Recording only a single message instance
Hi all,
I need to save some metadata about my recording session (e.g. camera info), but a recording session can last for several seconds to over an hour, so I don't want to be recording that same info every second.
I am interested in having a mechanism where a certain topic is recorded only once by rosbag, similarly to how /tf_static has only 1 message instance recorded every time you run "rosbag record".
Is there a way to reproduce this behavior? how would it be implemented?
(as in providing the rosbag command line some arguments not documented here or somehow letting the info-publishing node publish a message once only when another node subscribes to that topic or something).
P.S. I cannot use the parameter server for that job due to other system constraints.
Many thanks in advance,
Steve
Not an answer, but a comment on this part of your question:
The
tf_statictopic is using a latched topic, which is why only "a single message instance is recorded".This is not a property you can change without having access to the source of the publisher, so if the
CameraInfopublisher does not also use latching, you cannot add that later (I've also not seenCameraInfopublishers do that often, as there is the (implicit) assumption there is a 1-to-1 correspondence betweensensor_msgs/Images (and similar messages) andCameraInfomessages).