when environment noise exceeds a threshold.

Using QMicrophone

1. Download source code from here
2. Include QMicrophone directory into your project

.pro

        include(./QMicrophone/microphone.pri)

main.cpp

#include <QtGui/QApplication>
#include "qmlapplicationviewer.h"
 
#include <QtDeclarative>
#include "QMicrophone/qmicrophone.h"
 
Q_DECL_EXPORT int main(int argc, char *argv[])
{
    QScopedPointer<QApplication> app(createApplication(argc, argv));
 
    qmlRegisterType<QMicrophone>("Microphone", 1, 0, "Microphone");
 
    QmlApplicationViewer viewer;
    viewer.setOrientation(QmlApplicationViewer::ScreenOrientationLockPortrait);
    viewer.setMainQmlFile(QLatin1String("qml/QMicrophoneSample/main.qml"));
    viewer.showExpanded();
 
    return app->exec();
}

QML

How to Record Audio Files

import QtQuick 1.1
import Microphone 1.0
 
Rectangle {
Column {
        height: parent.height
        width: parent.width
        anchors.horizontalCenter: parent.horizontalCenter
        Rectangle {
            width: parent.width
            height: 100
            radius: 1
 
            Text {
                text: qsTr("Start recording for 5 sec")
                horizontalAlignment: Text.AlignLeft
                anchors.centerIn: parent
            }
            MouseArea {
                anchors.fill: parent
                onClicked: {
                    microphone.startRecording("test.wav", 5000);
                }
            }
        }
 
        Rectangle {
            width: parent.width
            height: 100
            radius: 1
 
            Text {
                text: qsTr("Start recording")
                anchors.centerIn: parent
            }
            MouseArea {
                anchors.fill: parent
                onClicked: {
                    microphone.startRecording("test.wav");
                }
            }
        }
 
        Rectangle {
            width: parent.width
            height: 100
            radius: 1
 
            Text {
                text: qsTr("Stop recording")
                anchors.centerIn: parent
            }
            MouseArea {
                anchors.fill: parent
                onClicked: {
                    microphone.stopRecording();
                }
            }
        }
 
    }
 
    Microphone {
        id:microphone       
        onRecordingStarted: console.log("Start recording")
        onRecordingStopped: console.log("Stop recording")
    }
}

startRecording has two parameters:

• filename where audio will be saved
• recording time in msec. If not set recording will continue until stopRecording will be called

How to manage Volume

import QtQuick 1.1
import Microphone 1.0
 
Rectangle {
Microphone {
        id:microphone
        threshold: 150       
        onThresholdExceeded: {
            console.log(volume)
        }
    }
 
    Component.onCompleted: {
        microphone.startVolumeAnalysis();
    }
}
 
This functionality is very useful if you wish to trigger an event when Volume exceed the threshold.
 
=== Restrictions ===
If you are already using Microphone to record an audio file, you cannot use in the same time volume management, due the fact the resource it's already busy.
 
=== Work in progress ===
* clap or fingers snapping detection
* simple command voice detection, like "up", "down", "left", "right", "stop"...