V4L2采集圖片源碼分享

把v4l2采集圖片測試程序，貼在這和大家共享，在此基礎上可以使實現視頻的采集，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。

采集效果如下：

源碼如下：

1. #include <stdio.h>
2. #include <stdlib.h>
3. #include <string.h>
4. #include <assert.h>
6. #include <getopt.h>
8. #include <fcntl.h>
9. #include <unistd.h>
10. #include <errno.h>
11. #include <malloc.h>
12. #include <sys/stat.h>
13. #include <sys/types.h>
14. #include <sys/time.h>
15. #include <sys/mman.h>
16. #include <sys/ioctl.h>
18. #include <asm/types.h>
19. #include <linux/videodev2.h>
21. #define CLEAR(x) memset (&(x), 0, sizeof (x))
23. struct buffer {
24. void * start;
25. size_t length;
26. };
28. static char * dev_name = "/dev/video0";
29. static int fd = -1;
30. struct buffer * buffers = NULL;
32. FILE *file_fd;
33. static unsigned long file_length;
34. static unsigned char *file_name;
36. int main (int argc,char ** argv)
37. {
38. struct v4l2_capability cap;
39. struct v4l2_format fmt;
41. file_fd = fopen("test.jpg", "w");
43. fd = open (dev_name, O_RDWR /* required */ | O_NONBLOCK, 0);
45. ioctl (fd, VIDIOC_QUERYCAP, &cap);
47. CLEAR (fmt);
48. fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
49. fmt.fmt.pix.width = 640;
50. fmt.fmt.pix.height = 480;
51. fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
52. fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
53. ioctl (fd, VIDIOC_S_FMT, &fmt);
55. file_length = fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;
57. buffers = calloc (1, sizeof (*buffers));
59. buffers[0].length = file_length;
60. buffers[0].start = malloc (file_length);
62. for (;;)
63. {
64. fd_set fds;
65. struct timeval tv;
66. int r;
68. FD_ZERO (&fds);
69. FD_SET (fd, &fds);
71. /* Timeout. */
72. tv.tv_sec = 3;
73. tv.tv_usec = 0;
75. r = select (fd + 1, &fds, NULL, NULL, &tv);
77. if (-1 == r) {
78. if (EINTR == errno)
79. continue;
80. printf ("select");
81. }
83. if (0 == r) {
84. fprintf (stderr, "select timeout\n");
85. exit (EXIT_FAILURE);
86. }
88. if (read (fd, buffers[0].start, buffers[0].length))
89. break;
90. }
92. fwrite(buffers[0].start, buffers[0].length, 1, file_fd);
94. free (buffers[0].start);
95. close (fd);
96. fclose (file_fd);
97. exit (EXIT_SUCCESS);
98. return 0;
99. }