我使用的是ffmpeg拉取实时流,并解码为yuv420p。然后用opengl转成rgb32渲染到qt中显示。

用ffmpeg解码实时流和网上一样。参考:https://blog.csdn.net/su_vast/article/details/52214642
<https://blog.csdn.net/su_vast/article/details/52214642> 进行修改和增加。
av_register_all(); avformat_network_init(); AVFormatContext *pAVFomatContext
= avformat_alloc_context(); AVCodecContext* pAVCodecContext = nullptr; AVFrame
*pAVFrame = av_frame_alloc(); AVFrame* pAVFrameYUV = av_frame_alloc(); int
result =
avformat_open_input(&pAVFomatContext,"rtsp://127.0.0.1:8554/1",nullptr,nullptr);
if(result < 0){ qDebug() << QStringLiteral("打开视频失败"); return; } result =
avformat_find_stream_info(pAVFomatContext,nullptr); if(result < 0){ qDebug() <<
QStringLiteral("获取视频流信息失败"); return; } int videoStreamIndex = -1; for(uint i =
0; i < pAVFomatContext->nb_streams; i++){
if(pAVFomatContext->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO){
videoStreamIndex = i; break; } } if(videoStreamIndex == -1){ qDebug() <<
QStringLiteral("获取视频流索引失败"); return; } pAVCodecContext =
pAVFomatContext->streams[videoStreamIndex]->codec; int videoWidth =
pAVCodecContext->width; int videoHeight = pAVCodecContext->height; AVCodec
*pAVCodec; pAVCodec = avcodec_find_decoder(pAVCodecContext->codec_id);
SwsContext* pSwsContext =
sws_getContext(videoWidth,videoHeight,pAVCodecContext->pix_fmt,videoWidth,videoHeight,AV_PIX_FMT_YUV420P,SWS_BICUBIC,nullptr,nullptr,nullptr);
int numBytes = avpicture_get_size(AV_PIX_FMT_YUV420P,videoWidth,videoHeight);
uint8_t *out_buffer = (uint8_t*)av_malloc(numBytes * sizeof(uint8_t));
avpicture_fill((AVPicture*)pAVFrameYUV,out_buffer,AV_PIX_FMT_YUV420P,videoWidth,videoHeight);
int y_size = pAVCodecContext->width * pAVCodecContext->height; AVPacket*
pAVPacket = (AVPacket*) malloc(sizeof(AVPacket));
av_new_packet(pAVPacket,y_size);
av_dump_format(pAVFomatContext,0,"rtsp://127.0.0.1:8554/1",0); result =
avcodec_open2(pAVCodecContext,pAVCodec,nullptr); if(result < 0){ qDebug() <<
QStringLiteral("打开解码器失败"); return; } qDebug() << QStringLiteral("视频流初始化成功");
int got_picture = 0; int _num = 0; while (!isInterruptionRequested()) {
if(av_read_frame(pAVFomatContext,pAVPacket) <0){ break; }
avcodec_decode_video2(pAVCodecContext,pAVFrame,&got_picture,pAVPacket);
if(got_picture){ qDebug() << __LINE__; sws_scale(pSwsContext,(const uint8_t
*const*)pAVFrame->data,pAVFrame->linesize,0,videoHeight,pAVFrameYUV->data,pAVFrameYUV->linesize);
emit sigYuv((uchar*)out_buffer,videoWidth,videoHeight); }
av_free_packet(pAVPacket); } // av_free(pAVPicture);
avcodec_close(pAVCodecContext); avformat_close_input(&pAVFomatContext);



这样就得到yuv数据了。下面是用opegl渲染到qt的widgets。我使用的是QOpenglWidget和QOpenglFunctions

头文件声明如下
#ifndef GLYUVWIDGET_H #define GLYUVWIDGET_H #include <QOpenGLWidget> #include
<QOpenGLFunctions> #include <QOpenGLBuffer> #include <QTimer>
QT_FORWARD_DECLARE_CLASS(QOpenGLShaderProgram)
QT_FORWARD_DECLARE_CLASS(QOpenGLTexture) class GLYuvWidget : public
QOpenGLWidget, protected QOpenGLFunctions { Q_OBJECT public:
GLYuvWidget(QWidget *parent =0); ~GLYuvWidget(); public slots: void
slotShowYuv(uchar *ptr,uint width,uint height); //显示一帧Yuv图像 protected: void
initializeGL() Q_DECL_OVERRIDE; void paintGL() Q_DECL_OVERRIDE; private:
QOpenGLShaderProgram *program; QOpenGLBuffer vbo; GLuint
textureUniformY,textureUniformU,textureUniformV; //opengl中y、u、v分量位置
QOpenGLTexture *textureY = nullptr,*textureU = nullptr,*textureV = nullptr;
GLuint idY,idU,idV; //自己创建的纹理对象ID,创建错误返回0 uint videoW,videoH; uchar *yuvPtr =
nullptr; }; #endif // GLYUVWIDGET_H
下面是cpp中的实现,主要利用了QOpenglFunctions中集成的opengl的函数
#include "glyuvwidget.h" #include <QOpenGLShaderProgram> #include
<QOpenGLTexture> #include <QDebug> #define VERTEXIN 0 #define TEXTUREIN 1
GLYuvWidget::GLYuvWidget(QWidget *parent): QOpenGLWidget(parent) { }
GLYuvWidget::~GLYuvWidget() { makeCurrent(); vbo.destroy();
textureY->destroy(); textureU->destroy(); textureV->destroy(); doneCurrent(); }
void GLYuvWidget::slotShowYuv(uchar *ptr, uint width, uint height) { yuvPtr =
ptr; videoW = width; videoH = height; update(); } void
GLYuvWidget::initializeGL() { initializeOpenGLFunctions();
glEnable(GL_DEPTH_TEST); static const GLfloat vertices[]{ //顶点坐标 -1.0f,-1.0f,
-1.0f,+1.0f, +1.0f,+1.0f, +1.0f,-1.0f, //纹理坐标 0.0f,1.0f, 0.0f,0.0f, 1.0f,0.0f,
1.0f,1.0f, }; vbo.create(); vbo.bind();
vbo.allocate(vertices,sizeof(vertices)); QOpenGLShader *vshader = new
QOpenGLShader(QOpenGLShader::Vertex,this); const char *vsrc = "attribute vec4
vertexIn; \ attribute vec2 textureIn; \ varying vec2 textureOut; \ void
main(void) \ { \ gl_Position = vertexIn; \ textureOut = textureIn; \ }";
vshader->compileSourceCode(vsrc); QOpenGLShader *fshader = new
QOpenGLShader(QOpenGLShader::Fragment,this); const char *fsrc = "varying vec2
textureOut; \ uniform sampler2D tex_y; \ uniform sampler2D tex_u; \ uniform
sampler2D tex_v; \ void main(void) \ { \ vec3 yuv; \ vec3 rgb; \ yuv.x =
texture2D(tex_y, textureOut).r; \ yuv.y = texture2D(tex_u, textureOut).r - 0.5;
\ yuv.z = texture2D(tex_v, textureOut).r - 0.5; \ rgb = mat3( 1, 1, 1, \ 0,
-0.39465, 2.03211, \ 1.13983, -0.58060, 0) * yuv; \ gl_FragColor = vec4(rgb,
1); \ }"; fshader->compileSourceCode(fsrc); program = new
QOpenGLShaderProgram(this); program->addShader(vshader);
program->addShader(fshader);
program->bindAttributeLocation("vertexIn",VERTEXIN);
program->bindAttributeLocation("textureIn",TEXTUREIN); program->link();
program->bind(); program->enableAttributeArray(VERTEXIN);
program->enableAttributeArray(TEXTUREIN);
program->setAttributeBuffer(VERTEXIN,GL_FLOAT,0,2,2*sizeof(GLfloat));
program->setAttributeBuffer(TEXTUREIN,GL_FLOAT,8*sizeof(GLfloat),2,2*sizeof(GLfloat));
textureUniformY = program->uniformLocation("tex_y"); textureUniformU =
program->uniformLocation("tex_u"); textureUniformV =
program->uniformLocation("tex_v"); textureY = new
QOpenGLTexture(QOpenGLTexture::Target2D); textureU = new
QOpenGLTexture(QOpenGLTexture::Target2D); textureV = new
QOpenGLTexture(QOpenGLTexture::Target2D); textureY->create();
textureU->create(); textureV->create(); idY = textureY->textureId(); idU =
textureU->textureId(); idV = textureV->textureId();
glClearColor(0.0,0.0,0.0,0.0); } void GLYuvWidget::paintGL() { // QMatrix4x4 m;
// m.perspective(60.0f, 4.0f/3.0f, 0.1f, 100.0f
);//透视矩阵随距离的变化,图形跟着变化。屏幕平面中心就是视点(摄像头),需要将图形移向屏幕里面一定距离。 //
m.ortho(-2,+2,-2,+2,-10,10);//近裁剪平面是一个矩形,矩形左下角点三维空间坐标是(left,bottom,-near),右上角点是(right,top,-near)所以此处为负,表示z轴最大为10;
//远裁剪平面也是一个矩形,左下角点空间坐标是(left,bottom,-far),右上角点是(right,top,-far)所以此处为正,表示z轴最小为-10;
//此时坐标中心还是在屏幕水平面中间,只是前后左右的距离已限制。 glActiveTexture(GL_TEXTURE0);
//激活纹理单元GL_TEXTURE0,系统里面的 glBindTexture(GL_TEXTURE_2D,idY);
//绑定y分量纹理对象id到激活的纹理单元 //使用内存中的数据创建真正的y分量纹理数据
glTexImage2D(GL_TEXTURE_2D,0,GL_RED,videoW,videoH,0,GL_RED,GL_UNSIGNED_BYTE,yuvPtr);
//https://blog.csdn.net/xipiaoyouzi/article/details/53584798 纹理参数解析
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glActiveTexture(GL_TEXTURE1); //激活纹理单元GL_TEXTURE1
glBindTexture(GL_TEXTURE1,idU); //使用内存中的数据创建真正的u分量纹理数据
glTexImage2D(GL_TEXTURE_2D,0,GL_RED,videoW >> 1, videoH >>
1,0,GL_RED,GL_UNSIGNED_BYTE,yuvPtr + videoW * videoH);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glActiveTexture(GL_TEXTURE2); //激活纹理单元GL_TEXTURE2
glBindTexture(GL_TEXTURE_2D,idV); //使用内存中的数据创建真正的v分量纹理数据
glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, videoW >> 1, videoH >> 1, 0, GL_RED,
GL_UNSIGNED_BYTE, yuvPtr+videoW*videoH*5/4);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
//指定y纹理要使用新值 glUniform1i(textureUniformY, 0); //指定u纹理要使用新值
glUniform1i(textureUniformU, 1); //指定v纹理要使用新值 glUniform1i(textureUniformV, 2);
//使用顶点数组方式绘制图形 glDrawArrays(GL_TRIANGLE_FAN, 0, 4); }

本程序中yuv图像到rgb32的转换通过opengl在gpu中完成,利用gpu处理图像,使用widgets界面线程有大量的空闲时间处理其它事情,所以widgets界面相当流畅。

以下是主程序中的使用,我在这里画了一个框在上面
#include <QApplication> #include "GLYuvWidget/glyuvwidget.h" #include
"Rtsp/rtsp.h" #include <QLabel> #include <QHBoxLayout> #include <QPixmap>
#include <QPainter> int main(int argc, char *argv[]) { QApplication a(argc,
argv); Rtsp rtsp; GLYuvWidget w; QLabel label; label.setScaledContents(true);
QHBoxLayout hLay; hLay.addWidget(&label); w.setLayout(&hLay); QPixmap
pix(w.size()); pix.fill(Qt::transparent); QPainter p(&pix);
p.setRenderHint(QPainter::Antialiasing); p.setPen(QPen(Qt::yellow,4));
p.drawRoundRect(w.rect().adjusted(20,20,-20,-20)); label.setPixmap(pix);
QObject::connect(&rtsp,SIGNAL(sigYuv(uchar*,uint,uint)),&w,SLOT(slotShowYuv(uchar*,uint,uint)));
rtsp.start(); QObject::connect(&a,&QApplication::lastWindowClosed,[&]{
rtsp.requestInterruption(); rtsp.quit(); rtsp.wait(); }); w.show(); return
a.exec(); }以下为视频效果