I'm going to analyze video.
I want to convert video to image per sec.
I mean if the video which I want to analyze is 1 hour. The program which I want to make will make output 3600 image files.
How can I make it?
Is there any solution for it?
The worst case is that I have to run the video and take snapshot per second.
I need your help. Thank you.
All you need is to load the video and save individual frames in a loop. This is not exactly a snapshot, but, you are just saving each and every frame.
Please mind the resolution of the video can also affect the speed in which the frames are processed.
I am going to assume you are using C++. For this, the code will look like this:
VideoCapture cap("Your_Video.mp4");
// Check if camera opened successfully
if(!cap.isOpened())
{
cout << "Error opening the video << endl;
return -1;
}
while(1)
{
Mat frame;
cap.read(frame);
if (frame.empty())
{
break;
}
// This is where you save the frame
imwrite( "Give your File Path", frame );
}
cap.release();
destroyAllWindows();
return 0;
}
Related
I was trying to get 8 single shot frames from 5 x CU135M E-con cameras using OpenCV(4.5.5-dev).
Each ~20 seconds every camera take single shot (one cam by one so stream should not be overloaded).
I use powered USB-hub so all of them are connected to single USB 3.2 port in my computer.
My problem is that recived frames are sometimes (20-30% of them) over-saturated with pink or yellow.
Example of correctly recorded pic:
Example of yellow over-saturated pic:
Code for recording frames is quite simple -
cv::VideoCapture cap;
cap.open("SOME_CAMERA_ID", CAP_V4L2);
cap.set(CAP_PROP_FRAME_WIDTH, 4208);
cap.set(CAP_PROP_FRAME_HEIGHT, 3120);
Mat frame;
try{
for(int i = 0; i < 4; i++) //need this so i dont recive pure green screen frames
cap.read(frame);
while(frame.empty()){
if( cap.read(frame) )
break;
}
} catch (Exception e) {
//some error handling
}
imwrite("someFileName.png", frame );
cap.release();
I was trying to set denoise and default setings using hidraw, hovewer without results.
I'd be glad for any help.
I'm trying to grab two pictures from an basler GigE camera video feed with pylon and opencv. The two pictures are converted to grayscale and compared using absdiff. The pixels that have changed should be the object i'm looking for.
Here is the while-loop of the code.
while(camera.IsGrabbing()) {
camera.RetrieveResult(5000,ptrGrabResult, TimeoutHandling_ThrowException);
if(ptrGrabResult->GrabSucceeded()){
formatConverter.Convert(pylonImage, ptrGrabResult);
openCVImage1 = cv::Mat(ptrGrabResult->GetHeight(), ptrGrabResult->GetWidth(), CV_8UC3, (uint8_t *) pylonImage.GetBuffer());
}
else{
cout<<"ERROR OpenCVImage1:" <<ptrGrabResult->GetErrorCode()<<ptrGrabResult->GetErrorDescription()<< endl;
}
camera.RetrieveResult(5000,ptrGrabResult, TimeoutHandling_ThrowException);
if(ptrGrabResult->GrabSucceeded()){
formatConverter.Convert(pylonImage, ptrGrabResult);
openCVImage2 = cv::Mat(ptrGrabResult->GetHeight(), ptrGrabResult->GetWidth(), CV_8UC3, (uint8_t *) pylonImage.GetBuffer());
}
else{
cout<<"ERROR OpenCVImage2:" <<ptrGrabResult->GetErrorCode()<<ptrGrabResult->GetErrorDescription()<< endl;
}
cvtColor(openCVImage1,grayImage1,CV_BGR2GRAY);
cvtColor(openCVImage2,grayImage2,CV_BGR2GRAY);
absdiff(grayImage1,grayImage2,differenceImage);
imshow("DiffImage", differenceImage);
threshold(differenceImage,thresholdImage,sensitivity, 255, THRESH_BINARY);
switch(waitKey(10)){
case 27: //ESC
return 0;
case 116: //t
trackingEnabled = !trackingEnabled;
if(trackingEnabled=false) cout<<"tracking disabled"<<endl;
else cout<<"tracking enabled"<<endl;
break;
case 112: //d
debugMode=!debugMode;
if(debugMode==false){cout<<"Code paused, press 'p' again to resume"<<endl;
while (pause==true) {
switch(waitKey(0)){
case 112: //p
pause = false;
cout<<"Code Resumed"<<endl;
break;
}
}
}
}
//do stuff
}
I have three problems doing that.
First: The differenceImage is always black. Altough I'm moving in fornt of the camera. Probably I'm not grabbing the pictures correctly. Does anyone know what i'm doing wrong? Already tried to add a waitKey(10) before the second RetrieveResult.
Second: The switch(waitKey(10)) is not working. No Matter what i press on the keyboard, there is no output on the screen. Already tried it using if and else if, but that didn't solve the problem either.
Third: If i stop debugging and start debugging again, i get an exception caught by my catch block. Probably this is because the camera didn't stop Grabbing after i stopped debugging. If i plug the camera out and back in the script runs. I tried using stopGrabbing() and close() but it didn't work.
I'm using windows 7 with visual studio 2010!!
Thanks a lot in Advance!
I have the following code to get a video feed from a network cam and subsequently perform a HOG detection.
However, when i add the HOG detection code , the code is only able to grab the first image upon running and it doesnt refresh on subsequent iteration. I have checked, using breakpoint, that the program is continuously running.
Please advise. Thank you.
void doDetection(void){
VideoCapture cap("http://user:password#10.0.0.1/mjpg/video.mjpg");
if (!cap.isOpened())
return;
HOGDescriptor hog;
hog.setSVMDetector(HOGDescriptor::getDefaultPeopleDetector());
while (true)
{
Mat img, mono_img;
bool status = cap.read(img);
if (status == false) break;
vector<Rect> found, found_filtered;
cvtColor(img, mono_img, CV_BGR2GRAY);
equalizeHist(mono_img, mono_img);
// this is the problem statement , when removed this program refresh fine
hog.detectMultiScale(mono_img, found, 0, Size(8, 8), Size(50, 50), 1.05, 2);
imshow("Show", img);
if (waitKey(20) >= 0)
break;
}
}
I have found this to happen even when you pause the execution of the code for a little while.
In my case MJPEG OVERREAD would appear in the console, after which no more images would get grabbed from the stream, but the stream would still be `open´
I build this little check around this problem which resets the capture. just place this in your WHILE
if (cap.isOpened())
{
cap.read(img);
if (img.rows == 0)
{
cap.release();
cap.open("");//Insert own url
cap.read(img);
}
}
else
{
cap.open(""); //Insert own url
cap.read(img);
}
if this "solves" the problem by keeping you app running, you should capture the frames on a separate thread to prevent the stream from dying like this.
If this does not "solve" the problem, I'm not sure what else could be wrong
1) Is there a way to know the number of the frames of a video after we load it but before playing it??
2) Also I want to take the first column from each frame. What I have thought is to read the whole video and store into an ArrayList every frame I read and then parse again the whole ArrayList and take the the first column from each frame. Is any more optimal way to do this?
Is any function in OpenCV that can help???
Take a look at the VideoCapture class in OpenCV. Specifically the get function for retrieving video properties.
You can load each frame and store the first column like this:
//Video capture object
cv::VideoCapture cap;
cap.open("filename");
//Storage for video frames and columns
cv::Mat frame;
std::vector<cv::Mat> cols;
//Get each frame
while(true){
//Load next frame
cap >> frame;
//If no frame, end of video
if(!frame.data) break;
//Store first column
cv::Mat col;
frame.col(0).copyTo(col);
cols.push_back(col);
}
I'm coding an opencv 2.1 program with visual c++ 2008 express. I want to get each pixel color data of each pixel and modify them by pixel.
I understand that the code "frmSource.channels();" returns the color channels of the mat frmSource, but it always returns 1 even if it is absolutely color video image, not 3 or 4.
Am I wrong?
If I'm wrong, please guide me how to get the each color component data of each pixel.
Also, the total frame count by "get(CV_CAP_PROP_FRAME_COUNT)" is much larger than the frame count I expected, so I divide the "get(CV_CAP_PROP_FRAME_COUNT) by get(CV_CAP_PROP_FPS Frame rate.") and I can get the result as I expected.
I understand that the frame is like a cut of a movie, and 30 frames per sec. Is that right?
My coding is as follows:
void fEditMain()
{
VideoCapture vdoCap("C:/Users/Public/Videos/Sample Videos/WildlifeTest.wmv");
// this video file is provided in window7
if( !vdoCap.isOpened() )
{
printf("failed to open!\n");
return;
}
Mat frmSource;
vdoCap >> frmSource;
if(! frmSource.data) return;
VideoWriter vdoRec(vRecFIleName, CV_FOURCC('W','M','V','1'), 30, frmSource.size(), true);
namedWindow("video",1);
// record video
int vFrmCntNo=1;
for(;;)
{
int vDepth = frmSource.depth();
vChannel = frmSource.channels();
// here! vChannel is always 1, i expect 3 or 4 because it is color image
imshow("video", frmSource);// frmSource Show
vdoRec << frmSource;
vdoCap >> frmSource;
if(! frmSource.data)
return;
}
return;
}
I am not sure if this will answer your question but if you use IplImage it will be very easy to get the correct number of channels as well as manipulate the image. Try using:
IplImage *frm = cvQueryFrame(cap);
int numOfChannels = channelfrm->nChannels;
A video is composed of frames and you can know how many frames pass in a second by using get(CV_CAP_PROP_FPS). If you divide the frame count by the FPS you'll get the number of seconds for the clip.