标签：count int errno void 控制程序 jpeg exit buf 摄像头

/*
 *  V4L2 video capture example
 *
 *  This program can be used and distributed without restrictions.
 *
 *      This program is provided with the V4L2 API
 * see https://linuxtv.org/docs.php for more information
 */

#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 <linux/videodev2.h>

#define CLEAR(x) memset(&(x), 0, sizeof(x))


enum io_method {
        IO_METHOD_READ,
        IO_METHOD_MMAP,
        IO_METHOD_USERPTR,
};

struct buffer {
        void   *start;
        size_t  length;
};

static char            *dev_name;
static enum io_method   io = IO_METHOD_MMAP;
static int              fd = -1;
struct buffer          *buffers;
static unsigned int     n_buffers;
static int              out_buf;
static int              frame_count = 1;

int width  = 1280;
int height = 720;
int format = V4L2_PIX_FMT_MJPEG;

/*
在长字符串中根据给定短字符串分割字符串，
需要在外部声明指向指针变量的数据，获取数据后在外部free掉
input   ：输入长串
splitstr：输入子串
output  ：保存输出结果
num     ：子串个数
*/
int StrSplit(char * input, char* splitstr, char ** output, int *num)
{
    int tmplen = 0;
    int totallen = 0;
    int count = 0;
    int nRtn = 0;
    char *p = input;
    int nSrcLen = strlen(input);
    int nSplStrLen = strlen(splitstr);
    
    if (input == NULL || nSrcLen == 0) //如果传入的地址为空或长度为0，直接终止 
    {
        return -1;
    }
        
    if (splitstr == NULL || nSplStrLen == 0) //如未指定分割的字符串，直接终止 
    {
        return -1;
    }
    
    //若第一个字符与短串相同，按短串长度比较
    while((*p != '\0'))
    {
        if (*p == splitstr[0])
        {
            if (0 == strncmp(p, splitstr, nSplStrLen))
            {
                //开辟内存，地址放在output[count]中
                output[count] = (char*)malloc(tmplen+1);
                //把分割出的字串拷贝到output[count]内存中
                strncpy(output[count], input + totallen, tmplen);
                //添加截止符
                (output[count])[tmplen] = '\0';
                //printf("output[%d]: [%s]\n", count, output[count]);
                //字串个数加一
                count++;
                //p移动的长度增加
                totallen += (tmplen + nSplStrLen);
                //p指向新的地址
                p += nSplStrLen;
                //下个字串长度
                tmplen = 0;
                continue;
            }
        }
        p++;
        tmplen++;
    }
    //最后一个字串
    output[count] = (char*)malloc(tmplen+1);
    strncpy(output[count], input + totallen, tmplen);
    (output[count])[tmplen] = '\0';
    //printf("output[%d]: [%s]\n", count, output[count]);
    count++;
    
    *num = count;

    return 0;
}

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 fh, int request, void *arg)
{
        int r;

        do {
              r = ioctl(fh, request, arg);
        } while (-1 == r && EINTR == errno);

        return r;
}

static void process_image(const void *p, int size)
{
    char file_name[256] = {0};
    static int cunt = 0;
    cunt++;
    snprintf(file_name,256,"%d.jpg",cunt);
    int sf_fd = open(file_name, O_RDWR | O_CREAT, 0777);

    if (sf_fd < 0)
    {
        printf("open save image file failed\n");
        return ;
    }

    int w_size = write(sf_fd, p , size);
    if (w_size != size)
    {
        printf("write image failed,wirte w_size = %d\n",w_size);
        return;
    }

    close(sf_fd);

    fflush(stderr);
    fflush(stdout);
}

static int read_frame(void)
{
    struct v4l2_buffer buf;

    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:
            {
                printf("EAGAIN\n");
                break;
            }
            case EIO:
            {
                printf("Could ignore EIO, see spec\n");
                break;
            }
            default:
                    errno_exit("VIDIOC_DQBUF");
            }
    }

    assert(buf.index < n_buffers);

    process_image(buffers[buf.index].start, buffers[buf.index].length);

    if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
            errno_exit("VIDIOC_QBUF");

    return 1;
}

static void mainloop(void)
{
    unsigned int count;

    count = frame_count;

    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");
                        continue;
                }

                if (read_frame())
                        break;
                /* EAGAIN - continue select loop. */
        }
    }
}

static void stop_capturing(void)
{
    enum v4l2_buf_type type;

    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    if (-1 == xioctl(fd, VIDIOC_STREAMOFF, &type))
            errno_exit("VIDIOC_STREAMOFF");
}

static void start_capturing(void)
{
    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(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");
}

static void uninit_device(void)
{
    unsigned int i;

    for (i = 0; i < n_buffers; ++i)
            if (-1 == munmap(buffers[i].start, buffers[i].length))
                    errno_exit("munmap");

    free(buffers);
}


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 mappingn", 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_device(void)
{
    struct v4l2_capability cap;
    struct v4l2_format fmt;
    struct v4l2_streamparm Stream_Parm;

    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");
            }
    }

    if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE)) {
            fprintf(stderr, "%s is no video capture device\\n",
                     dev_name);
            exit(EXIT_FAILURE);
    }

    if (!(cap.capabilities & V4L2_CAP_STREAMING)) {
            fprintf(stderr, "%s does not support streaming i/o\\n",
                     dev_name);
            exit(EXIT_FAILURE);
    }

    /* Select video input, video standard and tune here. */

    CLEAR(fmt);

    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    fmt.fmt.pix.width       = width;
    fmt.fmt.pix.height      = height;
    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;
    fmt.fmt.pix.field       = V4L2_FIELD_INTERLACED;

    if (-1 == xioctl(fd, VIDIOC_S_FMT, &fmt))
            errno_exit("VIDIOC_S_FMT");

    memset(&(Stream_Parm), 0, sizeof(Stream_Parm));
    Stream_Parm.type=V4L2_BUF_TYPE_VIDEO_CAPTURE;
    Stream_Parm.parm.capture.timeperframe.denominator = 5;
    Stream_Parm.parm.capture.timeperframe.numerator =1;
    if(ioctl(fd,VIDIOC_S_PARM,&Stream_Parm)==-1)
    {
        printf("VIDIOC_S_PARM = %s",strerror(errno));
        return ;
    }

    init_mmap();
}

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 devicen", 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 void usage(FILE *fp, int argc, char **argv)
{
    fprintf(fp,
             "Usage: %s [options]\n"
             "Version 1.3\n"
             "Options:\n"
             "-d | --device name   Video device name [%s]\n"
             "-h | --help          Print this messagen\n"
             "-s | --size          set image size\n"
             "-c | --count         %d Number of image\n"
             "",
             argv[0], dev_name, frame_count);
}

static const char short_options[] = "d:h:s:c:";

static const struct option
long_options[] = {
        { "device", required_argument, NULL, 'd' },
        { "help",   no_argument,       NULL, 'h' },
        { "size",   required_argument, NULL, 's' },
        { "count",  required_argument, NULL, 'c' },
        { 0, 0, 0, 0 }
};

int main(int argc, char **argv)
{
    char *apbyRtn[5] = {0};	//指针类型的数组，每个元素保存一个指针，必须足够大
    int num = 0;
    dev_name = "/dev/video0";

    for (;;) {
            int idx;
            int c;

            c = getopt_long(argc, argv,
                            short_options, long_options, &idx);

            if (-1 == c)
                    break;

            switch (c) {
            case 0: /* getopt_long() flag */
                    break;

            case 'd':
                    dev_name = optarg;
                    break;

            case 'h':
                    usage(stdout, argc, argv);
                    exit(EXIT_SUCCESS);

            case 's':
                    printf("test\n");
                    StrSplit(optarg,"*",apbyRtn,&num);
                    //获取结果并释放
                    for (int i = 0; i < num; i++)
                    {
                        if (0 == i)
                        {
                            width = strtol(apbyRtn[i],NULL, 0);
                        }
                        if (1 == i)
                        {
                            height = strtol(apbyRtn[i],NULL, 0);
                        }
                        free(apbyRtn[i]);
                    }

                    printf("image size = %d*%d\n",width,height);
                    break;

            case 'c':
                    errno = 0;
                    frame_count = strtol(optarg, NULL, 0);
                    if (errno)
                            errno_exit(optarg);
                    break;

            default:
                    usage(stderr, argc, argv);
                    exit(EXIT_FAILURE);
            }
    }

    open_device();
    init_device();
    start_capturing();
    mainloop();
    stop_capturing();
    uninit_device();
    close_device();
    return 0;
}

标签：count,int,errno,void,控制程序,jpeg,exit,buf,摄像头
来源： https://blog.csdn.net/shenlong1356/article/details/120338462

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