那些年啊，那些事---V4L2采集图片源码分享

把v4l2采集图片测试程序，贴在这和大家共享，在此基础上可以使实现视频的采集，只不过在pc机上写个上位机进行显示或者直接写个Qt在开发板上显示即可，

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采集效果如下：

源码如下：

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <assert.h> #include <getopt.h> #include <fcntl.h> #include <unistd.h> #include <errno.h> #include <malloc.h> #include <sys/stat.h> #include <sys/types.h> #include <sys/time.h> #include <sys/mman.h> #include <sys/ioctl.h> #include <asm/types.h> #include <linux/videodev2.h> #define CLEAR(x) memset (&(x), 0, sizeof (x)) struct buffer { void * start; size_t length; }; static char * dev_name = "/dev/video0"; static int fd = -1; struct buffer * buffers = NULL; FILE *file_fd; static unsigned long file_length; static unsigned char *file_name; int main (int argc,char ** argv) { struct v4l2_capability cap; struct v4l2_format fmt; file_fd = fopen("test.jpg", "w"); fd = open (dev_name, O_RDWR /* required */ | O_NONBLOCK, 0); ioctl (fd, VIDIOC_QUERYCAP, &cap); CLEAR (fmt); fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; fmt.fmt.pix.width = 640; fmt.fmt.pix.height = 480; fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV; fmt.fmt.pix.field = V4L2_FIELD_INTERLACED; ioctl (fd, VIDIOC_S_FMT, &fmt); file_length = fmt.fmt.pix.bytesperline * fmt.fmt.pix.height; buffers = calloc (1, sizeof (*buffers)); buffers[0].length = file_length; buffers[0].start = malloc (file_length); for (;;) { fd_set fds; struct timeval tv; int r; FD_ZERO (&fds); FD_SET (fd, &fds); /* Timeout. */ tv.tv_sec = 3; tv.tv_usec = 0; r = select (fd + 1, &fds, NULL, NULL, &tv); if (-1 == r) { if (EINTR == errno) continue; printf ("select"); } if (0 == r) { fprintf (stderr, "select timeout\n"); exit (EXIT_FAILURE); } if (read (fd, buffers[0].start, buffers[0].length)) break; } fwrite(buffers[0].start, buffers[0].length, 1, file_fd); free (buffers[0].start); close (fd); fclose (file_fd); exit (EXIT_SUCCESS); return 0; }