OpenCV加载视频

一、加载视频

	//视频路径
	QString appPath = QCoreApplication::applicationDirPath();
	QString videoPath = appPath + "/vtest.avi";
	cv::VideoCapture capture;
	capture.open(videoPath.toStdString(),CAP_FFMPEG);
	//从摄像头读取
	//capture.open(0, CAP_DSHOW);

	cv::Mat frame;
	while (true) {
		//读帧
		bool ret = capture.read(frame);
		if (!ret)
			break;
		imshow("frame", frame);
		//添加帧处理 等待 100 毫秒，检查用户是否按下键盘上的按键
		char c = waitKey(100);
		//按下的是 ESC 键 (ASCII 值为 27)，则跳出循环，停止播放视频
		if (c == 27)
			break;
	}
	waitKey(0);
	destroyAllWindows();

二、获取视频属性

	//视频路径
	QString appPath = QCoreApplication::applicationDirPath();
	QString videoPath = appPath + "/vtest.avi";
	cv::VideoCapture capture;
	capture.open(videoPath.toStdString(),CAP_FFMPEG);

	qDebug() << u8"高：" << capture.get(CAP_PROP_FRAME_HEIGHT);
	qDebug() << u8"宽：" << capture.get(CAP_PROP_FRAME_WIDTH);
	qDebug() << u8"帧率FPS：" << QString::number(capture.get(CAP_PROP_FPS));
	qDebug() << u8"总帧率：" << capture.get(CAP_PROP_FRAME_COUNT);

三、保存视频

	//视频路径
	QString appPath = QCoreApplication::applicationDirPath();
	QString videoPath = appPath + "/vtest.avi";
	cv::VideoCapture capture;
	capture.open(videoPath.toStdString(), CAP_FFMPEG);


	qDebug() << u8"高：" << capture.get(CAP_PROP_FRAME_HEIGHT);
	qDebug() << u8"宽：" << capture.get(CAP_PROP_FRAME_WIDTH);
	qDebug() << u8"帧率FPS：" << capture.get(CAP_PROP_FPS);
	qDebug() << u8"总帧率：" << capture.get(CAP_PROP_FRAME_COUNT);

	//保存视频路径
	QString savevideoPath = appPath + "/output.avi";

	cv::VideoWriter writer(savevideoPath.toStdString(), capture.get(CAP_PROP_FOURCC), capture.get(CAP_PROP_FPS), Size(capture.get(CAP_PROP_FRAME_WIDTH), capture.get(CAP_PROP_FRAME_HEIGHT)));

	cv::Mat frame;
	while (true) {
		//读帧
		bool ret = capture.read(frame);
		if (!ret)
			break;
		imshow("frame", frame);
		//添加帧处理 
		writer.write(frame);
		//等待 100 毫秒，检查用户是否按下键盘上的按键
		char c = waitKey(100);
		//按下的是 ESC 键 (ASCII 值为 27)，则跳出循环，停止播放视频
		if (c == 27)
			break;
	}
	capture.release();
	writer.release();
	waitKey(0);
	destroyAllWindows();

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