HI, All i got Ubuntu 12.04 OS, where i need to open two video device one being Unibrain IEEE1394 and another normal webcam

when i connect my webcam in dev shows Video0 After connecting my Unibrain IEEE13494 i get v4l ls /dev/v4l/ by-id by-path

where ls by-id usb-045e_USB_camera-video-index0 ls by-path pci-0000:00:1d.2-usb-0:2:1.0-video-index0 So this been a problem to access my both cameras from opencv capture index when i say Capture=cvCaptureFromCAM(0); i get Only IEE1394 not the webcam, is there any method to set the index of the device. Of course i am aware that Windows has got its own flavour of accessing through name. Any pointers will be appreciated.

Kindly excuse me. I find its 0101....take time.. some part are not getting formatted. I cut and pasted from gedit and gvim.

Thanks berak.

I finally did encoding and decoding using mat my code below the data is streamed using tcp Let me know if anyquestions. Encoding

#define JPEG_HEADER_0     0xff
#define JPEG_HEADER_1     0xd8

#define JPEG_END_2        0xff
#define JPEG_END_1        0xd9

Mat drawing; unsigned char VideoBuffer[1024*10] ; //ofcourse keep u r req size vector<int> param = vector<int>(2);

param[0]=CV_IMWRITE_JPEG_QUALITY;

param[1]=60;//default(95) 0-100

vector<uchar> encodeBuff;//buffer for coding
        imencode(".jpg",drawing,encodeBuff,param);      
        pthread_mutex_lock(&buffer_sync);
if(PacketSize > VIDEO_BUFFER_SIZE)
            printf("ERROR Packet Size --------> %d",PacketSize );
        PacketSize=encodeBuff.size();
        memcpy(&VideoBuffer[0],(char*)&encodeBuff[0],PacketSize);

Decoding

imageptr=&SendBuffer[4]; // ok i receive in sendbuffer of unsigned char

 if(  SendBuffer[4]== JPEG_HEADER_0 && 
                  SendBuffer[5] == JPEG_HEADER_1 && 
                          SendBuffer[length+3]== JPEG_END_1 &&
              SendBuffer[length+2] ==JPEG_END_2 )                 
             {

    std::vector<uchar> decodebuff(imageptr,imageptr+(size-4));
    Mat decode =imdecode(Mat(decodebuff),CV_LOAD_IMAGE_COLOR);
   }

Camera capture --> Encode -> stream (unsigned char )

-> Recieve -> Decode

Encoding side

unsigned char Buffer[1024*20];
IplImage *image   image=cvQueryFrame(Capture); 
   encode=cvEncodeImage(".jpg",image,encodeparams);

    decode=cvCreateMat(encode->rows,encode->cols,CV_8UC1);

decode->data.ptr=encode->data.ptr;

  cvShowImage("Server",image);
   cvWaitKey(1);
    Frame->iSync=0x1;
    Frame->iLength=(16+(encode->rows*encode->cols));
    Frame->iSize=(encode->rows*encode->cols);
    Frame->iWidth=(encode->rows);
    Frame->iHeight=(encode->cols);
        Frame->iSync=0x1;
    Frame->iLength=(16+(encode->rows*encode->cols));
    Frame->iSize=(encode->rows*encode->cols);
    Frame->iWidth=(encode->rows);
    Frame->iHeight=(encode->cols);

    memcpy(&bImageData[0],&Frame->iSync,sizeof(int));
    memcpy(&bImageData[4],&Frame->iLength,sizeof(int));

    memcpy(&bImageData[8],&Frame->iSize,sizeof(int));

    memcpy(&bImageData[12],&Frame->iWidth,sizeof(int));

    memcpy(&bImageData[16],&Frame->iHeight,sizeof(int));


memcpy(&bImageData[20],encode->data.ptr,sizeof(unsigned char)*encode->rows*encode->cols);

// printf("%d",length );
length = Frame->iLength;

    while( count < length)
{
        offset=send(connect,&bImageData[count],(length-count),0);

            if(offset > 1)
            {
                    count +=offset;
                  //  printf("\n Count &  %d %d \n",offset,count); 
            }
            if(offset == (-1))
            {
                printf("closed connection");
                goto _error_video_client; 
            }           
}
    recv(connect,RecvBuff,sizeof(RecvBuff),0); 

}

decoding side

define MAKEDWORD(B0,B1,B2,B3) (((unsigned long)B0)+

(((unsigned long)B1)<<8)+ (((unsigned long)B2)<<16)+ (((unsigned long)B3)<<24))

if(offset)
{
      if(size > PACKET_HEADER_SIZE )
      {   // using QT so this... to get the header info.
          iSync   = MAKEDWORD(CopyData.at(0),CopyData.at(1),CopyData.at(2),CopyData.at(3));
          iLength = MAKEDWORD(CopyData.at(4),CopyData.at(5),CopyData.at(6),CopyData.at(7));
          iSize   = MAKEDWORD(CopyData.at(8),CopyData.at(9),CopyData.at(10),CopyData.at(11));
          iRows  = MAKEDWORD(CopyData.at(12),CopyData.at(13),CopyData.at(14),CopyData.at(15));
          iCols =  MAKEDWORD(CopyData.at(16),CopyData.at(17),CopyData.at(18),CopyData.at(19));
          std::cout << "iLength " << iLength;
          std::cout << "isize " << iSize << "iWidth " << iRows  << " iHeight" << iCols;
          offset=0;
          if((iLength < 0) && iLength > FRAME_LENGTH )
                  offset=1;
          count=size;
          memcpy(&FrameBuffer[0],&CopyData,size);
          std::cout << "Size" << size;
       }


}
else
{   
    memcpy(&FrameBuffer[count],&CopyData,size); // keep until u reach the count == length 

    count+=size;
    if(count == iLength)
    {
         decode =cvCreateMat(iRows,iSize,CV_8UC1);
         decode->data.ptr=&FrameBuffer[20];
         frame = cvDecodeImage(decode,CV_LOAD_IMAGE_COLOR);
        if(frame)
           std::cout << "Valid Frame";
      else
       std::cout << "Not a Valid Frame "; // I am not aware why this is going invalid frame after sending all the trasnmission are using unsigned char buffer.

    }
}

I have a problem with finding contour point.

findContours(canny_output,contours,heirachy,CV_RETR_TREE,CV_CHAIN_APPROX_SIMPLE,Point(0,0));
for(unsigned int i=0;i<contours.size(),i++)
{

     for(unsigned int j=0;j<contours[i].size(),j++)
     {
         cout << "Point(x,y)=" << contours[i][j] << endl;
     }
}

How to get this to x & y of image matrix when i try to cout its 11122333 huge number number... ? Printing cvpoint is also huge number, I need (x,y) coordinates.

"OpenCV Error: Assertion failed ((globalDescIdx>=0) && (globalDescIdx < size())) in getLocalIdx, file opencv-2.4.7/modules/features2d/src/matchers.cpp, line 163 terminate called after throwing an instance of 'cv::Exception'"

I read that it happens because of the frame being empty so i make the code as below

    if(!**image.empty**())  // image from camera 
{ 
    detector.detect( image, kp_image );
    extractor.compute( image, kp_image, des_image );
            **if(!des_image.empty())**
    matcher.knnMatch(des_object, des_image, matches, 2);

    for(int i = 0; i < min(des_image.rows-1,(int) matches.size()); i++) //THIS LOOP IS SENSITIVE TO SEGFAULTS
    {
        if((matches[i][0].distance < 0.6*(matches[i][1].distance)) && ((int) matches[i].size()<=2 && (int) matches[i].size()>0))
        {
            good_matches.push_back(matches[i][0]);
        }
    }

        if((matches[i][0].distance < 0.6*(matches[i][1].distance)) && ((int) matches[i].size()<=2 && (int) matches[i].size()>0))
        {
            good_matches.push_back(matches[i][0]);
        }
    }

    //Draw only "good" matches
    //      drawMatches( object, kp_object, image, kp_image, good_matches, img_matches, Scalar::all(-1), Scalar::all(-1), vector<char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS );

    if (good_matches.size() >= 4)
    {
        for( int i = 0; i < good_matches.size(); i++ )
        {
            //Get the keypoints from the good matches
            obj.push_back( kp_object[ good_matches[i].queryIdx ].pt );
            scene.push_back( kp_image[ good_matches[i].trainIdx ].pt );
        }

        H = findHomography( obj, scene, CV_RANSAC );

        perspectiveTransform( obj_corners, scene_corners, H);

        cout << "X and Y  " <<  scene_corners[2].x << "  " <<scene_corners[2].y<< "\n";

     //Draw lines between the corners (the mapped object in the scene image )
      line( image, scene_corners[0] , scene_corners[1] , Scalar(0, 255, 0), 4 );
          line( image, scene_corners[1] , scene_corners[2] , Scalar( 0, 255, 0), 4 );  // vertical left top to bottom 

      line(image, scene_corners[2] , scene_corners[3] , Scalar( 0, 255, 0), 4 );



      line( image, scene_corners[3] , scene_corners[0] , Scalar( 0, 255, 0), 4 );
    }
    imshow( "good matches", image );

    key = waitKey(1);
}
   Still it throws the exception

Problem with the script in the same make file, so with the above flag opencv get linked in the project.

thanks

thanks..it solved problem

In my project i already have camera output in a buffer

ProcessFrames(unsigned char *RefFrame,unsigned char *CurrentFrame, int width,int height)

{


    IplImage *ReferenceImage = cvCreateImageHeader(cvSize(width,height),IPL_DEPTH_8U,1);
    IplImage *CurrentImage     = cvCreateImageHeader(cvSize(width,height),IPL_DEPTH_8U,1);
    IplImage *ResultImage       = cvCreateImageHeader(cvSize(width,height),IPL_DEPTH_8U,1);
   // my camera input is Grey so i keep all at same depth 
    cvSetData( ReferenceImage, RefFrame, width );
    cvSetData( CurrentImage, CurrentFrame, width ); // fine until here 

    cvAbsDiff(ReferenceImage, CurrentImage, ResultImage); 
           // here is the culprit for crash  
          // can somebody point what is going wrong here    

//finally i do this 

        cvReleaseImageHeader(&ReferenceImage);
    cvReleaseImageHeader(&CurrentImage);
        cvReleaseImageHeader(&ResultImage);
}

after core dump i get the message

OpenCV Error: Bad argument (Unknown array type) in cvarrToMat
Downloads/opencv-2.4.7/modules/core/src/matrix.cpp, line 698
terminate called after throwing an instance of 'cv::Exception'
  what():  Downloads/opencv-2.4.7/modules/core/src/matrix.cpp:698: error: (-5) Unknown array type in function cvarrToMat

It worked there was a problem because of the script.

thanks

I need to add the opencv for image detection into my existing camera project, I get link error that undefined reference to `cvCreateImage'. Can you pointout what need to be done in my Makefile i just added to my exsisting Makefile ( I cant use cMake)

CFLAGS = 'pkg-config --cflags opencv' -g -O2

CPP = gcc -E

DEPS_CFLAGS = -pthread -D_GNU_SOURCE=1 -D_REENTRANT -I/usr/include/gtk-3.0 -I/usr/include/pango-1.0 -I/usr/include/gio-unix-2.0/ -I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/freetype2 -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I/usr/include/pixman-1 -I/usr/include/libpng12 -I/usr/include/SDL -I/usr/local/include/opencv -I/usr/local/include/

DEPS_LIBS = 'pkg-config --libs opencv' -lgtk-3 -lgdk-3 -latk-1.0 -lgio-2.0 -lpangocairo-1.0 -lgdk_pixbuf-2.0 -lcairo-gobject -lpango-1.0 -lcairo -lgobject-2.0 -lglib-2.0 -lSDL -lportaudio -lasound -lm -lpthread -lpng12 -lavcodec -lavutil -lv4l2 -ludev -lrt

Can you guys point out what i wrong here in the Makefile.