The code is:
#include <iostream>
#include <opencv2/opencv.hpp>
int main (int argc, char** argv) {
auto path = "C:/Users/huhua/Pictures/11.jpg";
auto img = cv::imread(path);
if (img.empty()) {
std::cout << "is empty" << std::endl;
return 1;
}
cv::imshow("demo", img);
cv::waitKey(0);
return 0;
}
The 11.jpg exist. And if I use another 11.bmp. It works well.
After debug. The error is throw at libjpeg-trubo/src/jdatasr.c
fill_input_buffer(j_decompress_ptr cinfo)
{
my_src_ptr src = (my_src_ptr)cinfo->src;
size_t nbytes;
// error is throw at here
nbytes = JFREAD(src->infile, src->buffer, INPUT_BUF_SIZE);
// ...
}
Is my libjpeg issue??
How to fix this?
The 11.jpg image:
Update:
The OpenCV info
Update on 2021/10/19:
The reason is I set the cmake_toolchain_path after project(xxx). I should set the cmake_toolchain_path before project.
https://github.com/microsoft/vcpkg/discussions/20802
Related
This is what my code looks like, I got the undefined reference to imread and so on:
#include <iostream>
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;
int main( int argc, const char** argv )
{
Mat img = imread("MyPicture.jpg", CV_LOAD_IMAGE_UNCHANGED); //read the image data in the file "MyPic.JPG" and store it in 'img'
if (img.empty()) //check whether the image is loaded or not
{
cout << "Error : Image cannot be loaded..!!" << endl;
//system("pause"); //wait for a key press
return -1;
}
namedWindow("MyWindow", CV_WINDOW_AUTOSIZE); //create a window with the name "MyWindow"
imshow("MyWindow", img); //display the image which is stored in the 'img' in the "MyWindow" window
waitKey(0); //wait infinite time for a keypress
destroyWindow("MyWindow"); //destroy the window with the name, "MyWindow"
return 0;
}
I am using Codeblocks and the g++ compiler. Also I have linked the opencv_world310d.lib to debug and opencv_world310.lib to release.
Plus I have given the path in searchdirectory compiler and linker.
Any hints?
All examples and books I've seen so far recommends using waitKey(1) to force repaint OpenCV window. That looks weird and too hacky. Why wait for even 1ms when you don't have to?
Are there any alternatives? I tried cv::updateWindow but it seems to require OpenGL and therefore crashes. I'm using VC++ on Windows.
I looked in to source and as #Dan Masek said, there doesn't seem to be any other functions to process windows message. So I ended up writing my own little DoEvents() function for VC++. Below is the full source code that uses OpenCV to display video frame by frame while skipping desired number of frames.
#include <windows.h>
#include <iostream>
#include "opencv2/opencv.hpp"
using namespace cv;
using namespace std;
bool DoEvents();
int main(int argc, char *argv[])
{
VideoCapture cap(argv[1]);
if (!cap.isOpened())
return -1;
namedWindow("tree", CV_GUI_EXPANDED | CV_WINDOW_AUTOSIZE);
double frnb(cap.get(CV_CAP_PROP_FRAME_COUNT));
std::cout << "frame count = " << frnb << endl;
for (double fIdx = 0; fIdx < frnb; fIdx += 50) {
Mat frame;
cap.set(CV_CAP_PROP_POS_FRAMES, fIdx);
bool success = cap.read(frame);
if (!success) {
cout << "Cannot read frame " << endl;
break;
}
imshow("tree", frame);
if (!DoEvents())
return 0;
}
return 0;
}
bool DoEvents()
{
MSG msg;
BOOL result;
while (::PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE))
{
result = ::GetMessage(&msg, NULL, 0, 0);
if (result == 0) // WM_QUIT
{
::PostQuitMessage(msg.wParam);
return false;
}
else if (result == -1)
return true; //error occured
else
{
::TranslateMessage(&msg);
::DispatchMessage(&msg);
}
}
return true;
}
Can anyone tell me what's wrong with my code? I can use my webcam by other code, so there is nothing do with the supported problem. In my code below, I must set the camera index into a loop so that i can motivate my camera(the led inductor is on, simply set "CvCapture* camera=cvCaptureFromCAM(0)" can not run! that's wierd!).However, I just can obtain a greysreen,why?
#include "highgui.h"
#include "cv.h"
int main(int grac, char** grav)
{
CvCapture* camera;
int index;
for (index = -1; index <1; index++)
{
camera = cvCaptureFromCAM(index);
if (camera)
{
printf("%d\n", index);
IplImage* f;
cvNamedWindow("camera", CV_WINDOW_AUTOSIZE);
while (1)
{
f = cvQueryFrame(camera);
cvShowImage("camera", f);
char c = cvWaitKey(33);
if (c == 27)break;
}
}
}
cvReleaseCapture(&camera);
cvDestroyAllWindows;
}
I run a program similar to the one in this question: https://stackoverflow.com/a/8719192/26070
#include <opencv/highgui.h>
#include <iostream>
/** #function main */
int main( int argc, char** argv )
{
cv::VideoCapture vcap;
cv::Mat image;
const std::string videoStreamAddress = "rtsp://192.0.0.1:8081/live.sdp";
//open the video stream and make sure it's opened
if(!vcap.open(videoStreamAddress)) {
std::cout << "Error opening video stream or file" << std::endl;
return -1;
}
for(;;) {
if(!vcap.read(image)) {
std::cout << "No frame" << std::endl;
cv::waitKey(500);
} else {
cv::imshow("Output Window", image);
}
if(cv::waitKey(1) >= 0) break;
}
}
The program runs fine for a certain amount of time (about one minute or so) and then the call to read() (method from cv::VideoCapture) always returns false.
The output is as follows:
[mpeg4 # 00da27a0] ac-tex damaged at 22 7
[mpeg4 # 00da27a0] Error at MB: 309
No frame
No frame
No frame
Note: the first two lines are not always present.
So, how can I determine what the root of the problem is?
i am still new on opencv, i make simple program based on sample to access webcam but always fails. i change variable id to 0,1,2...100 but i got same result. this is my program:
#include "cv.h"
#include "highgui.h"
#include "stdio.h"
#include "iostream"
// A Simple Camera Capture Framework
int main()
{
IplImage* img = NULL;
CvCapture* cap = NULL;
int id=0;
cap = cvCaptureFromCAM(id);
cvNamedWindow("Images",CV_WINDOW_AUTOSIZE);
if ( !cap )
printf("ERROR\n\n");
else
for(;;)
{
img = cvQueryFrame(cap);
cvShowImage("Imagenes", img);
cvWaitKey(10);
}
cvReleaseImage(&img);
cvReleaseCapture(&cap);
return 0;
}
thank you for your help
Do yourself a favor and check the return of the functions. Maybe some of them are failing and you'll never know why.
Another tip: try with id = -1.
#include <iostream>
#include <sstream>
#include <string>
#include <cv.h>
#include <highgui.h>
int main()
{
CvCapture* capture = NULL;
if ((capture = cvCaptureFromCAM(-1)) == NULL)
{
fprintf(stderr, "ERROR: capture is NULL \n");
return -1;
}
cvNamedWindow("mywindow", CV_WINDOW_AUTOSIZE);
cvQueryFrame(capture); // Sometimes needed to get correct data
IplImage* frame = NULL;
while (1)
{
if ((frame = cvQueryFrame(capture)) == NULL)
{
fprintf( stderr, "ERROR: cvQueryFrame failed\n");
break;
}
if (frame == NULL)
{
usleep(100000);
continue;
}
cvShowImage("mywindow", frame); // Do not release the frame!
int key = cvWaitKey(10);
if (key == 27) // ESC was pressed
break;
}
cvReleaseCapture(&capture);
cvDestroyWindow("mywindow");
return 0;
}