How to use the user defined buffer to save the capture data(example saLoopbackFbdev,but not use fbdev buffer)

Hello all:

           I use the ADV7611(or TVP7002 ) which support HMDI receive to capture the 1280*720 video,and show on the  LCD screens  which only supports 

the resolution of 1024*600 and must be RGB ,not YUV .So based on the example of  saLoopbackFbedev, I have to get the 1280*720 capture data to another 

user buffer(not FBDEV buffer as the example) first and then extract 1024*600 by some algorithm ,But when I use my new user buffer to replace the fbdev buffer,

I found there are many *** question,eg:the programe will be crashed undefined,the picture is overlapping 。。。。althouh I use the methord to show the video on the TV Screeen which support 1280*720(so I not extract anything),still exist the above question,

My steps are: 

      (1)Add the new variable which will be used  to as the buffer  of caputre.

        unsigned char *captBufferArray[MAX_BUFFER];

     (3)In function "queueCaptureBuffers" ,Replace fbdev.buffer_addr  with the capBufferArray.

 static int queueCaptureBuffers(void)

{

int ret, i;

for (i = 0; i < MAX_BUFFER; i++) {

capt.buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

capt.buf.memory = V4L2_MEMORY_USERPTR;

capt.buf.index = i;

ret = ioctl(capt.fd, VIDIOC_QBUF, &capt.buf);

if (ret < 0) {

perror("VIDIOC_QBUF\n");

/*return -1;*/

}

}

return ret;

}

(4)

static int app_main(int argc , char *argv[])

{

-----------

    /*

  Get capture buffer using DQBUF ioctl

*/

/*printf("Get capture buffer 1\n");*/

ret = ioctl(capt.fd, VIDIOC_DQBUF, &capt.buf);

if (ret < 0) {

printf("VIDIOC_DQBUF\n");

/*return -1;*/

}

         memcpy(fbdev.buffer_addr[0],(unsigned char *)(capt.buf.m.userptr),1280*3*720);

-------------

ret = ioctl(capt.fd, VIDIOC_QBUF, &capt.buf);

if (ret < 0) {

perror("VIDIOC_QBUF\n");

/*return -1;*/

}

}

Am I right?Is there something wrong? 

Thanks very much.

                                       zhichao.