那些年啊，那些事—V4L2採集圖片源碼分享

把v4l2採集圖片測試程式，貼在這和大家共用，在此基礎上可以使實現視頻的採集，只不過在pc機上寫個上位機進行顯示或者直接寫個Qt在開發板上顯示即可，

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採集效果如下：

源碼如下：

#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;}