class Analiser{
    // some variables
    public:
    //! this function will called on each packet
    void nextPacket(char*){
        // How
    }
    Frame* getFrame(){
    }
    Image* getOpenCVImage(){
    }
}
class MPEG_DEVICE{
    // some variables & functions
    public:
    bool hasSignal();
    char* getNextPacket();
};
int main(){
    MPEG_DEVICE dev;
    Analiser a;
    while(true){
        if(dev.hasSignal()){
            a.nextPacket(dev.getNextPacket());
        }
    }
}