I want to record video with a usb webcam to process it later. To do that, I found limited info. One is to use `rosbag` to save published topics. Another way is to use opencv to write video. Which method would provide a simple solution to save video ? (maybe another alternative method beyond what I said) I have a source code of`image_pub`package to publish images as following;
#include
#include
#include
#include
#include
int main(int argc, char **argv)
{
ROS_INFO("Starting image_pub ROS node...\n");
ros::init(argc, argv, "image_pub");
ros::NodeHandle nh("~");
std::string camera_topic;
std::string camera_info_topic;
std::string camera_info_url;
std::string img_path;
std::string frame_id;
float pub_rate;
int start_sec;
bool repeat;
nh.param("camera_topic", camera_topic, "/camera/image_raw");
nh.param("camera_info_topic", camera_info_topic, "/camera/camera_info");
nh.param("camera_info_url", camera_info_url, "");
nh.param("img_path", img_path, "");
nh.param("frame_id", frame_id, "");
nh.param("pub_rate", pub_rate, 30.0f);
nh.param("start_sec", start_sec, 0);
nh.param("repeat", repeat, false);
ROS_INFO("CTopic : %s", camera_topic.c_str());
ROS_INFO("ITopic : %s", camera_info_topic.c_str());
ROS_INFO("CI URL : %s", camera_info_url.c_str());
ROS_INFO("Source : %s", img_path.c_str());
ROS_INFO("Rate : %.1f", pub_rate);
ROS_INFO("Start : %d", start_sec);
ROS_INFO("Repeat : %s", repeat ? "yes" : "no");
ROS_INFO("FrameID: %s", frame_id.c_str());
camera_info_manager::CameraInfoManager camera_info_manager(nh);
if (camera_info_manager.validateURL(camera_info_url))
camera_info_manager.loadCameraInfo(camera_info_url);
ros::Publisher img_pub = nh.advertise(camera_topic, 1);
ros::Publisher info_pub = nh.advertise(camera_info_topic, 1);
cv::VideoCapture vid_cap(img_path.c_str());
if (start_sec > 0)
vid_cap.set(CV_CAP_PROP_POS_MSEC, 1000.0 * start_sec);
ros::Rate rate(pub_rate);
while (ros::ok())
{
cv::Mat img;
if (!vid_cap.read(img))
{
if (repeat)
{
vid_cap.open(img_path.c_str());
if (start_sec > 0)
vid_cap.set(CV_CAP_PROP_POS_MSEC, 1000.0 * start_sec);
continue;
}
ROS_ERROR("Failed to capture frame.");
ros::shutdown();
}
else
{
//ROS_DEBUG("Image: %dx%dx%d, %zu, %d", img.rows, img.cols, img.channels(), img.elemSize(), img.type() == CV_8UC3);
if (img.type() != CV_8UC3)
img.convertTo(img, CV_8UC3);
// Convert image from BGR format used by OpenCV to RGB.
cv::cvtColor(img, img, CV_BGR2RGB);
auto img_msg = boost::make_shared();
img_msg->header.stamp = ros::Time::now();
img_msg->header.frame_id = frame_id;
img_msg->encoding = "rgb8";
img_msg->width = img.cols;
img_msg->height = img.rows;
img_msg->step = img_msg->width * img.channels();
auto ptr = img.ptr(0);
img_msg->data = std::vector(ptr, ptr + img_msg->step * img_msg->height);
img_pub.publish(img_msg);
if (camera_info_manager.isCalibrated())
{
auto info = boost::make_shared(camera_info_manager.getCameraInfo());
info->header = img_msg->header;
info_pub.publish(info);
}
}
ros::spinOnce();
rate.sleep();
}
return 0;
}
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