在Qt中使用V4L2驱动摄像头的代码
时间: 2024-03-26 11:38:06 浏览: 26
在Qt中使用V4L2驱动摄像头需要以下步骤:
1. 打开摄像头设备文件
```
int fd = open("/dev/video0", O_RDWR);
if (fd == -1) {
perror("Failed to open device");
return -1;
}
```
2. 设置摄像头参数
```
struct v4l2_format format;
format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
format.fmt.pix.width = 640;
format.fmt.pix.height = 480;
format.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
if (ioctl(fd, VIDIOC_S_FMT, &format) == -1) {
perror("Failed to set format");
return -1;
}
```
3. 请求缓冲区
```
struct v4l2_requestbuffers req;
req.count = 4;
req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
req.memory = V4L2_MEMORY_MMAP;
if (ioctl(fd, VIDIOC_REQBUFS, &req) == -1) {
perror("Failed to request buffers");
return -1;
}
```
4. 映射缓冲区
```
struct buffer {
void *start;
size_t length;
};
struct buffer *buffers = (struct buffer *)calloc(req.count, sizeof(*buffers));
for (int i = 0; i < req.count; i++) {
struct v4l2_buffer buf;
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
buf.index = i;
if (ioctl(fd, VIDIOC_QUERYBUF, &buf) == -1) {
perror("Failed to query buffer");
return -1;
}
buffers[i].length = buf.length;
buffers[i].start = mmap(NULL, buf.length, PROT_READ | PROT_WRITE, MAP_SHARED, fd, buf.m.offset);
if (buffers[i].start == MAP_FAILED) {
perror("Failed to map buffer");
return -1;
}
}
```
5. 将缓冲区入队
```
for (int i = 0; i < req.count; i++) {
struct v4l2_buffer buf;
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
buf.index = i;
if (ioctl(fd, VIDIOC_QBUF, &buf) == -1) {
perror("Failed to queue buffer");
return -1;
}
}
```
6. 开始采集
```
enum v4l2_buf_type type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
if (ioctl(fd, VIDIOC_STREAMON, &type) == -1) {
perror("Failed to start streaming");
return -1;
}
```
7. 循环读取数据
```
while (true) {
fd_set fds;
FD_ZERO(&fds);
FD_SET(fd, &fds);
if (select(fd + 1, &fds, NULL, NULL, NULL) == -1) {
perror("Failed to select");
return -1;
}
if (!FD_ISSET(fd, &fds)) {
continue;
}
struct v4l2_buffer buf;
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
if (ioctl(fd, VIDIOC_DQBUF, &buf) == -1) {
perror("Failed to dequeue buffer");
return -1;
}
// 处理数据
process_buffer(buffers[buf.index].start, buffers[buf.index].length);
if (ioctl(fd, VIDIOC_QBUF, &buf) == -1) {
perror("Failed to queue buffer");
return -1;
}
}
```
完整代码:https://github.com/chenxinyang2006/qt-v4l2-camera