Intel® Distribution of OpenVINO™ Toolkit
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stream_infer example

idata
Community Manager
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Does the stream_infer example works on the integrated webcam of a laptop because i cant get it to work..

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8 Replies
idata
Community Manager
238 Views

Hi @GoldenWings,

 

stream_infer does work on integrated webcams as long as its a video for linux device. Also, if you are running it on Raspberry Pi you will need to change one line of code, the exact line is commented in stream_infer.py. Finally, you need to have these gstreamer packages installed (they might not all be mandatory, but when you install all of them it runs):

 

gstreamer1.0-libav

 

gstreamer1.0-plugins-bad-faad

 

gstreamer1.0-plugins-bad-videoparsers

 

Neal

idata
Community Manager
238 Views

@neal_at_intel Thank you for your reply,

 

Actually i've all these packages installed on ubuntu in my VM

 

and still not works it hangs, please take a look at this screenshot.

8XbdHlx.png

 

idata
Community Manager
238 Views

@GoldenWings, I didn't realize you were running withing a VM. The screen shot looks similar to the issue of missing gstreamer packages, but must be something else if you have those installed. Does the built in cheese application work in the vm? If cheese works then the next thing I'd try to to is verify that gstreamer in general works in the VM and then that gstreamer works with the webcam as the video source.

 

Neal

idata
Community Manager
238 Views

@neal_at_intel

 

Yes cheese works in the vm also i've tried the following code using open cv and it works

 

import numpy as np import cv2 cap = cv2.VideoCapture(0) while(True): # Capture frame-by-frame ret, frame = cap.read() # Our operations on the frame come here gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY) # Display the resulting frame cv2.imshow('frame',gray) if cv2.waitKey(1) & 0xFF == ord('q'): break # When everything done, release the capture cap.release() cv2.destroyAllWindows()
idata
Community Manager
238 Views

@neal_at_intel how would i verify if gstreamer works?

idata
Community Manager
238 Views

@GoldenWings,

 

To start, see if you can play video files with gst-launch program. You can find some sample command lines here: https://gstreamer.freedesktop.org/documentation/frequently-asked-questions/using.html.

 

Then you can also check that you can stream the v4l2src camera device /dev/video0 . This page has some good sample commandlines for that: https://petehouston.com/2015/12/23/play-webcam-using-gstreamer/

idata
Community Manager
238 Views

Thanks,

 

I am having a problem when trying to stream v4l2src from the example you provided:

 

> Setting pipeline to PAUSED …

 

 

ERROR: Pipeline doesn't want to pause. ERROR: from element /GstPipeline:pipeline0/GstXvImageSink:xvimagesink0: Could not initialise Xv output Additional debug info: xvimagesink.c(1760): gst_xv_image_sink_open (): /GstPipeline:pipeline0/GstXvImageSink:xvimagesink0: No Xv Port available Setting pipeline to NULL ... Freeing pipeline ...

 

idata
Community Manager
238 Views

Hi GoldenWings, I had the exact same problem as you with the same setup. I did end up getting stream_infer.py working in a VM.

 

I think it comes down to the fact that in the VM Xv does not find any adapters present. You can verify this by checking xvinfo. This is what I see:

 

[~]$ xvinfo X-Video Extension version 2.2 screen #0 no adaptors present

 

So this makes me think the video sink xvimagesink will not work in our situation. Ok cool let's use ximagesink instead. For ximagesink to understand what is coming out of the source it needs to pass through videoconvert (I am not sure why, I actually have no idea how gstreamer works, but this is what I have pieced together from various forums posts and stack overflow answers).

 

You can test this by trying:

 

$ gst-launch-1.0 v4l2src ! videoconvert ! ximagesink

 

It should launch a window which displays the output of your webcam.

 

Great!

 

So now you need to modify the Python script stream_infer.py to use the new parameters.

 

I changed the value for SINK_NAME as well as for the view_launch_str as per below:

 

... SINK_NAME="ximagesink" # use for x86-64 platforms ... ... view_launch_str = "\ queue max-size-buffers=2 leaky=downstream ! videoconvert ! \ %s name=%s" % (SINK_NAME, GST_VIEW_NAME) ...

 

I can then run python3 stream_infer.py and I am able to launch the webcam view and begin detecting objects :)

 

I hope this helps, good luck.

 

d.

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