Closed dejongyeong closed 4 years ago
Hello @dejongyeong. I'm going to quote here a bit of extra info you sent me privately by email (please keep the conversations on this repository so other authors and users can help, and maybe the outcomes of this conversation may be useful for others):
I also tried executing the command: rosrun image_view image_view image:=/camera/image_raw camera:=/camera, it gave an error of "Segmentation fault (core dumped)". I would like to know how could I fix this issue?
I would also like to inquire about the buffer queue size. I noticed that there is a delay/lag in the image view (through rviz) when I walk in-front of the camera. Does the delayed or lagged due to the buffer queue size?
Seems like the image_view
node is crashing. Which is not a problem of this driver (I would think). You could get more information about why it's crashing by running image_view
in gdb.
But I'd first check what kind of images you are getting. Maybe there is something wrong in the image in the interpretation of image_view
.
I propose to just do a
rostopic echo /camera/image_raw -n 1 > one_image.txt
And check that the header makes sense, probably upload here the file as an attachment so we can see if we find anything that looks obviously wrong.
I also see you are able to see the images in Rviz, this may mean that the Rviz code is more lenient, or better implemented, to deal with some issue of the format of the images you are receiving. You could also try rqt_image_view
as I believe has yet another implementation.
About the buffer queue size, if you set it to 1 you will have no delay, but if there are issues related to not being able to process it fast enough at some side of the computation you may be losing frames. The buffer itself should only delay if there is another issue that's making that delay happen.
About the delay in the rtsp stream, there was this other issue: https://github.com/ros-drivers/video_stream_opencv/issues/56 where they reported the same behaviour. I personally didn't see any noticeable difference when I tried it many years ago with a local networked camera (compared to a native driver that existed for that camera), but it may have had a different compression type.
You should also test at which rate your image topic is publishing (rostopiz hz /camera/image_raw
).
You could also check if the latency comes from your network configuration itself.
You could try other drivers for rtsp, a quick search gave me:
I personally would try to see what happens with plain gstreamer
to get the stream. If it has better results than this driver, try gscam
with the configuration line you used for gstreamer
. If it doesn't work or you get the same results, maybe checking ros_rtsp
is worth it.
Be warned that if you look for another solution different of a Gstreamer
or a OpenCV
backend... You'll probably find ffmpeg
but OpenCV
is actually using ffmpeg
so I doubt you'll get any benefits. On a side note... there is some way to make OpenCV backend to use Gstreamer... but I never made it work, but that was at least 5 or 6 years ago.
Good luck!
Hi @awesomebytes. Thanks for quick response.
Here is the header of the first image of /camera/image_raw topic. It works on rqt_image_view
but not in image_view
. The video encoding of the employed camera is H.264.
The rate of the image topic is published at average rate of 25Hz.
I am using an external IP Camera and is there any difference using camera.launch
and rtsp_stream.launch
?
I am not sure about the latency from my network configuration but I will have to look into it in future as this is vital for large heavy autonomous vehicles.
Thanks for the pointers and helps.
In your screenshot I can guess you are in a virtualbox environment. Inside of it you must be running this package. Via opencv (and I think ffmpeg in the background) will be decoding the h264 stream.
Maybe the decoding is being slower cause of being inside of the virtual machine. I'm not an expert but the virtual machine may also not be having access to the GPU if it was to maybe provide any acceleration on that decoding (I'm not sure if that's the case). Every time I ran ROS in a virtual machine it was way slower.
Using Docker (using '--network host' to make your life easier with the networking stuff) you could try it with better performance.
If you try to run this package natively on your machine you may get better results almost for sure. If you just want to check if it works, and you haven't used docker before, maybe using a live-cd of Ubuntu and just installing ROS and this package on it for the sake of testing will give you an idea too. I recommend the Unetbootin software to write Ubuntu 18.04 on a USB stick for this test.
On the image_view issue... No idea, if it works on rqt_image_view and on rviz, I wouldn't care more about it.
The different launchfiles provided are just examples for you to modify for your needs. You probably wanna base it on the rtsp one.
Good luck!
On Sun, Apr 26, 2020, 23:17 De Jong Yeong notifications@github.com wrote:
Hi @awesomebytes https://github.com/awesomebytes. Thanks for quick response.
Here is the header of the first image of /camera/image_raw topic. It works on rqt_image_view but not in image_view. The video encoding of the employed camera is H.264.
[image: image] https://user-images.githubusercontent.com/22542203/80308468-28bdf200-87c7-11ea-8cd9-24100bdac1fa.png
The rate of the image topic is published at average rate of 25Hz. I am using an external IP Camera and is there any difference using camera.launch and rtsp_stream.launch?
I am not sure about the latency from my network configuration but I will have to look into it in future as this is vital for large heavy autonomous vehicles.
Thanks for the pointers and helps.
— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub https://github.com/ros-drivers/video_stream_opencv/issues/64#issuecomment-619548286, or unsubscribe https://github.com/notifications/unsubscribe-auth/AANEK5CCMECHGBBUDADNKOLROQYADANCNFSM4MRACMIQ .
Yes. I am running Ubuntu 18.04 on a virtualbox environemt (using Windows 10 at moment).
I used Docker before but not really familiar with it. But I will look into it in the future. Thanks for the guidance and pointers.
Take care.
Error occurs when the visualization is set to TRUE. How could I resolve this? Thanks for the help.
I'm using ROS Melodic with Python 3 and OpenCV2 vers. 3.2.0.