My problem is this:
I need to get the webcam video, get each frame of the video as VP8 frames to packetize it on a RTP stream or to directly get/create an RTP stream to send through a WebRTC application.
I saw that I can get the camera via OpenCV this is an complete example:
#include "opencv2/core.hpp"
#include "opencv2/imgproc.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/videoio.hpp"
#include <iostream>
using namespace cv;
using namespace std;
void drawText(Mat & image);
int main()
{
cout << "Built with OpenCV " << CV_VERSION << endl;
Mat image;
VideoCapture capture;
capture.open(0); // webcam device
if(capture.isOpened())
{
cout << "Capture is opened" << endl;
for(;;)
{
capture >> image;
if(image.empty())
break;
drawText(image);
imshow("Sample", image);
if(waitKey(10) >= 0)
break;
}
}
else
{
cout << "No capture" << endl;
image = Mat::zeros(480, 640, CV_8UC1);
drawText(image);
imshow("Sample", image);
waitKey(0);
}
return 0;
}
void drawText(Mat & image)
{
putText(image, "Hello OpenCV",
Point(20, 50),
FONT_HERSHEY_COMPLEX, 1, // font face and scale
Scalar(255, 255, 255), // white
1, LINE_AA); // line thickness and type
}
I have "Mat image", so I can the the Mat (each video frame into a OpenCV Mat) on the line:
capture >> image;
is it possible to get the bytes from the Mat class and encode it into a VP8 frame?
I saw there is a VideoWriter class on OpenCV where I can setup the VP8 encoding, but id like not to save anything on disk since I only need the VP8 bytes to send over a stream.
Is it possible to get the bytes from the camera and encode it to a VP8 frame or even to get the whole camera recording and setup a RTP stream with OpenCV?
Related
I am trying to detect the QR data from a blurry image and have not been successful till now.
I have tried a couple of morphology operations on the image and still did not get the data embedded in it.
How could I improve the situation?
I have tried this so far:
#include <iostream>
#include <opencv2/highgui.hpp>
#include <opencv2/imgcodecs.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/objdetect.hpp>
#include <opencv2/barcode.hpp>
int main() {
cv::Mat imageMat = cv::imread("/Users/apple/Downloads/36.jpg");
if(imageMat.empty()) {
std::cout << "Image not present and can not be opened" << std::endl;
return 0;
}
cv::Mat imageGray, imageBlur, imageCanny, imageDilated, imageEroded, thresholdImage;
cv::cvtColor(imageMat, imageGray, cv::COLOR_BGR2GRAY);
cv::GaussianBlur(imageGray, imageBlur, cv::Size(3,3), 3, 0);
std::cout << "Gaussian blur done" << std::endl;
// cv::Canny(imageBlur, imageCanny, 25, 75);
cv::Mat kernel = cv::getStructuringElement(cv::MORPH_RECT, cv::Size(3,3));
cv::dilate(imageBlur, imageDilated, kernel);
cv::erode(imageDilated, imageEroded, kernel);
cv::threshold(imageEroded, thresholdImage, 5, 255, cv::THRESH_BINARY+cv::THRESH_OTSU);
std::cout << "Threshold done" << std::endl;
// Reads the barcode/dat
cv::QRCodeDetector qrDecoder;
std::string decodedData = qrDecoder.detectAndDecode(thresholdImage);
std::cout << "Decoded data = " << decodedData << std::endl;
This code is not decoding the data from the image which has blurry QR code. What would you guys prefer to unblur the image and get the data embedded in it? Increase the contrast? Increase the brightness?
Any document can be helpful too.
Thank you in advance.
I am capturing a video with 30fps, but when I process the video with openCV for AruCo marker detection I am loosing almost half of the frames. So for a 5 min video I expect 5x60x30 = 9000 frames but I am getting only about 4500 frames. I tried different resolution and fps while recording but the problem still persists. My code is as follows. I later want to sync the video with the audio recorded from the camera, so even if I could know the frames which are being lost can solve my problem. Any pointers or suggestions are welcome.
#include "opencv2\core.hpp"
#include "opencv2\imgcodecs.hpp"
#include "opencv2\imgproc.hpp"
#include "opencv2\highgui.hpp"
#include "opencv2\aruco.hpp"
#include "opencv2\calib3d.hpp"
#include <time.h>
#include <sstream>
#include <iostream>
#include <fstream>
#include "stdafx.h"
using namespace std;
using namespace cv;
#define _CRT_SECURE_NO_WARNINGS 1
int startWebcamMonitoring() //(const Mat& cameraMatrix, const Mat&
distanceCoefficients, float arucoSquareDimensions)
{
Mat frame4;
Scalar_<double> borderColor, borderColor2, borderColor3;
vector<int> markerIds;
vector < vector<Point2f>> markerCorners, rejectedCandidates ;
aruco::DetectorParameters parameters;
Ptr<aruco::Dictionary> makerDiktionary = aruco::getPredefinedDictionary(aruco::PREDEFINED_DICTIONARY_NAME::DICT_4X4_50);
VideoCapture cap("sample.mp4");
double fps = cap.get(CV_CAP_PROP_FPS);
cout << "Frames per second : " << fps << endl;
while (true)
{
cap >> sample;
if (!cap.read(frame4))
break;
aruco::detectMarkers(frame4, makerDiktionary, markerCorners, markerIds);
aruco::drawDetectedMarkers(frame4, markerCorners, markerIds, borderColor);
aruco::estimatePoseSingleMarkers(markerCorners, arucoSquareDimension,
cameraMatrix, distanceCoefficients, rotationVectors, translationVectors);
Mat rotationMatrix
for (int i = 0; i < markerIds.size(); i++)
{
aruco::drawAxis(frame4, cameraMatrix, distanceCoefficients, rotationVectors[i], translationVectors[i], 0.01f);
Rodrigues(rotationVectors[i], rotationMatrix);
time_t current = time(0);
cout << " Translation " << translationVectors[i] << " ID" << markerIds[i] << " Euler angles " << 180 / 3.1415*rotationMatrixToEulerAngles(rotationMatrix) << "current time " << ctime(¤t) << endl;
}
freopen("output_sample", "a", stdout);
imshow("recording", frame4);
if (waitKey(30) >= 0) break;
}
The problem is:
cap >> sample;
if (!cap.read(frame4))
break;
the program is reading a frame from source twice in every iteration.
You should remove the cap >> sample; line and it will be fine.
I am trying to do Frame subtraction in a video.Steps I am following
Get a image , convert it into grayscale.
Subtract it from previous frame grayscale.
All I see in diff2(and diff also) a complete black image.One observation I made is that pixel value of gray1 and gray2 become equal.
My code
#include "opencv2/core/core.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/objdetect/objdetect.hpp"
#include <opencv2/video/background_segm.hpp>
#include <iostream>
using namespace cv;
using namespace std;
RNG rng(12345);
int main( int argc, const char** argv )
{
VideoCapture cap(0);
if ( !cap.isOpened() )
{
cout << "Cannot open the web cam" << endl;
return -1;
}
Mat img1,img2,diff,gray1,gray2,diff2;
bool bSuccess = cap.read(img1); // read a new frame from video
if (!bSuccess) //if not success, break loop
{
cout << "Cannot read a frame from video stream" << endl;
return -1;
}
cvtColor( img1,gray1, CV_BGR2GRAY );
while (true)
{
bSuccess = cap.read(img2); // read a new frame from video
if (!bSuccess) //if not success, break loop
{
cout << "Cannot read a frame from video stream" << endl;
break;
}
cvtColor( img2,gray2, CV_BGR2GRAY );
absdiff(gray2,gray1,diff);
threshold(diff, diff2, 150, 255, CV_THRESH_BINARY);
cout<<gray2.at<uchar>(100,200) <<endl;
cout<<gray1.at<uchar>(100,200) <<endl;
gray1=gray2;
imshow("1",gray1);
imshow("2",diff2);
if (waitKey(1000) == 27) //wait for 'esc' key press for 30ms. If 'esc' key is pressed, break loop
{
cout << "esc key is pressed by user" << endl;
break;
}
}
return -1;
}
please try this code. It looks like you're overwriting gray1 so that gray1 and gray2 use the very same data memory positions.
You could either use gray1=gray2.clone(); instead or use some real "swapping" of the buffers instead of overwriting. My code should perform a simple buffer swapping and has some comments about the problem.
#include "opencv2/core/core.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/objdetect/objdetect.hpp"
#include <opencv2/video/background_segm.hpp>
#include <iostream>
using namespace cv;
using namespace std;
RNG rng(12345);
int main( int argc, const char** argv )
{
VideoCapture cap(0);
if ( !cap.isOpened() )
{
cout << "Cannot open the web cam" << endl;
return -1;
}
Mat img1,img2,diff,gray1,gray2,diff2;
Mat tmp; // used to swap the buffers
bool bSuccess = cap.read(img1); // read a new frame from video
if (!bSuccess) //if not success, break loop
{
cout << "Cannot read a frame from video stream" << endl;
return -1;
}
// this will allocate memory of gray1 if not allocated yet
cvtColor( img1,gray1, CV_BGR2GRAY );
while (true)
{
bSuccess = cap.read(img2); // read a new frame from video
if (!bSuccess) //if not success, break loop
{
cout << "Cannot read a frame from video stream" << endl;
break;
}
// memory for gray2 won't be allocated if it is present already => if gray2 and gray1 use the same data memory, you'll overwrite gray1's pixels here and obviously gray1 and gray2 will have the same pixel values then
cvtColor( img2,gray2, CV_BGR2GRAY );
absdiff(gray2,gray1,diff);
threshold(diff, diff2, 150, 255, CV_THRESH_BINARY);
cout<<gray2.at<uchar>(100,200) <<endl;
cout<<gray1.at<uchar>(100,200) <<endl;
// don't lose the memory of gray1
tmp = gray1;
// this means gray1 and gray2 will use the same data memory location
gray1=gray2;
// give gray2 a new data memory location. Since previous gray1 memory is still present but wont be used anymore, use it here.
gray2=tmp;
imshow("1",gray1);
imshow("2",diff2);
if (waitKey(1000) == 27) //wait for 'esc' key press for 30ms. If 'esc' key is pressed, break loop
{
cout << "esc key is pressed by user" << endl;
break;
}
}
return -1;
}
in addition, a thres difference threshold of 150 might be very high for common tasks, but it might be ok for your special task. Typical difference values/thresholds in background subtraction for foreground extraction are around 20 to 30 from my experience, but at the end it depends on your task/problem/domain.
I am using OpenCV on an embedded target board (FriendlyARM mini6410, processor arm 1176 running linux kernel 2.6.38).
I compiled OpenCV 2.4.4 library using toolchain provided for the board, found in the ftp (pls see the website of FriendlyARM). I disabled GTK, ffmpeg and enable v4l. The library is compiled successfully.
Then I write code:
#include <opencv.hpp>
#include <highgui/highgui.hpp>
#include <imgproc/imgproc.hpp>
#include <iostream>
#include <stdio.h>
using namespace cv;
using namespace std;
int main()
{
int i;
cout << "initialise" << endl;
IplImage* img=0;
cout << "capturing ..." << endl;
CvCapture* capture = cvCaptureFromCAM(2);
cout << "get here" << endl;
if(!capture){
cout << "not capture" << endl;
return -1;
}
cout << "captured" << endl;
img=cvQueryFrame(capture);
IplImage* img1 = cvCreateImage(cvGetSize(img),8,3);
// cvCvtColor(img,img1,CV_RGB2GRAY);
cvCopy(img, img1);
cvSaveImage("cam_snap.jpg",img1);
cvReleaseImage( &img1 );
cvReleaseImage( &img );
cvReleaseCapture( &capture );
cout << "exit" << endl;
return 0;
}
The code is built successfully. I run the .elf executable in the target board, connected to camera (PS3 eye), but the resulting image looks like a broken television (noise-like):
While in my host, the resulting image is as expected (scene in front of camera). Can you provide me suggestion as to what went wrong or where should I start on debugging?
You should check your depth and channels. It is probably a matter of alignement, moreover be careful your image is probably in BGR and not in RGB.
And you should use cv::Mat instead of IplImage in C++ and VideoCapture instead of CVCapture.
This sample of code should work. (Not tested on the same arch as your)
#include <opencv.hpp>
#include <highgui/highgui.hpp>
#include <imgproc/imgproc.hpp>
#include <iostream>
#include <stdio.h>
using namespace cv;
using namespace std;
int main()
{
VideoCapture capture = cv::VideoCapture(0);
cout << "get here" << endl;
if(!capture.isOpened()) // check if we succeeded
return -1;
cout << "captured" << endl;
Mat img;
capture >> img;
imwrite("./test.png", img);
capture.release();
cout << "exit" << endl;
return 0;
}
Hope it helped.
Okay, confirmed. mini 6410 runs USB 1.0, and ps3 eye needs USB 2.0. I tried the program using standard webcam (chinese product, itech pc camera), works wonderfully. Saved image is showing scene in front of camera
I am trying to detect objects with cvblob. Somehow, my code only marks the white objects. How to mark objects of other colors, like a can of beer or a bottle of water.
Here is my code:
#include "highgui.h"
#include "cv.h"
#include "cvaux.h"
#include "iostream"
#include <stdio.h>
#include <ctype.h>
#include <cvblob.h>
using namespace cv;
using namespace std;
using namespace cvb;
int main(int argc, char** argv) {
CvTracks tracks;
cvNamedWindow("frame", CV_WINDOW_AUTOSIZE);
cvMoveWindow("frame", 50, 100);
CvCapture* capture;
IplImage* frame = 0;
capture = cvCreateCameraCapture( 0 ); //capture frames from cam on index 0: /dev/video0/
if (!capture) {
return -1;
}
cvSetCaptureProperty(capture, CV_CAP_PROP_FRAME_WIDTH, 320);
cvSetCaptureProperty(capture, CV_CAP_PROP_FRAME_HEIGHT, 240);
frame = cvQueryFrame(capture);
while(frame) {
IplImage *gray = cvCreateImage(cvGetSize(frame), IPL_DEPTH_8U, 1);
cvCvtColor(frame, gray, CV_BGR2GRAY);
cvThreshold(gray, gray, 150, 255, CV_THRESH_BINARY);
IplImage *labelImg=cvCreateImage(cvGetSize(gray), IPL_DEPTH_LABEL, 1);
CvBlobs blobs;
unsigned int result=cvLabel(gray, labelImg, blobs);
cvFilterByArea(blobs, 500, 1000000);
// cvRenderBlobs(labelImg, blobs, frame, frame, CV_BLOB_RENDER_BOUNDING_BOX);
cvRenderBlobs(labelImg, blobs, frame, frame, CV_BLOB_RENDER_CENTROID);
cvUpdateTracks(blobs, tracks, 200., 5);
cvRenderTracks(tracks, frame, frame, CV_TRACK_RENDER_ID|CV_TRACK_RENDER_BOUNDING_BOX);
for (CvBlobs::const_iterator it=blobs.begin(); it!=blobs.end(); ++it) {
cout << "Blob #" << it->second->label << ": Area=" << it->second->area << ", Centroid=(" << it->second->centroid.x << ", " << it->second->centroid.y << ")" << endl;
}
cvShowImage("frame", frame);
cout << "----------------------------" << endl;
frame = cvQueryFrame(capture);
char c = cvWaitKey(10);
if(c==27)
break;
}
}
Any tip is appreciated.
Milo
That's the option by default and you cannot change it if you don't change the source code in cvblob library.
If you really want to change this is so easy, you can create a copy of the same method adding a new input var like CvScalar to select output color. It's so easy.
The method cvRenderBlob will be in cvcontour.cpp.
I've been made many improvement in cvblob library and in next months I will push it to the creator.
Try adding:
"cvInRangeS(hsvframe,cvScalar(23,41,133),cvScalar(40,150,255),threshy);//for yellow"
Before Filtering the blobs. Its a range of HSV(instead of RGB) values that defines the threshold of the desire color.
Hope it helps.