V4L image grab

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Hi,

with this code from the internet I only get pictures with some undefined pixels on the top and black pixels on the bottom.

Where's the problem? I only want a simple example for image captureing.

Here is the code:

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <libv4l1.h>
#include <linux/videodev.h>

#define GES_LAENGE (640*480)

unsigned char  bild[GES_LAENGE];

int main()
{
       int fd;
       long laenge;
       struct video_window video_win;
       FILE *bilddatei;

       if((fd = v4l1_open("/dev/video0", O_RDONLY)) == -1)
       {
               printf("Fehler beim Oeffnen von /dev/video0\r\n");
               return 1;
       }
       if( v4l1_ioctl( fd, VIDIOCGWIN, &video_win) == -1)
       {
               printf("Fehler beim setzen der Einstellungen\r\n");
               return 1;
       }
       laenge = video_win.width * video_win.height;
       if( laenge > GES_LAENGE)
       {
               printf("Bild ist groesser als angegeben\r\n");
               return 1;
       }


       if( v4l1_read( fd, bild, laenge) == -1)
       {
               printf("Auslesen der Kamera nicht möglch\r\n");
               return 1;
       }
       if((bilddatei = fopen( "bild.ppm", "w+b")) == NULL)
       {
               printf("Konnte die datei zum schreiben nicht öffnen\r\n");
               return 1;
       }
       v4l1_close(fd);
       fprintf( bilddatei, "P6\n%d %d\n255\n",video_win.width,
video_win.height);
       fwrite( bild, 1, video_win.width*video_win.height,bilddatei);
       fclose(bilddatei);
       return 0;
}

Regards, Joern
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