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Displaying video with ffmpeg or opencv works, but I get a lot of messages

martinpi

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I display the video from the camera with one of these methods.

Code:
import cv2

cap = cv2.VideoCapture("udp://@0.0.0.0:11111")

while(True):
    # Capture frame-by-frame
    ret, frame = cap.read()
    if(ret):
        cv2.imshow('Tello Video',frame)
    if cv2.waitKey(1) == ord('q'):
        break

cap.release()
cv.destroyAllWindows()

or by letting FFmpeg do the job

Code:
oscommand FFmpeg -i udp://192.168.10.1:11111 -f sdl "Tello Video"

Both work, but I get lots of messages looking like this:

ffmpeg_cv2_messages.jpg

I would like to get rid of them by
a) finding some settings so that the errors don't occur (preferred) or
b) somehow suppressing or redirecting the messages

I tried adding an error handler with the with cv.redirectError(handleError) but it didn't help. Any ideas?
 

cumulus

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You will get these messages for every frame until the decoder sees a key frame.
Configure the Tello camera to send key frames in regular intervals.
 

martinpi

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New answers raise new questions.

How do I configure the Tello Camera?
As far as I understand, using the SDK you cannot do much about it.

The other way round, is there a possibility to increase some sort of timeout in opencv?
 

robagar

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As far as I can tell, these messages are from the h264 decoder code in the libav library, not opencv itself. I haven't found any way to disable them yet, but they seem to be harmless
 

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