diff options
| -rw-r--r-- | Documentation/video4linux/v4lgrab.c | 25 |
1 files changed, 17 insertions, 8 deletions
diff --git a/Documentation/video4linux/v4lgrab.c b/Documentation/video4linux/v4lgrab.c index 079b628481c..d6e70bef8ad 100644 --- a/Documentation/video4linux/v4lgrab.c +++ b/Documentation/video4linux/v4lgrab.c @@ -4,12 +4,21 @@ * * Compile with: * gcc -s -Wall -Wstrict-prototypes v4lgrab.c -o v4lgrab - * Use as: - * v4lgrab >image.ppm + * 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). + * Copied from http://www.tazenda.demon.co.uk/phil/vgrabber.c + * with minor modifications (Dave Forrest, drf5n@virginia.edu). + * + * + * For some cameras you may need to pre-load libv4l to perform + * the necessary decompression, e.g.: + * + * export LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so + * ./v4lgrab >image.ppm + * + * see http://hansdegoede.livejournal.com/3636.html for details. * */ @@ -24,7 +33,7 @@ #include <linux/types.h> #include <linux/videodev.h> -#define FILE "/dev/video0" +#define VIDEO_DEV "/dev/video0" /* Stole this from tvset.c */ @@ -90,7 +99,7 @@ int get_brightness_adj(unsigned char *image, long size, int *brightness) { int main(int argc, char ** argv) { - int fd = open(FILE, O_RDONLY), f; + int fd = open(VIDEO_DEV, O_RDONLY), f; struct video_capability cap; struct video_window win; struct video_picture vpic; @@ -100,13 +109,13 @@ int main(int argc, char ** argv) unsigned int i, src_depth; if (fd < 0) { - perror(FILE); + perror(VIDEO_DEV); exit(1); } if (ioctl(fd, VIDIOCGCAP, &cap) < 0) { perror("VIDIOGCAP"); - fprintf(stderr, "(" FILE " not a video4linux device?)\n"); + fprintf(stderr, "(" VIDEO_DEV " not a video4linux device?)\n"); close(fd); exit(1); } |