camera_view

Camera view

This metapackage contains the necessary tools to view, save, and load video streams/files.

Viewing Videos

Single Video Stream

You can view a live video stream by using the command

rosrun image_view image_view image:=<image_topic>

where image_topic is the topic of the published video stream. For example, to view the downward camera, you would use

rosrun image_view image_view image:=/camera/down/raw_image

where the subscribed topic is /camera/down/raw_image.

Stereo Video Stream

You can view a stream from stereo cameras using the command

rosrun image_view stereo_view stereo:=<stereo_namespace> image:=<image_topic>

where stereo namespace represents the overall namespace of the cameras and image topic is the specific image identifier. For example, to view our left/right stereo cams you would use

rosrun image_view stereo_view stereo:=camera image:=raw_image

where the subscribed topics are /camera/left/raw_image and /camera/right/raw_image.

Saving Videos

ROS bags

You can save your video stream to ROS bags for easy playback to ROS topics. Be warned that this will take significant storage space. To record a basic ROS bag, use

rosbag record -O output_name <topic_names>

where output_name is the name of the output file and topic_names are a list of topics to record. For example, to record the downward camera, use

rosbag record -O down_cam.bag /camera/down/raw_image

Video converter

You can also use the video recorder tool in ROS image viewer to record video files. By default it encodes the video as MPG, encapsulated in a AVI container at 15 fps, and produces a file called output.avi in the current directory, but this can be changed. For more info, view the documentation here.

To record, use the command

rosrun image_view video_recorder image:=<image_topic>

where image_topic is the topic of the video steam.

Streaming Videos

ROS bags

To stream a ROS bag from a bag file, you can simply use

rosbag play <bag_files>

where bag_files are the file locations of the bag files.

Video files

You can stream avi motion files using the image publisher node. To do this, use

rosrun image_publisher image_publisher image_raw:=<image_topic>

Converting between ROS bags and Video files

ROS Bag to Video file

You can use the bag_to_video script provided using

rosrun camera_view bag_to_video.py _bag_file:=<bag_file_name> _video_file:=<list_of_video_files> _topic_name:=<list_of_topic_names>

where the bag_file_name is the name of the bag file to convert. The list_of_video_files is a list of the video files to write. The list_of_topic_names is a list of topic names that correspond to the topic names to write to video files. Each video file will be the stream of images to the corresponding topic at the same index in the topic list. The video file list and topic list must be the same length. For instance, you can run

rosrun camera_view bag_to_video.py _bag_file:="vid.bag" _video_file:=["vid1.avi", "vid2.avi"] _topic_name:=["/camera/image/vid1", "/camera/image/vid2]

Video file to ROS Bag

You can use the video_to_bag script provided using

rosrun camera_view video_to_bag.py _bag_file:=<bag_file_name> _video_file:=<list_of_video_files> _topic_name:=<list_of_topic_names>

which has the same parameters as in the ROS bag to video file converter. Multiple video files can be written to the same ROS bag using this script.