ffmpeg linux 摄像头 加视频水印 C语言完整代码

下面是一个完整的C语言代码示例，使用FFmpeg库在Linux上将摄像头流与视频水印合并：

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

#define WIDTH 640
#define HEIGHT 480
#define FPS 30
#define WATERMARK_FILE "watermark.png"
#define OUTPUT_FILE "output.mp4"

int main(void) {
    int fd;
    struct v4l2_format fmt;
    struct v4l2_requestbuffers req;
    struct v4l2_buffer buf;
    enum v4l2_buf_type type;
    FILE *pipein;
    FILE *pipeout;
    char command[256];
    int frame_size = WIDTH * HEIGHT * 3;

    // 打开摄像头设备
    fd = open("/dev/video0", O_RDWR);
    if (fd == -1) {
        perror("Error opening video device");
        return -1;
    }

    // 配置摄像头格式
    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_RGB24;
    fmt.fmt.pix.field = V4L2_FIELD_NONE;
    if (ioctl(fd, VIDIOC_S_FMT, &fmt) == -1) {
        perror("Error setting video format");
        close(fd);
        return -1;
    }

    // 请求摄像头缓冲区
    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("Error requesting buffers");
        close(fd);
        return -1;
    }

    // 映射摄像头缓冲区到用户空间
    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("Error querying buffer");
        close(fd);
        return -1;
    }
    void *buffer_start = mmap(NULL, buf.length, PROT_READ | PROT_WRITE, MAP_SHARED, fd, buf.m.offset);
    if (buffer_start == MAP_FAILED) {
        perror("Error mapping buffer");
        close(fd);
        return -1;
    }

    // 开始摄像头流捕获
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    if (ioctl(fd, VIDIOC_STREAMON, &type) == -1) {
        perror("Error starting streaming");
        munmap(buffer_start, buf.length);
        close(fd);
        return -1;
    }

    // 构建FFmpeg命令
    sprintf(command, "ffmpeg -f rawvideo -pixel_format rgb24 -video_size %dx%d -framerate %d -i - -i %s -filter_complex overlay=W-w-10:H-h-10 -c:v libx264 %s", WIDTH, HEIGHT, FPS, WATERMARK_FILE, OUTPUT_FILE);

    // 打开管道
    pipein = popen(command, "w");
    if (pipein == NULL) {
        perror("Error opening pipe for input");
        munmap(buffer_start, buf.length);
        close(fd);
        return -1;
    }

    // 循环读取摄像头帧并写入pipein以合并水印
    while (1) {
        // 从摄像头获取帧
        memset(&buf, 0, sizeof(buf));
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        buf.memory = V4L2_MEMORY_MMAP;
        if (ioctl(fd, VIDIOC_QBUF, &buf) == -1) {
            perror("Error queuing buffer");
            break;
        }

        // 开始采集帧
        if (ioctl(fd, VIDIOC_DQBUF, &buf) == -1) {
            perror("Error dequeuing buffer");
            break;
        }

        // 将帧数据写入pipein以合并水印
        if (fwrite(buffer_start, 1, frame_size, pipein) != frame_size) {
            perror("Error writing to pipe");
            break;
        }

        // 重新将帧放回摄像头缓冲区队列
        if (ioctl(fd, VIDIOC_QBUF, &buf) == -1) {
            perror("Error requeuing buffer");
            break;
        }
    }

    // 停止摄像头流捕获
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    if (ioctl(fd, VIDIOC_STREAMOFF, &type) == -1) {
        perror("Error stopping streaming");
    }

    // 释放资源
    pclose(pipein);
    munmap(buffer_start, buf.length);
    close(fd);

    return 0;
}

在上述代码中，我们通过FFmpeg的`overlay`滤镜将摄像头流与指定的视频水印合并，并输出到指定的文件中。你需要将`/dev/video0`替换为你的摄像头设备文件路径，`WATERMARK_FILE`替换为你的水印文件路径，以及将`OUTPUT_FILE`替换为你想要输出的文件路径。请确保你已经安装了FFmpeg库和相关的编译工具链。