Qt 多媒体模块提供了一套完整的 API，用于开发音频和视频处理应用。从简单的媒体播放到复杂的音视频编辑，Qt 都提供了相应的工具和组件。本文将从基础到高级全面解析 Qt 多媒体开发。

一、Qt 多媒体模块概述

1. 主要组件

Qt 多媒体模块包含以下核心组件：

QMediaPlayer：音频/视频播放器，支持多种格式
QMediaRecorder：媒体录制器，用于录制音频或视频
QCamera：摄像头访问和控制
QAudioInput/QAudioOutput：低级别音频输入/输出
QVideoWidget：视频显示组件
QMediaPlaylist：播放列表管理
QSoundEffect：简单音效播放（低延迟）

2. 平台支持

Qt 多媒体模块在不同平台上依赖于底层的多媒体框架：

Windows：DirectShow、Media Foundation
macOS：QuickTime、AVFoundation
Linux：GStreamer
Android：Android Media Framework
iOS：AVFoundation

二、基础应用：音频与视频播放

1. 简单音频播放器

#include <QApplication>
#include <QMediaPlayer>
#include <QPushButton>
#include <QVBoxLayout>
#include <QWidget>int main(int argc, char *argv[])
{QApplication a(argc, argv);// 创建主窗口和布局QWidget window;QVBoxLayout *layout = new QVBoxLayout(&window);// 创建媒体播放器QMediaPlayer *player = new QMediaPlayer;player->setMedia(QUrl::fromLocalFile("/path/to/music.mp3"));// 创建播放按钮QPushButton *playButton = new QPushButton("Play");QObject::connect(playButton, &QPushButton::clicked, player, &QMediaPlayer::play);// 创建暂停按钮QPushButton *pauseButton = new QPushButton("Pause");QObject::connect(pauseButton, &QPushButton::clicked, player, &QMediaPlayer::pause);// 创建停止按钮QPushButton *stopButton = new QPushButton("Stop");QObject::connect(stopButton, &QPushButton::clicked, player, &QMediaPlayer::stop);// 添加按钮到布局layout->addWidget(playButton);layout->addWidget(pauseButton);layout->addWidget(stopButton);// 显示窗口window.show();return a.exec();
}

2. 视频播放器

#include <QApplication>
#include <QMediaPlayer>
#include <QVideoWidget>
#include <QPushButton>
#include <QVBoxLayout>
#include <QHBoxLayout>
#include <QSlider>
#include <QFileDialog>int main(int argc, char *argv[])
{QApplication a(argc, argv);// 创建主窗口和布局QWidget window;QVBoxLayout *mainLayout = new QVBoxLayout(&window);QHBoxLayout *controlLayout = new QHBoxLayout;// 创建媒体播放器QMediaPlayer *player = new QMediaPlayer;// 创建视频显示组件QVideoWidget *videoWidget = new QVideoWidget;player->setVideoOutput(videoWidget);// 创建控制按钮QPushButton *openButton = new QPushButton("Open");QPushButton *playButton = new QPushButton("Play");QPushButton *pauseButton = new QPushButton("Pause");QPushButton *stopButton = new QPushButton("Stop");// 创建进度条QSlider *positionSlider = new QSlider(Qt::Horizontal);// 添加控件到布局controlLayout->addWidget(openButton);controlLayout->addWidget(playButton);controlLayout->addWidget(pauseButton);controlLayout->addWidget(stopButton);controlLayout->addWidget(positionSlider);mainLayout->addWidget(videoWidget);mainLayout->addLayout(controlLayout);// 连接信号和槽QObject::connect(openButton, &QPushButton::clicked, [player]() {QString fileName = QFileDialog::getOpenFileName(nullptr, "Open Video File");if (!fileName.isEmpty()) {player->setMedia(QUrl::fromLocalFile(fileName));player->play();}});QObject::connect(playButton, &QPushButton::clicked, player, &QMediaPlayer::play);QObject::connect(pauseButton, &QPushButton::clicked, player, &QMediaPlayer::pause);QObject::connect(stopButton, &QPushButton::clicked, player, &QMediaPlayer::stop);// 更新进度条QObject::connect(player, &QMediaPlayer::positionChanged, positionSlider, &QSlider::setValue);QObject::connect(positionSlider, &QSlider::sliderMoved, player, &QMediaPlayer::setPosition);// 显示窗口window.show();return a.exec();
}

三、高级功能：音频处理与录制

1. 音频录制

#include <QApplication>
#include <QMediaRecorder>
#include <QAudioEncoderSettings>
#include <QVideoEncoderSettings>
#include <QPushButton>
#include <QVBoxLayout>
#include <QWidget>
#include <QFileDialog>int main(int argc, char *argv[])
{QApplication a(argc, argv);// 创建主窗口和布局QWidget window;QVBoxLayout *layout = new QVBoxLayout(&window);// 创建媒体录制器QMediaRecorder *recorder = new QMediaRecorder;// 设置音频编码参数QAudioEncoderSettings audioSettings;audioSettings.setCodec("audio/mp3");audioSettings.setQuality(QMultimedia::HighQuality);recorder->setAudioSettings(audioSettings);// 创建录制按钮QPushButton *recordButton = new QPushButton("Record");QObject::connect(recordButton, &QPushButton::clicked, [recorder]() {QString fileName = QFileDialog::getSaveFileName(nullptr, "Save Audio", "", "Audio Files (*.mp3)");if (!fileName.isEmpty()) {recorder->setOutputLocation(QUrl::fromLocalFile(fileName));recorder->record();}});// 创建停止按钮QPushButton *stopButton = new QPushButton("Stop");QObject::connect(stopButton, &QPushButton::clicked, recorder, &QMediaRecorder::stop);// 添加按钮到布局layout->addWidget(recordButton);layout->addWidget(stopButton);// 显示窗口window.show();return a.exec();
}

2. 低级别音频处理（生成音调）

#include <QApplication>
#include <QAudioOutput>
#include <QBuffer>
#include <QVector>
#include <QPushButton>
#include <QVBoxLayout>
#include <QWidget>// 生成正弦波音频数据
QByteArray generateTone(int sampleRate, int frequency, int durationMs)
{const int sampleCount = sampleRate * durationMs / 1000;const double twoPi = 2.0 * M_PI;const double amplitude = 32760.0;  // 16位音频的最大振幅QVector<qint16> samples(sampleCount);// 生成正弦波for (int i = 0; i < sampleCount; ++i) {samples[i] = static_cast<qint16>(amplitude * qSin(twoPi * frequency * i / sampleRate));}// 转换为字节数组QByteArray data;data.resize(samples.size() * sizeof(qint16));memcpy(data.data(), samples.data(), data.size());return data;
}int main(int argc, char *argv[])
{QApplication a(argc, argv);// 创建主窗口和布局QWidget window;QVBoxLayout *layout = new QVBoxLayout(&window);// 音频格式设置QAudioFormat format;format.setSampleRate(44100);format.setChannelCount(1);format.setSampleSize(16);format.setCodec("audio/pcm");format.setByteOrder(QAudioFormat::LittleEndian);format.setSampleType(QAudioFormat::SignedInt);// 创建音频输出QAudioOutput *audioOutput = new QAudioOutput(format);// 生成音频数据（440Hz 音调，持续1秒）QByteArray audioData = generateTone(44100, 440, 1000);// 创建数据缓冲区QBuffer *buffer = new QBuffer(&audioOutput);buffer->setData(audioData);buffer->open(QIODevice::ReadOnly);// 创建播放按钮QPushButton *playButton = new QPushButton("Play Tone");QObject::connect(playButton, &QPushButton::clicked, [audioOutput, buffer]() {buffer->seek(0);audioOutput->start(buffer);});// 添加按钮到布局layout->addWidget(playButton);// 显示窗口window.show();return a.exec();
}

四、视频处理与摄像头应用

1. 摄像头捕获

#include <QApplication>
#include <QCamera>
#include <QCameraViewfinder>
#include <QCameraImageCapture>
#include <QPushButton>
#include <QVBoxLayout>
#include <QWidget>
#include <QFileDialog>int main(int argc, char *argv[])
{QApplication a(argc, argv);// 创建主窗口和布局QWidget window;QVBoxLayout *layout = new QVBoxLayout(&window);// 创建摄像头QCamera *camera = new QCamera;// 创建取景器QCameraViewfinder *viewfinder = new QCameraViewfinder;camera->setViewfinder(viewfinder);// 创建图像捕获器QCameraImageCapture *imageCapture = new QCameraImageCapture(camera);// 创建拍照按钮QPushButton *captureButton = new QPushButton("Capture");QObject::connect(captureButton, &QPushButton::clicked, [imageCapture]() {QString fileName = QFileDialog::getSaveFileName(nullptr, "Save Image", "", "Image Files (*.jpg)");if (!fileName.isEmpty()) {imageCapture->capture(fileName);}});// 添加控件到布局layout->addWidget(viewfinder);layout->addWidget(captureButton);// 启动摄像头camera->start();// 显示窗口window.show();return a.exec();
}

2. 视频帧处理（简单滤镜）

#include <QApplication>
#include <QCamera>
#include <QCameraViewfinder>
#include <QCameraImageCapture>
#include <QAbstractVideoSurface>
#include <QVideoFrame>
#include <QImage>
#include <QPushButton>
#include <QVBoxLayout>
#include <QWidget>// 自定义视频表面，用于处理视频帧
class FrameProcessor : public QAbstractVideoSurface
{Q_OBJECT
public:explicit FrameProcessor(QObject *parent = nullptr) : QAbstractVideoSurface(parent) {}QList<QVideoFrame::PixelFormat> supportedPixelFormats(QAbstractVideoBuffer::HandleType handleType = QAbstractVideoBuffer::NoHandle) const override{Q_UNUSED(handleType);return QList<QVideoFrame::PixelFormat>()<< QVideoFrame::Format_RGB32<< QVideoFrame::Format_ARGB32<< QVideoFrame::Format_ARGB32_Premultiplied;}bool present(const QVideoFrame &frame) override{if (!frame.isValid())return false;QVideoFrame cloneFrame(frame);cloneFrame.map(QAbstractVideoBuffer::ReadOnly);// 获取帧数据并转换为图像QImage image(cloneFrame.bits(), cloneFrame.width(), cloneFrame.height(), cloneFrame.bytesPerLine(), QVideoFrame::imageFormatFromPixelFormat(cloneFrame.pixelFormat()));// 应用简单滤镜（灰度化）QImage filteredImage = image.convertToFormat(QImage::Format_Grayscale8);cloneFrame.unmap();// 在这里可以处理过滤后的图像（例如保存、显示等）emit frameProcessed(filteredImage);return true;}signals:void frameProcessed(const QImage &image);
};int main(int argc, char *argv[])
{QApplication a(argc, argv);// 创建主窗口和布局QWidget window;QVBoxLayout *layout = new QVBoxLayout(&window);// 创建摄像头QCamera *camera = new QCamera;// 创建取景器QCameraViewfinder *viewfinder = new QCameraViewfinder;camera->setViewfinder(viewfinder);// 创建帧处理器FrameProcessor *frameProcessor = new FrameProcessor;camera->setViewfinder(frameProcessor);// 添加控件到布局layout->addWidget(viewfinder);// 启动摄像头camera->start();// 显示窗口window.show();return a.exec();
}#include "main.moc"