一、通过V4l2来采集用qt显示
1.将V4L2获取摄像头数据封装成一个类
class V4L2API
{
public:
explicit V4L2API(const char *dev="/dev/video0");
~V4L2API();
int video_init();//打开设备、设置采集格式等
int video_start();//开始采集
int video_stop();//停止采集
int video_getframe(char *buffer, int *size);//读数据
int video_destroy();//释放空间、关闭设备
bool yuv422torgb24(unsigned char *buffer, unsigned char *rgbdata, int w, int h);//将YUV数据转化为RGB数据
private:
int fd;
char dev[64];
unsigned char *mmps[4];//保存映射空间首地址
unsigned int mmpsize[4];
};
2.设置开始按钮开始采集数据
void V4L2Win::on_startbt_clicked()
{
if(v4l2api == nullptr)
{
v4l2api = new V4L2API("/dev/video0");//初始化摄像头对象
}
v4l2api->video_start();//开始采集
//启动定时器,开始采集
mtimer.start(100);
}
3.设置停止按钮停止采集数据
void V4L2Win::on_stopbt_clicked()
{
//停止定时器
mtimer.stop();
if(v4l2api != nullptr)
{
v4l2api->video_stop();//停止采集
v4l2api->video_destroy();
delete v4l2api;
v4l2api = nullptr;
}
}
4.设置定时器不断采集数据
connect(&mtimer,&QTimer::timeout,this,&V4L2Win::get_frame);
void V4L2Win::get_frame()
{
v4l2api->video_getframe(buffer,&size); //得到的是YUYV--4:2:2
v4l2api->yuv422torgb24((unsigned char*)buffer, (unsigned char*)rgbdata, 640, 480); //把yuv4:2:2 转RGB
QImage image((uchar*)rgbdata,640,480,QImage::Format_RGB888);
ui->label->setPixmap(QPixmap::fromImage(image));
}
二、直接用qt多媒体模块来实现采集并且显示
1.在qt工程文件中添加
QT += multimedia
QT += multimediawidgets
QCamera --摄像头设备
QCameraViewfinder--预览显示
QCameraImageCapture--数据抓取
QCameraInfo---摄像头信息
2.获取系统所有摄像头设备
Cameralist = QCameraInfo::availableCameras();
foreach (QCameraInfo info, Cameralist)
{
qDebug()<<info.position()<<info.deviceName();
ui->comboBox->addItem(info.description());
}
3.开启摄像头并且显示预览
QCameraInfo info = Cameralist.at(ui->comboBox->currentIndex()); //获取一个摄像头信息
camera = new QCamera(info);//通过摄像头信息创建设备
viewFinder = new QCameraViewfinder(ui->cameraView);//创建一个预览窗口
camera->setViewfinder(viewFinder);
viewFinder->resize(ui->cameraView->size());
viewFinder->show();
camera->start();//开始
4.初始化抓取数据的对象
imageCap = new QCameraImageCapture(camera);
connect(imageCap,&QCameraImageCapture::imageCaptured,this,&ModelWin::get_frame);
5.发送抓取数据的信号
filename = QFileDialog::getSaveFileName(this);//选择文件存放的路径
imageCap->capture();//发送一个信号
6.数据抓取
image.save(filename);