Answer by ChriMo for 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 ofimage_pubpackage to publish images as following;#include <ros/ros.h> #include <camera_info_manager/camera_info_manager.h> #include <sensor_msgs/Image.h> #include <sensor_msgs/CameraInfo.h> #include <opencv2/opencv.hpp> 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<std::string>("camera_topic", camera_topic, "/camera/image_raw"); nh.param<std::string>("camera_info_topic", camera_info_topic, "/camera/camera_info"); nh.param<std::string>("camera_info_url", camera_info_url, ""); nh.param<std::string>("img_path", img_path, ""); nh.param<std::string>("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<sensor_msgs::Image>(camera_topic, 1); ros::Publisher info_pub = nh.advertise<sensor_msgs::CameraInfo>(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<sensor_msgs::Image>(); 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<unsigned char>(0); img_msg->data = std::vector<unsigned char>(ptr, ptr + img_msg->step * img_msg->height); img_pub.publish(img_msg); if (camera_info_manager.isCalibrated()) { auto info = boost::make_shared<sensor_msgs::CameraInfo>(camera_info_manager.getCameraInfo()); info->header = img_msg->header; info_pub.publish(info); } } ros::spinOnce(); rate.sleep(); } return 0; }

I'm not sure, what you mean with process later, but capture a camera view from the robot is easy. run web_video_server node and connect with VLC to the stream. VLC can record the complete stream for later processing/viewing.