/* v4lfps.c: based on Phil Blundell's v4lgrab.c */

#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <stdlib.h>
#include <signal.h>

#include <linux/types.h>
#include <linux/videodev.h>

#define FILE "/dev/video0"

volatile int i = 0;

void timeout(int x)
{
  printf("Read %d frames in 10 seconds.\n", i);
  exit(0);
}

int main(int argc, char ** argv)
{
  int fd = open(FILE, O_RDONLY), f;
  struct video_capability cap;
  struct video_window win;
  struct video_picture vpic;

  unsigned char *buffer, *src;
  int bpp = 24, r, g, b;
  unsigned src_depth;

  if (fd < 0) {
    perror(FILE);
    exit(1);
  }

  if (ioctl(fd, VIDIOCGCAP, &cap) < 0) {
    perror("VIDIOGCAP");
    fprintf(stderr, "(" FILE " not a video4linux device?)\n");
    close(fd);
    exit(1);
  }

  if (ioctl(fd, VIDIOCGWIN, &win) < 0) {
    perror("VIDIOCGWIN");
    close(fd);
    exit(1);
  }

  if (ioctl(fd, VIDIOCGPICT, &vpic) < 0) {
    perror("VIDIOCGPICT");
    close(fd);
    exit(1);
  }

  if (cap.type & VID_TYPE_MONOCHROME) {
    bpp = 8;
    vpic.depth=8;
    vpic.palette=VIDEO_PALETTE_GREY;    /* 8bit grey */
    if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
      vpic.depth=6;
      if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
        vpic.depth=4;
        if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
          fprintf(stderr, "Unable to find a supported capture format.\n");
          close(fd);
          exit(1);
        }
      }
    }
  } else {
    vpic.depth=24;
    vpic.palette=VIDEO_PALETTE_RGB24;
    
    if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
      vpic.palette=VIDEO_PALETTE_RGB565;
      vpic.depth=16;
      
      if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) {
        vpic.palette=VIDEO_PALETTE_RGB555;
        vpic.depth=15;
        
        if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) {
          fprintf(stderr, "Unable to find a supported capture format.\n");
          return -1;
        }
      }
    }
  }

  bpp /= 8;

  buffer = malloc(win.width * win.height * bpp);
  if (!buffer) {
    fprintf(stderr, "Out of memory.\n");
    exit(1);
  }

  printf("Waiting for 10 seconds to measure FPS...\n");
  fflush(stdout);

  i = 0;

  signal(SIGALRM, timeout);
  alarm(10);

  while (1) {
    read(fd, buffer, win.width * win.height * bpp);
    i++;
  }

  return 0;
}