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使用V4L2做图片采集,查询到摄像头制式是YUYV,设置,申请帧缓存,读取,存储,得到.raw的文件,拿到windows下用picasa打开出现如下图片,请问可能是什么方面的原因?贴代码如下
- /*
- * V4L2 video capture example
- */
- #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 <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>
- //#include "YUV2JPEG.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;
- };
- static char *dev_name = NULL;
- static io_method io = IO_METHOD_MMAP;
- /* can be V4L2_PIX_FMT_YUV420 or V4L2_PIX_FMT_PWC2 */
- static int pixel_format = V4L2_PIX_FMT_YUYV;
- static int fd = -1;
- struct buffer *buffers = NULL;
- static unsigned int n_buffers = 0;
- static unsigned int width = 640;
- static unsigned int height = 480;
- static unsigned int count = 2;
- 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, ssize_t size)
- {
- static int no_image = 0;
- char filename[1024];
- int fd;
- ssize_t written = 0;
- snprintf(filename, sizeof(filename), "/mnt/webcam-%5.5d.%s",
- no_image++, pixel_format == V4L2_PIX_FMT_YUYV ? "raw" : "raw");
- // snprintf(filename,sizeof(filename),"/mnt/picture%d.jpg",no_image++);
- fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, S_IRUSR | S_IWUSR);
- if (fd < 0)
- {
- fputc('*', stdout);
- fflush(stdout);
- return;
- }
- do
- {
- int ret;
- ret = write(fd, p + written, size - written);
- if (ret < 0)
- {
- fputc('+', stdout);
- fflush(stdout);
- return;
- }
- written += ret;
- }
- while (written < size);
- close(fd);
- // YUV2JPEG((unsigned char *)p,640,480,filename);
- fputc('.', stdout);
- fflush(stdout);
- }
- static int read_frame(void)
- {
- struct v4l2_buffer buf;
- unsigned int i;
- ssize_t read_bytes;
- unsigned int total_read_bytes;
- switch (io)
- {
- case IO_METHOD_READ:
- total_read_bytes = 0;
- do
- {
- read_bytes = read(fd, buffers[0].start, buffers[0].length);
- if (read_bytes < 0)
- {
- switch (errno)
- {
- case EIO:
- case EAGAIN:
- continue;
- default:
- errno_exit("read");
- }
- }
- total_read_bytes += read_bytes;
- } while (total_read_bytes < buffers[0].length);
- process_image(buffers[0].start, buffers[0].length);
- 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);
- process_image(buffers[buf.index].start, buf.length);
- 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);
- process_image((void *) buf.m.userptr, buf.length);
- if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
- errno_exit("VIDIOC_QBUF");
- break;
- }
- return 1;
- }
- static void mainloop(void)
- {
- 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.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_read(unsigned int buffer_size)
- {
- buffers = calloc(1, sizeof(*buffers));
- if (!buffers)
- {
- fprintf(stderr, "Out of memory\n");
- exit(EXIT_FAILURE);
- }
- buffers[0].length = buffer_size;
- buffers[0].start = malloc(buffer_size);
- if (!buffers[0].start)
- {
- fprintf(stderr, "Out of memory\n");
- exit(EXIT_FAILURE);
- }
- }
- static void init_mmap(void)
- {
- struct v4l2_requestbuffers req;
- CLEAR(req);
- req.count = 4;
- req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- req.memory = V4L2_MEMORY_MMAP;
- if (-1 == xioctl(fd, VIDIOC_REQBUFS, &req))
- {
- if (EINVAL == errno)
- {
- fprintf(stderr, "%s does not support "
- "memory mapping\n", dev_name);
- exit(EXIT_FAILURE);
- }
- else
- {
- errno_exit("VIDIOC_REQBUFS");
- }
- }
- if (req.count < 2)
- {
- fprintf(stderr, "Insufficient buffer memory on %s\n", dev_name);
- exit(EXIT_FAILURE);
- }
- buffers = calloc(req.count, sizeof(*buffers));
- if (!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(fd, VIDIOC_QUERYBUF, &buf))
- errno_exit("VIDIOC_QUERYBUF");
- buffers[n_buffers].length = buf.length;
- buffers[n_buffers].start = mmap(NULL /* start anywhere */ ,
- buf.length,
- PROT_READ | PROT_WRITE /* required */ ,
- MAP_SHARED /* recommended */ ,
- fd, buf.m.offset);
- if (MAP_FAILED == buffers[n_buffers].start)
- errno_exit("mmap");
- }
- }
- static void init_userp(unsigned int buffer_size)
- {
- struct v4l2_requestbuffers req;
- CLEAR(req);
- req.count = 4;
- req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- req.memory = V4L2_MEMORY_USERPTR;
- if (-1 == xioctl(fd, VIDIOC_REQBUFS, &req))
- {
- if (EINVAL == errno)
- {
- fprintf(stderr, "%s does not support "
- "user pointer i/o\n", dev_name);
- exit(EXIT_FAILURE);
- }
- else
- {
- errno_exit("VIDIOC_REQBUFS");
- }
- }
- buffers = calloc(4, sizeof(*buffers));
- if (!buffers)
- {
- fprintf(stderr, "Out of memory\n");
- exit(EXIT_FAILURE);
- }
- for (n_buffers = 0; n_buffers < 4; ++n_buffers)
- {
- buffers[n_buffers].length = buffer_size;
- buffers[n_buffers].start = malloc(buffer_size);
- if (!buffers[n_buffers].start)
- {
- fprintf(stderr, "Out of memory\n");
- exit(EXIT_FAILURE);
- }
- }
- }
- static void init_device(void)
- {
- struct v4l2_capability cap;
- struct v4l2_cropcap cropcap;
- struct v4l2_crop crop;
- struct v4l2_format fmt;
- unsigned int min;
- if (-1 == xioctl(fd, VIDIOC_QUERYCAP, &cap))
- {
- if (EINVAL == errno)
- {
- fprintf(stderr, "%s is no V4L2 device\n", dev_name);
- exit(EXIT_FAILURE);
- }
- else
- {
- errno_exit("VIDIOC_QUERYCAP");
- }
- }
- printf("cam name:%s\n driver name:%s\n driver version:%d\n businfo:%s\n"
- ,cap.card,cap.driver,cap.version,cap.bus_info);
- if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE))
- {
- fprintf(stderr, "%s is no video capture device\n",cap.card);
- exit(EXIT_FAILURE);
- }
- else
- {
- printf("%s is video capture device\n",cap.card);
- }
- switch (io)
- {
- case IO_METHOD_READ:
- if (!(cap.capabilities & V4L2_CAP_READWRITE))
- {
- fprintf(stderr, "%s does not support read i/o\n",cap.card);
- exit(EXIT_FAILURE);
- }
- else
- {
- printf("%s support read i/o\n",cap.card);
- }
- break;
- case IO_METHOD_MMAP:
- case IO_METHOD_USERPTR:
- if (!(cap.capabilities & V4L2_CAP_STREAMING))
- {
- fprintf(stderr, "%s does not support streaming i/o\n",cap.card);
- exit(EXIT_FAILURE);
- }
- else
- {
- printf("%s support streaming i/o\n",cap.card);
- }
- break;
- }
- /* Select video input, video standard and tune here. */
- cropcap.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- if (-1 == xioctl(fd, VIDIOC_CROPCAP, &cropcap))
- {
- /* Errors ignored. */
- }
- crop.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- crop.c = cropcap.defrect; /* reset to default */
- if (-1 == xioctl(fd, VIDIOC_S_CROP, &crop))
- {
- switch (errno)
- {
- case EINVAL:
- printf("Cropping not supported\n");
- /* Cropping not supported. */
- break;
- default:
- /* Errors ignored. */
- break;
- }
- }
- CLEAR(fmt);
- fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- fmt.fmt.pix.width = width;
- fmt.fmt.pix.height = height;
- fmt.fmt.pix.pixelformat = pixel_format;
- fmt.fmt.pix.field = V4L2_FIELD_SEQ_BT;//V4L2_FIELD_INTERLACED;
- if (-1 == xioctl(fd, VIDIOC_S_FMT, &fmt))
- errno_exit("VIDIOC_S_FMT");
- /* Note VIDIOC_S_FMT may change width and height. */
- width = fmt.fmt.pix.width;
- height = fmt.fmt.pix.height;
- switch (io)
- {
- case IO_METHOD_READ:
- init_read(fmt.fmt.pix.sizeimage);
- break;
- case IO_METHOD_MMAP:
- init_mmap();
- break;
- case IO_METHOD_USERPTR:
- init_userp(fmt.fmt.pix.sizeimage);
- break;
- }
- }
- static void close_device(void)
- {
- if (-1 == close(fd))
- errno_exit("close");
- fd = -1;
- }
- static void open_device(void)
- {
- struct stat st;
- if (-1 == stat(dev_name, &st))
- {
- fprintf(stderr, "Cannot identify '%s': %d, %s\n",
- dev_name, errno, strerror(errno));
- exit(EXIT_FAILURE);
- }
- if (!S_ISCHR(st.st_mode))
- {
- fprintf(stderr, "%s is no device\n", dev_name);
- exit(EXIT_FAILURE);
- }
- fd = open(dev_name, O_RDWR /* required */ | O_NONBLOCK, 0);
- if (-1 == fd)
- {
- fprintf(stderr, "Cannot open '%s': %d, %s\n",
- dev_name, errno, strerror(errno));
- exit(EXIT_FAILURE);
- }
- }
- static const char short_options[] = "c:d:f:hmrs:u";
- static const struct option long_options[] = {
- {"count", required_argument, NULL, 'c'},
- {"device", required_argument, NULL, 'd'},
- {"format", required_argument, NULL, 'f'},
- {"help", no_argument, NULL, 'h'},
- {"mmap", no_argument, NULL, 'm'},
- {"read", no_argument, NULL, 'r'},
- {"size", required_argument, NULL, 's'},
- {"userp", no_argument, NULL, 'u'},
- {0, 0, 0, 0}
- };
- static int video_fmtdesc(int fd)
- {
- /***********Format Enumeration************/
- int ret = 0;
- struct v4l2_fmtdesc fmtdes;
- CLEAR(fmtdes);
- fmtdes.index = 0;
- fmtdes.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- printf("\n****vidioc enumeration stream format informations:****\n");
- while (1) {
- ret = ioctl(fd, VIDIOC_ENUM_FMT, &fmtdes);
- if (ret < 0)
- break;
- printf("{ pixelformat = %c%c%c%c, description = %s }\n",
- (fmtdes.pixelformat & 0xFF),
- (fmtdes.pixelformat >> 8) & 0xFF,
- (fmtdes.pixelformat >> 16) & 0xFF,
- (fmtdes.pixelformat >> 24) & 0xFF,
- fmtdes.description);
- if (fmtdes.type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
- printf("video capture type:\n");
- if (fmtdes.pixelformat == V4L2_PIX_FMT_YUYV)
- printf("V4L2_PIX_FMT_YUYV\n");
- fmtdes.index++;
- }
- return 0;
- }
- int main(int argc, char **argv)
- {
- dev_name = "/dev/video0";
- open_device();
- init_device();
- video_fmtdesc(fd);
- start_capturing();
- mainloop();
- stop_capturing();
- uninit_device();
- close_device();
- exit(EXIT_SUCCESS);
- return 0;
- }
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