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Required Internet Speed for Publishing two Video Streams over ROS network

asked 2019-09-18 11:14:48 -0500

zulfiz gravatar image

I have two machines connected to each other via ROS. One of the machines has two cameras running on it. The feed from these cameras is being published over ROS. When I try to see the images in the other machine via rqt_image_view there is a lag of seconds. My network's upload speed is 3.08 Mbps and download speed is 90 Mbps. How much is the recommended upload speed to get the video feed working without any lag? Thank you!

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How much is the recommended upload speed to get the video feed working without any lag?

without knowing something about the cameras used and the configuration of those cameras your question cannot be answered.

What resolution? How many fps? What bit depth? Colour? Black-and-white? Is compression OK? Lossy or lossless? Etc.

gvdhoorn gravatar image gvdhoorn  ( 2019-09-18 12:33:30 -0500 )edit

@gvdhoorn I use usb_cam package to launch the cameras. I modified the launch file, so that it launches two cameras instead of one. The parameters in the launch file I set are as following (for both the cameras):

image_width = 640 image_height = 480 pixel_format = mjpeg camera_frame_id = yuyv io_method = mmap

Please let me know if you need any other onfo. Thanks for the help!

zulfiz gravatar image zulfiz  ( 2019-09-19 15:27:01 -0500 )edit

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answered 2019-09-19 04:26:54 -0500

ingo gravatar image

As @gvdhoorn already mentioned, if you really want the speed, this is computed by multiplying the size of your data (in this case, images), by the rate, and adding some overhead.

That said, your case sounds as if there is a different issue. First of all, the computers are most likely both on your local network, so your Internet speed is not relevant.

Secondly, a consistent delay of a few seconds is normally caused by compression. Therefore, try pointing rqt_image_view at your "/camera/image_raw" topic and see what happens.

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I answered @gvdhoorn questions. Please let me know if you also have some insights regarding this. Also, I am using rqt_image_view with "/camera1/image_raw". But, the video is lagging a lot. It updates the frame after every few seconds. Thank you!

zulfiz gravatar image zulfiz  ( 2019-09-19 15:29:24 -0500 )edit

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Asked: 2019-09-18 11:14:48 -0500

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Last updated: Sep 19 '19