Qt+ffmpeg实现视频流播放-蒲公英云

1.版本

Qt版本：5.11 64位

ffmpeg版本：>3.0 64位

2.实现思路

ffmpeg拉流、解码，因为Qt不支持显示yuv数据，需要ffmpeg转换为rgb数据，再用QImage显示，这种方式性能会不好，暂时先实现这种简单的。一般情况下会用opengl渲染。

3.示例

拉流cctv1：http://ivi.bupt.edu.cn/hls/cctv1hd.m3u8，此例子只解码视频数据，不处理音频。

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代码：解码线程

#pragma once
#include <QThread>
#include <QImage>
extern "C"
{
#include "libavformat/avformat.h"
#include "libavutil/dict.h"
#include "libswscale/swscale.h"
#include "libavutil/imgutils.h"  
};
class DecodeThread : public QThread
{
    Q_OBJECT
public:
    DecodeThread(QObject *parent);
    ~DecodeThread();
Q_SIGNALS:
    void sigData(uint8_t* rgbBuffer);
public:
    void setUrl(QString url);
    void setStoped(bool stop);
protected:
    void run();
protected:
    double r2d(AVRational r);
    void decodeStream();
private:
    QString m_url;
    bool m_isStop = false;
private:
    AVFormatContext* m_pFormatCtx = NULL;
    AVCodecContext* m_pCodecCtx = NULL;
    AVPacket* m_avpacket = NULL;
    AVFrame *m_frame = NULL;
    //视频index
    int m_videoIndex = -1;
    //视频总时间,单位ms
    int64_t m_totalTime = 0;
    //视频宽度;
    int m_width = 0;
    //视频高度;
    int m_height = 0;
    //视频帧率;
    int m_fps = 0;
};
#include "DecodeThread.h"
DecodeThread::DecodeThread(QObject *parent)
    : QThread(parent)
{
}
DecodeThread::~DecodeThread()
{
    if (m_pFormatCtx != NULL)
    {
        avformat_close_input(&m_pFormatCtx);
        avformat_free_context(m_pFormatCtx);
        m_pFormatCtx = NULL;
    }
    if (m_pCodecCtx != NULL)
    {
        avcodec_close(m_pCodecCtx);
        avcodec_free_context(&m_pCodecCtx);
        m_pCodecCtx = NULL;
    }
    if (m_avpacket != NULL)
    {
        av_packet_unref(m_avpacket);
        delete m_avpacket;
        m_avpacket = NULL;
    }
    if (m_frame != NULL)
    {
        av_frame_free(&m_frame);
        m_frame = NULL;
    }
}
void DecodeThread::setUrl(QString url)
{
    m_url = url;
}
void DecodeThread::setStoped(bool stop)
{
    m_isStop = stop;
}
void DecodeThread::run()
{
    //注册所有组件 新版本已弃用
    av_register_all();
    //打开输入视频文件
    if (avformat_open_input(&m_pFormatCtx, m_url.toStdString().c_str(), NULL, NULL) != 0)
    {
        printf("Couldn't open input stream.\n");
    }
    if (avformat_find_stream_info(m_pFormatCtx, NULL) < 0)
    {
        printf("Couldn't find stream information.\n");
    }
    for (int i = 0; i < m_pFormatCtx->nb_streams/*视音频流的个数*/; i++)
    {
        //查找视频
        if (m_pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
        {
            m_videoIndex = i;
            break;
        }
    }
    if (m_videoIndex == -1)
    {
        printf("Couldn't find a video stream.\n");
    }
    /**
    *  不赞成这样使用
    *  pCodecCtx = pFormatCtx->streams[videoIndex]->codec;    //指向AVCodecContext的指针
    */
    m_pCodecCtx = avcodec_alloc_context3(NULL);
    if (m_pCodecCtx == NULL)
    {
        printf("Could not allocate AVCodecContext\n");
    }
    avcodec_parameters_to_context(m_pCodecCtx, m_pFormatCtx->streams[m_videoIndex]->codecpar);
    //指向AVCodec的指针.查找解码器
    AVCodec *pCodec = avcodec_find_decoder(m_pCodecCtx->codec_id);
    if (pCodec == NULL)
    {
        printf("Codec not found pCodec\n");
    }
    //打开解码器
    if (avcodec_open2(m_pCodecCtx, pCodec, NULL) < 0)
    {
        printf("Could not open codec.\n");
    }
    //视频宽
    m_width = m_pFormatCtx->streams[m_videoIndex]->codecpar->width;
    //视频高
    m_height = m_pFormatCtx->streams[m_videoIndex]->codecpar->height;
    //获取帧率;
    m_fps = r2d(m_pFormatCtx->streams[m_videoIndex]->avg_frame_rate);
    if (m_fps == 0)
    {
        m_fps = 25;
    }
    //初始化AVPacket
    m_avpacket = new AVPacket;
    av_init_packet(m_avpacket);
    m_avpacket->data = NULL;
    //初始化frame,
    m_frame = av_frame_alloc();
    if (!m_frame)
    {
        printf("av_frame_alloc fail\n");
    }
    //开始解码
    decodeStream();
}
double DecodeThread::r2d(AVRational r)
{
    return r.den == 0 ? 0 : (double)r.num / (double)r.den;
}
void DecodeThread::decodeStream()
{
    while (av_read_frame(m_pFormatCtx, m_avpacket) >= 0)
    {
        if (m_avpacket->stream_index == m_videoIndex)
        {
            int ret = avcodec_send_packet(m_pCodecCtx, m_avpacket);
            if (ret >= 0)
            {
                ret = avcodec_receive_frame(m_pCodecCtx, m_frame);
                if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
                {
                    return;
                }
                else if (ret < 0)
                {
                    return;
                }
                switch (m_pCodecCtx->pix_fmt)
                {
                case AV_PIX_FMT_YUV420P:
                {
                    int width = m_frame->width;
                    int height = m_frame->height;
                    AVFrame *pFrameRGB = av_frame_alloc();
                    int numBytes = avpicture_get_size(AV_PIX_FMT_RGB32, width, height);
                    int nBGRFrameSize = av_image_get_buffer_size(AV_PIX_FMT_RGB32, width, height, 1);
                    uint8_t* rgbBuffer = (uint8_t*)av_malloc(nBGRFrameSize);
                    av_image_fill_arrays(pFrameRGB->data, pFrameRGB->linesize, rgbBuffer, AV_PIX_FMT_RGB32, width, height, 1);
                    //改变像素格式
                    SwsContext *img_convert_ctx = sws_getContext(width, height, AV_PIX_FMT_YUV420P, width, height, AV_PIX_FMT_RGB32, SWS_BICUBIC, NULL, NULL, NULL);
                    //颜色空间转换 yuv420p --> rgb32
                    sws_scale(img_convert_ctx,
                        (uint8_t const *const *)m_frame->data,
                        m_frame->linesize, 0, height, pFrameRGB->data,
                        pFrameRGB->linesize);
                    //发送信号，转换后的rgb buffer
                    emit sigData(rgbBuffer);
                    //释放内存
                    av_frame_free(&pFrameRGB);
                }break;
                default:
                {
                    printf("default format:%d\n", m_pCodecCtx->pix_fmt);
                    return;
                }
                }
            }
        }
    }
}

代码：ui界面

#pragma once
#include <QtWidgets/QWidget>
#include "ui_QtGuiApplication1.h"
#include "DecodeThread.h"
class QtGuiApplication1 : public QWidget
{
    Q_OBJECT
public:
    QtGuiApplication1(QWidget *parent = Q_NULLPTR);
    ~QtGuiApplication1();
private:
    Ui::QtGuiApplication1Class ui;
private Q_SLOTS:
    void slotBtnClicked();
    void slotData(uint8_t* data);
private:
    DecodeThread *m_thead = nullptr;
};
#include "QtGuiApplication1.h"
QtGuiApplication1::QtGuiApplication1(QWidget *parent)
    : QWidget(parent)
{
    ui.setupUi(this);
    m_thead = new DecodeThread(this);
    connect(ui.pushButton, &QPushButton::clicked, this, &QtGuiApplication1::slotBtnClicked);
    connect(m_thead, &DecodeThread::sigData, this, &QtGuiApplication1::slotData);
}
QtGuiApplication1::~QtGuiApplication1()
{
}
void QtGuiApplication1::slotBtnClicked()
{
    QString url = ui.lineEdit->text();
    m_thead->setUrl(url);
    m_thead->start();
}
void QtGuiApplication1::slotData(uint8_t* data)
{
    QImage image(data, 1920, 1080, QImage::Format_ARGB32);
    ui.lbImage->setPixmap(QPixmap::fromImage(image));
    av_free(data);
}