Qt 环境实现视频和音频播放

在这个示例中，我们将使用 FFmpeg 进行视频和音频的解码，并使用 Qt 的界面进行显示和控制。为了实现音频和视频的解码以及同步显示，我们需要使用 FFmpeg 的解码库进行视频和音频解码，使用 Qt 的 QLabel 显示解码后的视频帧，使用 QAudioOutput 来播放解码后的音频。

环境依赖
FFmpeg：用于解码音视频数据。
Qt：用于图形界面和音频输出。
示例代码
这是一个使用 Qt 和 FFmpeg 结合实现的视频播放器，包括播放、暂停、进度条等功能。

#include <QMainWindow>
#include <QTimer>
#include <QSlider>
#include <QLabel>
#include <QPushButton>
#include <QHBoxLayout>
#include <QVBoxLayout>
#include <QWidget>
#include <QImage>
#include <QPixmap>
#include <QFileDialog>
#include <QAudioOutput>
#include <QAudioFormat>// FFmpeg 头文件
extern "C" {
#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <libswscale/swscale.h>
#include <libswresample/swresample.h>
#include <libavutil/imgutils.h>
}class VideoPlayer : public QMainWindow {Q_OBJECTpublic:VideoPlayer(QWidget *parent = nullptr);~VideoPlayer();private slots:void play();void pause();void openFile();void updateFrame();private:void initializeFFmpeg();void decodeVideo();void decodeAudio();void displayFrame(AVFrame *frame);void initializeAudio();void audioOutput();AVFormatContext *formatContext;AVCodecContext *videoCodecContext;AVCodecContext *audioCodecContext;SwsContext *swsContext;SwrContext *swrContext;int videoStreamIndex;int audioStreamIndex;QLabel *videoLabel;QPushButton *playButton;QPushButton *pauseButton;QSlider *progressSlider;QTimer *timer;QAudioOutput *audioOutputDevice;QByteArray audioBuffer;bool isPlaying;
};VideoPlayer::VideoPlayer(QWidget *parent) : QMainWindow(parent), isPlaying(false) {// GUI 部件初始化videoLabel = new QLabel(this);playButton = new QPushButton("Play", this);pauseButton = new QPushButton("Pause", this);progressSlider = new QSlider(Qt::Horizontal, this);timer = new QTimer(this);// 布局QHBoxLayout *controlLayout = new QHBoxLayout;controlLayout->addWidget(playButton);controlLayout->addWidget(pauseButton);controlLayout->addWidget(progressSlider);QVBoxLayout *mainLayout = new QVBoxLayout;mainLayout->addWidget(videoLabel);mainLayout->addLayout(controlLayout);QWidget *centralWidget = new QWidget(this);centralWidget->setLayout(mainLayout);setCentralWidget(centralWidget);// 连接信号和槽connect(playButton, &QPushButton::clicked, this, &VideoPlayer::play);connect(pauseButton, &QPushButton::clicked, this, &VideoPlayer::pause);connect(timer, &QTimer::timeout, this, &VideoPlayer::updateFrame);// 初始化 FFmpeginitializeFFmpeg();initializeAudio();
}VideoPlayer::~VideoPlayer() {avcodec_free_context(&videoCodecContext);avcodec_free_context(&audioCodecContext);avformat_close_input(&formatContext);sws_freeContext(swsContext);swr_free(&swrContext);
}void VideoPlayer::initializeFFmpeg() {av_register_all();formatContext = avformat_alloc_context();QString fileName = QFileDialog::getOpenFileName(this, "Open Video File");if (fileName.isEmpty()) {return;}// 打开文件并找到流avformat_open_input(&formatContext, fileName.toStdString().c_str(), nullptr, nullptr);avformat_find_stream_info(formatContext, nullptr);// 查找视频流和音频流for (unsigned int i = 0; i < formatContext->nb_streams; i++) {AVCodecParameters *codecParams = formatContext->streams[i]->codecpar;AVCodec *codec = avcodec_find_decoder(codecParams->codec_id);if (codecParams->codec_type == AVMEDIA_TYPE_VIDEO) {videoCodecContext = avcodec_alloc_context3(codec);avcodec_parameters_to_context(videoCodecContext, codecParams);avcodec_open2(videoCodecContext, codec, nullptr);videoStreamIndex = i;} else if (codecParams->codec_type == AVMEDIA_TYPE_AUDIO) {audioCodecContext = avcodec_alloc_context3(codec);avcodec_parameters_to_context(audioCodecContext, codecParams);avcodec_open2(audioCodecContext, codec, nullptr);audioStreamIndex = i;// 音频重采样设置swrContext = swr_alloc();swr_alloc_set_opts(swrContext, AV_CH_LAYOUT_STEREO, AV_SAMPLE_FMT_S16,audioCodecContext->sample_rate, audioCodecContext->channel_layout,audioCodecContext->sample_fmt, audioCodecContext->sample_rate, 0, nullptr);swr_init(swrContext);}}// 视频缩放上下文swsContext = sws_getContext(videoCodecContext->width, videoCodecContext->height,videoCodecContext->pix_fmt, videoCodecContext->width,videoCodecContext->height, AV_PIX_FMT_RGB24, SWS_BILINEAR,nullptr, nullptr, nullptr);
}void VideoPlayer::initializeAudio() {QAudioFormat format;format.setSampleRate(audioCodecContext->sample_rate);format.setChannelCount(2);format.setSampleSize(16);format.setCodec("audio/pcm");format.setByteOrder(QAudioFormat::LittleEndian);format.setSampleType(QAudioFormat::SignedInt);audioOutputDevice = new QAudioOutput(format, this);
}void VideoPlayer::play() {isPlaying = true;audioOutputDevice->start();timer->start(30);  // 30ms刷新一次
}void VideoPlayer::pause() {isPlaying = false;audioOutputDevice->suspend();timer->stop();
}void VideoPlayer::updateFrame() {decodeVideo();decodeAudio();
}void VideoPlayer::decodeVideo() {AVPacket packet;while (av_read_frame(formatContext, &packet) >= 0) {if (packet.stream_index == videoStreamIndex) {avcodec_send_packet(videoCodecContext, &packet);AVFrame *frame = av_frame_alloc();if (avcodec_receive_frame(videoCodecContext, frame) == 0) {displayFrame(frame);}av_frame_free(&frame);}av_packet_unref(&packet);}
}void VideoPlayer::decodeAudio() {AVPacket packet;while (av_read_frame(formatContext, &packet) >= 0) {if (packet.stream_index == audioStreamIndex) {avcodec_send_packet(audioCodecContext, &packet);AVFrame *frame = av_frame_alloc();if (avcodec_receive_frame(audioCodecContext, frame) == 0) {// 音频重采样int outSamples = swr_convert(swrContext, nullptr, 0,(const uint8_t **)frame->data, frame->nb_samples);audioBuffer.resize(outSamples * 2 * sizeof(int16_t));audioOutputDevice->write(audioBuffer.data(), audioBuffer.size());}av_frame_free(&frame);}av_packet_unref(&packet);}
}void VideoPlayer::displayFrame(AVFrame *frame) {AVFrame *rgbFrame = av_frame_alloc();int numBytes = av_image_get_buffer_size(AV_PIX_FMT_RGB24, videoCodecContext->width,videoCodecContext->height, 1);uint8_t *buffer = (uint8_t *)av_malloc(numBytes);av_image_fill_arrays(rgbFrame->data, rgbFrame->linesize, buffer, AV_PIX_FMT_RGB24,videoCodecContext->width, videoCodecContext->height, 1);sws_scale(swsContext, frame->data, frame->linesize, 0, videoCodecContext->height,rgbFrame->data, rgbFrame->linesize);QImage img(rgbFrame->data[0], videoCodecContext->width, videoCodecContext->height,QImage::Format_RGB888);videoLabel->setPixmap(QPixmap::fromImage(img));av_free(buffer);av_frame_free(&rgbFrame);
}#include "main.moc"

代码说明
FFmpeg 初始化和解码：通过 initializeFFmpeg 初始化视频和音频流，设置解码器以及音视频重采样（用于音频）。
音频输出：通过 QAudioOutput 将解码后的音频数据写入到音频输出设备中。
视频显示：解码后的视频帧通过 sws_scale 转换为 RGB24 格式并在 QLabel 中显示。
播放控制：实现了播放和暂停控制，同时可以通过定时器 (`