基于GTK的USB视频采集测试程序

#include <asm/types.h> /* for videodev2.h */ #include <fcntl.h> /* low-level i/o */ #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 <stdio.h> #include <stdlib.h> #include <string.h> #include <assert.h> #include "v4l2.h" #define CLEAR(x) memset (&(x), 0, sizeof (x)) static unsigned int n_buffers = 0; void errno_exit(const char *s) { fprintf (stderr, "%s error %d, %s\n", s, errno, strerror (errno)); exit (EXIT_FAILURE); } static int xioctl(int fd, int request, void *arg) { int r; do { r = ioctl (fd, request, arg); } while (-1 == r && EINTR == errno); return r; } void open_camera(struct camera *cam) { struct stat st; if (-1 == stat (cam->device_name, &st)) { fprintf (stderr, "Cannot identify '%s': %d, %s\n", cam->device_name, errno, strerror (errno)); exit (EXIT_FAILURE); } if (!S_ISCHR (st.st_mode)) { fprintf (stderr, "%s is no device\n", cam->device_name); exit (EXIT_FAILURE); } cam->fd = open (cam->device_name, O_RDWR /* required */ | O_NONBLOCK, 0); if (-1 == cam->fd) { fprintf (stderr, "Cannot open '%s': %d, %s\n", cam->device_name, errno, strerror (errno)); exit (EXIT_FAILURE); } } void close_camera(struct camera *cam) { if (-1 == close (cam->fd)) errno_exit ("close"); cam->fd = -1; } int read_frame(struct camera *cam) { struct v4l2_buffer buf; CLEAR (buf); buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; buf.memory = V4L2_MEMORY_MMAP; if (quit_flag == 0) { if (-1 == xioctl (cam->fd, VIDIOC_DQBUF, &buf)) { switch (errno) { case EAGAIN: return 0; case EIO: /* Could ignore EIO, see spec. */ /* fall through */ default: errno_exit ("VIDIOC_DQBUF"); } } } assert (buf.index < n_buffers); process_image (cam->buffers[buf.index].start, cam); if (quit_flag == 0) { if (-1 == xioctl (cam->fd, VIDIOC_QBUF, &buf)) errno_exit ("VIDIOC_QBUF"); } return 1; } void start_capturing(struct camera *cam) { unsigned int i; enum v4l2_buf_type type; for (i = 0; i < n_buffers; ++i) { struct v4l2_buffer buf; CLEAR (buf); buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; buf.memory = V4L2_MEMORY_MMAP; buf.index = i; if (-1 == xioctl (cam->fd, VIDIOC_QBUF, &buf)) errno_exit ("VIDIOC_QBUF"); } type = V4L2_BUF_TYPE_VIDEO_CAPTURE; if (-1 == xioctl (cam->fd, VIDIOC_STREAMON, &type)) errno_exit ("VIDIOC_STREAMON"); } void stop_capturing(struct camera *cam) { enum v4l2_buf_type type; type = V4L2_BUF_TYPE_VIDEO_CAPTURE; if (-1 == xioctl (cam->fd, VIDIOC_STREAMOFF, &type)) errno_exit ("VIDIOC_STREAMOFF"); } void uninit_camera(struct camera *cam) { unsigned int i; for (i = 0; i < n_buffers; ++i) if (-1 == munmap (cam->buffers[i].start, cam->buffers[i].length)) errno_exit ("munmap"); free (cam->buffers); } static void init_mmap(struct camera *cam) { struct v4l2_requestbuffers req; CLEAR (req); req.count = 4; req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; req.memory = V4L2_MEMORY_MMAP; if (-1 == xioctl (cam->fd, VIDIOC_REQBUFS, &req)) { if (EINVAL == errno) { fprintf (stderr, "%s does not support " "memory mapping\n", cam->device_name); exit (EXIT_FAILURE); } else { errno_exit ("VIDIOC_REQBUFS"); } } if (req.count < 2) { fprintf (stderr, "Insufficient buffer memory on %s\n", cam->device_name); exit (EXIT_FAILURE); } cam->buffers = calloc (req.count, sizeof (*(cam->buffers))); if (!cam->buffers) { fprintf (stderr, "Out of memory\n"); exit (EXIT_FAILURE); } for (n_buffers = 0; n_buffers < req.count; ++(n_buffers)) { struct v4l2_buffer buf; CLEAR (buf); buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; buf.memory = V4L2_MEMORY_MMAP; buf.index = n_buffers; if (-1 == xioctl (cam->fd, VIDIOC_QUERYBUF, &buf)) errno_exit ("VIDIOC_QUERYBUF"); cam->buffers[n_buffers].length = buf.length; cam->buffers[n_buffers].start = mmap (NULL /* start anywhere */, buf.length, PROT_READ | PROT_WRITE /* required */, MAP_SHARED /* recommended */, cam->fd, buf.m.offset); if (MAP_FAILED == cam->buffers[n_buffers].start) errno_exit ("mmap"); } } void init_camera(struct camera *cam) { struct v4l2_capability *cap; struct v4l2_cropcap *cropcap; struct v4l2_crop crop; struct v4l2_format *fmt; unsigned int min; cap = &(cam->v4l2_cap); cropcap = &(cam->v4l2_cropcap); fmt = &(cam->v4l2_fmt); if (-1 == xioctl (cam->fd, VIDIOC_QUERYCAP, cap)) { if (EINVAL == errno) { fprintf (stderr, "%s is no V4L2 device\n", cam->device_name); exit (EXIT_FAILURE); } else { errno_exit ("VIDIOC_QUERYCAP"); } } if (!(cap->capabilities & V4L2_CAP_VIDEO_CAPTURE)) { fprintf (stderr, "%s is no video capture device\n", cam->device_name); exit (EXIT_FAILURE); } if (!(cap->capabilities & V4L2_CAP_STREAMING)) { fprintf (stderr, "%s does not support streaming i/o\n", cam->device_name); exit (EXIT_FAILURE); } #ifdef DEBUG_CAM printf("\nVIDOOC_QUERYCAP\n"); printf("the camera driver is %s\n", cap->driver); printf("the camera card is %s\n", cap->card); printf("the camera bus info is %s\n", cap->bus_info); printf("the version is %d\n", cap->version); #endif /* Select video input, video standard and tune here. */ CLEAR (*cropcap); cropcap->type = V4L2_BUF_TYPE_VIDEO_CAPTURE; if (0 == xioctl (cam->fd, VIDIOC_CROPCAP, cropcap)) { crop.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; crop.c = cropcap->defrect; /* reset to default */ if (-1 == xioctl (cam->fd, VIDIOC_S_CROP, &crop)) { switch (errno) { case EINVAL: /* Cropping not supported. */ break; default: /* Errors ignored. */ break; } } } else { /* Errors ignored. */ } CLEAR (*fmt); fmt->type = V4L2_BUF_TYPE_VIDEO_CAPTURE; fmt->fmt.pix.width = cam->width; fmt->fmt.pix.height = cam->height; fmt->fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV; fmt->fmt.pix.field = V4L2_FIELD_INTERLACED; if (-1 == xioctl (cam->fd, VIDIOC_S_FMT, fmt)) errno_exit ("VIDIOC_S_FMT"); /* Note VIDIOC_S_FMT may change width and height. */ /* Buggy driver paranoia. */ min = fmt->fmt.pix.width * 2; if (fmt->fmt.pix