How to improve speed of receiving image data with Wi-fi connection

[jhforstudy]

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Required Info
Camera Model	{ D400 }
Firmware Version	05.13.00.50
Operating System & Version	Ubuntu 18.04
Kernel Version (Linux Only)	4.9.253-tegra
Platform	Jetson nano
SDK Version	{ legacy / 2.50.0 }
Language	{Python }
Segment	{Robot }

Issue Description

Hi, I want to ask more about wi-fi connection of d435 camera.

This is my previous question : #10697
realsense-viewer is finally working well, and it looks like real-time video stream.

wireless_rs-2022-07-21_17.57.39.mp4

But the problem is, pyrealsense2_net module is not supported in Python now, so I cannot use it in my Python script.
Therefore, I changed my project to use ROS topic of depth camera :
/camera/color/image_raw, /camera/depth/image_rect_raw

I tried this method:

• In Jetson :
  change ROS_MASTER_URI in ~/.bashrc,
  and run roslaunch realsense2_camera rs_camera.launch

• In my laptop :
  run roscore & receive camera topic from Jetson

However, the speed of topic received is very slow. (about 15 seconds per 1 frame)

I think the difference is that,
in realsense-viewer I used independent rs-server so it was very fast
But in ROS communication, I didn't use any independent server so it was very slow.

I don't have any idea to improve the topic-received speed using Wifi connection.

Could you give me any advice for me?? Thanks in advance. 👍

[MartyG-RealSense]

Hi @jhforstudy In the couple of cases that I have seen where the rs-server networking system was adapted to use ROS protocols instead of the default RTSP protocol - such as IntelRealSense/realsense-ros#1808 - the best speed that was achieved was 10 Hz on a wired ethernet connection compared to 30 FPS in the original system setup.

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There was a discussion from July 2020 where someone used ethernet with realsense2_camera by configuring ROS_MASTER_URI and also ROS_IP.

https://answers.ros.org/question/357185/intel-realsense-nodelets-running-with-remote-roscore-are-dying-bond-broken/

When Intel's networking white-paper mentions ROS, it has the number [10] beside it that refers to a RealSense ROS guide listed in the references at the bottom of the paper for using 3 cameras across 2 computers:

https://github.com/IntelRealSense/realsense-ros/wiki/showcase-of-using-3-cameras-in-2-machines

This suggests to me that you are on the right track in using ROS_MASTER_URI

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IntelRealSense/realsense-ros#1673 has a similar situation to yours, where wi-fi streaming in ROS with a Jetson Nano (and a D455 instead of D435) was being attempted. The RealSense user in that particular case shared their eventual solution at IntelRealSense/realsense-ros#1673 (comment)

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At IntelRealSense/realsense-ros#2052 there is a lengthy discussion about wireless use of the camera in ROS and drops in performance. That RealSense ROS user found at IntelRealSense/realsense-ros#2052 (comment) that their infrared topic frequency was plummeting from 30 Hz to 5 Hz if they used a wireless mouse but had no problem with a wired mouse.

That case also references IntelRealSense/realsense-ros#2039 where a RealSense ROS user with a wireless LAN (WLAN) was experiencing very high delay with communicating with a mobile scale-model car. The delay started at zero and grew over time. That user's particular problem was resolved by reinstalling the RealSense ROS camera package.

IntelRealSense/realsense-ros#2052 (comment) references how some users with very slow performance have achieved gains by disabling wi-fi power saving. Disabling X11 forwarding has also helped some people - IntelRealSense/realsense-ros#2052 (comment)

[jhforstudy]

Thanks @MartyG-RealSense ! I'll try those methods.