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  *      For some cameras you may need to pre-load libv4l to perform
  16  *      the necessary decompression, e.g.:
  17  *
  18  *      export LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so
  19  *      ./v4lgrab >image.ppm
  20  *
  21  *      see http://hansdegoede.livejournal.com/3636.html for details.
  22  *
  23  */
  24
  25 #include <unistd.h>
  26 #include <sys/types.h>
  27 #include <sys/stat.h>
  28 #include <fcntl.h>
  29 #include <stdio.h>
  30 #include <sys/ioctl.h>
  31 #include <stdlib.h>
  32
  33 #include <linux/types.h>
  34 #include <linux/videodev.h>
  35
  36 #define VIDEO_DEV "/dev/video0"
  37
  38 /* Stole this from tvset.c */
  39
  40 #define READ_VIDEO_PIXEL(buf, format, depth, r, g, b)                   \
  41 {                                                                       \
  42         switch (format)                                                 \
  43         {                                                               \
  44                 case VIDEO_PALETTE_GREY:                                \
  45                         switch (depth)                                  \
  46                         {                                               \
  47                                 case 4:                                 \
  48                                 case 6:                                 \
  49                                 case 8:                                 \
  50                                         (r) = (g) = (b) = (*buf++ << 8);\
  51                                         break;                          \
  52                                                                         \
  53                                 case 16:                                \
  54                                         (r) = (g) = (b) =               \
  55                                                 *((unsigned short *) buf);      \
  56                                         buf += 2;                       \
  57                                         break;                          \
  58                         }                                               \
  59                         break;                                          \
  60                                                                         \
  61                                                                         \
  62                 case VIDEO_PALETTE_RGB565:                              \
  63                 {                                                       \
  64                         unsigned short tmp = *(unsigned short *)buf;    \
  65                         (r) = tmp&0xF800;                               \
  66                         (g) = (tmp<<5)&0xFC00;                          \
  67                         (b) = (tmp<<11)&0xF800;                         \
  68                         buf += 2;                                       \
  69                 }                                                       \
  70                 break;                                                  \
  71                                                                         \
  72                 case VIDEO_PALETTE_RGB555:                              \
  73                         (r) = (buf[0]&0xF8)<<8;                         \
  74                         (g) = ((buf[0] << 5 | buf[1] >> 3)&0xF8)<<8;    \
  75                         (b) = ((buf[1] << 2 ) & 0xF8)<<8;               \
  76                         buf += 2;                                       \
  77                         break;                                          \
  78                                                                         \
  79                 case VIDEO_PALETTE_RGB24:                               \
  80                         (r) = buf[0] << 8; (g) = buf[1] << 8;           \
  81                         (b) = buf[2] << 8;                              \
  82                         buf += 3;                                       \
  83                         break;                                          \
  84                                                                         \
  85                 default:                                                \
  86                         fprintf(stderr,                                 \
  87                                 "Format %d not yet supported\n",        \
  88                                 format);                                \
  89         }                                                               \
  90 }
  91
  92 static int get_brightness_adj(unsigned char *image, long size, int *brightness) {
  93   long i, tot = 0;
  94   for (i=0;i<size*3;i++)
  95     tot += image[i];
  96   *brightness = (128 - tot/(size*3))/3;
  97   return !((tot/(size*3)) >= 126 && (tot/(size*3)) <= 130);
  98 }
  99
 100 int main(int argc, char ** argv)
 101 {
 102   int fd = open(VIDEO_DEV, O_RDONLY), f;
 103   struct video_capability cap;
 104   struct video_window win;
 105   struct video_picture vpic;
 106
 107   unsigned char *buffer, *src;
 108   int bpp = 24, r = 0, g = 0, b = 0;
 109   unsigned int i, src_depth = 16;
 110
 111   if (fd < 0) {
 112     perror(VIDEO_DEV);
 113     exit(1);
 114   }
 115
 116   if (ioctl(fd, VIDIOCGCAP, &cap) < 0) {
 117     perror("VIDIOGCAP");
 118     fprintf(stderr, "(" VIDEO_DEV " not a video4linux device?)\n");
 119     close(fd);
 120     exit(1);
 121   }
 122
 123   if (ioctl(fd, VIDIOCGWIN, &win) < 0) {
 124     perror("VIDIOCGWIN");
 125     close(fd);
 126     exit(1);
 127   }
 128
 129   if (ioctl(fd, VIDIOCGPICT, &vpic) < 0) {
 130     perror("VIDIOCGPICT");
 131     close(fd);
 132     exit(1);
 133   }
 134
 135   if (cap.type & VID_TYPE_MONOCHROME) {
 136     vpic.depth=8;
 137     vpic.palette=VIDEO_PALETTE_GREY;    /* 8bit grey */
 138     if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
 139       vpic.depth=6;
 140       if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
 141         vpic.depth=4;
 142         if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
 143           fprintf(stderr, "Unable to find a supported capture format.\n");
 144           close(fd);
 145           exit(1);
 146         }
 147       }
 148     }
 149   } else {
 150     vpic.depth=24;
 151     vpic.palette=VIDEO_PALETTE_RGB24;
 152
 153     if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
 154       vpic.palette=VIDEO_PALETTE_RGB565;
 155       vpic.depth=16;
 156
 157       if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) {
 158         vpic.palette=VIDEO_PALETTE_RGB555;
 159         vpic.depth=15;
 160
 161         if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) {
 162           fprintf(stderr, "Unable to find a supported capture format.\n");
 163           return -1;
 164         }
 165       }
 166     }
 167   }
 168
 169   buffer = malloc(win.width * win.height * bpp);
 170   if (!buffer) {
 171     fprintf(stderr, "Out of memory.\n");
 172     exit(1);
 173   }
 174
 175   do {
 176     int newbright;
 177     read(fd, buffer, win.width * win.height * bpp);
 178     f = get_brightness_adj(buffer, win.width * win.height, &newbright);
 179     if (f) {
 180       vpic.brightness += (newbright << 8);
 181       if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) {
 182         perror("VIDIOSPICT");
 183         break;
 184       }
 185     }
 186   } while (f);
 187
 188   fprintf(stdout, "P6\n%d %d 255\n", win.width, win.height);
 189
 190   src = buffer;
 191
 192   for (i = 0; i < win.width * win.height; i++) {
 193     READ_VIDEO_PIXEL(src, vpic.palette, src_depth, r, g, b);
 194     fputc(r>>8, stdout);
 195     fputc(g>>8, stdout);
 196     fputc(b>>8, stdout);
 197   }
 198
 199   close(fd);
 200   return 0;
 201 }