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itsrifat/extract_frames.cpp

Last active July 13, 2023 18:48
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simple c++ functions to extract frames of a video file into a vector of Mat and saving the vector as jpg images using OpenCV 2.4.9
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extract_frames.cpp
void extract_frames(const string &videoFilePath,vector<Mat>& frames){
try{
//open the video file
VideoCapture cap(videoFilePath); // open the video file
if(!cap.isOpened()) // check if we succeeded
return -1;
//cap.get(CV_CAP_PROP_FRAME_COUNT) contains the number of frames in the video;
for(int frameNum = 0; frameNum < cap.get(CV_CAP_PROP_FRAME_COUNT);frameNum++)
{
Mat frame;
cap >> frame; // get the next frame from video
frames.push_back(frame);
}
}
catch( cv::Exception& e ){
const char* err_msg = e.what();
std::cout << "exception caught: " << err_msg << std::endl;
}
}
void save_frames(vector<Mat>& frames, const string& outputDir){
vector<int> compression_params;
compression_params.push_back(CV_IMWRITE_JPEG_QUALITY);
compression_params.push_back(100);
for(std::vector<Mat>::iterator frame = frames.begin(),frameNumber=0; frame != frame.end(); ++frame){
string filePath = outputDir + to_string(static_cast<long long>(frameNumber))+ ".jpg";
imwrite(filePath,*frame,compression_params);
}
}
@itsrifat
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itsrifat commented Nov 7, 2014

to call the function:

//to extract
vector<Mat> frames;
extract_frames("C:\\myvideo.mp4",frames);
//to save
save_frames(frames, "c\\myvideo_frames\\")

@IvanPizhenko
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what do I need to #include to get this working?

@futurestark
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OpenCV library header files to see imwrite method and others, like #include "opencv2/core.hpp"
#include "opencv2/video.hpp"
#include "opencv2/imgproc.hpp"
#include "opencv2/videoio.hpp"
#include "opencv2/highgui.hpp" and STL containers like vector #include

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