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Trouble trying to subscribe to roslibjs node and show with OpenCV

asked 2020-07-08 08:25:43 -0600

サイトダニエロ gravatar image

I'm following RosLibJs Video Publishing with CV_bridge tutorial to read images from mobile camera to show them in openCV in server and I'm with two problems: First is that for some reason the camera does not work into smartphone (using Vivaldi browser) . Second: when opening into computer's browser (also vivaldi) the node into WebSocket used to communicate with server send Base64 images but when I "rostopic echo /camera/image/compressed " in the server it shows 0-255 numbers that keep the same even if I block with thumb or release the camera. I suspect that is the cause of OpenCV visualizer crash opening in the subscriber into the server. I would like some help to these two problems that I suspect that are related, reason why I publish in same question. Want to understand better what is happening here.

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answered 2020-07-08 15:55:42 -0600

サイトダニエロ gravatar image

I figured it out and I think this should be better explained, one parameter was missing in the subscriber in the server, image_sub_ = it_.subscribe("/camera/image", 1, &ImageConverter::imageCb, this, image_transport::TransportHints("compressed")); which this part: image_transport::TransportHints("compressed") is important to make they both (publisher and subscriber) interact with compressed image. I was trying to figure out the problem and messed up the code which I managed to go back to what is in the tutorial, more or less. There is a problem in the tutorial of publishing image with RosLibJs because that method of get the camera is deprecated, as I could se, as well as the method of closing and releasing it.

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Lol, I've figured out and need more points to declare this my answer :c, but ok

サイトダニエロ gravatar image サイトダニエロ  ( 2020-08-06 12:55:39 -0600 )edit

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Asked: 2020-07-08 08:25:43 -0600

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Last updated: Jul 08 '20