Read rosbag with javascript?

Question

I'd like to use bag files as a generic output data format, but I'd also like to display text and numbers out of the bags in a javascript browser environment. It isn't necessary to handle arrays of binary data.

Is it possible to read a bag directly from javascript (using a library)?

Or what would be a good way to save data into a bag (which is easy with the rosbag api), then programmatically convert the bag to json, yaml, or less desirably a csv? It looks like from http://answers.ros.org/question/55037/is-there-a-way-to-save-all-rosbag-data-into-a-csv-or-text-file/ there are command lines to convert to csv, is there an api call to do the same thing?

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Originally posted by lucasw on ROS Answers with karma: 8729 on 2016-02-08

Post score: 1

Answer 1

It looks like jsonpickle will do the job:

sudo apt-get install python-jsonpickle

Then in python:

import json-pickle
from std_msgs.msg import Header
h = Header()
h.frame_id = "map"
a = jsonpickle.encode(h)

And the the following could be easily written to disk, or sent directly to a web server:

>>>> a
'{"py/object": "std_msgs.msg._Header.Header", "stamp": {"py/object": "genpy.rostime.Time", "secs": 0, "nsecs": 0}, "seq": 0, "frame_id": "map"}'

A python script could convert bags to json pickle format as a ros node or offline, and if conversion back for reading in C++ is necessary a python intermediary could read the json and write out a bag (I assume even if there is a generic C++ json pickle reader it would create strange python objects and not C++ ros messages, and additional custom conversion machinery would be required to close the loop, could be worth trying).

It looks like http://answers.ros.org/question/44224/i-am-unable-to-serialize-and-deserialize-ros-msgs-please-help/ came to a similar conclusion.

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Originally posted by lucasw with karma: 8729 on 2016-02-09

This answer was ACCEPTED on the original site

Post score: 2

Answer 2

Cruise Automation recently open sourced a Javascript library for parsing rosbag files. This should allow you to more easily get the information you're looking for directly into the browser:

https://github.com/cruise-automation/rosbag.js

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Originally posted by samjabrahams with karma: 11 on 2018-04-06

This answer was NOT ACCEPTED on the original site

Post score: 1