因为使用OpenCV对映射的帧缓冲设备（例如/ dev / fb0）进行memcopy有点困惑。
例如，查看C和C ++的OpenCV捕获函数之一：
C: IplImage* cvQueryFrame(CvCapture* capture)
C++: bool VideoCapture::read(Mat& image)
看起来图像数据存储在C ++的矩阵结构（MAT）和C的CvCapture黑盒结构中。有很多关于如何在网络上使用它们的例子，所以很好。< / p>
但是，我没有找到任何好的（一致的）代码片段，它们展示了如何获取存储在这些结构中的图像数据并将其复制到帧缓冲区。
是否有人知道或拥有此需要的转换示例？
（Linux和OpenCV的Noob）
答案 0 :(得分：1)
无论这种方法是否被认为是好的，你都可以这样做（只支持像素格式的某些组合）：
/**
* @file fbwrite_video.cpp
* Displays OpenCV video on framebuffer.
* Compile with
* g++ -o fbwrite_video -lopencv_core -lopencv_highgui -lopencv_imgproc fbwrite_video.cpp
*
* Contains code from https://stackoverflow.com/questions/4722301/writing-to-frame-buffer
*/
#include <iostream> // for std::cerr
#include <opencv2/imgproc/imgproc.hpp> // for cv::cvtColor
#include <opencv2/highgui/highgui.hpp> // for cv::VideoCapture
#include <fstream> // for std::ofstream
#include <boost/timer/timer.hpp> // for boost::timer::cpu_timer
// this is C :/
#include <stdint.h> // for uint32_t
#include <sys/ioctl.h> // for ioctl
#include <linux/fb.h> // for fb_
#include <fcntl.h> // for O_RDWR
struct framebuffer_info {
uint32_t bits_per_pixel; uint32_t xres_virtual;
};
struct framebuffer_info get_framebuffer_info(const char* framebuffer_device_path) {
struct framebuffer_info info;
struct fb_var_screeninfo screen_info;
int fd = -1;
fd = open(framebuffer_device_path, O_RDWR);
if (fd >= 0) {
if (!ioctl(fd, FBIOGET_VSCREENINFO, &screen_info)) {
info.xres_virtual = screen_info.xres_virtual;
info.bits_per_pixel = screen_info.bits_per_pixel;
}
}
return info;
};
// C ends here
int main(int, char**) {
const int frame_width = 320;
const int frame_height = 240;
const int frame_rate = 10;
framebuffer_info fb_info = get_framebuffer_info("/dev/fb0");
cv::VideoCapture cap(0);
if(!cap.isOpened()) {
std::cerr << "Could not open video device." << std::endl;
return 1;
} else {
std::cout << "Successfully opened video device." << std::endl;
cap.set(CV_CAP_PROP_FRAME_WIDTH,frame_width);
cap.set(CV_CAP_PROP_FRAME_HEIGHT,frame_height);
cap.set(CV_CAP_PROP_FPS,frame_rate);
std::ofstream ofs("/dev/fb0");
cv::Mat frame;
while (true) {
cap >> frame;
if (frame.depth() != CV_8U) {
std::cerr << "Not 8 bits per pixel and channel." << std::endl;
} else if (frame.channels() != 3) {
std::cerr << "Not 3 channels." << std::endl;
} else {
// 3 Channels (assumed BGR), 8 Bit per Pixel and Channel
int framebuffer_width = fb_info.xres_virtual;
int framebuffer_depth = fb_info.bits_per_pixel;
cv::Size2f frame_size = frame.size();
cv::Mat framebuffer_compat;
switch (framebuffer_depth) {
case 16:
cv::cvtColor(frame, framebuffer_compat, cv::COLOR_BGR2BGR565);
for (int y = 0; y < frame_size.height ; y++) {
ofs.seekp(y*framebuffer_width*2);
ofs.write(reinterpret_cast<char*>(framebuffer_compat.ptr(y)),frame_size.width*2);
}
break;
case 32: {
std::vector<cv::Mat> split_bgr;
cv::split(frame, split_bgr);
split_bgr.push_back(cv::Mat(frame_size,CV_8UC1,cv::Scalar(255)));
cv::merge(split_bgr, framebuffer_compat);
for (int y = 0; y < frame_size.height ; y++) {
ofs.seekp(y*framebuffer_width*4);
ofs.write(reinterpret_cast<char*>(framebuffer_compat.ptr(y)),frame_size.width*4);
}
} break;
default:
std::cerr << "Unsupported depth of framebuffer." << std::endl;
}
}
}
}
}
答案 1 :(得分：0)