ubuntu ffmpeg 摄像头采集 位图 代码

以下是基于 Ubuntu 系统的使用 FFmpeg 进行摄像头采集并保存位图的代码：

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

#define DEVICE "/dev/video0"
#define IMAGE_WIDTH 640
#define IMAGE_HEIGHT 480

int main(int argc, char **argv) {
    int fd = 0;
    struct v4l2_capability cap;
    struct v4l2_format fmt;
    struct v4l2_requestbuffers req;
    struct v4l2_buffer buf;
    void *buffer_start = NULL;
    FILE *fp = NULL;
    char filename[32] = {0};
    int n_buffers = 0;
    int ret = 0;

    // 打开视频设备
    fd = open(DEVICE, O_RDWR);
    if (-1 == fd) {
        perror("open");
        return errno;
    }

    // 查询设备能力
    ret = ioctl(fd, VIDIOC_QUERYCAP, &cap);
    if (-1 == ret) {
        perror("ioctl(VIDIOC_QUERYCAP)");
        return errno;
    }

    // 设置视频格式
    memset(&fmt, 0, sizeof(fmt));
    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    fmt.fmt.pix.width = IMAGE_WIDTH;
    fmt.fmt.pix.height = IMAGE_HEIGHT;
    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
    fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
    ret = ioctl(fd, VIDIOC_S_FMT, &fmt);
    if (-1 == ret) {
        perror("ioctl(VIDIOC_S_FMT)");
        return errno;
    }

    // 请求分配内存
    memset(&req, 0, sizeof(req));
    req.count = 4;
    req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    req.memory = V4L2_MEMORY_MMAP;
    ret = ioctl(fd, VIDIOC_REQBUFS, &req);
    if (-1 == ret) {
        perror("ioctl(VIDIOC_REQBUFS)");
        return errno;
    }

    // 映射缓冲区
    buffer_start = mmap(NULL, req.count * fmt.fmt.pix.sizeimage,
                         PROT_READ | PROT_WRITE, MAP_SHARED,
                         fd, 0);
    if (MAP_FAILED == buffer_start) {
        perror("mmap");
        return errno;
    }

    // 缓存入队
    for (n_buffers = 0; n_buffers < req.count; ++n_buffers) {
        memset(&buf, 0, sizeof(buf));
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        buf.memory = V4L2_MEMORY_MMAP;
        buf.index = n_buffers;
        ret = ioctl(fd, VIDIOC_QBUF, &buf);
        if (-1 == ret) {
            perror("ioctl(VIDIOC_QBUF)");
            return errno;
        }
    }

    // 开始采集
    enum v4l2_buf_type type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    ret = ioctl(fd, VIDIOC_STREAMON, &type);
    if (-1 == ret) {
        perror("ioctl(VIDIOC_STREAMON)");
        return errno;
    }

    // 采集图像
    for (int i = 0; i < 10; ++i) {
        memset(&buf, 0, sizeof(buf));
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        buf.memory = V4L2_MEMORY_MMAP;
        ret = ioctl(fd, VIDIOC_DQBUF, &buf);
        if (-1 == ret) {
            perror("ioctl(VIDIOC_DQBUF)");
            return errno;
        }

        // 保存位图
        sprintf(filename, "image%d.bmp", i);
        fp = fopen(filename, "wb");
        fwrite(buffer_start, fmt.fmt.pix.sizeimage, 1, fp);
        fclose(fp);

        // 重新入队
        ret = ioctl(fd, VIDIOC_QBUF, &buf);
        if (-1 == ret) {
            perror("ioctl(VIDIOC_QBUF)");
            return errno;
        }
    }

    // 停止采集
    ret = ioctl(fd, VIDIOC_STREAMOFF, &type);
    if (-1 == ret) {
        perror("ioctl(VIDIOC_STREAMOFF)");
        return errno;
    }

    // 取消映射
    munmap(buffer_start, req.count * fmt.fmt.pix.sizeimage);

    // 关闭设备
    close(fd);

    return 0;
}

注意：在运行该代码之前，需要先安装 FFmpeg 和视频设备的驱动。