![Mauro Carvalho Chehab](/assets/img/avatar_default.png)
Documentation/video4linux/v4lgrab.c: In function ‘main’: Documentation/video4linux/v4lgrab.c:193: warning: ‘src_depth’ is used uninitialized in this function Documentation/video4linux/v4lgrab.c:108: warning: ‘b’ may be used uninitialized in this function Documentation/video4linux/v4lgrab.c:108: warning: ‘g’ may be used uninitialized in this function Documentation/video4linux/v4lgrab.c:108: warning: ‘r’ may be used uninitialized in this function Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
202 lines
5.7 KiB
C
202 lines
5.7 KiB
C
/* Simple Video4Linux image grabber. */
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/*
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* Video4Linux Driver Test/Example Framegrabbing Program
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*
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* Compile with:
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* gcc -s -Wall -Wstrict-prototypes v4lgrab.c -o v4lgrab
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* Use as:
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* v4lgrab >image.ppm
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*
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* Copyright (C) 1998-05-03, Phil Blundell <philb@gnu.org>
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* Copied from http://www.tazenda.demon.co.uk/phil/vgrabber.c
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* with minor modifications (Dave Forrest, drf5n@virginia.edu).
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*
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*
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* For some cameras you may need to pre-load libv4l to perform
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* the necessary decompression, e.g.:
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*
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* export LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so
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* ./v4lgrab >image.ppm
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*
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* see http://hansdegoede.livejournal.com/3636.html for details.
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*
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*/
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <sys/ioctl.h>
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#include <stdlib.h>
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#include <linux/types.h>
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#include <linux/videodev.h>
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#define VIDEO_DEV "/dev/video0"
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/* Stole this from tvset.c */
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#define READ_VIDEO_PIXEL(buf, format, depth, r, g, b) \
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{ \
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switch (format) \
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{ \
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case VIDEO_PALETTE_GREY: \
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switch (depth) \
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{ \
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case 4: \
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case 6: \
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case 8: \
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(r) = (g) = (b) = (*buf++ << 8);\
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break; \
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\
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case 16: \
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(r) = (g) = (b) = \
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*((unsigned short *) buf); \
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buf += 2; \
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break; \
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} \
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break; \
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\
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\
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case VIDEO_PALETTE_RGB565: \
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{ \
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unsigned short tmp = *(unsigned short *)buf; \
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(r) = tmp&0xF800; \
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(g) = (tmp<<5)&0xFC00; \
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(b) = (tmp<<11)&0xF800; \
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buf += 2; \
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} \
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break; \
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\
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case VIDEO_PALETTE_RGB555: \
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(r) = (buf[0]&0xF8)<<8; \
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(g) = ((buf[0] << 5 | buf[1] >> 3)&0xF8)<<8; \
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(b) = ((buf[1] << 2 ) & 0xF8)<<8; \
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buf += 2; \
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break; \
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\
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case VIDEO_PALETTE_RGB24: \
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(r) = buf[0] << 8; (g) = buf[1] << 8; \
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(b) = buf[2] << 8; \
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buf += 3; \
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break; \
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\
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default: \
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fprintf(stderr, \
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"Format %d not yet supported\n", \
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format); \
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} \
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}
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int get_brightness_adj(unsigned char *image, long size, int *brightness) {
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long i, tot = 0;
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for (i=0;i<size*3;i++)
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tot += image[i];
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*brightness = (128 - tot/(size*3))/3;
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return !((tot/(size*3)) >= 126 && (tot/(size*3)) <= 130);
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}
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int main(int argc, char ** argv)
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{
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int fd = open(VIDEO_DEV, O_RDONLY), f;
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struct video_capability cap;
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struct video_window win;
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struct video_picture vpic;
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unsigned char *buffer, *src;
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int bpp = 24, r = 0, g = 0, b = 0;
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unsigned int i, src_depth = 16;
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if (fd < 0) {
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perror(VIDEO_DEV);
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exit(1);
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}
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if (ioctl(fd, VIDIOCGCAP, &cap) < 0) {
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perror("VIDIOGCAP");
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fprintf(stderr, "(" VIDEO_DEV " not a video4linux device?)\n");
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close(fd);
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exit(1);
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}
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if (ioctl(fd, VIDIOCGWIN, &win) < 0) {
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perror("VIDIOCGWIN");
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close(fd);
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exit(1);
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}
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if (ioctl(fd, VIDIOCGPICT, &vpic) < 0) {
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perror("VIDIOCGPICT");
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close(fd);
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exit(1);
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}
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if (cap.type & VID_TYPE_MONOCHROME) {
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vpic.depth=8;
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vpic.palette=VIDEO_PALETTE_GREY; /* 8bit grey */
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if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
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vpic.depth=6;
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if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
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vpic.depth=4;
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if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
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fprintf(stderr, "Unable to find a supported capture format.\n");
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close(fd);
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exit(1);
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}
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}
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}
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} else {
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vpic.depth=24;
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vpic.palette=VIDEO_PALETTE_RGB24;
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if(ioctl(fd, VIDIOCSPICT, &vpic) < 0) {
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vpic.palette=VIDEO_PALETTE_RGB565;
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vpic.depth=16;
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if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) {
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vpic.palette=VIDEO_PALETTE_RGB555;
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vpic.depth=15;
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if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) {
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fprintf(stderr, "Unable to find a supported capture format.\n");
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return -1;
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}
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}
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}
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}
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buffer = malloc(win.width * win.height * bpp);
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if (!buffer) {
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fprintf(stderr, "Out of memory.\n");
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exit(1);
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}
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do {
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int newbright;
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read(fd, buffer, win.width * win.height * bpp);
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f = get_brightness_adj(buffer, win.width * win.height, &newbright);
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if (f) {
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vpic.brightness += (newbright << 8);
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if(ioctl(fd, VIDIOCSPICT, &vpic)==-1) {
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perror("VIDIOSPICT");
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break;
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}
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}
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} while (f);
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fprintf(stdout, "P6\n%d %d 255\n", win.width, win.height);
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src = buffer;
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for (i = 0; i < win.width * win.height; i++) {
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READ_VIDEO_PIXEL(src, vpic.palette, src_depth, r, g, b);
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fputc(r>>8, stdout);
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fputc(g>>8, stdout);
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fputc(b>>8, stdout);
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}
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close(fd);
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return 0;
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}
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