一、完善上章的功能,形成一个小工具
QT开发技术【ffmpeg + QAudioOutput】音乐播放器
二、增加歌曲保存类
#include "../Include/MusicListManager.h"
#include "QtGui/Include/Conversion.h"
#include <QFile>
#include <QXmlStreamReader>
#include <QXmlStreamWriter>
#include <QDebug>
CMusicListManager::CMusicListManager()
{
}
CMusicListManager::~CMusicListManager()
{
}
bool CMusicListManager::AddMusic(const std::string& strMusicFilePath)
{
for (auto& itr : m_vecMusicList)
{
if (itr.strMusicPath == strMusicFilePath)
{
return false;
}
}
stMusicInfo stMusicInfo;
stMusicInfo.strMusicName = strMusicFilePath.substr(strMusicFilePath.find_last_of("\\/") + 1).substr(0, strMusicFilePath.find_last_of("."));
stMusicInfo.strMusicPath = strMusicFilePath;
m_vecMusicList.push_back(stMusicInfo);
return true;
}
void CMusicListManager::RemoveMusic(const std::string& strMusicFilePath)
{
for (auto itr = m_vecMusicList.begin(); itr!= m_vecMusicList.end(); ++itr)
{
if (itr->strMusicPath == strMusicFilePath)
{
m_vecMusicList.erase(itr);
return;
}
}
}
stMusicInfo CMusicListManager::GetMusicInfoByIndex(int nIndex) const
{
if (nIndex < 0)
{
nIndex = m_vecMusicList.size() - 1;
}
else if (nIndex >= (int)m_vecMusicList.size())
{
nIndex = 0;
}
return m_vecMusicList[nIndex];
}
void CMusicListManager::Clear()
{
m_vecMusicList.clear();
}
std::vector<stMusicInfo> CMusicListManager::GetMusicList() const
{
return m_vecMusicList;
}
void CMusicListManager::Load(const std::string& strSaveFilePath)
{
m_strSaveFilePath = strSaveFilePath;
QFile file(TransString2Unicode(strSaveFilePath));
if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
{
qDebug() << TransString2Unicode("无法打开文件:" +strSaveFilePath);
return;
}
m_vecMusicList.clear();
QXmlStreamReader xmlReader(&file);
while (!xmlReader.atEnd() && !xmlReader.hasError())
{
QXmlStreamReader::TokenType token = xmlReader.readNext();
if (token == QXmlStreamReader::StartElement)
{
if (xmlReader.name() == "Music")
{
QXmlStreamAttributes attributes = xmlReader.attributes();
if (attributes.hasAttribute("name") && attributes.hasAttribute("path")) {
QString name = attributes.value("name").toString();
QString path = attributes.value("path").toString();
stMusicInfo stMusicInfo;
stMusicInfo.strMusicName = TransUnicode2String(name);
stMusicInfo.strMusicPath = TransUnicode2String(path);
m_vecMusicList.push_back(stMusicInfo);
}
}
}
}
}
void CMusicListManager::Save()
{
QFile file(TransString2Unicode(m_strSaveFilePath));
if (!file.open(QIODevice::WriteOnly | QIODevice::Text))
{
qDebug() << TransString2Unicode("无法打开文件进行写入:" + m_strSaveFilePath);
return;
}
QXmlStreamWriter xmlWriter(&file);
xmlWriter.setAutoFormatting(true); // 自动格式化 XML 内容
xmlWriter.writeStartDocument();
xmlWriter.writeStartElement("MusicList");
for (auto& itr : m_vecMusicList)
{
xmlWriter.writeStartElement("Music");
xmlWriter.writeAttribute("name", TransString2Unicode(itr.strMusicName));
xmlWriter.writeAttribute("path", TransString2Unicode(itr.strMusicPath));
xmlWriter.writeEndElement(); // 结束 Music 元素
}
xmlWriter.writeEndElement(); // 结束 MusicList 元素
xmlWriter.writeEndDocument();
file.close();
}
三、界面一些按钮控制实现
#include "../Include/EMusicMainWindow.h"
#include "ui_EMusicMainWindow.h"
#include "QtGui/Include/Conversion.h"
#include <QFileDialog>
#include <QThread>
#include <QDebug>
CEMusicMainWindow::CEMusicMainWindow(QWidget* parent)
: QMainWindow(parent)
, ui(std::make_unique<Ui::CEMusicMainWindow>())
{
ui->setupUi(this);
InitUI();
}
CEMusicMainWindow::~CEMusicMainWindow()
{
m_AudioPlayer.Stop();
m_AudioPlayer.Quit();
m_pMusicLocalListManager->Save();
}
void CEMusicMainWindow::InitUI()
{
m_bIsPlaying = false;
m_bSeeking = false;
m_eCycleType = E_CYCLE_ALL;
m_pMusicLocalListManager = std::make_unique<CMusicListManager>();
std::string strMusicListPath = TransUnicode2String(QCoreApplication::applicationDirPath()) + "/MusicList.xml";
m_pMusicLocalListManager->Load(strMusicListPath);
std::vector<stMusicInfo> vecMusicList = m_pMusicLocalListManager->GetMusicList();
for (auto musicInfo : vecMusicList)
{
QListWidgetItem* item = new QListWidgetItem(QIcon(":/Music_File.png"), TransString2Unicode(musicInfo.strMusicName));
ui->listWidget_All->addItem(item);
}
connect(&m_AudioPlayer, &CAudioPlayer::SigDuration, this, &CEMusicMainWindow::SlotUpdateLyricsAndTime);
connect(&m_AudioPlayer, &CAudioPlayer::SigSeekOk, this, &CEMusicMainWindow::SlotSeekOk);
}
void CEMusicMainWindow::on_pushButton_StopOrPlay_clicked()
{
if (m_strMusicFilePath.isEmpty())
{
return;
}
if (m_bIsPlaying)
{
m_bIsPlaying = false;
m_AudioPlayer.Pause();
ui->pushButton_StopOrPlay->setStyleSheet("image: url(:/Play.png);");
}
else
{
m_bIsPlaying = true;
m_bSeeking = false;
ui->pushButton_StopOrPlay->setStyleSheet("image: url(:/Stop.png);");
if (m_strOldMusicFilePath.isEmpty())
{
m_strOldMusicFilePath = m_strMusicFilePath;
m_LyricsReader.LoadLrcFile(m_strMusicFilePath.split('.').first() + ".lrc");
m_AudioPlayer.Play(TransUnicode2String(m_strMusicFilePath));
}
else if (m_strMusicFilePath != m_strOldMusicFilePath)
{
m_strOldMusicFilePath = m_strMusicFilePath;
m_LyricsReader.LoadLrcFile(m_strMusicFilePath.split('.').first() + ".lrc");
m_AudioPlayer.Play(TransUnicode2String(m_strMusicFilePath));
}
else if(m_AudioPlayer.GetControlType() == CAudioPlayer::E_CONTROL_PAUSE)
{
m_AudioPlayer.Resume();
}
else
{
m_strOldMusicFilePath = m_strMusicFilePath;
m_AudioPlayer.Play(TransUnicode2String(m_strMusicFilePath));
}
}
}
void CEMusicMainWindow::SlotUpdateLyricsAndTime(int nCurrentTime, int nDestTime)
{
std::string strLyrics = m_LyricsReader.GetCurrentLyrics(nCurrentTime);
ui->label_Words->setText(TransString2Unicode(strLyrics));
if (nCurrentTime == nDestTime && nCurrentTime != 0)
{
if (m_eCycleType == E_CYCLE_SINGLE)
{
m_AudioPlayer.Play(TransUnicode2String(m_strMusicFilePath));
}
else
{
on_pushButton_Next_clicked();
}
}
static int currentMs1 = -1, destMs1 = -1;
if (currentMs1 == nCurrentTime && destMs1 == nDestTime)
{
return;
}
currentMs1 = nCurrentTime;
destMs1 = nDestTime;
//qDebug() << "onDuration:" << nCurrentTime << nDestTime << m_bSeeking;
QString currentTime = QString("%1:%2:%3").arg(currentMs1 / 360000 % 60, 2, 10, QChar('0')).arg(currentMs1 / 6000 % 60, 2, 10, QChar('0')).arg(currentMs1 / 1000 % 60, 2, 10, QChar('0'));
QString destTime = QString("%1:%2:%3").arg(destMs1 / 360000 % 60, 2, 10, QChar('0')).arg(destMs1 / 6000 % 60, 2, 10, QChar('0')).arg(destMs1 / 1000 % 60, 2, 10, QChar('0'));
ui->label_Process->setText(currentTime + "/" + destTime);
if (!m_bSeeking) //未滑动
{
ui->slider_Seek->setMaximum(nDestTime);
ui->slider_Seek->setValue(nCurrentTime);
}
}
void CEMusicMainWindow::SlotSeekOk()
{
m_bSeeking = false;
}
void CEMusicMainWindow::on_slider_Seek_sliderPressed()
{
m_bSeeking = true;
}
void CEMusicMainWindow::on_slider_Seek_sliderReleased()
{
m_AudioPlayer.Seek(ui->slider_Seek->value());
}
void CEMusicMainWindow::on_listWidget_All_itemDoubleClicked(QListWidgetItem* item)
{
int nIndex = ui->listWidget_All->row(item);
if (nIndex < 0)
{
return;
}
stMusicInfo musicInfo = m_pMusicLocalListManager->GetMusicInfoByIndex(nIndex);
if (musicInfo.strMusicPath.empty())
{
return;
}
m_strMusicFilePath = TransString2Unicode(musicInfo.strMusicPath);
m_bIsPlaying = false;
on_pushButton_StopOrPlay_clicked();
}
void CEMusicMainWindow::on_pushButton_CycleOrSingle_clicked()
{
if (m_eCycleType == E_CYCLE_ALL)
{
m_eCycleType = E_CYCLE_SINGLE;
ui->pushButton_CycleOrSingle->setStyleSheet("image: url(:/SingleCycle.png);");
}
else
{
m_eCycleType = E_CYCLE_ALL;
ui->pushButton_CycleOrSingle->setStyleSheet("image: url(:/Cycle.png);");
}
}
void CEMusicMainWindow::on_pushButton_Prev_clicked()
{
int nIndex = ui->listWidget_All->currentRow();
if (nIndex < 0)
{
return;
}
stMusicInfo musicInfo = m_pMusicLocalListManager->GetMusicInfoByIndex(nIndex - 1);
if (musicInfo.strMusicPath.empty())
{
return;
}
if (nIndex - 1 < 0)
{
ui->listWidget_All->setCurrentRow(ui->listWidget_All->count() - 1);
}
else
{
ui->listWidget_All->setCurrentRow(nIndex - 1);
}
m_strMusicFilePath = TransString2Unicode(musicInfo.strMusicPath);
m_bIsPlaying = false;
on_pushButton_StopOrPlay_clicked();
}
void CEMusicMainWindow::on_pushButton_Next_clicked()
{
int nIndex = ui->listWidget_All->currentRow();
if (nIndex < 0)
{
return;
}
stMusicInfo musicInfo = m_pMusicLocalListManager->GetMusicInfoByIndex(nIndex + 1);
if (musicInfo.strMusicPath.empty())
{
return;
}
if (nIndex + 1 >= ui->listWidget_All->count())
{
ui->listWidget_All->setCurrentRow(0);
}
else
{
ui->listWidget_All->setCurrentRow(nIndex + 1);
}
m_strMusicFilePath = TransString2Unicode(musicInfo.strMusicPath);
m_bIsPlaying = false;
on_pushButton_StopOrPlay_clicked();
}
void CEMusicMainWindow::on_pushButton_DeleteAll_clicked()
{
ui->listWidget_All->clear();
m_pMusicLocalListManager->Clear();
}
void CEMusicMainWindow::on_pushButton_Select_clicked()
{
QDir dir = QFileDialog::getExistingDirectory(this, TransString2Unicode("选择音乐文件夹"), QDir::currentPath());
if (dir.exists())
{
QStringList filters;
filters << "*.mp3";
QStringList files = dir.entryList(filters, QDir::Files);
for (auto file : files)
{
std::string strFilePath = TransUnicode2String(dir.absoluteFilePath(file));
if (m_pMusicLocalListManager->AddMusic(strFilePath))
{
QListWidgetItem* item = new QListWidgetItem(QIcon(":/Music_File.png"), file.split('.').first());
ui->listWidget_All->addItem(item);
}
}
}
}
四、总结
成功利用 Qt 和 FFmpeg 实现了一个简单的音乐播放器,掌握了音频解码、播放以及用户界面设计等相关技术。
音频解码技术详解
音频解码是将压缩的数字音频数据还原为原始波形信号的过程,是现代数字音频处理的核心环节。
音频解码的基本流程
数据输入:接收压缩的音频数据流(如MP3、AAC、FLAC等格式文件)
格式解析:识别音频文件的封装格式和编码标准
解码运算:根据特定算法进行解压缩运算,常见方法包括:
频率域变换(如MP3使用的MDCT变换)
预测编码解算
熵解码(Huffman编码等)
后处理:包括重采样、抖动处理、声道映射等
输出PCM:最终产生脉冲编码调制(PCM)信号,供数模转换器使用
主要音频编码标准
有损压缩
MP3(MPEG-1 Audio Layer III):使用心理声学模型,去除人耳不敏感的频段
AAC(Advanced Audio Coding):改进的MP3算法,效率提高约30%
Opus:低延迟编码,适合实时通信
无损压缩
FLAC(Free Lossless Audio Codec):保持原始音质,压缩率约50%
ALAC(Apple Lossless):苹果设备常用无损格式
应用场景
消费电子:智能手机、数字音乐播放器
广播系统:数字广播、网络流媒体
专业音频:录音棚、现场扩声系统
车载音响:支持多格式解码的高保真系统
关键技术指标
解码延迟
资源占用率
格式兼容性
音质还原度
错误恢复能力
现代音频解码器通常集成DSP处理功能,可同时实现均衡、混响等效果处理。随着AI技术的发展,基于神经网络的音频解码算法正在逐步商业化。