一Qt 音频基础知识

1. QT += multimedia
2. QMediaPlayer 类：媒体播放器，主要用于播放歌曲、网络收音 机等功能。
3. QMediaPlaylist 类：专用于播放媒体内容的列表。

二 音频项目实战程序

//版本5.12.8
.pro


QT       += core gui
QT +=   multimedia
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

CONFIG += c++11

# The following define makes your compiler emit warnings if you use
# any Qt feature that has been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
    main.cpp \
    mainwindow.cpp

HEADERS += \
    mainwindow.h

FORMS += \
    mainwindow.ui

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

RESOURCES += \
        images.qrc

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QMediaPlayer>
#include <QMediaPlaylist>
#include <QFileDialog>
#include <QStringList>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private:
    Ui::MainWindow *ui;

    //定义播放对象
    QMediaPlayer * player;//播放对象
    QMediaPlaylist *playlist;//播放列表

    QString drtTime;//歌曲时长
    QString psTime;//播放位置，进度

private slots:

    void onstatechg(QMediaPlayer::State state);//播放按钮的切换状态
    void onplaylisting(int pos);//播放列表
    void onDrtchg(qint64 drt);//歌曲总时间长度
    void onpstchg(qint64 pos);//播放歌曲当前位置



    void on_pushButton_open_clicked();
    void on_pushButton_Player_clicked();
    void on_pushButton_Pause_clicked();
    void on_pushButton_Stop_clicked();
    void on_pushButton_Prev_clicked();
    void on_pushButton_Next_clicked();
    void on_pushButton_Volumn_clicked();
    void on_horizontalSlider_Volumn_valueChanged(int value);
    void on_horizontalSlider_Speed_valueChanged(int value);
};
#endif // MAINWINDOW_H

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);


    player = new QMediaPlayer(this);
    playlist = new QMediaPlaylist(this);
    playlist->setPlaybackMode(QMediaPlaylist::Loop);//默认循环模式

    player->setPlaylist(playlist);

    connect(player,SIGNAL(statechanged(QMediaPlayer::State)),this,SLOT(onstatechg(QMediaPlayer::State)));

    //信号与槽的链接

    connect(player,SIGNAL(positionChanged(qint64)),this,SLOT(onpstchg(qint64)));


    connect(player,SIGNAL(durationChanged(qint64)),this,SLOT(onDrtchg(qint64)));


    connect(playlist,SIGNAL(currentIndexChanged(int)),this,SLOT(onplaylisting(int)));





}

MainWindow::~MainWindow()
{
    delete ui;
}
//播放按钮的切换状态
void MainWindow::onstatechg(QMediaPlayer::State state)
{
    ui->pushButton_Player->setEnabled(!(state==QMediaPlayer::PlayingState));
    ui->pushButton_Pause->setEnabled(state==QMediaPlayer::PlayingState);
    ui->pushButton_Stop->setEnabled(state==QMediaPlayer::PlayingState);
}
//播放列表
void MainWindow::onplaylisting(int pos)
{

    ui->listWidget->setCurrentRow(pos);//选中当前行

    QListWidgetItem *item = ui->listWidget->currentItem();

    if(item)
        ui->label_Name->setText(item->text());


}
//歌曲总时间长度,更新变化进度
void MainWindow::onDrtchg(qint64 drt)
{

    ui->horizontalSlider_Speed->setMaximum(drt);

    int sec = drt/1000;//秒

    int min = sec/60;//分

    sec = sec%60;//余数为妙

    //
    drtTime =QString::asprintf("%d:%d",min,sec);

    ui->label_Time->setText(psTime+"|"+drtTime);


}
//播放歌曲当前位置,更新变化情况
void MainWindow::onpstchg(qint64 pos)
{
    if(ui->horizontalSlider_Speed->isSliderDown())
        return;

    //
    ui->horizontalSlider_Speed->setSliderPosition(pos);

    int sec = pos/1000;//秒

    int min = sec/60;//分

    sec = sec%60;//余数为妙

    //
    psTime =QString::asprintf("%d:%d",min,sec);

    ui->label_Time->setText(psTime+"|"+drtTime);

}
//44:20

void MainWindow::on_pushButton_open_clicked()
{
    //添加歌曲文件

    QString currentpath = QDir::homePath();//获取当前目录

    QString dlgtitle = "请选择音频文件";//文件的对话框的标题

    QString strfilter = "所有文件(*.*);;音频文件(*.mp3 *.wav);;MP3文件(*.mp3);;WAV文件(*.wav)";

    QStringList filelist = QFileDialog::getOpenFileNames(this,dlgtitle,currentpath,strfilter);

    if(filelist.count()<1)
    {
        return;
    }
    for(int i = 0;i<filelist.count();i++)
    {
        //添加文件实现播放
        QString afile =filelist.at(i);

        playlist->addMedia(QUrl::fromLocalFile(afile));//添加文件，

        QFileInfo fileinfo(afile);
        //将文件添加到 listwidget控件来
        ui->listWidget->addItem(fileinfo.fileName());
    }

    if(player->state()!=QMediaPlayer::PlayingState)
    {

        playlist->setCurrentIndex(0);
    }
    //播放
    player->play();



}

void MainWindow::on_pushButton_Player_clicked()
{
    //判断当前播放哪一个
    if(playlist->currentIndex()<0)
        playlist->setCurrentIndex(0);
    player->play();

}

void MainWindow::on_pushButton_Pause_clicked()
{

    //暂停
    player->pause();
}

void MainWindow::on_pushButton_Stop_clicked()
{

    //停止
    player->stop();
}

void MainWindow::on_pushButton_Prev_clicked()
{

    //上一曲
    playlist->previous();
}

void MainWindow::on_pushButton_Next_clicked()
{

    //下一曲
    playlist->next();
}

void MainWindow::on_pushButton_Volumn_clicked()
{
    //控制静音状态
    bool mute = player->isMuted();

    player->setMuted(!mute);

    if(mute)
    {
        ui->pushButton_Volumn->setIcon(QIcon(":/new/prefix1/images/volumn.bmp"));
    }
    else
    {
        ui->pushButton_Volumn->setIcon(QIcon(":/new/prefix1/images/mute.bmp"));
    }

}

void MainWindow::on_horizontalSlider_Volumn_valueChanged(int value)
{
    //调整音量
    player->setVolume(value);
    ui->label_VolumeSize->setNum(value);
}

void MainWindow::on_horizontalSlider_Speed_valueChanged(int value)
{
    //调整播放进度
    player->setPosition(value);

}