Frame Navigation instead of loading the entire video into memory.

OpenCVVideoParser/OpenCVVideoParser.vcxproj

@@ -97,6 +97,7 @@
       <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;WIN32;NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <ConformanceMode>true</ConformanceMode>
       <AdditionalIncludeDirectories>C:\Users\sigon\Downloads\opencv\build\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <LanguageStandard>stdcpp17</LanguageStandard>
     </ClCompile>
     <Link>
       <SubSystem>Console</SubSystem>
@@ -134,6 +135,7 @@
       <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;NDEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <ConformanceMode>true</ConformanceMode>
       <AdditionalIncludeDirectories>C:\Users\sigon\Downloads\opencv\build\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <LanguageStandard>stdcpp17</LanguageStandard>
     </ClCompile>
     <Link>
       <SubSystem>Console</SubSystem>

OpenCVVideoParser/main.cpp

@@ -19,13 +19,19 @@ void extract_frames(const std::string &videoFilePath,std::vector<cv::Mat>& frame
   	if(!cap.isOpened())  // check if we succeeded
 		cv::error(CV_StsError,"Can not open Video file",__FUNCTION__,"C:\\Users\\sigon\\source\\repos\\OpenCVVideoParser\\OpenCVVideoParser\\main.cpp",14);
 	
+
+	/*
   	//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++)
   	{
   		cv::Mat frame;
   		cap >> frame; // get the next frame from video
   		frames.push_back(frame);
-  	}
+  	}*/
+	cap.set(cv::CAP_PROP_POS_FRAMES,100);
+  	cv::Mat frame;
+  	cap >> frame; // get the next frame from video
+  	frames.push_back(frame);
   }
   catch( cv::Exception& e ){
     std::cerr << e.msg << std::endl;
@@ -33,6 +39,12 @@ void extract_frames(const std::string &videoFilePath,std::vector<cv::Mat>& frame
   }
 	
 }
+cv::Mat get_frame(cv::VideoCapture&video,int frameNumb){
+	  video.set(cv::CAP_PROP_POS_FRAMES,frameNumb);
+	  cv::Mat frame;
+	  video	>> frame;
+	return frame;
+}
 
 /*
 It saves a vector of frames into jpg images into the outputDir as 1.jpg,2.jpg etc where 1,2 etc represents the frame number
@@ -69,16 +81,17 @@ public:
 public:
 	std::vector<cv::Mat>frames;
 	float frameView=0;
+  	cv::VideoCapture video; // open the video file
 	bool OnUserCreate() override
 	{
 		// Called once at the start, so create things here
-		extract_frames("C:/users/sigon/Videos/test.mp4",frames);
+		video.open("C:/users/sigon/Videos/test.mp4");
 		return true;
 	}
 
 	void UpdateScreen(){
 		Clear(BLACK);
-		cv::Mat&targetFrame=frames[int(frameView)];
+		cv::Mat targetFrame=get_frame(video,std::clamp(int(frameView),0,int(video.get(cv::CAP_PROP_FRAME_COUNT))));
 		for(int y=0;y<targetFrame.rows;y++){
 			for(int x=0;x<targetFrame.cols;x++){
 				cv::Vec3b col=targetFrame.at<cv::Vec3b>(cv::Point{x,y});
@@ -93,10 +106,18 @@ public:
 	bool OnUserUpdate(float fElapsedTime) override
 	{
 		// Called once per frame, draws random coloured pixels
+		if(GetKey(RIGHT).bPressed){
+			frameView+=1;
+			UpdateScreen();
+		}
 		if(GetKey(RIGHT).bHeld){
 			frameView+=fElapsedTime*60;
 			UpdateScreen();
 		}
+		if(GetKey(LEFT).bPressed){
+			frameView-=1;
+			UpdateScreen();
+		}
 		if(GetKey(LEFT).bHeld){
 			frameView-=fElapsedTime*60;
 			UpdateScreen();