OpenCV3.1录制视频+把图片合成视频（同时解决一个OpenCV不能打开自己录制的视频的小问题）

刺骨的言语ヽ痛彻心扉 2022-05-09 10:20 117阅读 0赞

记一下，备忘。

用OpenCV打开OpenCV录制的视频，发现报错，代码如下

cv::VideoCapture capture;
    	capture.open("E:\\opencv.avi");

追踪了一下，原来是打开要求用MJPG，

bool AviMjpegStream::parseStrl(MjpegInputStream& in_str, uint8_t stream_id)
    {
    ...
    ========> 这里要求是MJPG_CC
            if(strm_hdr.fccType == VIDS_CC && strm_hdr.fccHandler == MJPG_CC) 
            {...
            }
    ...
    }

所以录制时把属性设置为 VideoWriter::fourcc('M', 'J', 'P', 'G')即可，下面是录制视频的原码，

#include "stdafx.h"
    
    #include<opencv2/opencv.hpp>
    #include<opencv2\highgui\highgui.hpp>
    #include<opencv2\imgproc\imgproc.hpp>
    #include<opencv2\core\core.hpp>
    using namespace cv;
    
    #pragma comment(lib, "opencv_world310d.lib")
    
    #include<iostream>
    using namespace std;
    
    
    int main()
    {
    	//打开摄像头
    	VideoCapture captrue(0);
    	//视频写入对象
    	VideoWriter write;
    	//写入视频文件名
    	string outFlie = "E://opencv.avi";
    	//获得帧的宽高
    	int w = static_cast<int>(captrue.get(CV_CAP_PROP_FRAME_WIDTH));
    	int h = static_cast<int>(captrue.get(CV_CAP_PROP_FRAME_HEIGHT));
    	Size S(w, h);
    	//获得帧率
    	captrue.set(CV_CAP_PROP_FPS, 25);
    	double fps = captrue.get(CV_CAP_PROP_FPS);
    	//打开视频文件，准备写入
    	//write.open(outFlie, -1, r, S, true);
    	//write.open(outFlie, CV_FOURCC('M', 'J', 'P', 'G'), fps, S, true); // this is OK too
    	int val = VideoWriter::fourcc('M', 'J', 'P', 'G');
    	write.open(outFlie, val, fps, S, true);
    	//打开失败
    	if (!captrue.isOpened())
    	{
    		return 1;
    	}
    	bool stop = false;
    	Mat frame;
    	//循环
    	while (!stop)
    	{
    		//读取帧
    		if (!captrue.read(frame))
    			break;
    		imshow("Video", frame);
    		//写入文件
    		write.write(frame);
    		if (waitKey(10) > 0)
    		{
    			stop = true;
    		}
    	}
    	//释放对象
    	captrue.release();
    	write.release();
    	cvDestroyWindow("Video");
    	return 0;
    }

如果要把图片合成视频，代码也差不多，同样需要指定MJPG编码

#include "stdafx.h"
    
    #include<opencv2/opencv.hpp>
    #include<opencv2\highgui\highgui.hpp>
    #include<opencv2\imgproc\imgproc.hpp>
    #include<opencv2\core\core.hpp>
    using namespace cv;
    
    #pragma comment(lib, "opencv_world310d.lib")
    
    #include<iostream>
    using namespace std;
    
    int main()
    {
    	Mat image;
    	char filename[1000]; //图片的名称
    	int isColor = 1;     //如果为0 ，可输出灰度图像
    	int fps = 10;        //设置输出视频的帧率
    					   
    	VideoWriter writer("video_out.avi", VideoWriter::fourcc('M', 'J', 'P', 'G'), fps,
    		Size(360,240), isColor);
    
    	for (unsigned int i = 1; i<=120; i++)
    	{
            //我的图片名称是：0001.jpg, ..... 0120.jpg
    		sprintf(filename, "E:/sequences/Crossing/img/0%03d.jpg", i);   
    		image = imread(filename);//导入图片
    		if (image.empty())
    		{
    			break;
    		}
    		waitKey(0);
    		//cout << image.channels() << endl; //调试用
    		//cout << image.size() << endl;     //调试用
    		writer.write(image); 
    	}
    	writer.release();
    	return 0;
    }