Documentation/video4linux/v4lgrab.c

   1 /* Simple Video4Linux image grabber. */
   2 /*
   3  *      Video4Linux Driver Test/Example Framegrabbing Program
   4  *
   5  *      Compile with:
   6  *              gcc -s -Wall -Wstrict-prototypes v4lgrab.c -o v4lgrab
   7  *      Use as:
   8  *              v4lgrab >image.ppm
   9  *
  10  *      Copyright (C) 1998-05-03, Phil Blundell <philb@gnu.org>
  11  *      Copied from http://www.tazenda.demon.co.uk/phil/vgrabber.c
  12  *      with minor modifications (Dave Forrest, drf5n@virginia.edu).
  13  *
  14  */
  15
  16 #include <unistd.h>
  17 #include <sys/types.h>
  18 #include <sys/stat.h>
  19 #include <fcntl.h>
  20 #include <stdio.h>
  21 #include <sys/ioctl.h>
  22 #include <stdlib.h>
  23
  24 #include <linux/types.h>
  25 #include <linux/videodev.h>
  26
  27 #define FILE "/dev/video0"
  28
  29 /* Stole this from tvset.c */
  30
  31 #define READ_VIDEO_PIXEL(buf, format, depth, r, g, b)                   \
  32 {                                                                       \
  33         switch (format)                                                 \
  34         {                                                               \
  35                 case VIDEO_PALETTE_GREY:                                \
  36                         switch (depth)                                  \
  37                         {                                               \
  38                                 case 4:                                 \
  39                                 case 6:                                 \
  40                                 case 8:                                 \
  41                                         (r) = (g) = (b) = (*buf++ << 8);\
  42                                         break;                          \
  43                                                                         \
  44                                 case 16:                                \
  45                                         (r) = (g) = (b) =               \
  46                                                 *((unsigned short *) buf);      \
  47                                         buf += 2;                       \
  48                                         break;                          \
  49                         }                                               \
  50                         break;                                          \
  51                                                                         \
  52                                                                         \
  53                 case VIDEO_PALETTE_RGB565:                              \
  54                 {                                                       \
  55                         unsigned short tmp = *(unsigned short *)buf;    \
  56                         (r) = tmp&0xF800;                               \
  57                         (g) = (tmp<<5)&0xFC00;                          \
  58                         (b) = (tmp<<11)&0xF800;                         \
  59                         buf += 2;                                       \
  60                 }                                                       \
  61                 break;                                                  \
  62                                                                         \
  63                 case VIDEO_PALETTE_RGB555:                              \
  64                         (r) = (buf[0]&0xF8)<<8;                         \
  65                         (g) = ((buf[0] << 5 | buf[1] >> 3)&0xF8)<<8;    \
  66                         (b) = ((buf[1] << 2 ) & 0xF8)<<8;               \
  67                         buf += 2;                                       \
  68                         break;                                          \
  69                                                                         \
  70                 case VIDEO_PALETTE_RGB24:                               \
  71                         (r) = buf[0] << 8; (g) = buf[1] << 8;           \
  72                         (b) = buf[2] << 8;                              \
  73                         buf += 3;                                       \
  74                         break;                                          \
  75                                                                         \
  76                 default:                                                \
  77                         fprintf(stderr,                                 \
  78                                 "Format %d not yet supported\n",        \
  79                                 format);                                \
  80         }                                                               \
  81 }
  82
  83 int get_brightness_adj(unsigned char *image, long size, int *brightness) {
  84   long i, tot = 0;
  85   for (i=0;i<size*3;i++)
  86     tot += image[i];
  87   *brightness = (128 - tot/(size*3))/3;
  88   return !((tot/(size*3)) >= 126 && (tot/(size*3)) <= 130);
  89 }
  90
  91 int main(int argc, char ** argv)
  92 {
  93   int fd = open(FILE, O_RDONLY), f;
  94   struct video_capability cap;
  95   struct video_window win;
  96   struct video_picture vpic;
  97
  98   unsigned char *buffer, *src;
  99   int bpp = 24, r, g, b;
 100   unsigned int i, src_depth;
 101
 102   if (fd < 0) {
 103     perror(FILE);
 104     exit(1);
 105   }
 106
 107   if (ioctl(fd, VIDIOCGCAP, &cap) < 0) {
 108     perror("VIDIOGCAP");
 109     fprintf(stderr, "(" FILE " not a video4linux device?)\n");
 110     close(fd);
 111     exit(1);
 112   }
 113
 114   if (ioctl(fd, VIDIOCGWIN, &win) < 0) {
 115     perror("VIDIOCGWIN");
 116     close(fd);
 117     exit(1);
 118   }
 119
 120   if (ioctl(fd, VIDIOCGPICT, &vpic) < 0) {
 121     perror("VIDIOCGPICT");
 122     close(fd);
 123     exit(1);
 124   }
 125
 126   if (cap.type & VID_TYPE_MONOCHROME) {
 127     vpic.depth=8;
 128     vpic.palette=VIDEO_PALETTE_GREY;    /* 8bit grey */
 129     if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
 130       vpic.depth=6;
 131       if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
 132         vpic.depth=4;
 133         if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
 134           fprintf(stderr, "Unable to find a supported capture format.\n");
 135           close(fd);
 136           exit(1);
 137         }
 138       }
 139     }
 140   } else {
 141     vpic.depth=24;
 142     vpic.palette=VIDEO_PALETTE_RGB24;
 143
 144     if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
 145       vpic.palette=VIDEO_PALETTE_RGB565;
 146       vpic.depth=16;
 147
 148       if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) {
 149         vpic.palette=VIDEO_PALETTE_RGB555;
 150         vpic.depth=15;
 151
 152         if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) {
 153           fprintf(stderr, "Unable to find a supported capture format.\n");
 154           return -1;
 155         }
 156       }
 157     }
 158   }
 159
 160   buffer = malloc(win.width * win.height * bpp);
 161   if (!buffer) {
 162     fprintf(stderr, "Out of memory.\n");
 163     exit(1);
 164   }
 165
 166   do {
 167     int newbright;
 168     read(fd, buffer, win.width * win.height * bpp);
 169     f = get_brightness_adj(buffer, win.width * win.height, &newbright);
 170     if (f) {
 171       vpic.brightness += (newbright << 8);
 172       if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) {
 173         perror("VIDIOSPICT");
 174         break;
 175       }
 176     }
 177   } while (f);
 178
 179   fprintf(stdout, "P6\n%d %d 255\n", win.width, win.height);
 180
 181   src = buffer;
 182
 183   for (i = 0; i < win.width * win.height; i++) {
 184     READ_VIDEO_PIXEL(src, vpic.palette, src_depth, r, g, b);
 185     fputc(r>>8, stdout);
 186     fputc(g>>8, stdout);
 187     fputc(b>>8, stdout);
 188   }
 189
 190   close(fd);
 191   return 0;
 192 }