c++ - OpenCV 2.4.5 & Boost for Passing VideoCapture -

issue: want pass cv::videocapture objects different thread. want able dynamically handle how many cameras can have.

proposed solution: insert vector , pass argument thread:

inserting mechanism:

std::vector< boost::shared_ptr<cv::videocapture> > camvect; for(int i=0;i<6;i++){     boost::shared_ptr<cv::videocapture> cvinputobj(new cv::videocapture(i));     if((*cvinputobj.get()).isopened()){         camvect.push_back(cvinputobj);         validcams++;     } } 

retrieval mechanism:create local vector , assign passed in data vector such:

cvision::cvision(std::vector< boost::shared_ptr<cv::videocapture> > camvect) {     cameras=camvect; } 

following go ahead , following pull out image:

note, typedefs below:

typedef std::vector< boost::shared_ptr<cv::videocapture> > cameracontainer; typedef cameracontainer::iterator camiterator; 

using this, create iterator , try retrieve images. gathered class definition '>>' operator grab() followed retrieve()

void cvision::grabimage(int camnumber){ int index=0; for(camiterator it=cameras.begin();it!=cameras.end();++it) {     if(index==camnumber) {         if((*it)->grab()) {             cout<<"successfully grabbed!"<<endl;             if((*it)->retrieve(imcur[camnumber],0))                 cout<<"successfully retrieved!"<<endl;             else                 cout<<"error retrieving"<<endl;         }     } else index++; } } 

issue: seems calling grab() method, fails on retrieve? (this guess):

libv4l2: error dequeuing buf: invalid argument vidioc_dqbuf: invalid argument grabbed! 

any advice immensely helpful!

i figured out how circumvent this. i.e. defining following global main():

std::vector< boost::shared_ptr<cv::videocapture> > camvect; 

following called same method thread , worked expected.

still not sure why happened though.