Re: problems with cleaning up after capturing...

I just solved the problem...

Never forget to unmap the memmapped memory. ;)

Sorry for wasting your time!

----- Original Message -----

From: Preuss.t@xxxxxxxxxxxx

To: video4linux-list@xxxxxxxxxx

Sent: Wednesday, December 18, 2002 10:34 AM

Subject: problems with cleaning up after capturing...

Hello!

I'm currently working on an application(using svgalib)that starts capturing(v4l and bttv of course) from a Haupauge BT878 chip after a certain serial command...

This works fine...but only once.

When i captured once and i try to open the device again then i get the error message : "device or resource busy"!

Maybe this is because of my poor cleanup routine.

I only close the filedescriptor after the capture process.

(I also tried to end caturing by sending VIDIOCCAPTURE via ioctl but this causes an error too... "Invalid argument")

Can anyone solve this riddle?

Here is the source code that runs in a thread...

void* OldInterpreter::VIDEOCAP(void *arg)
{
clock_t  cstart=0;
clock_t  clast=0;
float  fps=0;
int  frame_count=0;
int fd=-1;
struct params *threadparams=(struct params *) arg;
struct video_channel mychannel;
DisplayVideoData=1;

cout<<threadparams->vidwidth<<endl;
cout<<threadparams->vidheight<<endl;
cout<<threadparams->vidinputchannel<<endl;

if (-1 == (fd = open(VideoDevice.c_str(), O_RDWR))) {
  perror("An error occured while opening the device:");
  goto err;
}

Trace("Video Device opened...");
if (-1 == ioctl(fd,VIDIOCGCAP,&capability)) {
  Trace("Error: ioctl(fd,VIDIOCGCAP,&capability)\n");
  goto err;
}

cout<<"Channels: "<<capability.channels<<endl;

if (threadparams->vidinputchannel>0 && threadparams->vidinputchannel<capability.channels)
   {
    mychannel.channel=threadparams->vidinputchannel;

    if (-1 == ioctl(fd,VIDIOCGCHAN,&mychannel)) {
   Trace("Error: ioctl(fd,VIDIOGCHAN,&mychannel)\n");
   goto err;
    }

    if (-1 == ioctl(fd,VIDIOCSCHAN,&mychannel)) {
   Trace("Error: ioctl(fd,VIDIOCSCHAN,&mychannel)\n");
   goto err;
    }
   }

   fcntl(fd,F_SETFD,FD_CLOEXEC);

   if (-1 == ioctl(fd,VIDIOCGMBUF,&gb_buffers)) {
  Trace("Error: Error getting buffers, I think\n");
  goto err;
   }

   memmap = (char *)mmap(0,gb_buffers.size,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0);
   if (mmap == NULL) {
  Trace("Error: Mmap returned NULL\n");
  goto err;
}


   // Set up out capture to use the correct resolution
   my_buf.width = threadparams->vidwidth;
   my_buf.height = threadparams->vidheight;
   my_buf.format = VIDEO_PALETTE_RGB565;

   cout<<threadparams->vidwidth<<threadparams->vidheight<<endl;

   // Tell the capture card to fill frame 0
   my_buf.frame = 0;
   if (-1 == ioctl(fd, VIDIOCMCAPTURE, &my_buf)) {
printf("Error: Grabber chip can't sync (no station tuned in?)");
perror(" ");
    goto err;
   }

    do {

  my_buf.frame = 1;
  if (-1 == ioctl(fd, VIDIOCMCAPTURE, &my_buf)) {
   printf("Error: Grabber chip can't sync (no station tuned in?)");
   perror(" ");
   goto err;
  }

  my_buf.frame = 0;
  if (-1 == ioctl(fd, VIDIOCSYNC, &my_buf.frame)) {
    printf("Error on sync!");
   perror(" ");
   goto err;
  }

  my_buf.frame = 0;
  if (-1 == ioctl(fd, VIDIOCMCAPTURE, &my_buf)) {
   printf("Error: Grabber chip can't sync (no station tuned in?)");
   perror(" ");
   goto err;
  }

  my_buf.frame = 1;
  if (-1 == ioctl(fd, VIDIOCSYNC, &my_buf.frame)) {
   Trace("Error on sync!");
   perror(" ");
   goto err;
  }

    } while (DisplayVideoData);

    if (threadparams)
  delete(threadparams);
    close(fd);

    err:

     if (threadparams)
      delete(threadparams);

     close(fd);

return NULL;
}