linux c 读摄像头

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>              
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/videodev2.h>

#define WIDTH 640
#define HEIGHT 480

int main() {
    int fd;
    struct v4l2_format fmt;
    struct v4l2_buffer buf;
    struct v4l2_requestbuffers req;
    void *buffer;

    // 打开摄像头设备
    fd = open("/dev/video0", O_RDWR);
    if (fd == -1) {
        perror("Cannot open device");
        exit(1);
    }

    // 获取摄像头格式
    memset(&fmt, 0, sizeof(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_YUYV;
    fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
    if (ioctl(fd, VIDIOC_S_FMT, &fmt) == -1) {
        perror("Setting pixel format");
        exit(1);
    }

    // 请求缓冲区
    memset(&req, 0, sizeof(req));
    req.count = 1;
    req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    req.memory = V4L2_MEMORY_MMAP;
    if (ioctl(fd, VIDIOC_REQBUFS, &req) == -1) {
        perror("Requesting buffer");
        exit(1);
    }

    // 查询缓冲区
    memset(&buf, 0, sizeof(buf));
    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    buf.memory = V4L2_MEMORY_MMAP;
    buf.index = 0;
    if (ioctl(fd, VIDIOC_QUERYBUF, &buf) == -1) {
        perror("Querying buffer");
        exit(1);
    }

    // 映射缓冲区
    buffer = mmap(NULL, buf.length, PROT_READ | PROT_WRITE, MAP_SHARED, fd, buf.m.offset);
    if (buffer == MAP_FAILED) {
        perror("Mapping buffer");
        exit(1);
    }

    // 开始捕获
    if (ioctl(fd, VIDIOC_STREAMON, &buf.type) == -1) {
        perror("Starting stream");
        exit(1);
    }

    // 进入捕获循环
    if (ioctl(fd, VIDIOC_QBUF, &buf) == -1) {
        perror("Queueing buffer");
        exit(1);
    }

    fd_set fds;
    FD_ZERO(&fds);
    FD_SET(fd, &fds);

    struct timeval tv;
    tv.tv_sec = 2;
    tv.tv_usec = 0;

    if (select(fd+1, &fds, NULL, NULL, &tv) == -1) {
        perror("Select error");
        exit(1);
    }

    if (ioctl(fd, VIDIOC_DQBUF, &buf) == -1) {
        perror("Dequeueing buffer");
        exit(1);
    }

    // 处理视频数据（这里简单地打印缓冲区地址）
    printf("Buffer address: %p\n", buffer);

    // 清理
    munmap(buffer, buf.length);
    close(fd);

    return 0;
}