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Web server image stream... rather slow?
Christian Reese from United States  [2 posts]
3 years
I've run into a bit of a dilemma... We have some webcams on our FRC robot which we're using for vision processing with our on-board laptop. All that runs well and good and gives a good speed of around 15 - 30 FPS. So once the vision program finishes it draws a box around whatever it finds and sends it the image stream off from the Web Server. We can get an image feed from our driver station laptop (we've tried Firefox directly and VLC player). The problem is... this feed is slow and choppy, when viewing from either program. I looked at the bandwidth usage and it is hovering around 1 Mbps, so that can't be an issue. Even after dropping the cam resolution to 320x240, it is still just as slow. We've accessed axis webcams at this resolution using MJPEG and have gotten much better performance. So could the problem be when the webserver is broadcasting via the network? Is there anything we can do to profile performance at that end?

Anyone have some advice about this? Or do we need to switch to axis cameras to get our image feeds?

Thanks

Christian Reese
Lead Programmer FRC Team 2077
Steven Gentner from United States  [1370 posts] 3 years
If you run a browser ON the robot's machine do you see the same choppy results? That would eliminate any issues that the network may be causing.

Another option is to try reducing the image quality in the Options->Webserver tab and see if that makes any difference. If these items do help then you have a network problem ... if they don't help then it is probably something with the robot machine. In that case, what's the CPU utilization on that box?

STeven.
Christian Reese from United States  [2 posts] 3 years
Our problem seems to be fixed. We switched from a Logitech c250 webcam to a Genius Widecam, and the frame rate is perfect. Perhaps something about the Logitech c250 is incompatible with RoboRealm. I also changed it to low quality in the web server settings, so I'll change that back to HQ to make sure that isn't a factor.
Steven Gentner from United States  [1370 posts] 3 years
Christian,

Most likely the problem is one of lighting ... some webcams will reduce their frame rate when not enough light is present. This is very common. You can test this by pointing the camera directly at a light bulb and then covering it with your hand to see the fps change.

As far as we know all Logitech cameras work just fine with RR.

STeven.

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