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r: 29979
b: refs/heads/master
c: a22f1cb
h: refs/heads/master
i:
  29977: 9fa7f74
  29975: 327c60e
v: v3
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Randy Dunlap authored and Mauro Carvalho Chehab committed Jun 25, 2006
1 parent b989856 commit c424f12
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2 changes: 1 addition & 1 deletion [refs]
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---
refs/heads/master: c003d467bd71a7da22554e0d812a646ab58abea5
refs/heads/master: a22f1cbc2d3acd99986e96092109f6ced0f0022e
203 changes: 3 additions & 200 deletions trunk/Documentation/video4linux/CQcam.txt
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Expand Up @@ -185,207 +185,10 @@ this work is documented at the video4linux2 site listed below.

9.0 --- A sample program using v4lgrabber,

This program is a simple image grabber that will copy a frame from the
v4lgrab is a simple image grabber that will copy a frame from the
first video device, /dev/video0 to standard output in portable pixmap
format (.ppm) Using this like: 'v4lgrab | convert - c-qcam.jpg'
produced this picture of me at
http://mug.sys.virginia.edu/~drf5n/extras/c-qcam.jpg

-------------------- 8< ---------------- 8< -----------------------------

/* Simple Video4Linux image grabber. */
/*
* Video4Linux Driver Test/Example Framegrabbing Program
*
* Compile with:
* gcc -s -Wall -Wstrict-prototypes v4lgrab.c -o v4lgrab
* Use as:
* v4lgrab >image.ppm
*
* Copyright (C) 1998-05-03, Phil Blundell <philb@gnu.org>
* Copied from http://www.tazenda.demon.co.uk/phil/vgrabber.c
* with minor modifications (Dave Forrest, drf5n@virginia.edu).
*
*/

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

#define FILE "/dev/video0"

/* Stole this from tvset.c */

#define READ_VIDEO_PIXEL(buf, format, depth, r, g, b) \
{ \
switch (format) \
{ \
case VIDEO_PALETTE_GREY: \
switch (depth) \
{ \
case 4: \
case 6: \
case 8: \
(r) = (g) = (b) = (*buf++ << 8);\
break; \
\
case 16: \
(r) = (g) = (b) = \
*((unsigned short *) buf); \
buf += 2; \
break; \
} \
break; \
\
\
case VIDEO_PALETTE_RGB565: \
{ \
unsigned short tmp = *(unsigned short *)buf; \
(r) = tmp&0xF800; \
(g) = (tmp<<5)&0xFC00; \
(b) = (tmp<<11)&0xF800; \
buf += 2; \
} \
break; \
\
case VIDEO_PALETTE_RGB555: \
(r) = (buf[0]&0xF8)<<8; \
(g) = ((buf[0] << 5 | buf[1] >> 3)&0xF8)<<8; \
(b) = ((buf[1] << 2 ) & 0xF8)<<8; \
buf += 2; \
break; \
\
case VIDEO_PALETTE_RGB24: \
(r) = buf[0] << 8; (g) = buf[1] << 8; \
(b) = buf[2] << 8; \
buf += 3; \
break; \
\
default: \
fprintf(stderr, \
"Format %d not yet supported\n", \
format); \
} \
}

int get_brightness_adj(unsigned char *image, long size, int *brightness) {
long i, tot = 0;
for (i=0;i<size*3;i++)
tot += image[i];
*brightness = (128 - tot/(size*3))/3;
return !((tot/(size*3)) >= 126 && (tot/(size*3)) <= 130);
}

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 int i, 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) {
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;
}
}
}
}

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

do {
int newbright;
read(fd, buffer, win.width * win.height * bpp);
f = get_brightness_adj(buffer, win.width * win.height, &newbright);
if (f) {
vpic.brightness += (newbright << 8);
if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) {
perror("VIDIOSPICT");
break;
}
}
} while (f);

fprintf(stdout, "P6\n%d %d 255\n", win.width, win.height);

src = buffer;

for (i = 0; i < win.width * win.height; i++) {
READ_VIDEO_PIXEL(src, vpic.palette, src_depth, r, g, b);
fputc(r>>8, stdout);
fputc(g>>8, stdout);
fputc(b>>8, stdout);
}

close(fd);
return 0;
}
-------------------- 8< ---------------- 8< -----------------------------
format (.ppm) To produce .jpg output, you can use it like this:
'v4lgrab | convert - c-qcam.jpg'


10.0 --- Other Information
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