基于ARM的V4L2图形采集工程源代码

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <assert.h> #include <getopt.h> /* getopt_long() */ #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 <asm/types.h> /* for videodev2.h */ #include <linux/videodev2.h> #define CLEAR(x) memset (&(x), 0, sizeof (x)) typedef enum { IO_METHOD_READ, IO_METHOD_MMAP, IO_METHOD_USERPTR, } io_method; struct buffer { void * start; size_t length;//buffer's length is different from cap_image_size }; static char * dev_name = NULL; static io_method io = IO_METHOD_MMAP;//IO_METHOD_READ;//IO_METHOD_MMAP; static int fd = -1; struct buffer * buffers = NULL; static unsigned int n_buffers = 0; static FILE * outf = 0; static unsigned int cap_image_size = 0;//to keep the real image size!! ////////////////////////////////////////// static 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; } static void process_image(const void * p, int len) { //static char[115200] Outbuff ; fputc('.', stdout); if (len > 0) { fputc('.', stdout); fwrite(p, 1, len, outf); } fflush(stdout); } static int read_frame(void) { struct v4l2_buffer buf; unsigned int i; switch (io) { case IO_METHOD_READ: if (-1 == read(fd, buffers[0].start, buffers[0].length)) { switch (errno) { case EAGAIN: return 0; case EIO: /* Could ignore EIO, see spec. */ /* fall through */ default: errno_exit("read"); } } // printf("length = %d\r", buffers[0].length); // process_image(buffers[0].start, buffers[0].length); printf("image_size = %d\t IO_METHOD_READ buffer.length=%d\r",cap_image_size, buffers[0].length); process_image(buffers[0].start, cap_image_size); break; case IO_METHOD_MMAP: CLEAR (buf); buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; buf.memory = V4L2_MEMORY_MMAP; if (-1 == xioctl(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); // printf("length = %d\r", buffers[buf.index].length); // process_image(buffers[buf.index].start, buffers[buf.index].length); printf("image_size = %d,\t IO_METHOD_MMAP buffer.length=%d\r",cap_image_size,buffers[0].length); process_image(buffers[0].start, cap_image_size); if (-1 == xioctl(fd, VIDIOC_QBUF, &buf)) errno_exit("VIDIOC_QBUF"); break; case IO_METHOD_USERPTR: CLEAR (buf); buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; buf.memory = V4L2_MEMORY_USERPTR; if (-1 == xioctl(fd, VIDIOC_DQBUF, &buf)) { switch (errno) { case EAGAIN: return 0; case EIO: /* Could ignore EIO, see spec. */ /* fall through */ default: errno_exit("VIDIOC_DQBUF"); } } for (i = 0; i < n_buffers; ++i) if (buf.m.userptr == (unsigned long) buffers[i].start && buf.length== buffers[i].length) break; assert(i < n_buffers); // printf("length = %d\r", buffers[i].length); // process_image((void *) buf.m.userptr, buffers[i].length); printf("image_size = %d,\t IO_METHOD_USERPTR buffer.length=%d\r",cap_image_size, buffers[0].length); process_image(buffers[0].start, cap_image_size); if (-1 == xioctl(fd, VIDIOC_QBUF, &buf)) errno_exit("VIDIOC_QBUF"); break; } return 1; } static void mainloop(void) { unsigned int count; count = 1; while (count-- > 0) { for (;;) { fd_set fds; struct timeval tv; int r; FD_ZERO(&fds); FD_SET(fd, &fds); /* Timeout. */ tv.tv_sec = 2; tv.tv_usec = 0; r = select(fd + 1, &fds, NULL, NULL, &tv); if (-1 == r) { if (EINTR == errno) { continue; } errno_exit("select"); } if (0 == r) { fprintf(stderr, "select timeout\n"); exit(EXIT_FAILURE); } if (read_frame()) { break; } /* EAGAIN - continue select loop. */ } } } static void stop_capturing(void) { enum v4l2_buf_type type; switch (io) { case IO_METHOD_READ: /* Nothing to do. */ break; case IO_METHOD_MMAP: case IO_METHOD_USERPTR: type = V4L2_BUF_TYPE_VIDEO_CAPTURE; if (-1 == xioctl(fd, VIDIOC_STREAMOFF, &type)) { errno_exit("VIDIOC_STREAMOFF"); } break; } } static void start_capturing(void) { unsigned int i; enum v4l2_buf_type type; switch (io) { case IO_METHOD_READ: /* Nothing to do. */ break; case IO_METHOD_MMAP: 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(fd, VIDIOC_QBUF, &buf)) errno_exit("VIDIOC_QBUF"); } type = V4L2_BUF_TYPE_VIDEO_CAPTURE; if (-1 == xioctl(fd, VIDIOC_STREAMON, &type)) errno_exit("VIDIOC_STREAMON"); break; case IO_METHOD_USERPTR: for (i = 0; i < n_buffers; ++i) { struct v4l2_buffer buf; CLEAR (buf); buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; buf.memory = V4L2_MEMORY_USERPTR; buf.index = i; buf.m.userptr = (unsigned long) buffers[i].start; buf.length = buffers[i].length; if (-1 == xioctl(fd, VIDIOC_QBUF, &buf)) errno_exit("VIDIOC_QBUF"); } type = V4L2_BUF_TYPE_VIDEO_CAPTURE; if (-1 == xioctl(fd, VIDIOC_STREAMON, &type)) errno_exit("VIDIOC_STREAMON"); break; } } static void uninit_device(void) { unsigned int i; switch (io) { case IO_METHOD_READ: free(buffers[0].start); break; case IO_METHOD_MMAP: for (i = 0; i < n_buffers; ++i) { if (-1 == munmap(buffers[i].start, buffers[i].length)) { errno_exit("munmap"); } } break; case IO_METHOD_USERPTR: for (i = 0; i < n_buffers; ++i) { free(buffers[i].start); } break; } free(buffers); } static void init_re