python - 如何进行视频取景？

Question

我想输入一个视频并逐帧保存视频，我使用 opencv python 完成了它，但我想要它在 c++ 中。作为 C++ 新手，请帮助我。

这是我的python代码

import cv2 

# Function to extract frames 
def FrameCapture(path): 

    # Path to video file 
    vidObj = cv2.VideoCapture(path) 

    # Used as counter variable 
    count = 0

    # checks whether frames were extracted 
    success = 1

    while success: 

        # vidObj object calls read 
        # function extract frames 
        success, image = vidObj.read() 

        # Saves the frames with frame-count 
        cv2.imwrite("frame%d.jpg" % count, image) 

        count += 1

# Driver Code 
if __name__ == '__main__': 

    # Calling the function
    FrameCapture(path of the video)

标签： pythonc++opencv

Answer 1

Here is what you need. This code simply read frame and write it to a directory. 




#include <opencv2/core.hpp>
#include <opencv2/videoio.hpp>
#include <opencv2/highgui.hpp>
#include <iostream>
#include <stdio.h>
using namespace cv;
using namespace std;
int main(int, char**)
{
    Mat src;
    // use default camera as video source
    VideoCapture cap(0);
    // check if we succeeded
    if (!cap.isOpened()) {
        cerr << "ERROR! Unable to open camera\n";
        return -1;
    }
    // get one frame from camera to know frame size and type
    cap >> src;
    // check if we succeeded
    if (src.empty()) {
        cerr << "ERROR! blank frame grabbed\n";
        return -1;
    }
    bool isColor = (src.type() == CV_8UC3);
    //--- INITIALIZE VIDEOWRITER
    VideoWriter writer;
    int codec = VideoWriter::fourcc('M', 'J', 'P', 'G');  // select desired codec (must be available at runtime)
    double fps = 25.0;                          // framerate of the created video stream
    string filename = "/home/rnd/TEST/live.avi";             // name of the output video file
    writer.open(filename, codec, fps, src.size(), isColor);
    // check if we succeeded
    if (!writer.isOpened()) {
        cerr << "Could not open the output video file for write\n";
        return -1;
    }
    //--- GRAB AND WRITE LOOP
    cout << "Writing videofile: " << filename << endl
         << "Press any key to terminate" << endl;
    for (;;)
    {
        // check if we succeeded
        if (!cap.read(src)) {
            cerr << "ERROR! blank frame grabbed\n";
            break;
        }
        // encode the frame into the videofile stream
        writer.write(src);
        // show live and wait for a key with timeout long enough to show images
        imshow("Live", src);
        if (waitKey(5) >= 0)
            break;
    }
    // the videofile will be closed and released automatically in VideoWriter destructor
    return 0;
}